Double-end-face gas film supporting follow-up type gas film end cylindrical surface sealing structure

Abstract

The invention discloses a double-end-face air film supporting follow-up type air film end cylindrical surface sealing structure which comprises a sealing cavity, a floating ring mounting base fixedly connected to one end of the sealing cavity and a rotor eccentrically penetrating through the sealing cavity. A first sealing cavity is formed between the floating ring mounting base and the sealing cavity. A graphite floating ring, a floating ring base and a second labyrinth sealing piece are sequentially installed in the first sealing cavity from top to bottom, a first floating sealing gap is formed between the rotor and the graphite floating ring in the radial direction, a second floating sealing gap is formed between the first sealing end face and the floating ring base in the axial direction, and a pump-out type dynamic pressure groove is formed in the first sealing end face. The end faces of the two sides of the graphite floating ring seal generate remarkable fluid film bearing force, non-contact operation can be achieved between the end faces of the graphite floating ring seal and components on the two sides, the sealing performance of the graphite floating ring seal is improved, and the sealing performance of the graphite floating ring seal is improved. The end face abrasion and friction force of the floating ring are reduced, and the service life of the graphite floating ring is prolonged.

Description

Technical Field

[0001] The invention relates to the field of lubricating oil seals for rotating machinery bearing cavities, and in particular to a double-end-face air film support follower type air film end cylindrical seal structure. Background Art

[0002] The bearing cavity of rotating machinery such as aircraft engines and turbine compressors needs to be sealed to prevent the lubricating oil from leaking or entering the equipment. As the operating parameters of aircraft engines continue to improve, the requirements for the leakage of lubricating oil seals in the bearing cavity are also getting higher and higher.

[0003] As a non-contact small gap seal, floating ring seal is being widely used in the main bearing cavity of aircraft engines. Floating ring seal is a kind of cylindrical seal. When in a static state, the floating ring is suspended on the shaft by gravity; when the shaft starts, the shaft drives the fluid in the gap to rotate to generate air film bearing force, so that the floating ring overcomes gravity and floats up, thereby realizing non-contact operation of the seal. During the floating process of the floating ring seal, it is affected by the air film bearing force, gravity and end face friction. Under the premise of a certain gravity, the size of the air film bearing force and the end face friction force become the main factors determining the floating performance of the floating ring. How to improve the floating performance and reduce the wear of the floating ring is one of the main driving forces of the floating ring design.

[0004] At present, the design of improving the floating performance of the floating ring mainly focuses on changing the structure to improve the support force of the sealing air film. By opening a dynamic pressure groove or a throttle hole on the inner cylindrical surface, the pressure of the local fluid on the cylindrical surface is increased to increase the bearing capacity of the fluid, thereby improving the floating performance of the floating ring. However, the current floating ring design only considers the wear and failure of the main sealing surface, and does not pay enough attention to the wear caused by dry grinding between the ring and the primary and secondary sealing surfaces during the seal startup process; in addition, with the increase in the operating temperature of the aircraft engine, excessive temperature changes will cause radial displacement of the seal; excessive end face friction will cause poor tracking performance of the seal. All of the above factors will cause contact wear on the inner cylindrical surface of the floating ring, and then cause the floating ring to fail. How to effectively cool the seal and reduce the change in radial displacement of the seal has become the key to the design and application of floating rings in aircraft engine bearing cavities. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention proposes a double-end-surface air film support follower type air film end cylindrical sealing structure which can realize floating in radial direction and axial direction at the same time.

[0006] Compared with the prior art, the technical solution of the present invention is as follows:

[0007] A double-end-face air film support follower type air film end cylindrical sealing structure comprises a sealing cavity, a floating ring mounting seat fixedly connected to one end of the sealing cavity, and a rotor eccentrically passing through the sealing cavity, wherein a first sealing cavity is arranged between the floating ring mounting seat and the sealing cavity, wherein a graphite floating ring, a floating ring seat and a second comb seal are sequentially installed in the first sealing cavity from top to bottom, wherein a first floating sealing gap is arranged radially between the rotor and the graphite floating ring, wherein the lower surface of the graphite floating ring is a first sealing end surface, wherein a second floating sealing gap is arranged axially between the first sealing end surface and the floating ring seat, wherein the first sealing end surface is uniformly provided with a plurality of pump-out type dynamic pressure grooves along its circumferential direction, wherein the upper surface of the graphite floating ring is a second sealing end surface, wherein a third floating sealing gap is arranged between the second sealing end surface and the end surface of the floating ring mounting seat, wherein the second sealing end surface is uniformly provided with a plurality of pump-in type dynamic pressure grooves along its circumferential direction, wherein the pump-out type dynamic pressure grooves are communicated with the inner diameter side of the graphite floating ring, and wherein the pump-in type dynamic pressure grooves are communicated with the outer diameter side of the graphite floating ring.

