An improved inter-shaft seal arrangement for a primary seal ring

Abstract

The application provides an improved inter-shaft sealing structure of a main sealing ring, comprising: a sealing bush; a high-pressure rotor; a sealing seat arranged on the outer side of the high-pressure rotor, which is provided with a front sealing track and a main sealing ring, the front sealing track is in contact with the front end surface of the main sealing ring for sealing, the sealing seat is provided with a groove, a secondary sealing ring is arranged in the groove, the sealing bush is arranged on the outer side of the main sealing ring and is in contact with the main sealing ring for sealing; a wave spring is arranged between the end surface of the high-pressure rotor and the sealing seat and between the sealing seat and the front sealing track; a rear sealing track is arranged on the outer side of the high-pressure rotor and is in contact with the rear end surface of the main sealing ring for sealing; wherein the main sealing ring is an open graphite ring structure, the outer edge surface of the main sealing ring is provided with a first air inlet hole and a second air inlet hole, the two air inlet holes are alternately distributed in the circumferential direction, the main sealing ring is provided with a first air outlet hole and a second air outlet hole, the first air outlet hole is in communication with the first air inlet hole, and the second air outlet hole is in communication with the second air inlet hole.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aero-engine sealing, and particularly relates to an improved shaft-seal structure of a main seal ring. BACKGROUND

[0002] With the continuous increase of high thrust ratio, high pressure ratio and high temperature ratio of an aero-engine, the linear speed of a main shaft seal, the sealing differential pressure and the use temperature are continuously increased, and the working condition is increasingly harsh. In an advanced engine, the high-pressure turbine is usually supported on the low-pressure turbine, and the spatial position of the bearing cavity seal is limited, so a compact shaft-seal device needs to be used. Meanwhile, the sealing differential pressure of the advanced engine is relatively high, and the traditional non-contact labyrinth seal will cause high temperature of the bearing cavity and large oil consumption, which brings great loss to the performance of the engine.

[0003] As shown in Figure 1 and Figure 2 , the shaft-seal structure 10 in the prior art is composed of a whole main seal ring 11 and an open first carbon graphite ring 12 installed on the main seal ring 11, and is a sealing device arranged between an outer rotating shaft 16 and an inner rotating shaft 17. An open second carbon graphite ring 14 is installed on a front seal track 13 to perform secondary sealing. The front seal track 13 has a certain axial adaptability through a wave spring 15, so as to realize wear compensation of the sealing surface of the main seal ring 11. Gas flows into cavities B and C of the main seal ring through throttle holes d1-d2 from the high-pressure end, and forms a gas film seal on both sides of the main seal ring 11.

[0004] In the working process, the first carbon graphite ring 12 in the main seal ring 11 rotates with the outer rotating shaft 16, and the remaining parts rotate with the inner rotating shaft 17. This structure has the following disadvantages:

[0005] 1) Since the main seal ring 11 is a whole ring structure, it will be leaned against the lower side of the outer rotating shaft 16 due to the influence of gravity at the beginning of work, and a large eccentricity exists. In addition, a huge eccentric centrifugal force is generated due to the influence of the rotating speed in the working process. At the same time, due to the influence of the eccentricity of the main seal ring 11, local wear of the main seal ring 11 is easily caused, and the main seal ring 11 is damaged;

[0006] 2) There are multiple sealing surfaces in the shaft-seal structure, such as the first carbon graphite ring 12 and the outer rotating shaft 16, the first carbon graphite ring 12 and the main seal ring 11, the main seal ring 11 and the rear seal track end surface, and the second carbon graphite ring 14 and the front seal track 13. Air leakage occurs at each sealing surface, resulting in large leakage;

[0007] 3) When the main seal ring 11 is subjected to unbalanced gas film force on both sides, axial movement of the main seal ring 11 will occur. At this time, the sealing surfaces of the first carbon graphite ring 12 and the main seal ring 11 can be separated, causing the sealing function to fail;

[0008] 4) The maximum pressure difference that the inter-shaft seal can withstand is the pressure difference that the open carbon graphite ring can withstand, and the ability to adapt to large pressure differences is weak. SUMMARY

[0009] The purpose of the present application is to provide an improved inter-shaft sealing structure of the main sealing ring to solve or alleviate at least one problem in the background art.

