Low-temperature ball valve with valve seat pre-tightening force self-compensation structure

Abstract

The low-temperature ball valve with the valve seat pretightening force self-compensation structure comprises a valve body, a ball body and a valve seat assembly are arranged in the valve body, the valve seat assembly is in matched contact with the ball body through a sealing face, the valve seat assembly comprises a valve seat, a fixator, a wedge-shaped ring, a Z-shaped sleeve and an elastic element, one end of the elastic element is connected with the valve body, and the other end of the elastic element is connected with the valve body. One end of the ball body is connected with the valve seat, the other end of the ball body is connected with the Z-shaped sleeve, a wedge-shaped ring is arranged in the Z-shaped sleeve, a second inclined face of the wedge-shaped ring is attached to a first inclined face of the fixing device, the valve seat is installed on the fixing device and attached to the ball body in a sealed mode, and the wedge-shaped ring is made of low-temperature-resistant non-metal materials. According to the low-temperature ball valve, the wedge-shaped ring shrinks in the radial direction under the action of thermal stress and the inclined face and slides along the inclined face, then the outer step face of the Z-shaped sleeve is driven to move towards the elastic element and compress the elastic element, and it is guaranteed that enough pre-tightening force is kept between the ball body and the valve seat in the low-temperature environment.

Description

Technical Field

[0001] The present invention relates to the technical field of ball valves, and in particular to a cryogenic ball valve with a valve seat pre-tightening force self-compensation structure. Background Art

[0002] With the rapid development of the petroleum, chemical and gas industries, especially the widespread application of liquefied natural gas (LNG) as an emerging energy source, the demand for ultra-low temperature ball valves with good sealing performance, low flow resistance and fast opening and closing has increased rapidly.

[0003] The core components of a cryogenic ball valve are a precision-machined ball and valve seat. These are typically made of stainless steel or high-strength, cryogenic-resistant materials. Currently, an elastic element is commonly installed behind the valve seat to prevent unstable sealing due to spring degradation after long-term use. Chinese patent application number 202421793004.5 discloses a multi-seal, compensated cryogenic-resistant ball valve comprising a ball sealing seat, a ball compensating seal assembly, and a valve ball. The ball sealing seat is fixedly mounted on the ball valve body, and the ball compensating seal assembly is mounted on the ball sealing seat. The ball compensating seal assembly is in close contact with the surface of the valve ball. This solution can enhance elasticity and extend spring life by adjusting the spring position, thereby reducing replacement frequency. However, this invention requires manual adjustment of the spring compression and cannot achieve automatic compensation of the spring force at low temperatures. Furthermore, the spring adjustment device is set through the valve body, which increases the leakage channel of the valve body and the risk of leakage.

[0004] The ball valve uses the pre-tightening force of the elastic element to achieve the initial sealing of the valve under low pressure. In ultra-low temperature environment, the shrinkage of the material will cause the compression of the elastic element to decrease, which in turn leads to a decrease in the pre-tightening force of the valve seat. Ultimately, the valve sealing surface will leak due to insufficient pre-tightening force.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The problem solved by the present invention is that the initial sealing performance of the valve seat is poor due to insufficient pre-tightening sealing force of the valve seat in a ball valve under ultra-low temperature environment.

[0007] To solve the above problems, the present invention provides a low-temperature ball valve with a valve seat preload self-compensation structure, comprising a valve body, a ball and a valve seat assembly arranged in the valve body, the valve seat assembly and the ball being in contact through a sealing surface, the valve seat assembly comprising a valve seat, a retainer, a wedge ring, a Z-shaped sleeve, and an elastic element, one end of the elastic element being connected to the valve body, and the other end being connected to the Z-shaped sleeve, a wedge ring being arranged in the Z-shaped sleeve, the second inclined surface of the wedge ring being in contact with the first inclined surface of the retainer, the valve seat being mounted on the retainer and in contact and sealing with the ball, and the material of the wedge ring being a low-temperature resistant non-metallic material.

[0008] The present application utilizes the difference in linear expansion coefficients between non-metallic materials and metallic materials. By matching a wedge ring made of non-metallic material with a retainer made of metallic material through an inclined surface, the radial contraction of the second inclined surface of the wedge ring at a temperature of -196°C is greater than the radial contraction of the first inclined surface of the retainer. Under the action of thermal stress, the second inclined surface slides inward along the first inclined surface, thereby causing the wedge ring to drive the Z-shaped sleeve to compress the elastic element, automatically compensating for the compression of the elastic element, and solving the problem of the compression of the elastic element being reduced due to the shrinkage of the materials of various valve parts at low temperatures, thereby ensuring that the pre-tightening sealing force of the sealing surface formed between the ball and the valve seat will be maintained without decreasing.

