Parallel type radial double-sealing-face circumferential graphite sealing structure and application

Abstract

The invention discloses a parallel type radial double-sealing-face circumferential graphite sealing structure which is mainly composed of a sealing seat, an inner graphite sealing ring, an outer graphite sealing ring, a rear baffle, an axial compression spring, a radial compression spring and the like. The inner graphite sealing ring and the outer graphite sealing ring form sealing faces with the outer diameter of the sealing runway and the inner surface of the sealing seat respectively, the inner graphite sealing ring and the outer graphite sealing ring are assembled in a Z shape, a plurality of embedded radial compression springs are arranged between the inner graphite sealing ring and the outer graphite sealing ring, and double-end-face staggered axial compression springs are installed on the two sides of the graphite sealing ring assembly. Pre-tightening force needed by graphite sealing is provided through the embedded radial compression spring, it is guaranteed that when an engine is in a static or starting state, the sealing faces of the graphite sealing can be tightly attached, meanwhile, it is guaranteed that the graphite sealing can still have the good sealing performance under the negative pressure working condition through axial symmetrical distribution, and the sealing performance of the graphite sealing is improved. In addition, when the rotor is disturbed to generate vibration or axial movement, good follow-up performance can be kept, and lubricating oil leakage of a bearing cavity is remarkably reduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of contact type circumferential graphite seal in aero-engine sealing technology, and relates to a parallel type radial double-seal-face circumferential graphite seal structure, in particular to a new type of seal structure applied to air systems, rim sealing and bearing cavity sealing of turboshaft engines, rocket-based combined cycle engines, air-turborocket combined power engines, aero-engines, gas turbines or steam turbines and other rotating machinery, which is used to improve sealing performance and prolong service life, and can meet the sealing requirements of bearing cavity lubricating oil of modern high-performance aero-engines and the like. BACKGROUND

[0002] For modern high-performance aero-engines, in order to pursue higher thrust-to-weight ratio, thermal efficiency and reduce specific fuel consumption and control pollutant emissions, continuous breakthroughs in sealing technology are particularly important. Research shows that for every 1% reduction in sealing leakage, the engine thrust increases by 1% and the specific fuel consumption decreases by 0.1%. As a contact type seal, circumferential graphite seal is widely used in aero-engine main shaft bearing cavities due to its high technical maturity, good sealing performance, large allowable pressure difference, compact structure and no restriction on rotor axial movement, etc., and plays an important role in preventing lubricating oil leakage in the bearing cavity. The circumferential graphite seal is usually composed of a sealing element, a sealing seat, a circumferential spring, an axial compression spring and other structural components. The circumferential graphite seal forms a circumferential main sealing surface by the contact between the inner diameter of the sealing element and the outer surface of the sealing runway, and forms an end face auxiliary sealing surface by the contact between the end face of the sealing element and the convex edge end face of the sealing seat, thereby realizing the sealing performance of the circumferential graphite seal.

[0003] As a contact type seal, when stationary, the graphite element of the circumferential graphite seal is clamped on the sealing runway by the circumferential spring to form a static seal. When the rotor moves, the graphite element will separate from the rotor due to the existence of gas film force, and at the same time will drive the graphite ring to begin synchronous precession with the rotor. When reaching a steady state, the precession of the rotor and the graphite ring is nearly synchronous, and a thin gas film is formed between them, thereby achieving the effects of lubrication and sealing. However, as the sealing working environment becomes more and more complex and extreme, the sealing runway often exhibits radial runout and circumferential runout during operation, and the dynamic response of the sealing gap between the graphite ring and the runway occurs, accompanied by pressure and temperature deformation of the graphite ring. The size and position of the gap change with the rotor vibration state, and the deformation is most severe at the lap joint of the graphite ring, which affects the sealing performance of the circumferential graphite seal. At the same time, since the circumferential graphite seal belongs to a contact type seal, it will generate a large amount of friction and wear under high-speed and high-pressure working conditions, resulting in severe wear of the main sealing band and auxiliary sealing band of the sealing element, which greatly limits the service life of the circumferential graphite seal.