[0010] The technical solution of the present application is: an improved inter-shaft sealing structure of the main sealing ring, comprising:

[0011] a sealing bushing;

[0012] a high-pressure rotor;

[0013] a sealing seat located between the sealing bushing and the high-pressure rotor and arranged on the outer side surface of the high-pressure rotor, the sealing seat being provided with a front sealing runway and a main sealing ring, the front sealing runway being in contact with the front end surface of the main sealing ring, the sealing seat being provided with a groove, and a secondary sealing ring being arranged in the groove, the sealing bushing being arranged on the outer side of the main sealing ring and being in contact with the main sealing ring;

[0014] a wave spring arranged between the end surface of the high-pressure rotor and the sealing seat and between the sealing seat and the front sealing runway;

[0015] a rear sealing runway arranged on the outer side surface of the high-pressure rotor, the rear sealing runway being in contact with the rear end surface of the main sealing ring;

[0016] wherein the main sealing ring is an open graphite ring structure, the outer edge surface of the main sealing ring is provided with a first gas inlet hole and a second gas inlet hole, the first gas inlet hole and the second gas inlet hole are alternately distributed in the circumferential direction, the front end surface of the main sealing ring is provided with a first gas outlet hole, and the rear end surface is provided with a second gas outlet hole, the first gas outlet hole is in communication with the first gas inlet hole, and the second gas outlet hole is in communication with the second gas inlet hole.

[0017] In the preferred embodiment of the present application, a coating is sprayed on the mating inner diameter surface of the sealing bushing in contact with the main sealing ring.

[0018] In the preferred embodiment of the present application, the maximum opening gap of the main sealing ring is 0.1 mm.

[0019] In the preferred embodiment of the present application, the diameter of the first gas outlet hole is smaller than the diameter of the first gas inlet hole, and the diameter of the second gas outlet hole is smaller than the diameter of the second gas inlet hole.

[0020] In the preferred embodiment of the present application, the outer surface of the front sealing runway is provided with a plurality of grid teeth, and the grid teeth form a sealing structure with the sealing bushing.

[0021] In a preferred embodiment of this application, the number of teeth in the comb is 5 to 6.

[0022] In a preferred embodiment of this application, a vent is provided on one side of the front sealing runway adapter main sealing ring to facilitate airflow for air film sealing.

[0023] The shaft sealing structure provided in this application adopts an open-type main sealing ring structure, which is simple in structure, can eliminate the friction and wear caused by the eccentricity of the original main sealing ring, reduce leakage, eliminate the risk of the sealing surface separating, and at the same time increase the pressure difference that the shaft seal can withstand. Attached Figure Description

[0024] 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.

[0025] Figure 1 This is a schematic diagram of an inter-shaft seal structure in the prior art.

[0026] Figure 2 This is a schematic diagram of the flow path of an inter-shaft sealing structure in the prior art.

[0027] Figure 3 This is a schematic diagram of the inter-shaft sealing structure of this application (the main sealing ring draws air to the right).

[0028] Figure 4 This is a schematic diagram of the inter-shaft sealing structure of this application (the main sealing ring draws air to the left).

[0029] Figure 5 This is a schematic diagram of the main sealing ring structure of this application.

[0030] Figure 6 Based on Figure 5 Sectional view of the main sealing ring in the BB direction.

[0031] Figure 7 Based on Figure 5 Sectional view of the main sealing ring along the AA direction.

[0032] Figure 8 This is a schematic diagram of the front-sealed runway structure of this application.

[0033] Figure 9 This is a schematic diagram of the flow path of the inter-shaft sealing structure of this application (the main sealing ring draws air to the right).

[0034] Figure 10 This is a schematic diagram of the flow path of the inter-shaft sealing structure of this application (the main sealing ring draws air to the left).

[0035] Figure 11 This is a schematic diagram of the force applied to the main sealing ring in this application. DETAILED DESCRIPTION

[0036] For the purpose, technical solutions and advantages of the present application, the technical solutions 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.

[0037] In order to solve the problem that the whole ring structure of the main sealing ring is easy to be eccentric and cause wear and damage in the prior art inter-shaft sealing structure, or the problem that the sealing surface of the inter-shaft sealing is too much and causes large leakage, or the problem that the main sealing ring and the first carbon graphite ring are separated in work, the present application provides a novel inter-shaft sealing structure, which designs the main sealing ring into an open ring sealing, cancels the original carbon graphite ring, and the open ring form main sealing is attached to the sealing bush (outer rotating shaft) in work, avoiding the eccentricity problem of the main sealing ring, reducing the sealing surface of the original carbon graphite ring and the main sealing ring, and designing a grate on the front sealing runway, which can greatly reduce the leakage and directly avoid the separation problem of the original carbon graphite and the main sealing ring.

