A series container type combined sealing structure

Abstract

The application discloses a series connection type combined sealing structure, which mainly solves the problems of easy wear and failure of a floating ring under high pressure and high speed, complex sealing structure and poor stability. The sealing structure comprises a shell (2), an axial high-low tooth labyrinth sealing ring (3), a floating ring sealing device (4), a sealing end cover (5) and three sealing rings. The high-low tooth labyrinth sealing ring is internally provided with alternately arranged rectangular sealing teeth, and is located at a high pressure side of a working condition. The floating ring sealing device is located at a low pressure side of the working condition. The two are fixed on the shell in series connection with the sealing end cover. One of the sealing rings is embedded in an axial end face mounting groove of the axial high-low tooth labyrinth sealing ring. The other two sealing rings are respectively embedded in mounting grooves of an inner circumference of the shell, so that multi-stage sealing of a working condition rotating shaft is realized. The application effectively reduces the pressure directly acting on the end face of the floating ring under high pressure and high speed, can automatically compensate eccentric run-out and axial run-out of the main shaft, has simple structure and low cost, and can be used for high-speed and high-pressure working condition equipment.

Description

Technical Field

[0001] This invention belongs to the field of mechanical component technology, and specifically relates to a combined sealing structure that can be used in equipment operating under conditions of high speed and high pressure differential rotation shaft. Background Technology

[0002] In rotating machinery such as centrifugal pumps, compressors, and speed reducers, sealing is crucial to prevent media leakage or the ingress of external impurities. Existing labyrinth seals primarily rely on the flow resistance created by the tortuous path for throttling, and are non-contact seals. While they have a long lifespan, their effectiveness is limited at low speeds. Traditional sealing technologies, due to their reliance on rigid material ring supports, require high precision machining of the main unit's sealing components, resulting in complex assembly and difficulty in preventing media leakage, especially under high-pressure and high-speed environments where their pressure resistance is insufficient. Furthermore, during startup, shutdown, or when the rotor exceeds its critical speed, the floating ring seal is prone to dry friction with the shaft, easily leading to ring burnout. Additionally, the use of a single floating ring makes it highly sensitive to upstream pressure fluctuations, thus easily causing unstable oscillations.

[0003] With industrial development, the requirements for the reliability, high-pressure resistance, and adaptability to complex working conditions of sealing components are constantly increasing, driving innovation in combined sealing technology. Combined seals, through the synergistic effect of multiple sealing elements, compensate for the shortcomings of single elements, becoming a key solution for improving system sealing performance. However, the auxiliary systems of combined seals are complex and bulky, and experience significant wear in contact with shafts or housings. Many researchers have proposed addressing issues such as wear and high leakage rates in combined seals by modifying the combined seal structure or using floating ring seals.

[0004] Patent document CN 223282542 U discloses a double-end-face brush-labyrinth combined seal structure, which combines a double-end-face brush seal and a labyrinth seal. A first brush filament bundle is designed between the front baffle and the middle baffle, and a second brush filament bundle is designed between the middle baffle and the rear baffle. While this structure, using a double-end-face brush seal ring, saves material and space compared to conventional two-stage tandem brush seals, and the throttling effect of the labyrinth seal provides auxiliary sealing, the brush seal portion generates additional heat compared to a purely non-contact seal. If the frictional heat cannot be dissipated in time, the lubricating oil may coke at the brush filaments, potentially damaging the seal.

[0005] Patent document CN103939607 B discloses an integrated shaft end sealing technology, which employs a two-stage combination structure of multiple floating ring seals and packing seals. This combined sealing structure requires the introduction of gas at a pressure higher than the working pressure inside the equipment housing to achieve sealing. Therefore, compared to purely non-contact labyrinth seals and improved floating ring seals with translational freedom, the contact friction between its packing assembly and the rotating shaft is more significant, which is detrimental to the miniaturization design and cost control of the equipment.

