Graphite circumferential seal structure based on hydrostatic pressure

Abstract

The application provides a graphite circumferential sealing structure based on hydrostatic pressure, which comprises a sealing seat, a sealing runway, a graphite ring arranged between the sealing seat and the sealing runway, an inner surface of the graphite ring and an outer cylindrical surface of the sealing runway forming a main sealing surface, an end surface of the graphite ring and a convex edge end surface of the sealing seat forming an auxiliary sealing surface, a circumferential spring clamped on an outer surface of the graphite ring, a pressing plate arranged on the end surface of the graphite ring, a clasp and a wave spring seat installed on the sealing seat, a wave spring arranged between the pressing plate and the wave spring seat, an anti-rotation pin with one end inserted into the sealing seat and the other end matched with the graphite ring to realize anti-rotation, and radial gas film throttling holes and axial gas film throttling holes penetrating through the graphite ring in the radial direction and the axial direction, and gas film formed on the main sealing surface and the auxiliary sealing surface by the sealing gas of the high-pressure side from the radial gas film throttling holes and the axial gas film throttling holes.

Description

Technical Field

[0001] This application belongs to the field of aero-engine sealing technology, and specifically relates to a graphite circumferential sealing structure based on hydrostatic pressure. Background Technology

[0002] Graphite circumferential seals are a type of contact seal. Due to their compact structure and lower leakage rate compared to toothed seals, they are widely used in engine bearing cavity sealing.

[0003] A graphite circumferential seal typically consists of a sealing element, a sealing seat, a circumferential spring, a wave spring, and other structural components. The main sealing surface in the circumferential direction is formed by the contact between the inner diameter of the sealing element and the outer surface of the sealing track. The auxiliary sealing surface is formed by the contact between the end face of the sealing element and the convex edge end face of the sealing seat, thereby achieving the sealing performance of the graphite circumferential seal.

[0004] Since graphite circumferential seals are contact seals, they will experience significant friction and wear under high-speed and high-pressure operating conditions. This results in severe wear on the main sealing strip and auxiliary sealing strip of the seal, greatly limiting the service life of the graphite circumferential seal. Summary of the Invention

[0005] The purpose of this application is to provide a graphite circumferential sealing structure based on hydrostatic pressure to solve or mitigate at least one of the problems in the prior art.

[0006] The technical solution of this application is: a graphite circumferential sealing structure based on hydrostatic pressure, comprising:

[0007] Sealing seat;

[0008] Sealed runway;

[0009] A graphite ring is disposed between the sealing seat and the sealing track. The inner surface of the graphite ring and the outer cylindrical surface of the sealing track form the main sealing surface, and the end face of the graphite ring and the convex edge end face of the sealing seat form the auxiliary sealing surface.

[0010] A circumferential spring clamped to the outer surface of the graphite ring is used to provide the initial contact load between the graphite ring and the main sealing surface of the sealing track.

[0011] A pressure plate, a retaining ring, and a wave spring seat are mounted on the end face of the graphite ring and installed on the sealing seat. A wave spring is provided between the pressure plate and the wave spring seat to provide the initial contact load of the auxiliary sealing surface between the graphite ring and the sealing seat.

[0012] The anti-rotation pin has one end inserted into the sealing seat and the other end engaged with the graphite ring to prevent rotation.

[0013] The graphite ring has radial and axial through-holes, and the sealing air duct on the high-pressure side can form an air film on the main sealing surface and the auxiliary sealing surface through the radial and axial through-holes.

[0014] In a preferred embodiment of this application, the axis of the radial air film throttling orifice is located within the range of the main sealing surface, thereby dividing the main sealing surface into two axial parts. The axis of the axial air film throttling orifice is located within the range of the auxiliary sealing surface, thereby dividing the auxiliary sealing surface into two radial parts.

[0015] In a preferred embodiment of this application, a first annular pressure equalization groove is provided on one side of the main sealing surface of the radial air film throttling orifice, and a first pressure equalization ring of porous medium material is provided in the first annular pressure equalization groove.

[0016] In a preferred embodiment of this application, a second annular pressure equalization groove is provided on one side of the auxiliary sealing surface of the axial air film throttling orifice, and a second pressure equalization ring of porous medium material is provided in the second annular pressure equalization groove.

[0017] In a preferred embodiment of this application, the radial air film throttling orifice and the axial air film throttling orifice are staggered in the circumferential direction.

[0018] In a preferred embodiment of this application, the graphite ring is composed of several equally divided high-precision graphite material arc segments distributed along the circumference. The first annular pressure equalizing groove, the second annular pressure equalizing groove, the first pressure equalizing ring, and the second pressure equalizing ring are all arc segment structures and are adapted to be disposed on each arc segment of the graphite ring.

[0019] The graphite circumferential sealing structure of this application can change the original contact seal into a gas film seal by machining a gas film throttling hole on the graphite ring without changing the original graphite circumferential sealing structure. This changes the contact state of the sealing surface and greatly reduces friction and wear. Attached Figure Description

[0020] To more clearly illustrate the technical solutions provided in this application, the accompanying drawings will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application.