[0038] As shown in Figure 3 and Figure 4 , the inter-shaft sealing structure 20 provided by the present application includes a sealing bush 21, a front sealing runway 22, a main sealing ring 23, a rear sealing runway 24, a secondary sealing ring 25, a wave spring 26, a sealing seat 27 and a high-pressure rotor 28.

[0039] The sealing seat 27 is arranged on the outer side surface of the high-pressure rotor 28, the front sealing runway 22 and the main sealing ring 23 are arranged on the sealing seat 27, and the front sealing runway 22 is in contact with the main sealing ring 23 for sealing, the wave spring 26 is arranged between the end surface of the high-pressure rotor 28 and the sealing seat 27, and between the sealing seat 27 and the front sealing runway 22. The rear sealing runway 24 is arranged on the outer side surface of the high-pressure rotor 28, and is in contact with the main sealing ring 23 for sealing. The sealing seat 27 is provided with a groove, the secondary sealing ring 25 is arranged in the groove, and the secondary sealing ring 25 is in contact with the front sealing runway 22 to form secondary sealing. The sealing bush 21 is arranged on the outer side of the main sealing ring 23, and is in contact with the main sealing ring 23 for sealing.

[0040] In the preferred embodiment of the present application, a coating layer 211 is sprayed on the cooperation inner diameter surface of the sealing bush 21 and the main sealing ring 23 for contact sealing, for reducing the friction coefficient, thereby reducing the friction and wear of the main sealing ring 23.

[0041] As shown in Figures 5 to 7As shown, the main sealing ring 23 is an open graphite ring structure, and the maximum value of the open gap S is 0.1 mm. The first gas inlet hole 231 and the second gas inlet hole 233 are arranged on the outer edge surface of the main sealing ring 23, and the first gas inlet hole 231 and the second gas inlet hole 233 are alternately distributed in the circumferential direction. The first gas outlet hole 232 is arranged on the front end surface (high pressure side) of the main sealing ring 23, and the second gas outlet hole 234 is arranged on the rear end surface (low pressure side) of the main sealing ring 23. The first gas outlet hole 232 is in communication with the first gas inlet hole 231, and the second gas outlet hole 234 is in communication with the second gas inlet hole 233. The diameter of the first gas outlet hole 232 is smaller than the diameter of the first gas inlet hole 231, so that a throttling effect is formed in the gas flow process, and a hydrostatic pressure gas film sealing effect is formed between the main sealing ring 23 and the front sealing track 22. Similarly, the diameter of the second gas outlet hole 234 is smaller than the diameter of the second gas inlet hole 233, so that a throttling effect is formed in the gas flow process, and a hydrostatic pressure gas film sealing effect is formed between the main sealing ring 23 and the rear sealing track 24.

[0042] As shown in Figure 8 The outer surface of the front sealing track 22 is provided with a certain number of grate teeth 221, and the number of the grate teeth 221 is 5-6. In the working process, the sealing structure formed by the grate teeth 221 and the sealing bush 21 will bear part of the pressure, thereby increasing the use pressure difference of the reverse shaft sealing. At the same time, the front sealing track 22 is provided with a gas hole 222 on the side matched with the main sealing ring 23, which is used for realizing the gas flow of the gas film sealing. The front sealing track of the application solves the problem of weak large pressure difference adaptability in the prior art. When high pressure air comes, the grate teeth are first sealed to achieve a certain pressure drop, thereby reducing the pressure borne by the main sealing ring, thereby improving the pressure difference borne by the whole shaft sealing.

[0043] As shown in Figure 9 and Figure 10As shown, the main sealing ring 23 is an open ring. Under the action of the opening force, the main sealing ring 23 is close to the inner diameter of the sealing bushing 21. During operation, the main sealing ring 23 and the sealing bushing 21 rotate together with the low-pressure shaft (not shown), and the other components rotate with the high-pressure rotor 28. At this time, sealing air with a high pressure difference is introduced into the high-pressure side. After the sealing air passes through the grates 221 on the front sealing track 22, a pressure drop will occur. The sealing gas venting is then divided into four main flow paths: the sealing gas in the first path enters the low-pressure side (i.e., the bearing cavity) directly through the main sealing surface between the main sealing ring 23 and the sealing bushing 21; the second path passes through the contact sealing surface between the main sealing ring 23 and the front sealing raceway 22; the third path passes through the first air inlet 231 and the first air outlet 232, forming a hydrostatic pressure gas film seal at the sealing contact surface between the main sealing ring 23 and the front sealing raceway 22; the fourth path passes through the second air inlet 233 and the second air outlet 234, forming a hydrostatic pressure seal at the contact surface between the main sealing ring 23 and the rear sealing raceway 24, with some sealing gas venting flowing through the main sealing surface into the bearing cavity on the low-pressure side; and some sealing gas from the second, third, and fourth paths enters the low-pressure side through the vent on the rear sealing raceway 24.