[0009] Preferably, the first bevel of the retainer and the second bevel of the wedge ring have inclination angles α and θ, respectively, where 25° ≤ α = θ ≤ 45°. This arrangement ensures a high conversion rate of shrinkage energy at low temperatures, converting small radial contraction into large axial displacement, effectively resolving the problem of rapid preload attenuation at low temperatures. It also reduces peak contact stress, preventing wedge ring failure.

[0010] Preferably, the wedge ring is made of PCTFE, RPTFE or PEEK, and the fixer is made of metal.

[0011] Preferably, the valve seat assembly further comprises a universal seal ring, the end face of the universal seal ring abuts against the third step surface of the holder (32), the inner side of the universal seal ring is in close contact with the first outer cylindrical surface of the holder, and the outer side of the universal seal ring is in close contact with the inner hole of the valve body. This arrangement can compensate for the increase in the gap between the valve body and the holder due to the difference in material shrinkage, and can adaptively seal the micron-level gap change between the valve body and the holder. A rectangular groove is provided on the inner hole side of the holder to facilitate the installation and matching of the ball and the valve seat assembly.

[0012] Preferably, the valve body includes a first step surface and a second step surface, the second step surface is arranged lower than the first step surface, the first step surface is used to abut against the elastic element, the second step surface is located on the side of the Z-shaped sleeve away from the holder and there is a gap L between the second step surface and the Z-shaped sleeve, and the maximum compression amount of the elastic element is δ max , where L>δ max .

[0013] This setting provides a buffer space for the Z-shaped sleeve, so that the Z-shaped sleeve will not directly hit the second step surface when the elastic element is compressed, ensuring that the elastic element has sufficient compression. At the same time, it reduces the impact force, vibration and noise between moving parts and improves the smoothness of operation.

[0014] Preferably, the wedge ring is mounted on the inner step surface of the Z-shaped sleeve, with the second outer cylindrical surface of the wedge ring and the first inner cylindrical surface of the Z-shaped sleeve forming an interference fit. This arrangement ensures that the two will not become loose relative to each other. Furthermore, the wedge ring experiences significantly greater radial contraction than the Z-shaped sleeve at -196°C, converting 100% of this contraction difference into axial thrust, achieving zero-loss transmission of low-temperature contraction force.

[0015] Preferably, one side of the wedge-shaped ring forms a vertical second end surface for contacting the inner stepped surface of the Z-shaped sleeve. The other side of the wedge-shaped ring gradually expands outward, and its inner wall forms a second inclined surface for contacting the first inclined surface of the holder. The second outer cylindrical surface of the wedge-shaped ring is provided with multiple equally spaced outer exhaust grooves. This arrangement ensures that air between the two can be promptly exhausted during assembly with the Z-shaped sleeve.

[0016] Preferably, the second inclined surface is provided with a plurality of inner exhaust grooves arranged at equal intervals, and the inner exhaust grooves are located at positions corresponding to the outer exhaust grooves. This arrangement can promptly discharge the medium between the wedge ring and the retainer, avoid the formation of a vacuum area, and ensure that the wedge ring can slide smoothly along the first inclined surface.

[0017] Preferably, the Z-shaped sleeve has a left end face adjacent to the second step surface, the left end face is parallel to the second step surface and there is a gap between the two, the Z-shaped sleeve has an outer step surface corresponding to the first step surface, for assembling the elastic element, the Z-shaped sleeve forms a right end face arranged vertically at one end close to the fixer, the right end face is arranged back to back with the outer step surface, the Z-shaped sleeve also includes an inner step surface arranged back to back with the left end face, for abutting against the second end face of the wedge ring.

[0018] This setting makes the outer step surface contact with the elastic element, while the wedge ring installed on the inner step surface contacts the retainer. The axial dimension of the Z-type sleeve shrinks at low temperatures, causing the right end face to move toward the elastic element, which can produce the effect of simultaneously compressing the elastic element and pushing the valve seat toward the ball through the wedge ring, compensating for the pre-tightening sealing force between the valve seat and the ball at low temperatures, and solving the problem of reduced pre-tightening force of the elastic element due to shrinkage of materials of various valve parts at low temperatures.