[0008] Furthermore, the depth of the pump-out type dynamic pressure groove is 2-20 μm, preferably 3-6 μm, and the width h1 of the second floating seal gap is 1-10 μm, preferably 2-5 μm.

[0009] Furthermore, the depth of the pump-in type dynamic pressure groove ranges from 2 to 20 μm, preferably from 3 to 6 μm, and the width h2 of the third floating seal gap ranges from 1 to 10 μm, preferably from 2 to 5 μm.

[0010] Furthermore, the first sealing surface includes a first sealing surface sealing dam, and the pump-out type dynamic pressure groove is opened on the first sealing surface sealing dam; the second sealing end surface includes a second sealing surface sealing dam, and the pump-in type dynamic pressure groove is opened on the second sealing surface sealing dam.

[0011] Furthermore, a comb-tooth flow-blocking structure is provided on the inner diameter side of the floating ring seat, a second comb-tooth seal is installed in the mounting groove on the inner side of the sealing cavity, a second sealing cavity is provided between the comb-tooth flow-blocking structure and the second comb-tooth seal, a first fixed sealing gap is provided between the floating ring seat and the rotor in the radial direction, and a second fixed sealing gap is provided between the second comb-tooth seal and the rotor in the radial direction.

[0012] Furthermore, the sealing cavity is provided with a first air hole and a second air hole, the second air hole is connected to the second sealing cavity, and the two sides of the second sealing cavity are respectively connected to the first fixed sealing gap and the second fixed sealing gap; the first air hole is connected to the first sealing cavity.

[0013] Furthermore, an auxiliary sealing ring is provided in the sealing ring installation groove of the floating ring seat, an elastic element is axially provided between the floating ring seat and the sealing cavity, and an anti-rotation pin is installed in the pin hole of the floating ring seat.

[0014] Furthermore, a retaining spring for axially positioning the second comb tooth seal is provided between the second comb tooth seal and the sealing cavity.

[0015] The working principle of the present invention is as follows:

[0016] In the zero-speed and pressure-free state, the graphite floating ring will be suspended on the rotor, and the eccentricity of the first floating seal gap will reach the maximum; due to the elastic force of the elastic element, the floating ring seat will directly contact the graphite floating ring, and the graphite floating ring will be tightly pressed against the floating ring mounting seat; at this time, the second floating seal gap and the third floating seal gap are both zero, and the end face friction resistance is the largest. A higher pressure is introduced into the second sealing cavity from the second air hole, and the graphite floating ring is under zero-speed static pressure conditions; the gas pressure is still large after throttling by the comb tooth flow-blocking structure, and the airflow is divided into two streams after entering the first sealing cavity: one stream flows into the first fixed sealing gap along the axial direction, and flows out of the first sealing cavity after throttling; the other stream flows into the pump-out type dynamic pressure groove of the first sealing end face along the radial direction, so that the graphite floating ring overcomes the elastic force of the elastic element and breaks away from the floating ring seat. After the airflow is throttled through the second fixed seal gap, it is divided into two parts. One part flows out of the cavity through the first air hole, and the other part flows into the pump-in type dynamic pressure groove of the second seal end face in the radial direction. After the airflow is throttled through the third floating seal gap, it flows out of the first seal cavity, and the graphite floating ring overcomes the pressure of the second fixed seal gap, and then breaks away from the contact between the floating ring mounting seat, forming the third floating seal gap, and realizing the static pressure opening of the graphite floating ring. At this time, since the graphite floating ring is out of contact with the sealing components on both sides, the end face friction is minimized, which facilitates the follow-up movement between the graphite floating ring and the rotor.

[0017] Under the condition of speed and pressure, the graphite floating ring will follow the rotor in follow-up motion under the action of the contact friction force of the main sealing surface. Under the follow-up motion of the graphite floating ring, the pumping action of the pump-out type dynamic pressure groove and the pump-in type dynamic pressure groove is enhanced, and the opening force on both sides of the graphite floating ring is increased; because the pressure on the outlet side of the first sealing chamber is lower, and the pumping action of the pump-in type dynamic pressure groove is stronger, under certain pressure conditions, the forces on both sides of the graphite floating ring can be balanced, requiring the forces on both sides to meet the following conditions:

[0018] F ph =F pl

[0019] For floating ring seats, the following conditions need to be met between the elastic force and the second sealing gap force:

[0020] F pl =F p1 +F s +F p4 ±F f .