[0006] Patent document CN107084244 B discloses a combined sealing structure of a grate and a floating ring, which radially combines the floating ring and the grate, with the floating ring fitted radially outside the grate and the inner surface of the floating ring facing the tooth tip of the grate. However, this radial nesting allows the high-pressure medium to act directly on the grate and the floating ring, forcing the floating ring to withstand pressure fluctuations at the front end, which affects its stability and lifespan under high pressure and high pressure differential conditions.

[0007] Patent document CN 207687355 U discloses a combined sealing structure for an oilless screw compressor. It employs a discrete series structure of a spiral seal, a vent groove, and a labyrinth seal. In actual operation, this structure is highly dependent on an external high-pressure auxiliary air source. Fluctuations in the air source pressure can easily lead to media barrier failure, resulting in insufficient overall system reliability. Furthermore, its floating sealing unit uses only a single elastic plastic ring material, lacking an adaptive compensation mechanism for end face wear and spindle axial movement. It cannot provide real-time axial fit preload and struggles to maintain a stable sealing pressure under complex dynamic conditions.

[0008] In summary, although current combined sealing structures all adopt multi-stage structures and utilize the flow resistance generated when the fluid passes through each stage to achieve throttling and pressure reduction, the following problems still exist: First, the floating ring is prone to wear and failure under high pressure and high speed, resulting in poor system stability; second, the structure is redundant and complex, increasing installation costs. Summary of the Invention

[0009] The purpose of this invention is to address the shortcomings of the prior art by proposing a series-mounted combined sealing structure to reduce the working pressure on the floating ring end face under high-speed and high-pressure conditions, improve system stability, simplify system structure, and reduce installation costs.

[0010] To achieve the above objectives, the technical approach of this invention is as follows: an axial high-low tooth labyrinth sealing ring and a floating ring sealing device are connected in series and fixed on the housing; the labyrinth sealing ring on the high-pressure side at the left end is used for pre-pressure reduction, thereby reducing the working pressure on the end face of the floating ring; and the floating ring sealing mechanism provides an adaptive compensation structure to improve the stability of the system seal.

[0011] Based on the above ideas, the technical solution of the present invention is as follows:

[0012] A series-mounted combined sealing structure includes a housing 2, a floating ring sealing device 4 to the right of a high-low tooth labyrinth sealing ring 3, a sealing end cap 5, and a sealing ring 7. The high-low tooth labyrinth sealing ring 3 is located on the high-pressure side of the working condition, and the floating ring sealing device 4 is located on the low-pressure side of the working condition. The two are connected in series and fixed on the housing 2 to achieve multi-stage sealing of the rotating shaft.

[0013] Furthermore, the axial high and low tooth labyrinth sealing ring 3 is an integral structure with alternating peaks 31 and valleys 32 inside; multiple rectangular sealing teeth 34 and 33 are respectively provided on the peaks 31 and valleys 32, and the thickness of each sealing tooth is 0.2~0.8mm; these teeth are symmetrically spaced along the width direction of the peaks 31 and valleys 32, forming pressure-reducing cavities 35 of different sizes with the rotating shaft, which are used to form eddy current resistance between the tooth surfaces.

[0014] Furthermore, the floating ring sealing device includes a fixed base 42, a steel ring 43, a floating ring 44, a baffle 45, a wave spring 46, and a retaining ring 47; the left end face of the baffle 45 is in contact with the right end face of the floating ring 44; the floating ring 44 is suspended on the rotating shaft 1 and can float freely between the rotating shaft 1 and the fixed base 42; the steel ring 43 is assembled between the floating ring 44 and the fixed base 42 to limit the floating ring 44.

[0015] Furthermore, the floating ring 44 is made of graphite material with self-lubricating properties, and its radial clearance to the rotating shaft is δ2 = (0.1~1)d / 1000, its inner diameter is I1 = d + 2δ2, and its axial width is d2 = (0.2~0.3)d, where d is the diameter of the rotating shaft;

[0016] The thickness of the steel ring 43 is 1 / 2 to 2 / 3 of that of the floating ring 44;

[0017] The radial distance between the fixing seat 42 and the steel ring 43 is 0.5 mm to 1 mm.