[0019] Preferably, the cryogenic ball valve with a valve seat preload self-compensation structure also includes a valve cover, a valve stem, and an actuator. The valve cover is pressed onto the valve body, and the lower end of the valve stem passes through the valve cover and is fixedly connected to the ball, for driving the ball to rotate to regulate the flow rate. The other end of the valve stem is connected to the actuator.

[0020] Compared with the prior art, the low-temperature ball valve with a valve seat preload self-compensation structure described in the embodiment of the present invention has the following beneficial effects: 1) Since the radial contraction of the second inclined surface of the wedge ring, a non-metallic part, in an ultra-low temperature environment of -196°C is much greater than that of the metal retainer, the wedge ring radially contracts and slides along the inclined surface under the action of thermal stress and the inclined surface, thereby driving the outer step surface of the Z-type sleeve to move toward the elastic element, thereby causing the elastic element to be compressed, ensuring that sufficient preload is maintained between the ball and the valve seat; 2) The Z-type sleeve compresses the elastic element after the axial dimension shrinks, and at the same time, the wedge ring inclined surface effect drives the Z-type sleeve to compress the elastic element, thereby improving the valve seat sealing ability of the ball valve at low temperatures; 3) By providing an inner exhaust groove, the medium between the wedge ring and the retainer can be discharged in time to avoid the formation of a vacuum area and ensure that the wedge ring can slide smoothly along the inclined surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is an overall schematic diagram of a cryogenic ball valve with a valve seat preload self-compensation structure according to an embodiment of the present invention;

[0022] Figure 2 is a cross-sectional schematic diagram of the valve seat assembly according to an embodiment of the present invention;

[0023] Figure 3 Schematic cross-sectional view of the Z-shaped sleeve according to an embodiment of the present invention;

[0024] Figure 4 Schematic diagram of the compression process of the elastic element at low temperature according to an embodiment of the present invention;

[0025] Figure 5 Schematic cross-sectional view of the wedge ring according to an embodiment of the present invention;

[0026] Figure 6 This is the overall appearance of the wedge ring described in an embodiment of the present invention.

[0027] Description of reference numerals:

[0028] 1-valve body; 11-first step surface; 12-second step surface; 13-inner hole; 2-sphere; 3-valve seat assembly; 31-valve seat; 32-retainer; 321-rectangular groove; 322-first end face; 323-first inclined surface; 324-first outer cylindrical surface; 325-third step surface; 33-pan-seal ring; 34-wedge ring; 341-second inclined surface; 342-second end face; 343-outer exhaust groove; 344-inner exhaust groove; 345-second outer cylindrical surface; 35-Z-type sleeve; 351-outer step surface; 352-inner step surface; 353-left end face; 354-right end face; 355-first inner cylindrical surface; 36-elastic element; 4-valve cover; 5-valve stem; 6-actuator. DETAILED DESCRIPTION

[0029] To make the above-mentioned objects, features and advantages of the present invention more clearly understood, the following detailed description of the specific embodiments of the present invention is made in conjunction with the accompanying drawings. The technical features of the embodiments of the present invention can be combined with each other without conflict.

[0030] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative uses of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0031] Ultra-low-temperature ball valves feature excellent sealing, high reliability, low fluid resistance, long life, and rapid switching. They are widely used for regulating and controlling liquid cryogenic media such as liquid oxygen, liquid hydrogen, and liquefied natural gas. Currently, the minimum temperature requirement for liquefied natural gas is -163°C, while the minimum temperature requirement for liquid nitrogen applications is -196°C, placing even higher demands on the sealing performance of ball valves. Existing cryogenic ball valves operate at low temperatures, especially at -196°C, as the dimensions of various components shrink, reducing the compression of the elastic element. Because the preload sealing force between the ball and the valve seat is generated entirely by the elastic element, the preload sealing force between the ball and the valve seat decreases as the compression of the elastic element decreases, directly leading to a poorer sealing effect on the sealing surface and a greater risk of leakage. To this end, Chinese patent application number CN201710020776.3 discloses a cryogenic ball valve. While the synergistic effect of an inverted tapered ball seal ring structure and a dynamic pressure seal device can significantly improve the sealing level of the ball valve, the overall structure is relatively complex and cannot achieve automatic compensation of elastic preload at ultra-low temperatures. To this end, the applicant proposes the following technical solution:

[0032] like Figure 1-6As shown, a low-temperature ball valve with a valve seat preload self-compensation structure includes a valve body 1, a ball 2, and a valve seat assembly 3. The ball 2 and the valve seat assembly 3 are arranged in the valve body 1. The valve seat assembly 3 is in contact with the ball 2 through a sealing surface. The valve seat assembly 3 includes a valve seat 31, a retainer 32, a wedge ring 34, a Z-shaped sleeve 35, and an elastic element 36. One end of the elastic element 36 is connected to the valve body 1, and the other end is connected to the Z-shaped sleeve 35. A wedge ring 34 is arranged in the Z-shaped sleeve 35, and the second inclined surface 341 of the wedge ring 34 is in contact with the first inclined surface 323 of the retainer 32. The valve seat 31 is installed on the retainer 32 and is in contact with the ball 2. The materials of the wedge ring 34 and the retainer 32 are respectively non-metallic material resistant to -196°C and austenitic stainless steel material resistant to -196°C.

[0033] The present invention utilizes the property that the linear expansion coefficient of non-metallic materials is much greater than that of metallic materials. By using a wedge ring 34 made of non-metallic material and a retainer 32 made of metallic material, the beveled surfaces mate together, causing the radial contraction of the second beveled surface 341 of the wedge ring 34 to be greater than the radial contraction of the first beveled surface 323 of the retainer 32 at a temperature of -196°C. Under the action of thermal stress, the second beveled surface 341 slides inward along the first beveled surface 323, causing the wedge ring 34 to drive the Z-shaped sleeve 35 to compress the elastic element 36, compensating for the compression of the elastic element 36. This solves the problem of reduced compression of the elastic element 36 at low temperatures due to shrinkage of the valve components, ensuring that the preload sealing force of the sealing surface between the ball 2 and the valve seat 31 is maintained without reduction. As an example of the present invention, the wedge ring 34 and retainer 32 are made of PCTFE or RPTFE, PEEK, or 316 stainless steel, respectively.

[0034] As an example of the present invention, the first and second inclined surfaces 323 and 341 have the same inclination angle, ranging from 25° to 45°. This configuration ensures a high conversion rate of shrinkage energy at low temperatures, effectively resolving the issue of rapid preload attenuation. It also reduces peak contact stress, preventing failure of the wedge ring 34.

[0035] As an example of the present invention, the valve seat assembly 3 further includes a Variseal ring 33. The end surface of the Variseal ring 33 abuts against the third step surface 325 of the retainer 32. The inner side of the Variseal ring 33 seals against the first outer cylindrical surface 324 of the retainer 32, and the outer side of the Variseal ring 33 seals against the inner bore 13 of the valve body 1. This arrangement compensates for the increase in the gap between the valve body 1 and the retainer 32 due to material shrinkage differences, and provides an adaptive seal to micron-level variations in the gap between the valve body 1 and the retainer 32. As an example of the present invention, the inner and outer diameters of the Variseal ring 33, respectively matching the inner bore 13 of the valve body 1 and the first outer cylindrical surface 324 of the retainer 32, have a surface roughness of at least Ra 0.2. Preferably, the retainer 32 further includes a first end surface 322, which is positioned proximate to the right end surface 354. The first outer cylindrical surface 324 is disposed on the periphery of the retainer 32.

[0036] As an example of the present invention, the inner hole of the retainer 32 has a rectangular groove 321 , which can facilitate the assembly of the ball 2 and the valve seat assembly 3 .

[0037] As an example of the present invention, the valve body 1 includes a first step surface 11 and a second step surface 12, wherein the second step surface 12 is arranged lower than the first step surface 11, and the first step surface 11 is used to abut against the elastic element 36, and the second step surface 12 is located on the side of the Z-shaped sleeve 35 away from the holder 32 and there is a gap L between the second step surface 12 and the Z-shaped sleeve 35. The maximum compression amount of the elastic element 36 is δ max , where L>δ max This arrangement provides a buffer space for the Z-shaped sleeve 35. When the elastic element 36 is compressed, the Z-shaped sleeve 35 will not directly hit the second step surface 12, thereby reducing the impact force, vibration and noise between moving parts and improving the smoothness of operation.

[0038] Preferably, the wedge ring 34 is assembled on the inner stepped surface 352 of the Z-shaped sleeve 35, with the second outer cylindrical surface 345 of the wedge ring 34 and the first inner cylindrical surface 355 of the Z-shaped sleeve 35 forming an interference fit. This arrangement prevents relative looseness between the two. Furthermore, the radial shrinkage of the wedge ring 34 at -196°C is significantly greater than that of the Z-shaped sleeve 35. The interference fit converts 100% of this shrinkage difference into axial thrust, achieving zero-loss transmission of low-temperature shrinkage force.