[0004] In addition, when the aero-engine rotor and bearing rotate at high speed, one side of the circumferential graphite seal is the oil gas environment of the bearing cavity with lower pressure, and the other side is the high pressure air of the seal cavity with higher pressure. Under the action of pressure difference, the high pressure air of the seal cavity blows into the bearing cavity to prevent the leakage of lubricating oil through the circumferential graphite seal. However, when the aero-engine is in the transition state, slow running and the like, the pressure in the bearing cavity may be greater than that in the seal cavity (i.e. negative pressure condition), and at this time, the leakage of lubricating oil is prone to occur.

[0005] Therefore, how to improve the graphite seal structure to enhance the dynamic response capability of the graphite ring to the sealing track, reduce the friction and wear of the main sealing surface and the auxiliary sealing surface, ensure that the graphite seal still has good sealing performance during the start and stop of the engine, and prolong the service life of the sealing assembly has become a problem to be solved. SUMMARY

[0006] (I) Invention purposes

[0007] In view of the above defects and deficiencies of the prior art, the purpose of the present application is to provide a new sealing structure suitable for air systems, rim sealing and bearing cavity sealing of turboshaft engines, rocket-based combined cycle engines, air-turborocket combined power engines, aero-engines, gas turbines or steam turbines and other rotating machinery, which can improve the sealing performance and prolong the service life, and can meet the sealing requirements of bearing cavity lubricating oil of modern high-performance aero-engines and the like. In the case of increasingly harsh engine operating environment, the sealing performance of the graphite circumferential seal can be ensured, and when the rotor is disturbed and elliptical whirling occurs, the leakage is greatly reduced, and the service life of the graphite seal is prolonged. In addition, the friction and wear of the circumferential graphite seal and the sealing seat are also reduced. The present application mainly solves the problems of high reliability and long life sealing of traditional split type circumferential graphite seal structure under high pressure and high temperature, the dynamic response capability of the graphite ring to the track under small disturbance under high speed and high pressure working conditions, the friction and wear of the sealing surface under unbalanced load, and the leakage of lubricating oil due to the change of the sealing condition of the circumferential graphite seal in the bearing cavity to negative pressure condition in the transition state, slow running and the like of the engine.

[0008] (II) Technical solutions

[0009] To achieve the purpose of the present application and solve the technical problems, the present application adopts the following technical solutions:

[0010] The first inventive objective of the present application is to provide a parallel radial double sealing surface circumferential graphite sealing structure, which is installed on a sealing runway between a rotor and a stator of a rotating machinery, and is used to realize reliable sealing of sealing parts such as an air cavity, a rim and a bearing cavity under high temperature and high pressure, dynamic disturbance and negative pressure conditions, and at least comprises a sealing seat, an inner graphite sealing ring, an outer graphite sealing ring and a back baffle, wherein:

[0011] The sealing seat is arranged at an outer side fixed part of the sealing structure, and is formed as a support structure of the sealing structure, and at least comprises an integrally formed front end face and a cylindrical side wall face extending in an axial direction;

[0012] The inner graphite sealing ring and the outer graphite sealing ring are coaxially arranged in the sealing seat, wherein: an inner surface of the inner graphite sealing ring and an outer cylindrical surface of the sealing runway form a main sealing surface, an outer surface of the outer graphite sealing ring and an inner surface of the cylindrical side wall face of the sealing seat form an auxiliary sealing surface, and the main sealing surface and the auxiliary sealing surface are arranged in parallel in a radial direction; the outer surface of the inner graphite sealing ring and the inner surface of the outer graphite sealing ring are respectively machined to form annular wedge-shaped insertion grooves, the annular wedge-shaped insertion grooves of the two are inserted into each other in an axial direction, the inner graphite sealing ring and the outer graphite sealing ring are arranged in a Z-shaped upper and lower lap joint in a radial direction after being assembled to form an integrated sealing ring assembly; and a plurality of radial installation grooves are uniformly distributed in a circumferential direction on the outer surface of the inner graphite sealing ring and the inner surface of the outer graphite sealing ring, and the radial installation grooves of the two correspond to each other in the circumferential direction, and an inner embedded radial compression spring is arranged in each pair of corresponding radial installation grooves;

[0013] The back baffle is arranged at an outer side of rear end faces of the inner graphite sealing ring and the outer graphite sealing ring in an axial direction, and an outer side of the back baffle is provided with a clamping ring, the clamping ring is clamped on the cylindrical side wall face of the sealing seat, and is used to axially limit the sealing ring assembly;

[0014] A plurality of axial compression springs are uniformly arranged in a circumferential direction between the back baffle and the rear end face of the inner graphite sealing ring, and between an inner surface of the front end face of the sealing seat and the front end face of the outer graphite sealing ring, the axial compression springs arranged on the front and rear end faces of the sealing ring assembly are formed as a double-end-face staggered arrangement structure in space, and are used to provide axial elastic support when axial movement, start disturbance or unbalanced load occurs during engine operation, and to maintain a stable fitting state of the sealing ring assembly.