[0018] Furthermore, the wave spring 46 is sleeved on the rotating shaft 1, with one end abutting against the retaining ring 47 and the other end abutting against the baffle 45, which is used to provide pressure to the floating ring 44 so that its end face is pressed against the fixed seat 42 to achieve side sealing.

[0019] Furthermore, both the baffle 45 and the fixed seat 42 are made of stainless steel with high strength and good thermal stability. The two form a metal hard seal by axial contact. While maintaining the axial flow interception state, the hard seal allows the baffle 45 and the floating ring 44 to have micron-level sliding freedom in the axial direction, so as to dynamically compensate for component size changes caused by thermal expansion.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] Firstly, this invention achieves a highly efficient multi-stage sealing effect by cascading a high-low tooth labyrinth sealing ring and a floating ring sealing device. The left-side high-low tooth labyrinth sealing ring not only provides a seal but also acts as a pressure buffer chamber, reducing the pressure directly acting on the floating ring sealing device and thus preventing leakage during startup and shutdown.

[0022] Secondly, this invention features a radial clearance of δ2 in the floating ring structure of the floating ring sealing device, allowing an oil film to form in the sealing gap. This reduces the temperature rise of the shaft under high-speed rotation and provides radial floating to automatically compensate for the eccentric runout of the main shaft. Simultaneously, the floating ring sealing device allows the baffle and floating ring to have micron-level sliding freedom in the axial direction. When the shaft experiences slight axial movement or end-face wear, the spring on the right side will push the baffle and floating ring forward in real time, ensuring that the metal hard seal interface and the side sealing end face always remain in contact. This achieves adaptive dynamic compensation for axial and end-face wear, improving the stability of the sealing system.

[0023] Thirdly, since the present invention fastens the sealing device to the housing to form a modular housing package, the combined sealing structure can be pre-tested, and there is no need to measure the sealing working length during installation and there will be no leakage problem during startup, which facilitates the disassembly, inspection and installation of the overall structure. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0025] Figure 2 This is a half-sectional view of the axial high and low tooth labyrinth sealing ring in this invention.

[0026] Figure 3 This is a half-sectional view of the floating ring sealing device in this invention.

[0027] Figure 4 This is an external view of the wave spring in this invention. Detailed Implementation

[0028] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments:

[0029] Reference Figure 1This invention relates to a series-mounted combined sealing structure, comprising a housing 2, an axial high-low toothed labyrinth sealing ring 3, a floating ring sealing device 4, a sealing end cap 5, a sealing end cap bolt 6, a first sealing ring 7, and a second sealing ring 8. The axial high-low toothed labyrinth sealing ring 3 is positioned near the high-pressure side of the working condition to reduce the pressure of the high-pressure medium, ensuring that the medium pressure reaching the right-side floating ring sealing device 4 is less than 0.5 MPa. The floating ring sealing device 4 is positioned near the low-pressure side of the working condition to further seal the sealing medium. The axial high-low toothed labyrinth sealing ring 3 and the floating ring sealing device 4 are series-fixed to the housing 2 by the sealing end cap bolt 6, forming a two-stage sealing structure to improve the reliability and stability of the seal. Furthermore, the axial high-low toothed labyrinth sealing ring 3 has an end face mounting groove on its axial contact end face near the floating ring sealing device 4, within which the second sealing ring 8 is embedded, achieving a static seal at the contact surface between the axial high-low toothed labyrinth sealing ring 3 and the floating ring sealing device 4. Two mounting grooves are correspondingly formed on the inner circumferential surface of the housing 2, and a first sealing ring 7 is embedded in each mounting groove to achieve static sealing between the housing 2 and the contact surfaces of the axial high and low tooth labyrinth sealing ring 3 and the floating ring sealing device 4, respectively. The sealing end cap 5 is installed on the right end of the floating ring sealing device 4 by the sealing end cap bolt 6 to achieve a packaged encapsulation of the entire sealing structure. In use, the entire sealing structure is axially fitted onto the rotating shaft 1 of the working condition, and the radial clearance δ1 from the innermost end of the axial high and low tooth labyrinth sealing ring 3 to the rotating shaft 1 is ensured to be 0.2~0.5mm, and the radial clearance δ2 from the inner circumferential surface of the floating ring sealing device 4 to the rotating shaft 1 is δ2=(0.1~1)d / 1000, where d is the diameter of the rotating shaft 1.