[0021] Figure 1 This is a schematic diagram of the graphite circumferential seal structure based on hydrostatic pressure according to this application.

[0022] Figure 2 This is a schematic diagram of the radial air film throttling orifice of the graphite ring in this application.

[0023] Figure 3 This is a schematic diagram of the axial film throttling orifice of the graphite ring in this application.

[0024] Figure 4Based on Figure 3 Schematic diagram of radial air film throttling orifice in the AA section.

[0025] Figure 5 Based on Figure 3 Schematic diagram of the axial film throttling orifice in the B direction.

[0026] Figure 6 This is a schematic diagram of the flow path of the graphite circumferential sealing structure based on hydrostatic pressure in this application.

[0027] Figure 7 This is a schematic diagram of the force on the graphite ring in this application.

[0028] Figure 8 This is a schematic diagram of the flow path of a traditional graphite circumferential seal structure.

[0029] Figure 9 This is a schematic diagram of the forces acting on a traditional graphite ring.

[0030] Figure label:

[0031] 1-Sealing seat

[0032] 2-Graphite ring

[0033] 21-Radial film throttling orifice

[0034] 22-First annular uniform groove

[0035] 23-First equalizing ring

[0036] 24-Axial film throttling orifice

[0037] 25-Second annular groove

[0038] 26-Second equalizing ring

[0039] 3-Card Circle

[0040] 4-Spring seat

[0041] 5-Wave Spring

[0042] 6-Pressure plate

[0043] 7-Anti-spinning

[0044] 8-Sealed runway

[0045] 9-Circumferential Spring Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings.

[0047] To address the technical problems of high friction and wear, and severe wear of the main and auxiliary sealing strips in existing contact-type graphite circumferential seals, this application proposes a hydrostatic graphite circumferential seal structure. Specifically, a certain number and diameter of gas film lubrication holes are machined on the radial sealing surface and axial end face of the graphite ring. During operation, the graphite circumferential seal generates a hydrostatic effect on the main and auxiliary sealing surfaces, causing the sealing surfaces to be separated by a stable gas film. This significantly reduces frictional heat, and the gas film isolation greatly reduces wear on the sealing surfaces.

[0048] like Figure 1 As shown, the graphite circumferential sealing structure based on hydrostatic pressure provided in this application includes a sealing seat 1, a graphite ring 2, a retaining ring 3, a wave spring seat 4, a wave spring 5, a pressure plate 6, an anti-rotation pin 7, a sealing raceway 8, and a circumferential spring 9.

[0049] The inner surface of graphite ring 2 and the outer cylindrical surface of sealing track 8 form the main sealing surface A. The left end face of graphite ring 2 and the convex end face of sealing seat 1 form the auxiliary sealing surface B. A circumferential spring 9 is clamped to the outer surface of graphite ring 2 to provide the initial contact load between graphite ring 2 and the main sealing surface A of sealing track 8. A pressure plate 6 is provided on the right end face of graphite ring 2. A retaining ring 3 and a wave spring seat 4 are installed on sealing seat 1. A wave spring 5 is provided between pressure plate 6 and wave spring seat 4 to provide the initial contact load between graphite ring 2 and auxiliary sealing surface B of sealing seat 1. One end of anti-rotation pin 7 is inserted into sealing seat 1, and the other end cooperates with graphite ring 2 to achieve anti-rotation.

[0050] like Figure 2 As shown, the graphite ring 2 is composed of several equally divided high-precision graphite material arc segments distributed circumferentially. A radial air film throttling hole 21 is provided in the radial direction of the graphite ring 2. The radial air film throttling hole 21 penetrates radially and divides the main sealing surface A into two axial front and rear parts. At the same time, in order to ensure the uniformity of the throttling section, a circumferential first annular pressure equalization groove 22 is provided at the lower end of the radial air film throttling hole 21 (i.e., one end of the main sealing surface A). In order to further ensure the throttling pressure equalization effect, a first pressure equalization ring 23 of porous medium material is installed in the first annular pressure equalization groove 22.

[0051] like Figure 3 As shown, an axial air film throttling orifice 24 is provided on the axial direction of the graphite ring 2. The axial air film throttling orifice 24 penetrates axially and divides the auxiliary sealing surface B into two radial upper and lower parts. At the same time, in order to ensure the uniformity of the throttling section, a circumferential second annular pressure equalizing groove 25 is provided at the front end of the axial air film throttling orifice 24 (i.e., one end of the auxiliary sealing surface B). In order to further ensure the throttling pressure equalizing effect, a second pressure equalizing ring 26 of porous medium material is installed in the second annular pressure equalizing groove 25.