[0015] The second inventive objective of the present application is to provide a rotating machinery of an impeller, which is provided with the above-mentioned parallel radial double sealing surface circumferential graphite sealing structure of the present application on a sealing runway, and the rotating machinery of the impeller is a turbine-based combined cycle engine, a rocket-based combined cycle engine, an air turbine rocket combined power engine, an aero-engine, a gas turbine or a steam turbine.

[0016] (Three) Technical effects

[0017] Compared with the prior art, the parallel radial double-sealing surface circumferential graphite sealing structure and application has the following advantages:

[0018] (1) The parallel radial double-sealing surface circumferential graphite sealing structure can provide the required pre-tightening force for graphite sealing and reduce the influence of sealing runway movement, so that the sealing ring can maintain a good follow-up characteristic, the main sealing surface and the auxiliary sealing surface can always maintain good contact, the graphite sealing performance is good, and the reliability of the sealing is ensured.

[0019] (2) The graphite sealing structure is improved, so that when the rotor is subjected to small disturbance, start-stop stage and axial movement, the axial compression spring installed on both sides of the inner and outer graphite sealing rings can well offset the influence on the graphite ring, so that the graphite ring can maintain stability, the graphite sealing leakage can be effectively reduced, and the service life of the circumferential graphite sealing is greatly prolonged.

[0020] (3) The inner and outer graphite sealing rings and the sealing runway are in contact to form a static seal when the circumferential graphite sealing is in a negative pressure working condition, the sealing performance is good, the service life of the circumferential graphite sealing is improved, and the safe and stable operation of the aero-engine is ensured.

[0021] (4) The auxiliary sealing surface is adjusted from the traditional graphite sealing end surface slot to the outer surface slot, the contact area with the inner surface of the sealing seat is greatly reduced, the problem of serious wear and easy fracture of the auxiliary sealing surface of the circumferential graphite sealing ring is well solved, and the service life of the graphite sealing is greatly prolonged.

[0022] (5) The parallel radial double-sealing surface circumferential graphite sealing structure increases the thickness of the end surface of the main sealing surface, significantly enhances the wear resistance of the material, the auxiliary sealing surface and the main sealing surface are arranged in an upper-lower symmetrical manner, effectively reduces the wear of the graphite sealing part, prolongs the service life of the graphite sealing part, reduces the scrap rate of the graphite sealing part, and improves the sealing performance of the graphite sealing part. BRIEF DESCRIPTION OF DRAWINGS

[0023] The accompanying drawings which form a part of this application are intended to provide further understanding of the application and are incorporated herein in connection with this application. The schematic examples of the application and the description thereof are used to explain the application, and do not constitute undue limitation on the application. In the drawings:

[0024] Figure 1 is an assembly drawing (front view) of the graphite sealing structure of the application;

[0025] Figure 2Figure 1 is a schematic diagram of the assembly of the graphite sealing structure (back view) of the present application;

[0026] Figure 3 Figure 2 is a schematic diagram of the graphite sealing ring in the graphite sealing structure of the present application;

[0027] Figure 4 Figure 3 is a schematic diagram of the half-section of the graphite sealing ring in the graphite sealing structure of the present application;

[0028] Figure 5 Figure 4 is a schematic diagram of the cross-section of the assembly A-A angle of the graphite sealing structure of the present application;

[0029] Figure 6 Figure 5 is a schematic diagram of the cross-section of the assembly B-B angle of the graphite sealing structure of the present application;

[0030] Figure 7 Figure 6 is a schematic diagram of the cross-section of the assembly C-C angle of the graphite sealing structure of the present application;

[0031] Figure 8 Figure 7 is a schematic diagram of the enlarged view of the auxiliary sealing surface in the graphite sealing structure of the present application.