[0030] Reference Figure 2 The axial high-low tooth labyrinth sealing ring 3 is an integral structure comprising a peak 31 and a valley 32. The peak 31 has multiple rectangular sealing teeth 34 with a height of H1, satisfying H1 = (5~15)L1; the valley 32 has multiple rectangular sealing teeth 33 with a height of H2, satisfying H2 = H1 + (3~6), where L1 = (8~36)δ1 is the axial gap between the center lines of adjacent sealing teeth. The thickness of these sealing teeth is 0.2~0.8mm, and they are not evenly distributed; instead, the varying tooth heights create corresponding pressure-reducing cavities 35 of different sizes with the rotating shaft. When fluid enters each pressure-reducing cavity 35, the fluid velocity continuously decreases. Simultaneously, due to viscous forces, strong vortices are generated within the pressure-reducing cavity 35 to dissipate energy, thereby reducing pressure and achieving a sealing effect. This design of sealing teeth with varying heights is more conducive to forming vortices within the pressure-reducing cavity 35, resulting in better sealing performance.

[0031] The total number of the plurality of rectangular sealing teeth 34 with height H1 and the plurality of rectangular sealing teeth 33 with height H2 is... pass The calculation yields P. in P is the inlet pressure of the sealing medium entering the axial high and low tooth labyrinth seal ring. out For its export pressure and satisfying P out ≤0.5MPa, P1 is the static pressure of the cavity of the sealing tooth i = 1. To prevent cavitation caused by excessive instantaneous pressure difference when the front sealing tooth is subjected to the initial high pressure, its P1 satisfies P1≥2.85MPa.

[0032] refer to Figure 3 The floating ring sealing device 4 includes a fixed base 42, a steel ring 43, a floating ring 44, a baffle 45, a wave spring 46, and a retaining ring 47. Wherein:

[0033] The steel ring 43 is installed between the float ring 44 and the fixed seat 42 to limit the float ring 44.

[0034] The distance between the fixed seat 42 and the steel ring 43 in the radial dimension is 0.5~1mm to ensure that the floating ring 44 can float freely.

[0035] The inner diameter of the float ring 44 is I1 = d + 2δ2, and the axial width is L = (0.2~0.3)d; the total thickness of the float ring steel ring is C = (0.1~0.15)d, and the thickness B2 of the steel ring 43 is 1 / 2~2 / 3 of the thickness of the float ring 44, ensuring that the float ring 44 has sufficient mechanical strength to resist the radial compression of the high-pressure medium; the entire float ring is installed between the fixed seats 42 and suspended on the rotating shaft, and can float freely in the radial direction with a floating range of 0.02~0.08mm. When the float ring 44 is automatically aligned, a graphite material with good self-lubricating properties should be used to ensure a smooth contact surface between the float ring 44 and the fixed seat 42.

[0036] The baffle 45 is in close contact with the end face of the floating ring 44. Both the baffle 45 and the fixed seat 42 are made of stainless steel with high strength and good thermal stability. The two form a metal hard seal by axial contact. While maintaining the axial flow interception state, the hard seal allows the baffle 45 and the floating ring 44 to have micron-level sliding freedom in the axial direction, so as to dynamically compensate for component size changes caused by thermal expansion.

[0037] The wave spring 46 is sleeved on the rotating shaft 1, with one end abutting against the retaining ring 47 and the other end abutting against the baffle 45. It is used to provide pressure to the floating ring 44 so that its end face is pressed against the fixed seat 42 to achieve side sealing.

[0038] refer to Figure 4 The elastic force of the wave spring is , where p s The spring specific pressure can be selected from 0.15 to 0.3 MPa, where A is the effective contact area of ​​the end face. (I) 外 2 - I12 ), where I 外 Let I be the outer diameter of the floating ring, satisfying I 外 = I1 + B1.