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] 1) The present invention provides dynamic pressure grooves with pumping capability on both side end faces of the graphite floating ring, thereby generating air film reaction force on both side end faces at the same time, so that the end face of the graphite floating ring and the end face of the retaining ring are out of contact. On the one hand, the end face contact friction can be reduced, and the floating performance of the graphite floating ring can be improved; on the other hand, the wear of the end face of the graphite floating ring can be reduced, the seal wear failure can be prevented, and the service life of the seal can be extended;

[0023] 2) In the first sealing cavity of the present invention, a second comb seal is installed, and a comb flow-blocking structure is provided on the inner diameter side of the floating ring seat. High-pressure cooling gas is introduced into the air inlet between the two-stage comb sealing rings to prevent the lubricating oil in the bearing cavity from leaking outward. The cooling air enters the gaps on both sides of the inner and outer circular surfaces of the floating ring after being depressurized by the comb ring of the retaining ring and pumped by the spiral groove, and plays a cooling role when the graphite floating ring is overheated in the working state. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic cross-sectional structure diagram of the sealing structure of the present invention;

[0025] Figure 2 It is a schematic diagram of the three-dimensional structure of the present invention;

[0026] Figure 3 This is a schematic diagram of the low-pressure side end face groove structure of the graphite floating ring of the present invention;

[0027] Figure 4 This is a schematic diagram of the groove structure on the high-pressure side end face of the graphite floating ring of the present invention;

[0028] Figure 5 This is a schematic diagram of the sealing gap of the present invention;

[0029] Figure 6 This is a schematic diagram of airflow distribution of the present invention;

[0030] Figure 7 This is a force analysis diagram of the double-end air film floating ring of the present invention;

[0031] Figure 8 It is a force analysis diagram of the real retaining ring of the present invention.

[0032] In the figure: 1. rotor; 2. graphite floating ring; 21. first sealing end face; 22. second sealing end face; 23. pump-out type dynamic pressure groove; 24. pump-in type dynamic pressure groove; 25. first sealing surface sealing dam; 26. second sealing surface sealing dam; 3. first sealing cavity; 31. first floating sealing gap; 32. second floating sealing gap; 33. third floating sealing gap; 34. floating ring seat; 341. comb tooth flow blocking structure; 35. elastic element; 36. auxiliary sealing ring; 37. anti-rotation pin; 4. sealing cavity; 41. first air hole; 42. second air hole; 43. second comb tooth seal; 5. floating ring mounting seat; 51. screw; 6. second sealing cavity; 61. retaining spring; 11. first fixed sealing gap; 12. second fixed sealing gap. DETAILED DESCRIPTION

[0033] The present invention will be further described below in conjunction with the accompanying drawings, but the scope of protection of the present invention is not limited to the described scope.

[0034] Please refer to Figure 1-4 A double-end-face air film support follower air film end cylindrical sealing structure, comprising a sealing cavity 4, a floating ring mounting seat 5 fixedly connected to one end of the sealing cavity 4, and a rotor 1 eccentrically passing through the sealing cavity 4, a first sealing cavity 3 is arranged between the floating ring mounting seat 5 and the sealing cavity 4, a graphite floating ring 2, a floating ring seat 34 and a second comb seal 43 are sequentially installed in the first sealing cavity 3 from top to bottom, a first floating sealing gap 31 is radially provided between the rotor 1 and the graphite floating ring 2, the lower surface of the graphite floating ring 2 is a first sealing end face 21, and the first sealing end face There is a second floating seal gap 32 axially between the first sealing end face 21 and the floating ring seat 34, a plurality of pump-out type dynamic pressure grooves 23 are evenly formed along the circumferential direction of the first sealing end face 21, the upper surface of the graphite floating ring 2 is the second sealing end face 22, a third floating seal gap 33 is formed between the second sealing end face 22 and the end face of the floating ring mounting seat 5, a plurality of pump-in type dynamic pressure grooves 24 are evenly formed along the circumferential direction of the second sealing end face 22, the pump-out type dynamic pressure grooves 23 are connected to the inner diameter side of the graphite floating ring 2, and the pump-in type dynamic pressure grooves 24 are connected to the outer diameter side of the graphite floating ring 2.