[0032] Explanation of reference signs:

[0033] 1-sealing seat, 2-sealing runway, 3-outer graphite sealing ring, 4-inner graphite sealing ring, 5-rear baffle, 6-retaining ring, 7-axial compression spring, 7-1-outer ring axial compression spring, 7-2-inner ring axial compression spring, 8-embedded radial compression spring, 9-anti-rotation pin, 10-positioning pin. DETAILED DESCRIPTION

[0034] The present application aims to provide a parallel type radial double sealing surface circumferential graphite sealing structure and application, for realizing reliable sealing of the sealing parts such as air cavity, rim and bearing cavity in the impeller machinery under high temperature and high pressure, dynamic disturbance and negative pressure working conditions. In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme in the embodiments of the present application will be described in more detail below in combination with the drawings in the embodiments of the present application. The described embodiments are part of the embodiments of the present application, not all the embodiments. The embodiments described below by referring to the drawings are exemplary, and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0035] As a specific example, as Figures 1-8As shown, the parallel type radial double sealing surface circumferential graphite sealing structure provided by the embodiment of the present application mainly comprises a sealing seat 1, a sealing runway 2, an outer graphite sealing ring 3, an inner graphite sealing ring 4, a rear baffle 5, a clamping ring 6, an axial compression spring 7, an embedded radial compression spring 8, an anti-rotation pin 9, a positioning pin 10 and the like structure and components. The parallel type radial double sealing surface circumferential graphite sealing structure of the present application is based on modular design, and can be assembled into a circumferential graphite sealing structure with different number of split rings according to different sealing runway size and sealing pressure difference requirements.

[0036] Specifically, in the parallel type radial double sealing surface circumferential graphite sealing structure of the present application, the sealing seat 1 is arranged at the outer side fixed part of the sealing structure, and is an annular rigid structure as a whole, and is formed as a support structure of the sealing structure, and at least comprises a front end face and a cylindrical side wall face extending in the axial direction. The inner graphite sealing ring 4 and the outer graphite sealing ring 3 are coaxially arranged in the sealing seat 1, and the outer graphite sealing ring 3 is arranged at the outer side of the inner graphite sealing ring 4. The inner surface of the inner graphite sealing ring 4 and the outer cylindrical surface of the sealing runway 2 constitute a main sealing surface, and the outer surface of the outer graphite sealing ring 3 and the inner surface of the cylindrical side wall face of the sealing seat 1 constitute an auxiliary sealing surface, and the main sealing surface and the auxiliary sealing surface are arranged in parallel in the radial direction.

[0037] In the present application, the outer surface of the inner graphite sealing ring 4 and the inner surface of the outer graphite sealing ring 3 are respectively machined into annular wedge-shaped insertion grooves, and after the annular wedge-shaped insertion grooves of the two are inserted in the axial direction, the inner graphite sealing ring 4 and the outer graphite sealing ring 3 are arranged in a Z-shaped upper and lower lap joint in the radial direction, and are assembled into an integrated sealing ring assembly. In addition, the inner graphite sealing ring 4 and the outer graphite sealing ring 3 are preferably arranged as a fan-shaped split ring lap joint structure, a plurality of fan-shaped split ring bodies are spliced in the circumferential direction and connected in the circumferential direction through the lap joint surface, and the lap joint surface between adjacent split ring bodies is a geometric interface with structural symmetry (for example, rectangular lap joint, triangular lap joint or arc-shaped lap joint and the like), so as to ensure that the overall sealing ring assembly has good structural rigidity and assembly stability under thermal load or rotational disturbance, the number of fan-shaped split ring bodies is adjusted according to actual application requirements to adapt to sealing requirements of different sizes and working conditions, and the split ring positions of the inner graphite sealing ring 4 and the outer graphite sealing ring 3 are consistent in the circumferential direction, so as to facilitate the symmetry and air tightness of the overall sealing structure assembly, so as to improve the structural strength and sealing continuity of the split ring connection.