[0039] The evaluation criteria for judging whether a seal is qualified in this invention adopts a dual quantitative constraint mechanism of pressure gradient interception and final stage laminar flow leakage, as described in detail below:

[0040] The first-level pressure gradient qualification is determined by an iterative formula. The calculation determines whether the residual static pressure at the front end of the right-side floating ring sealing device 4 after the fluid pressure reduction through the axial high-low tooth labyrinth sealing ring meets the requirement of ≤0.5MPa. If it does, the pressure reduction and buffering effect of the preceding axial high-low tooth labyrinth sealing ring 3 is deemed qualified. Where: i represents the number of throttling teeth; N represents the total number of throttling teeth, i.e., the total number of sealing teeth; P... i P is the pressure passing through the i-th tooth; out This refers to the pressure at the outlet of the axial high and low tooth labyrinth seal ring.

[0041] For the second-level leakage rate qualification, provided that the above pressure boundary is met, the leakage rate formula under laminar flow conditions is used for incompressible liquids. Calculate whether the final leakage can be controlled to less than 35 ml / h, where: d is the shaft diameter; δ2 is the radial clearance from the inner circumferential surface of the floating ring seal device to the rotating shaft; This refers to the pressure difference before and after the floating ring sealing end; is the dynamic viscosity of the sealing medium; L is the axial width and length of the float ring.

[0042] In use, the tandem cartridge-type combined sealing structure is fitted onto the outer circumference of the sealing shaft and rigidly fixed to the stationary housing of the equipment by bolts on the outer circumference of the housing.

[0043] The following are two specific examples of using the tandem cartridge-type combined sealing structure of the present invention:

[0044] Example 1: The sealing structure is used in a centrifugal compressor.

[0045] First, the parameters of the series-type combined seal structure are calculated based on the operating parameters of the centrifugal compressor.

[0046] The operating parameters of the centrifugal compressor include: the diameter d of the sealed shaft is 120 mm, and the inlet medium pressure P... in The pressure is 3MPa, the speed is 9000r / min, the working temperature is 65℃, and the sealing medium is hydraulic oil.

[0047] Based on the aforementioned operating parameters, the parameter settings for the structure in this example are as follows:

[0048] Assume the radial clearance δ1 between the axial high and low tooth labyrinth sealing ring 3 and the outer surface of the rotating shaft 1 is 0.5mm, and the radial clearance δ2 between the inner circumferential surface of the floating ring sealing device 4 and the rotating shaft 1 is 0.02mm;

[0049] Assume the axial gap L1 between the center lines of adjacent sealing teeth of the axial high and low tooth labyrinth sealing ring is 2mm, the height H1 of the rectangular sealing tooth 34 on its peak 31 is 10mm, the height H2 of the rectangular sealing tooth 33 on its valley 32 is 15mm, and the thickness of these sealing teeth is 0.2mm.

[0050] Assume the outlet pressure P under this operating condition out Given a static pressure P1 of 0.5 MPa for the cavity with sealing tooth i = 1 and a static pressure P1 of 2.85 MPa, the total number of rectangular sealing teeth 34 and 33 is calculated. ≥9.97, this example uses 11.

[0051] Assume that the inner diameter I1 of the float ring 44 in the float ring sealing device is 120.04 mm, and its axial width L is 25 mm; the total thickness C of the float ring 44 and the steel ring 43 is 10 mm; the thickness B1 of the float ring 44 is 6 mm; and the thickness B2 of the steel ring 43 is 4 mm.

[0052] Let the elastic force of the wave spring be... In this operating condition, the spring specific pressure p s Choosing 0.2 MPa, the calculated elastic force is 194.43 N; in this example, 200 N is used. During unit startup or sudden surging during high-speed operation, relying on the micron-level axial freedom of the stainless steel ground surface baffle and graphite floating ring, this wave spring can push the component to slide in real time, dynamically and adaptively compensating for end face wear.

[0053] Secondly, under the above operating parameters, the pressure of the sealing medium after pressure reduction through the labyrinth seal and reaching the right floating ring seal structure is calculated to be approximately 0.5 MPa using the iterative formula, which meets the first-level pressure gradient qualification requirement.