[0052] like Figure 4 and Figure 5As shown, the radial air film throttling orifice 21 and the axial air film throttling orifice 24 on the graphite ring 2 are alternately distributed in the circumferential direction. The first annular pressure equalizing groove 22, the second annular pressure equalizing groove 25, the first pressure equalizing ring 23, and the second pressure equalizing ring 26 are all arc-shaped segment structures, which are adapted to be set on each arc-shaped segment of the graphite ring 2.

[0053] like Figure 6 and Figure 7 The diagram shown illustrates the flow path and force distribution of the graphite ring in the circumferential graphite sealing structure of this application. In this application, high-pressure sealing air is introduced from the high-pressure side. A portion of the high-pressure sealing air flows directly to the low-pressure side through the main sealing surface A between the graphite ring 2 and the sealing raceway 8. Another portion of the high-pressure sealing air is introduced into the main sealing surface A between the graphite ring 2 and the sealing raceway 8 through the radial gas film throttling orifice 21. This changes the pressure distribution between the sealing surfaces, achieving a balance with the sealing pressure. This reduces the sealing closing force to generate a limited gas film, forming fluid lubrication to avoid large frictional wear on the friction contact surface. Similarly, a portion of the high-pressure sealing bleed air flows directly to the low-pressure side through the auxiliary sealing surface B between the graphite ring 2 and the sealing seat 1, while another portion of the high-pressure sealing bleed air is introduced into the auxiliary sealing surface B between the graphite ring 2 and the sealing seat 1 through the axial gas film throttling orifice 24. This changes the pressure distribution between the sealing surfaces, achieving a balance with the sealing pressure, thereby reducing the sealing closing force to generate a limited gas film, which forms fluid lubrication to avoid large frictional wear on the friction contact surface.

[0054] Compared to Figure 8 and Figure 9 The diagram shows the flow path and force distribution of the graphite ring in a traditional circumferential graphite seal structure. The graphite circumferential seal structure of this application can change the original contact seal to a gas film seal by machining a gas film throttling hole on the graphite ring without altering the original circumferential graphite seal structure. This changes the contact state of the sealing surface and greatly reduces friction and wear. The structure is easy to implement and does not affect assembly and use.

[0055] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A graphite circumferential sealing structure based on hydrostatic pressure, characterized in that, include: Sealing seat (1); Sealed runway (8); A graphite ring (2) is set between the sealing seat (1) and the sealing track (8). The inner surface of the graphite ring (2) and the outer cylindrical surface of the sealing track (8) form the main sealing surface, and the end face of the graphite ring (2) and the convex end face of the sealing seat (1) form the auxiliary sealing surface. A circumferential spring (9) clamped to the outer surface of the graphite ring (2) is used to provide the initial contact load between the graphite ring (2) and the main sealing surface of the sealing runway (8); A pressure plate (6) is set on the end face of the graphite ring (2), a retaining ring (3) and a wave spring seat (4) are installed on the sealing seat (1), and a wave spring (5) is set between the pressure plate (6) and the wave spring seat (4) to provide the initial contact load of the auxiliary sealing surface between the graphite ring (2) and the sealing seat (1); The anti-rotation pin (7) has one end inserted into the sealing seat (1) and the other end engaged with the graphite ring (2) to achieve anti-rotation; The graphite ring (2) has radially penetrating and axially penetrating radial air film throttling holes (21) and axial air film throttling holes (24). The radial air film throttling holes (21) and axial air film throttling holes (24) are staggered in the circumferential direction. The sealing air duct on the high-pressure side can form an air film on the main sealing surface and the auxiliary sealing surface from the radial air film throttling holes (21) and the axial air film throttling holes (24).

2. The graphite circumferential sealing structure based on hydrostatic pressure as described in claim 1, characterized in that, The axis of the radial air film throttling orifice (21) is located within the range of the main sealing surface, thereby dividing the main sealing surface into two axial parts. The axis of the axial air film throttling orifice (24) is located within the range of the auxiliary sealing surface, thereby dividing the auxiliary sealing surface into two radial parts.

3. The graphite circumferential sealing structure based on hydrostatic pressure as described in claim 2, characterized in that, The radial air film throttling orifice (21) has a circumferential first annular pressure equalization groove (22) on one side of the main sealing surface, and a first pressure equalization ring (23) of porous medium material is provided in the first annular pressure equalization groove (22).

4. The graphite circumferential sealing structure based on hydrostatic pressure as described in claim 3, characterized in that, The axial air film throttling orifice (24) has a circumferential second annular pressure equalizing groove (25) on one side of the auxiliary sealing surface, and a second pressure equalizing ring (26) of porous medium material is provided in the second annular pressure equalizing groove (25).

5. The graphite circumferential sealing structure based on hydrostatic pressure as described in claim 4, characterized in that, The graphite ring (2) is composed of several equally divided high-precision graphite material arc segments distributed along the circumference. The first annular pressure equalizing groove (22), the second annular pressure equalizing groove (25), the first pressure equalizing ring (23), and the second pressure equalizing ring (26) are all arc segment structures and are adapted to be set on each arc segment of the graphite ring (2).

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