[0044] like Figure 11 As shown, under stable working conditions of the inter-shaft seal, the sealing gaps on both sides of the main sealing ring 23 are h1 and h2, respectively. When the sealing gap changes due to some disturbance, such as a decrease in gap h1 and an increase in gap h2, the low-pressure side force F2 decreases. At this time, the high-pressure side force F1 > the low-pressure side force F2. When the difference between the forces on both sides F1-F2 > the sliding friction force F f When the pressure is high, the force F1 on the high-pressure side at gap h1 pushes the main sealing ring 23 to the right, increasing gap h1 and decreasing gap h2. Conversely, the force F2 on the low-pressure side pushes the main sealing ring 23 to the left, decreasing gap h1 and increasing gap h2. This maintains the main sealing ring 23 to adapt to the relative displacement of the high and low pressure rotors caused by external interference. The wave spring 26 effectively compensates for the wear on the end face of the main sealing ring, ensuring sealing performance.

[0045] The shaft sealing structure provided in this application adopts an open-type main sealing ring structure, which is simple in structure, can eliminate the friction and wear caused by the eccentricity of the original main sealing ring, reduce leakage, eliminate the risk of the sealing surface separating, and at the same time increase the pressure difference that the shaft seal can withstand.

[0046] 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. An improved inter-shaft sealing structure for a main sealing ring, characterized in that, include: Sealing bushing (21); High-pressure rotor (28); A sealing seat (27) is located between the sealing bushing (21) and the high-pressure rotor (28) and is disposed on the outer side of the high-pressure rotor (28). The sealing seat (27) is provided with a front sealing track (22) and a main sealing ring (23). The front sealing track (22) is in contact with the front end face of the main sealing ring (23) for sealing. The sealing seat (27) is provided with a groove, and a secondary sealing ring (25) is provided in the groove. The sealing bushing (21) is disposed outside the main sealing ring (23) and is in contact with the main sealing ring (23) for sealing. Wave springs (26) are installed between the end face of the high-pressure rotor (28) and the sealing seat (27) and between the sealing seat (27) and the front sealing track (22); A rear sealing track (24) is provided on the outer side of the high-pressure rotor (28), and the rear sealing track (24) contacts and seals with the rear end face of the main sealing ring (23); The main sealing ring (23) is an open graphite ring structure. A first air inlet (231) and a second air inlet (233) are provided on the outer edge surface of the main sealing ring (23). The first air inlet (231) and the second air inlet (233) are alternately distributed in the circumferential direction. A first air outlet (232) is provided on the front end face of the main sealing ring (23) and a second air outlet (234) is provided on the rear end face. The first air outlet (232) is connected to the first air inlet (231) and the second air outlet (234) is connected to the second air inlet (233).

2. The improved inter-shaft sealing structure of the main sealing ring as described in claim 1, characterized in that, The sealing bushing (21) is coated with a coating (211) on the inner diameter surface of the mating seal where it contacts and seals the main sealing ring (23).

3. The improved inter-shaft sealing structure of the main sealing ring as described in claim 1, characterized in that, The maximum opening gap of the main sealing ring (23) is 0.1 mm.

4. The improved inter-shaft sealing structure of the main sealing ring as described in claim 1 or 3, characterized in that, The diameter of the first air outlet (232) is smaller than the diameter of the first air inlet (231), and the diameter of the second air outlet (234) is smaller than the diameter of the second air inlet (233).

5. The improved inter-shaft sealing structure of the main sealing ring as described in claim 1, characterized in that, The outer surface of the front sealing runway (22) is provided with a plurality of grates (221), and the grates (221) and the sealing bushing (21) form a sealing structure.

6. The improved inter-shaft sealing structure of the main sealing ring as described in claim 5, characterized in that, The number of teeth in the comb (221) is 5 to 6.

7. The improved inter-shaft sealing structure of the main sealing ring as described in claim 5 or 6, characterized in that, The front sealing runway (22) is provided with a vent (222) on one side of the main sealing ring (23) to achieve airflow for air film sealing.

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