[0038] The inner surface of the outer graphite sealing ring 3 and the outer surface of the inner graphite sealing ring 4 are uniformly provided with a plurality of embedded radial compression springs 8 in the circumferential direction, the embedded radial compression springs 8 apply a mutual separation pre-tightening force to the inner graphite sealing ring 4 and the outer graphite sealing ring 3 in the radial direction, so that the main sealing surface and the auxiliary sealing surface are tightly attached to the sealing runway outer cylindrical surface and the sealing seat cylindrical sidewall surface inner surface respectively. As preferred, the embedded radial compression spring 8 installation groove position is that a plurality of radial installation grooves are formed on the inner surface of the outer graphite sealing ring 3 and the outer surface of the inner graphite sealing ring 4 respectively in the circumferential direction, the shape of the radial installation groove is preferably a cylindrical, rectangular or elliptical installation groove to adapt to different shapes of the radial compression spring, the diameter and depth are consistent on the upper and lower parts of the sealing ring, and are symmetrically distributed on the inner and outer sealing rings, the installation grooves of the two embedded radial compression springs 8 are different by 24°, and four installation grooves are preferably formed on each segment to ensure the pre-tightening force required by the main sealing surface and the auxiliary sealing surface when at rest.

[0039] In addition, the embedded radial compression spring 8 is preferably an elastic element such as a spiral spring, a wave spring or a disc spring to provide different radial pre-tightening force characteristics, the material of the embedded radial compression spring 8 is selected from high-temperature-resistant and corrosion-resistant alloy materials to ensure its long-term reliability under harsh working conditions, and the stiffness and pre-tightening force of the embedded radial compression spring 8 are optimized to adapt to different sealing working conditions and performance requirements, so as to achieve the best sealing effect and service life.

[0040] In the present application, the axial lengths of the inner and outer graphite sealing rings are consistent, the slotting depths of the main sealing surface and the auxiliary sealing surface are both 1.5 mm, four circumferential V-shaped grooves are formed on the main sealing surface and the auxiliary sealing surface, the depth of the V-shaped groove is consistent with the slotting depth of the sealing surface, the included angle of the V-shaped groove is 60°, and the distance between two V-shaped grooves is kept between 0.8-1.2 mm. The circumferential V-shaped groove can reduce the contact area of the sealing surface, reduce the sealing wear, and improve the aerodynamic effect of the main sealing surface, so that the gas film is more easily formed on the main sealing surface of the sealing ring, and the sealing performance of the graphite sealing is improved.

[0041] In the preferred example of the present application, an axial air passage is formed on the main sealing surface and / or the auxiliary sealing surface, and the depth is consistent with the former, for example, five axial air passages can be formed on the inner / outer graphite sealing ring and symmetrically distributed, and the included angle between two axial air passages is 25°. By forming the axial air passage, a part of the high-pressure gas can flow in, the pressure difference on both sides of the graphite ring in the axial direction is reduced, and the service life of the graphite sealing ring is improved.

[0042] In the present application, the backstop 5 is arranged axially outside the rear end face of the inner graphite seal ring 4 and the outer graphite seal ring 3, and the outer side of the backstop 5 is provided with a clamping ring 6 clamped on the cylindrical side wall surface of the seal seat 1 for axially limiting the seal ring assembly. In addition, a plurality of axial compression springs are arranged circumferentially between the backstop 5 and the rear end face of the inner graphite seal ring 4, and between the inner surface of the front end face of the seal seat 1 and the front end face of the outer graphite seal ring 3, the axial compression springs 7 arranged on the front and rear end faces of the seal ring assembly are formed into a double-end staggered arrangement structure in space, for providing axial elastic support when axial movement, starting disturbance or unbalanced load occurs during engine operation, and maintaining the stable fitting state of the seal ring assembly.

[0043] In addition, the axial compression spring 7 is preferably an elastic element such as a helical spring, a disc spring or a wave spring, to provide different axial elastic support characteristics, the material of the axial compression spring 7 is selected from high-temperature-resistant and corrosion-resistant alloy materials to ensure its long-term reliability in harsh working conditions, and the stiffness and pre-tightening force of the axial compression spring 7 are optimized to adapt to different sealing working conditions and performance requirements, so as to achieve the best anti-disturbance ability and sealing effect.

[0044] More specifically, the inner and outer graphite seal rings are provided with axial grooves for the axial compression springs 7 on both sides of the end face, and the backstop 5 and the front end face of the seal seat 1 are also provided with axial grooves for the axial compression springs 7, the depth of the grooves is preferably 4mm, the diameter is 6mm, the angle between adjacent two installation grooves is 24°, four axial grooves are arranged on each segment and are symmetrically distributed, the two ends of each inner ring axial compression spring 7-2 located on the inner side in the radial direction are respectively installed in the corresponding axial grooves of the inner graphite seal ring 4 and the backstop 5, and the two ends of each outer ring axial compression spring 7-1 located on the outer side in the radial direction are respectively installed in the corresponding axial grooves of the outer graphite seal ring 3 and the front end face of the seal seat 1, and each inner ring axial compression spring 7-2 and outer ring axial compression spring 7-1 are formed into a double-end staggered arrangement structure in space. The double-end staggered axial compression springs 7 installed on both sides of the inner and outer graphite seal rings ensure good follow-up performance when the engine rotor is disturbed to produce circumferential jumping or axial movement, have good sealing performance, and do not leak.