[0039] As an example of the present invention, one side of the wedge ring 34 forms a vertical second end surface 342 for contacting the inner stepped surface 352 of the Z-shaped sleeve 35. The other side of the wedge ring 34 gradually expands outward, and its inner wall forms a second inclined surface 341 for contacting the first inclined surface 323 of the retainer 32. The second outer cylindrical surface 345 of the wedge ring 34 is provided with multiple equally spaced outer exhaust grooves 343. This arrangement ensures that air between the Z-shaped sleeve 35 and the wedge ring 34 can be promptly exhausted during assembly.

[0040] Preferably, the second inclined surface 341 is provided with a plurality of inner exhaust grooves 344 arranged at equal intervals, and the inner exhaust grooves 344 are provided at positions corresponding to the outer exhaust grooves 343. This arrangement can timely discharge the medium between the wedge ring 34 and the holder 32, ensuring that the wedge ring 34 can slide smoothly along the first inclined surface 323.

[0041] As an example of the present invention, the Z-shaped sleeve 35 has a left end face 353 adjacent to the second step surface 12, the left end face 353 is parallel to the second step surface 12 and there is a gap between the two, the Z-shaped sleeve 35 has an outer step surface 351 corresponding to the first step surface 11, for assembling the elastic element 36, the Z-shaped sleeve 35 forms a right end face 354 arranged vertically at one end close to the fixer 32, the right end face 354 is arranged in back to back with the outer step surface 351, and the Z-shaped sleeve 35 also includes an inner step surface 352 arranged in back to back with the left end face 353, for abutting against the second end face 342 of the wedge ring 34.

[0042] This arrangement makes the outer step surface 351 contact with the elastic element 36, and the wedge ring 34 installed on the inner step surface 352 contacts the retainer 32. The axial dimension of the Z-type sleeve 35 shrinks at low temperatures, causing the right end surface 354 to move toward the elastic element 36, which can produce the effect of simultaneously compressing the elastic element 36 and pushing the valve seat 31 toward the ball 2 through the wedge ring 34, compensating for the pre-tightening sealing force between the valve seat 31 and the ball 2 at low temperatures, and solving the problem of the reduction of the pre-tightening force of the elastic element 36 due to the shrinkage of the materials of various valve parts at low temperatures; it effectively ensures that the Z-type sleeve 35 compresses the elastic element 36 after the axial dimension shrinks, and at the same time drives the Z-type sleeve 35 to compress the elastic element 36 through the second inclined surface 341 of the wedge ring 34, thereby compensating for the pre-tightening sealing force between the ball 2 and the valve seat 31 at low temperatures, and improving the sealing ability of the valve seat 31 of the ball valve at low temperatures.

[0043] Preferably, the outer step surface 351 is compressed toward the elastic element 36 by a distance A at low temperatures, and the elastic element 36 is reduced in compression by a distance X at low temperatures, with A ≥ X. Simultaneously, when the Z-shaped sleeve 35 contracts axially due to the low temperature environment, the outer step surface 351 of the Z-shaped sleeve 35 moves a greater distance in the longitudinal direction of the elastic element 36, compensating for the elastic loss through rigid displacement, allowing the sealing preload force between the ball 2 and the valve seat 31 to be 100% restored to the normal temperature design value or even greater.

[0044] As an example of the present invention, the cryogenic ball valve with a valve seat preload self-compensation structure also includes a valve cover 4, a valve stem 5, and an actuator 6. The valve cover 4 is pressed onto the valve body 1. The lower end of the valve stem 5 passes through the valve cover 4 and is fixedly connected to the ball 2, which is used to drive the ball 2 to rotate to regulate the flow rate. The other end of the valve stem 5 is connected to the actuator 6.

[0045] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the scope defined by the claims.