[0035] Please refer to Figure 3 and 4 Furthermore, the first sealing surface 21 includes a first sealing surface sealing dam 25, and the pump-out type dynamic pressure groove 23 is opened on the first sealing surface sealing dam 25; the second sealing end surface 22 includes a second sealing surface sealing dam 26, and the pump-in type dynamic pressure groove 24 is opened on the second sealing surface sealing dam 26.

[0036] A comb-tooth flow-blocking structure 341 is provided on the inner diameter side of the floating ring seat 34, a second comb-tooth seal 43 is installed in the mounting groove on the inner side of the sealing cavity 4, a second sealing cavity 6 is provided between the comb-tooth flow-blocking structure 341 and the second comb-tooth seal 43, a first fixed sealing gap 11 is provided radially between the floating ring seat 34 and the rotor 1, and a second fixed sealing gap 12 is provided radially between the second comb-tooth seal 43 and the rotor 1.

[0037] The sealing cavity 4 is provided with a first air hole 41 and a second air hole 42, the second air hole 42 is connected to the second sealing cavity 6, and the two sides of the second sealing cavity 6 are respectively connected to the first fixed sealing gap 11 and the second fixed sealing gap 12; the first air hole 41 is connected to the first sealing cavity 3. The pressurized gas enters the second sealing cavity 6 from the second air hole 42, and flows to both sides from the first fixed sealing gap 11 and the second fixed sealing gap 12 respectively.

[0038] An auxiliary sealing ring 36 is provided in the sealing ring installation groove of the floating ring seat 34, an elastic element 35 is provided axially between the floating ring seat 34 and the sealing cavity 4, an anti-rotation pin 37 is installed in the pin hole of the floating ring seat 34, the outer surface of the anti-rotation pin 47 is provided with an external thread, and the pin hole is provided with an internal thread matching it, and the anti-rotation pin 37 is threadedly connected to the pin hole.

[0039] A retaining spring 61 is provided between the second comb teeth seal 43 and the sealing cavity 4 , and the retaining spring 61 is used for axially positioning the second comb teeth seal 43 .

[0040] In this embodiment, the floating ring mounting seat 5 and the sealing cavity 4 are fixed by screws 51 .

[0041] Reference Figures 3 to 5 The inner diameter and outer diameter of the first sealing end surface 21 are r ih and r oh , inner diameter r ih The groove radius of the pump-out type dynamic pressure groove 23 is r gh , the radial widths of the pump-out type dynamic pressure groove 23 and the first sealing end face sealing dam 25 are (r gh -r ih )、(r oh -r gh ); the depth of the pump-out dynamic pressure groove 23 ranges from 2 to 20 μm, preferably from 3 to 6 μm, and the width of the second floating seal gap h1 is from 1 to 10 μm, preferably from 2 to 5 μm;

[0042] The inner diameter and outer diameter of the second sealing end surface 22 are r il and r ol , inner diameter r il The groove radius of the pump-in type dynamic pressure groove 24 is r gl, then the radial widths of the pump-in type dynamic pressure groove 24 and the second sealing end face sealing dam 26 are (r ol -r gl )、(r gl -r il ); the depth range of the pump-in dynamic pressure groove 24 is 2 to 20 μm, preferably 3 to 6 μm, and the width of the third floating seal gap h2 is 1 to 10 μm, preferably 2 to 5 μm.

[0043] Please refer to Figures 6 to 8 , the axial force analysis is performed on both sides of the graphite floating ring 2. The pressure of the high-pressure cooling air entering the air inlet is p1, and the pressure of the high-pressure cooling air is p1. The pressure of the high-pressure cooling air is p1. After the high-pressure cooling air is depressurized by the comb-tooth flow-blocking structure 341, the pressure drops to p3. After that, the airflow is divided into two streams at the inner diameter of the high-pressure side of the graphite floating ring 2. One stream is pumped and pressurized by the pump-out type dynamic pressure groove 23 and the pressure changes to p4 after the end face gap is depressurized. The medium pressure remains basically constant and does not change with other pressure changes; the other stream enters the first floating seal gap 31, and the pressure drops to p5 after the first floating seal gap 31 is depressurized. The low-pressure side pressure p5 is always lower than the high-pressure side pressure p3, so the sealing gas can play a good sealing role for the bearing cavity lubricating oil. Part of the airflow at p4 flows to the outside through the first air hole 41, and the other part is pumped by the pump-in type dynamic pressure groove 24 at reverse pressure and then depressurized to p5 through the sealing gap, and flows out of the first sealing cavity 3 radially. The pressure p5 is always less than p4.