[0054] Furthermore, under the aforementioned operating parameters, the leakage rate Q after passing through the floating ring sealing device is calculated to be approximately 20.1 ml / h using the leakage rate formula. This calculated result is less than 35 ml / h, thus meeting the second-level leakage rate qualification requirement.

[0055] In this example, the cartridge-type housing encapsulation structure allows for offline airtightness pre-testing before the spindle is engaged. During assembly, it is directly fitted onto the rotating shaft 1 and secured by bolts 6. Relying on the dynamic oil film and spring self-adaptive mechanism, the potential for instantaneous media leakage during the start-up and shutdown phases of the centrifugal compressor is eliminated, thus improving the stability of the seal.

[0056] Example 2: The sealing structure is used for sealing the shaft end of a high-pressure boiler feedwater pump.

[0057] First, the parameters of the series-type combined sealing structure are calculated based on the operating parameters of the high-pressure boiler feed pump.

[0058] The shaft rotation speed is 4500 r / min, the shaft diameter d is 100 mm, the sealing medium is high-purity deoxygenated water, and the operating temperature is 160℃. in The inlet medium pressure is 4.0 MPa.

[0059] Based on the aforementioned operating parameters, the parameter settings for the structure in this example are as follows:

[0060] The radial clearance δ1 between the axial high and low tooth labyrinth sealing ring 3 and the outer surface of the rotating shaft 1 is set to 0.2 mm, and the radial clearance δ2 between the inner circumferential surface of the floating ring sealing device 4 and the rotating shaft 1 is set to 0.05 mm.

[0061] Assume that the axial clearance peak L1 of the axial high and low tooth labyrinth sealing ring is 4mm; the height H1 of the rectangular sealing tooth 34 on its peak 31 is 20mm; the height H2 of the rectangular sealing tooth 33 on its valley 32 is 24mm; and the thickness of these sealing teeth is 0.3mm.

[0062] Assume the outlet pressure P under this operating condition out The pressure is set to 0.4 MPa; the static pressure P1 of the cavity for sealing tooth i = 1 is set to 3.85 MPa; the total number of rectangular sealing teeth 34 and 33 is calculated. ≥10.15, take 11.

[0063] Assume that the inner diameter I1 of the float ring 44 in the float ring sealing device is 100.1 mm; its axial width L is 25 mm; the total thickness C of the float ring 44 and the steel ring 43 is 12 mm, of which the thickness B1 of the float ring 44 is 7.5 mm; and the thickness B2 of the steel ring 43 is 4.5 mm.

[0064] In this example, the elastic force of the wave spring Under this operating condition, the spring specific pressure p s Taking 0.25MPa, the calculated elastic force F is 305.8N, so we take 310N.

[0065] Secondly, under this operating condition, through iterative formula calculation, the pressure of the sealing medium after pressure reduction through the labyrinth seal and reaching the right floating ring seal structure is approximately 0.4 MPa, which meets the first-level pressure gradient qualification requirement.

[0066] Furthermore, the leakage rate Q after passing through the floating ring sealing device, calculated using the leakage rate formula, is approximately 24.5 ml / h. This meets the second-level leakage rate qualification requirement.

[0067] In this example, when the boiler feed pump rotor exceeds the critical speed or the main shaft experiences localized eccentricity during start-up and shutdown, the self-lubricating graphite floating ring 44 can form a small water film through its radial floating gap, reducing temperature rise and preventing dry friction burn-off. Simultaneously, the baffle 45's micron-level sliding freedom in the axial direction allows the right-side wave spring 46 to eliminate dimensional changes caused by high-temperature thermal expansion in real time, ensuring the long-term dynamic reliability of the system.

[0068] The above descriptions are merely a few specific examples of the present invention and do not constitute any limitation on the present invention. Obviously, those skilled in the art, after understanding the content and principles of the present invention, may make various modifications and changes in form and details without departing from the principles and structure of the present invention. For example, the number and thickness of the sealing teeth on the axial high and low tooth labyrinth sealing ring, the axial width and thickness of the floating ring in the floating ring sealing device, etc., can be designed with different parameters according to the working pressure and the shaft diameter of the sealing shaft. However, these modifications and changes based on the ideas of the present invention are still within the scope of protection of the claims of the present invention.