[0045] As a preferred, the inner ring axial compression spring 7-2 and the outer ring axial compression spring 7-1 are respectively located on both sides of the seal ring assembly in the axial direction, the installation positions of the inner and outer ring axial compression springs correspond to each other, the slotting positions on both sides have the same angle, the slotting depths are consistent, and the number of slots is consistent; and the number, length and elastic coefficient of the axial compression springs are adapted to the segment number and working condition requirements of the inner and outer graphite seal rings, to ensure that the inner graphite seal ring 4 and the outer graphite seal ring 3 are uniformly stressed in the axial direction.

[0046] In the application, the low pressure surface of the sealing ring is provided with a limiting groove, i.e. a limiting groove is provided at the junction of the front end surface of the inner and outer graphite sealing rings, and is located at the central axis of the inner and outer graphite rings, the width of the limiting groove is 6mm, and the limiting groove cooperates with the anti-rotation pin 9, one end of the anti-rotation pin 9 is arranged in the limiting groove, and the other end of the anti-rotation pin 9 extends into the limiting hole provided at the front end surface of the mounting seat 1, so that the graphite sealing ring is prevented from rotating with the rotor, and the anti-rotation pin 9 and the sealing ring are in cylindrical surface contact, so as to convert sliding friction into rolling friction, effectively reduce the wear amount and prolong the service life of the sealing assembly.

[0047] In addition, the clamping ring 6 in the application is preferably clamped and fixed through the clamping groove provided on the cylindrical side wall surface of the sealing seat 1, and the cylindrical side wall surface of the sealing seat 1 and the outer side wall of the back baffle 5 are provided with corresponding positioning holes for installing the positioning pin 10, and the positioning pin 10 is embedded in an interference fit or an interference fit, one end of the positioning pin 10 is inserted into the positioning hole on the sealing seat 1, and the other end of the positioning pin 10 is inserted into the corresponding hole on the back baffle 5, so as to prevent the back baffle from being offset due to mechanical vibration.

[0048] The parallel type radial double sealing surface circumferential graphite sealing structure of the application is mainly used for sealing the air system, the rim and the bearing cavity of various kinds of impeller rotating machines such as turbine-based combined cycle engines, rocket-based combined cycle engines, air turbine rocket combined power engines, aero-engines, gas turbines or steam turbines, and the working principle thereof is as follows:

[0049] The traditional graphite ring is divided into inner and outer graphite sealing rings, and grooves are formed on the outer and inner surfaces of the inner and outer graphite sealing rings to form upper and lower sealing surfaces. The present application proposes a novel parallel structure, and the parallel structure provides the pre-tightening force required by the graphite sealing by an embedded radial compression spring. When the rotor is stationary, due to the action of the embedded radial compression spring, the inner surface of the inner graphite sealing ring is tightly attached to the outer diameter of the sealing runway, and the outer surface of the outer graphite sealing ring is tightly attached to the inner diameter of the sealing seat, and both the main sealing surface and the auxiliary sealing surface form a good static seal. When the rotor is moving, the inner and outer graphite sealing rings will be separated from the rotor due to the existence of the gas film counterforce, and at the same time, the inner and outer graphite sealing rings will be driven to start synchronous precession with the rotor. When reaching a steady state, the precession of the rotor and the inner and outer graphite sealing rings is almost synchronous, and a thin gas film is formed between them, thereby achieving the effects of lubrication and sealing. At the auxiliary sealing surface, the inner and outer graphite sealing rings and the sealing seat always maintain good contact, ensuring the reliability of the sealing. When the rotor is subjected to small disturbances, start-stop stages, and axial movement, due to the action of the double-end staggered axial compression spring installed on both sides of the inner and outer graphite sealing rings, the spring can well offset the influence on the inner and outer graphite sealing rings, so that the inner and outer graphite sealing rings can remain stable, effectively reducing the graphite sealing leakage, maintaining good sealing performance of the graphite sealing, and greatly prolonging the service life of the circumferential graphite sealing. When the engine is at the start-stop stage, the bearing cavity pressure may be greater than the sealing cavity pressure (i.e. negative pressure working condition). The parallel radial double-sealing surface circumferential graphite sealing of the present application, due to the action of the pre-tightening force of the embedded radial compression spring, makes the inner and outer graphite sealing rings tightly attached to the outer surface of the sealing runway and the inner surface of the sealing seat respectively, thereby significantly reducing the bearing oil leakage.