[0044] The high and low pressures of the graphite floating ring 2 on the near-axial surface are p3 and p5 respectively, and the high pressure side pressure p3 is much greater than the low pressure side pressure p5. The closing force generated by the high pressure side gas medium on the first sealing end face 21 is F ph The closing force generated by the low-pressure side gas medium on the second sealing end face 22 is F pl The right side of the floating ring seat 34 is subjected to a closing force of F ph , which is the same as the opening force on the first sealing end face 21 of the graphite floating ring 2; the end face area of ​​the left side comb tooth flow blocking structure 341 of the floating ring seat 34 is A1, and the pressure it receives is the high-pressure cooling air pressure p1, then the closing force F on the left side comb tooth flow blocking structure 341 of the floating ring seat 34 is p1 =A1×p1; the remaining end surface area of ​​the floating ring seat 34 on the left side except the grate-tooth flow-blocking structure 341 is A2, and the pressure it receives is the outlet pressure p4, then the closing force F received by the other end surfaces on the left side of the floating ring seat 34 is p4 =A2×p4.

[0045] In this embodiment, the elastic element 35 is a spring. The spring is in a compressed state in the working state. The closing force it generates on the floating ring seat 34 is F sIt should be noted that the spring force is proportional to the spring compression. As the spring compression increases, the spring force will gradually increase. The friction force between the floating ring seat 34 and the sealing cavity 4 is F f , but the direction of the friction force is undetermined.

[0046] Taking the graphite floating ring 2 as the force analysis object, when the sealing gaps on both sides are the same, the pressure p3 on the second floating sealing gap 32 is higher than the pressure p5 on the third floating sealing gap 33. In design, since the pumping capacity of the pump-in type dynamic pressure groove 24 is stronger than that of the pump-out type dynamic pressure groove 23, the peak pressure p of the second sealing end face 22 is lmax Greater than the peak pressure p of the first sealing end face hmax , the opening forces on both sides can be balanced, that is, the axial force satisfies:

[0047] F ph =F pl

[0048] Assume that the area of ​​the first sealing end surface 21 is A h , the radial pressure distribution is p h (r), the area of ​​the second sealing end surface 22 is A l , the radial pressure distribution is p l (r), then the resultant force of the air film opening force on both sides is F ph and F pl They are

[0049]

[0050] In order to avoid uneven force on both sides of the graphite floating ring 2 to generate overturning moment, which causes the sealing ring to deflect and affect the end face gap, it is necessary to ensure that the gap air film opening force F ph and F pl If the pump-out type dynamic pressure groove 23 is located on the same axis, the radial width (r gh -r ih ) is smaller than the radial width (r ol -r gl ),Right now:

[0051] (r gh -r ih )<(r ol -r gl )

[0052] When the second floating seal gap width h1 is smaller than the third floating seal gap width h2, the pressure on the first sealing end face 21 increases and the pressure on the second sealing end face 22 decreases, and the opening forces on both sides of the graphite floating ring 2 are no longer balanced. The opening force F of the second floating seal gap 32 is ph Greater than the opening force F on the side of the third floating seal gap 33 pl, the graphite floating ring 2 is subjected to the opening force F ph The action moves toward the third floating seal gap 33, the gap width h1 of the second floating seal gap 32 increases, and the gap width h2 of the third floating seal gap 33 decreases. As the gaps on both sides change, the pressure and opening force on both sides of the floating ring also change accordingly. The opening force F on the second floating seal gap 32 side ph As the gap increases, the opening force F on the side of the third floating seal gap 33 decreases. pl As the gap decreases, it increases. When the floating ring moves to a certain position, the opening forces on both sides are equal, and the floating ring reaches balance again. When the side gap width h1 of the second floating seal gap 32 is greater than the side gap width h2 of the third floating seal gap 33, the change of the air film opening force is similar to the above process. Through the above principle, the graphite floating ring 2 can maintain a suitable sealing gap.

[0053] Taking the floating ring seat 34 as the force analysis object, when it is in a balanced state, its axial force satisfies:

[0054] F ph =F p1 +F p4 +F s ±F f

[0055] When the rotor 1 runs at too low a speed, the graphite floating ring 2 also runs at a low speed, and the high-pressure side opening force F ph The closing force on the left side of the floating ring seat 34 remains unchanged. The net force of the opening force and the closing force causes the floating ring seat 34 to move to the right. During this process, the deformation of the elastic element 35 decreases, and the elastic force F s When the floating ring seat 34 moves to a certain position, the opening force and the closing force are balanced again, and the floating ring seat 34 reaches a new equilibrium state. When the rotor 1 is too large, the operating principle of the floating ring seat 34 is similar to the above. The floating ring seat 34 can be automatically adjusted to a balanced position through the above principle.