Claims

1. A series-mounted combined sealing structure, comprising a housing (2), a floating ring sealing device (4) to the right of an axial high and low tooth labyrinth sealing ring (3), a sealing end cap (5), a sealing ring (7), and a sealing ring (8), characterized in that: The high and low tooth labyrinth sealing ring (3) is located on the high pressure side of the working condition, and the floating ring sealing device (4) is located on the low pressure side of the working condition; the two are connected in series and fixed on the housing (2) to achieve multi-stage sealing of the rotating shaft.

2. The structure according to claim 1, characterized in that, The axial high and low tooth labyrinth sealing ring (3) is an integral structure with alternating peaks (31) and valleys (32) inside. Multiple rectangular sealing teeth (34) and (33) are provided on the peaks (31) and valleys (32), respectively, and the thickness of each sealing tooth is 0.2~0.8mm. These teeth are symmetrically spaced along the width direction of the peaks (31) and valleys (32), forming pressure relief cavities (35) of different sizes with the rotating shaft, which are used to form eddy current resistance between the tooth surfaces.

3. The structure according to claim 2, characterized in that: The radial clearance δ1 from the innermost end of the axial high and low sealing ring (3) to the rotating shaft is 0.2~0.5mm, and the axial clearance between adjacent rectangular sealing teeth is L1, which satisfies L1=(8~36)δ1; The height H1 of the crest sealing tooth (34) on the peak (31) is (5~15)L1; The height of the valley sealing tooth (33) on the valley (32) is H2 = H1 + (3-6).

4. The structure according to claim 1, characterized in that: The floating ring sealing device includes a fixed seat (42), a steel ring (43), a floating ring (44), a baffle (45), a wave spring (46), and a retaining ring (47); the left end face of the baffle (45) is in contact with the right end face of the floating ring (44); the floating ring (44) is suspended on the rotating shaft (1) and can float freely between the rotating shaft (1) and the fixed seat (42); the steel ring (43) is assembled between the floating ring (44) and the fixed seat (42) to limit the floating ring (44).

5. The structure according to claim 4, characterized in that: The floating ring (44) is made of graphite material with self-lubricating properties. Its radial clearance to the shaft is δ2 = (0.1~1)d / 1000, its inner diameter is I1 = d + 2δ2, and its axial width is d2 = (0.2~0.3)d, where d is the diameter of the shaft. The thickness of the steel ring (43) is 1 / 2 to 2 / 3 of that of the floating ring (44); The radial distance between the fixing seat (42) and the steel ring (43) is 0.5 mm to 1 mm.

6. The structure according to claim 4, characterized in that: The wave spring (46) is sleeved on the rotating shaft (1), with one end abutting against the retaining ring (47) and the other end abutting against the baffle (45), and is used to provide pressure to the floating ring (44). Make its end face fit tightly against the fixed seat (42) to achieve side sealing.

7. The structure according to claim 4, characterized in that: Both the baffle (45) and the fixed seat (42) are made of stainless steel with high strength and good thermal stability. The two form a metal hard seal by axial contact. While maintaining the axial flow interception state, the hard seal allows the baffle (45) and the floating ring (44) to have micron-level sliding freedom in the axial direction, so as to dynamically compensate for the component size change caused by thermal expansion.

8. The structure according to claim 1, characterized in that: Two mounting grooves are provided on the inner circumferential surface of the housing (2), and a first sealing ring (7) is embedded in each mounting groove to achieve static sealing between the housing (2) and the contact surfaces of the axial high and low tooth labyrinth sealing ring (3) and the floating ring sealing device (4).

9. The structure according to claim 1, characterized in that: The axial high and low tooth labyrinth sealing ring (3) has an end face mounting groove on the axial contact end face near the floating ring sealing device (4). The mounting groove is embedded with a second sealing ring (8) to achieve static sealing of the contact surface between the axial high and low tooth labyrinth sealing ring (3) and the floating ring sealing device (4).

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