[0050] In summary, the parallel radial double-sealing surface circumferential graphite sealing structure of the present application can meet the sealing performance of the traditional circumferential graphite sealing, and has stronger anti-interference ability than the traditional circumferential graphite sealing, and can better adapt to the increasingly severe working environment of the engine. When the rotor is disturbed, the parallel radial double-sealing surface circumferential graphite sealing structure is less affected. The parallel structure of the sealing surface makes the sealing performance of the auxiliary sealing surface of the inner and outer graphite sealing rings close to that of the main sealing surface, and the symmetrical distribution makes the leakage small when the working condition is in a negative pressure state, greatly reduces the friction and wear of the graphite sealing, and prolongs the service life of the graphite sealing.

[0051] The above description is only used to illustrate the preferred embodiments of the present application, and is not intended to limit the technical solutions described in the present application. Therefore, although the present application has been described in detail with reference to the above embodiments, any modification or equivalent replacement of the present application is still possible. All technical solutions and improvements that do not deviate from the spirit and scope of the present application should be covered within the protection scope of the present application.

Claims

1. A parallel radial double seal face circumferential graphite seal structure installed on a seal race between a rotor and a stator of a rotating machinery of an impeller, characterized in that, At least comprising a sealing seat, an inner graphite sealing ring, an outer graphite sealing ring and a back baffle, wherein: The sealing seat is arranged on the outer side of the fixed part of the sealing structure and forms a support structure of the sealing structure, and at least comprises a front end face and a cylindrical side wall face formed integrally; The inner graphite sealing ring and the outer graphite sealing ring are coaxially arranged in the sealing seat, wherein: the inner surface of the inner graphite sealing ring and the outer cylindrical surface of the sealing runway form a main sealing surface, the outer surface of the outer graphite sealing ring and the inner surface of the cylindrical side wall face of the sealing seat form an auxiliary sealing surface, and the main sealing surface and the auxiliary sealing surface are arranged in parallel in the radial direction; the outer surface of the inner graphite sealing ring and the inner surface of the outer graphite sealing ring are respectively processed to form annular wedge-shaped insertion grooves, the annular wedge-shaped insertion grooves of the two are arranged in a Z-shaped upper and lower lap in the radial direction after being inserted into each other in the axial direction, and are assembled to form an integrated sealing ring assembly; and a plurality of radial installation grooves are uniformly distributed on the outer surface of the inner graphite sealing ring and the inner surface of the outer graphite sealing ring in the circumferential direction, and the radial installation grooves of the two correspond to each other in the circumferential direction, and each two corresponding radial installation grooves are provided with an embedded radial compression spring; The back baffle is arranged on the outer side of the rear end face of the inner graphite sealing ring and the outer graphite sealing ring in the axial direction, and the outer side of the back baffle is provided with a clamping ring clamped on the cylindrical side wall face of the sealing seat; and a plurality of axial compression springs are uniformly arranged in the circumferential direction between the back end face of the inner graphite sealing ring and the back baffle, and between the inner surface of the front end face of the sealing seat and the front end face of the outer graphite sealing ring, and the axial compression springs arranged on the front and rear end faces of the sealing ring assembly form a double-end staggered arrangement structure in space.

2. The parallel radial dual seal face circumferential graphite seal structure of claim 1 wherein, The inner graphite sealing ring and the outer graphite sealing ring are both fan-shaped split lap joint structures, a plurality of fan-shaped split bodies are spliced in the circumferential direction and connected in the circumferential direction through the lap joint faces, and the lap joint faces between adjacent split bodies are geometric interfaces with structural symmetry, the number of the fan-shaped split ring is adjusted according to actual application requirements to adapt to sealing requirements of different sizes and working conditions, and the split positions of the inner graphite sealing ring and the outer graphite sealing ring are consistent in the circumferential direction.