Claims

1. A double-end-face air film support follower type air film end cylindrical sealing structure, comprising a sealing cavity (4), a floating ring mounting seat (5) fixedly connected to one end of the sealing cavity (4), and a rotor (1) eccentrically passing through the sealing cavity (4), a first sealing cavity (3) is provided between the floating ring mounting seat (5) and the sealing cavity (4), a graphite floating ring (2), a floating ring seat (34) and a second comb tooth seal (43) are sequentially installed in the first sealing cavity (3) from top to bottom, a first floating sealing gap (31) is radially provided between the rotor (1) and the graphite floating ring (2), and is characterized in that The lower surface of the graphite floating ring (2) is a first sealing end surface (21), and a second floating sealing gap (32) is axially provided between the first sealing end surface (21) and a floating ring seat (34). The first sealing end surface (21) is evenly provided with a plurality of pump-out type dynamic pressure grooves (23) along its circumferential direction. The upper surface of the graphite floating ring (2) is a second sealing end surface (22), and a third floating sealing gap (33) is provided between the second sealing end surface (22) and an end surface of a floating ring mounting seat (5). The second sealing end surface (22) is evenly provided with a plurality of pump-in type dynamic pressure grooves (24) along its circumferential direction. The pump-out type dynamic pressure grooves (23) are connected to the inner diameter side of the graphite floating ring (2), and the pump-in type dynamic pressure grooves (24) are connected to the outer diameter side of the graphite floating ring (2).

2. A double-end air film support follower type air film end cylindrical sealing structure according to claim 1, characterized in that The depth of the pump-out type dynamic pressure groove (23) is 2 to 20 μm, preferably 3 to 6 μm, and the width h1 of the second floating seal gap is 1 to 10 μm, preferably 2 to 5 μm.

3. The double-end air film support follower type air film end cylindrical sealing structure according to claim 1 is characterized in that The depth of the pump-in type dynamic pressure groove (24) ranges from 2 to 20 μm, preferably from 3 to 6 μm, and the width h2 of the third floating seal gap ranges from 1 to 10 μm, preferably from 2 to 5 μm.

4. The double-end air film support follower type air film end cylindrical sealing structure according to claim 1 is characterized in that The first sealing surface (21) includes a first sealing surface sealing dam (25), and the pump-out type dynamic pressure groove (23) is opened on the first sealing surface sealing dam (25); the second sealing end surface (22) includes a second sealing surface sealing dam (26), and the pump-in type dynamic pressure groove (24) is opened on the second sealing surface sealing dam (26).

5. The double-end air film support follower type air film end cylindrical sealing structure according to claim 1 is characterized in that The inner diameter side of the floating ring seat (34) is provided with a comb-tooth flow-blocking structure (341); the mounting groove on the inner side of the sealing cavity (4) is provided with a second comb-tooth seal (43); a second sealing cavity (6) is provided between the comb-tooth flow-blocking structure (341) and the second comb-tooth seal (43); a first fixed sealing gap (11) is provided radially between the floating ring seat (34) and the rotor (1); and a second fixed sealing gap (12) is provided radially between the second comb-tooth seal (43) and the rotor (1).

6. A double-end air film support follower type air film end cylindrical sealing structure according to claim 5, characterized in that The sealed cavity (4) is provided with a first air hole (41) and a second air hole (42); the second air hole (42) is connected to the second sealed cavity (6); the two sides of the second sealed cavity (6) are respectively connected to the first fixed sealed gap (11) and the second fixed sealed gap (12); and the first air hole (41) is connected to the first sealed cavity (3).

7. The double-end air film support follower type air film end cylindrical sealing structure according to claim 5, characterized in that An auxiliary sealing ring (36) is arranged in the sealing ring installation groove of the floating ring seat (34), an elastic element (35) is arranged axially between the floating ring seat (34) and the sealing cavity (4), and an anti-rotation pin (37) is installed in the pin hole of the floating ring seat (34).

8. The double-end air film support follower type air film end cylindrical sealing structure according to claim 5, characterized in that A retaining spring (61) for axially positioning the second comb tooth seal (43) is provided between the second comb tooth seal (43) and the sealing cavity (4).

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