Claims

1. A cryogenic ball valve with a valve seat preload self-compensation structure, comprising a valve body (1), a ball (2) and a valve seat assembly (3) disposed within the valve body (1), the valve seat assembly (3) being in contact with the ball (2) via a sealing surface, characterized in that: The valve seat assembly (3) includes a valve seat (31), a retainer (32), a wedge ring (34), a Z-shaped sleeve (35), and an elastic element (36). One end of the elastic element (36) is connected to the valve body (1), and the other end is connected to the Z-shaped sleeve (35). A wedge ring (34) is arranged in the Z-shaped sleeve (35). The second inclined surface (341) of the wedge ring (34) is in contact with the first inclined surface (323) of the retainer (32). The valve seat (31) is installed on the retainer (32) and is in contact and sealed with the sphere (2). The material of the wedge ring (34) is a low-temperature resistant non-metallic material.

2. The cryogenic ball valve with a valve seat preload self-compensation structure according to claim 1, characterized in that: The inclination angles of the first inclined surface (323) of the fixer (32) and the second inclined surface (341) of the wedge ring (34) are α and θ respectively, wherein 25°≤α=θ≤45°.

3. The cryogenic ball valve with a valve seat preload self-compensation structure according to claim 1, characterized in that: The material of the wedge ring (34) is PCTFE, RPTFE or PEEK, and the material of the fixer (32) is metal.

4. The cryogenic ball valve with a valve seat preload self-compensation structure according to claim 1, characterized in that: The valve seat assembly (3) further includes a universal seal ring (33), the end face of the universal seal ring (33) abuts against the third step surface (325) of the holder (32), the inner side of the universal seal ring (33) is in close contact with the first outer cylindrical surface (324) of the holder (32), the outer side of the universal seal ring (33) is in close contact with the inner hole (13) of the valve body (1), and the inner hole of the holder (32) is provided with a rectangular groove (321).

5. The cryogenic ball valve with a valve seat preload self-compensation structure according to claim 1, characterized in that: The valve body (1) comprises a first step surface (11) and a second step surface (12), wherein the second step surface (12) is arranged lower than the first step surface (11), the first step surface (11) is used to abut against the elastic element (36), the second step surface (12) is located on a side of the Z-shaped sleeve (35) away from the holder (32) and there is a gap L between the second step surface (12) and the Z-shaped sleeve (35), and the maximum compression amount of the elastic element (36) is δ max , where L>δ max .

6. The cryogenic ball valve with a valve seat preload self-compensation structure according to claim 5, characterized in that: The wedge ring (34) is assembled on the inner step surface (352) of the Z-shaped sleeve (35), and the second outer cylindrical surface (345) of the wedge ring (34) and the first inner cylindrical surface (355) of the Z-shaped sleeve (35) are interference-fitted.

7. The cryogenic ball valve with a valve seat preload self-compensation structure according to claim 6, characterized in that: One side of the wedge ring (34) forms a vertical second end surface (342) for contacting the inner step surface (352) of the Z-shaped sleeve (35); the other side of the wedge ring (34) gradually expands outward and its inner wall forms a second inclined surface (341) for contacting the first inclined surface (323) of the holder (32); the second outer cylindrical surface (345) of the wedge ring (34) is provided with a plurality of outer exhaust grooves (343) arranged at equal intervals.

8. The cryogenic ball valve with a valve seat preload self-compensation structure according to claim 7, characterized in that: The second inclined surface (341) is provided with a plurality of inner exhaust grooves (344) arranged at equal intervals, and the inner exhaust grooves (344) are provided at positions corresponding to the outer exhaust grooves (343).

9. The cryogenic ball valve with a valve seat preload self-compensation structure according to claim 6, characterized in that: The Z-shaped sleeve (35) has a left end face (353) adjacent to the second step face (12), the left end face (353) is parallel to the second step face (12) and there is a gap between the two, the Z-shaped sleeve (35) has an outer step face (351) corresponding to the first step face (11) for assembling the elastic element (36), the Z-shaped sleeve (35) forms a right end face (354) arranged vertically at one end close to the fixer (32), the right end face (354) and the outer step face (351) are arranged in opposite directions, and the Z-shaped sleeve (35) also includes an inner step face (352) arranged in opposite directions to the left end face (353), for abutting against the second end face (342) of the wedge ring (34).

10. The cryogenic ball valve with a valve seat preload self-compensation structure according to any one of claims 1 to 9, characterized in that: The cryogenic ball valve with a valve seat preload self-compensation structure further comprises a valve cover (4), a valve stem (5), and an actuator (6); the valve cover (4) is press-fitted onto the valve body (1); the lower end of the valve stem (5) passes through the valve cover (4) and is fixedly connected to the ball (2) for driving the ball (2) to rotate to regulate flow; the other end of the valve stem (5) is connected to the actuator (6).

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