3. The parallel, radial, double seal face, circumferential, graphite seal structure of claim 2 wherein, Each split body of the inner graphite sealing ring and the outer graphite sealing ring is provided with a plurality of radial installation grooves uniformly distributed in the circumferential direction, both ends of each embedded radial compression spring are embedded in the radial installation grooves with a circular cross section arranged on the split bodies of the inner and outer graphite sealing rings, and each embedded radial compression spring is in a compressed preloaded state before assembly, so as to ensure that the main sealing surface and the auxiliary sealing surface obtain uniform and appropriate radial pre-tightening force distribution.

4. The parallel double radial seal surface circumferential graphite seal structure according to claim 2 or 3, characterized in that, The rear end face of the inner graphite seal ring and the front end face of the rear baffle are both provided with a plurality of axial grooves in the circumferential direction, and the axial grooves of the two correspond to each other in the circumferential direction and are located on the inner side in the radial direction; the two ends of each inner ring axial compression spring are respectively installed in the axial grooves provided on the inner graphite seal ring and the rear baffle; the front end face of the outer graphite seal ring and the inner surface of the front end face of the seal seat are both provided with a plurality of axial grooves in the circumferential direction, and the axial grooves of the two correspond to each other in the circumferential direction and are located on the outer side in the radial direction; the two ends of each outer ring axial compression spring are respectively installed in the axial grooves provided on the outer graphite seal ring and the front end face of the seal seat; and the inner ring axial compression spring and the outer ring axial compression spring are arranged in a double-end staggered structure in space.

5. The parallel, radial, double seal face, circumferential, graphite seal structure of claim 4 wherein, The inner ring axial compression spring and the outer ring axial compression spring are respectively located on the two sides of the seal ring assembly in the axial direction, the installation positions of the inner and outer ring axial compression springs correspond to each other, the slotted positions on the two sides have the same angle, the slotted depths are consistent, and the number of slots is consistent; and the number, length and elastic coefficient of the axial compression spring are adapted to the split number of the inner and outer graphite seal rings and the working condition requirements.

6. The parallel, radial dual seal face circumferential graphite seal structure of claim 1 wherein, A limiting groove is provided at the junction of the front end faces of the inner and outer graphite seal rings, for installing an anti-rotation pin, one end of the anti-rotation pin is arranged in the limiting groove, and the other end extends into a limiting hole provided on the front end face of the mounting seat, so as to prevent the inner and outer graphite seal rings from rotating, and the anti-rotation pin is in cylindrical surface contact with the seal ring.

7. The parallel, radial dual seal face circumferential graphite seal structure of claim 1 wherein, The clamping ring is fixed through a clamping groove provided on the cylindrical side wall surface of the seal seat, and a positioning hole is provided on the radial outer side wall of the seal seat cylindrical side wall surface and the rear baffle, for installing a positioning pin, the positioning pin is embedded in interference fit or interference fit, one end of the positioning pin is inserted into the positioning hole on the seal seat, and the other end is inserted into the corresponding hole on the rear baffle.

8. The parallel, radial dual seal face circumferential graphite seal structure of claim 1 wherein, The inner surface of the inner graphite seal ring and the outer surface of the outer graphite seal ring are both provided with a plurality of annular V-shaped grooves arranged in the axial direction, and the depth, width and spacing of the V-shaped grooves are optimized to adapt to different sealing working conditions and performance requirements.

9. The parallel, radial dual seal face circumferential graphite seal structure of claim 8 wherein, At least one of the sealing surfaces of the inner graphite seal ring and the outer graphite seal ring is provided with a plurality of axial ventilation grooves, the depth of the ventilation grooves is consistent with the groove depth of the sealing surface, each ventilation groove is arranged along the thickness direction of the graphite ring and is symmetrically distributed, and each two adjacent ventilation grooves have an included angle, so that part of the high-pressure gas flow flows into the sealing surface through the axial ventilation grooves, thereby reducing the pressure difference on both sides of the graphite ring.

10. An impeller rotary machine characterized by comprising: The sealing runway is provided with the parallel radial double-sealing surface circumferential graphite sealing structure according to any one of claims 1-9, and the impeller rotating machine is a turbine-based combined cycle engine, a rocket-based combined cycle engine, an air turbine rocket combined power engine, an aero-engine, a gas turbine or a steam turbine.

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