A labyrinth combined multi-stage brush seal structure

Abstract

The present invention discloses a labyrinth-combined multi-stage brush seal structure, and more particularly relates to a high-reliability and high-life labyrinth-combined multi-stage brush seal structure that utilizes a single-stage brush seal and a labyrinth seal in a megapascal ultra-high pressure differential sealing environment and flexibly optimizes the combination of the seal to meet the ultra-high pressure differential sealing requirements. The structure can be widely used in air systems, wheel rim seals, and bearing cavity seals of impeller rotating machinery such as turbine-based combined cycle engines, rocket-based combined cycle engines, air-turbine-rocket combined power engines, aircraft engines, gas turbines, steam turbines, and the like.

Description

Technical Field

[0001] The present invention belongs to the field of non-contact labyrinth seals and contact brush seals, and relates to a labyrinth combination multi-stage brush seal structure, and more particularly to a high-reliability and high-life labyrinth combination multi-stage brush seal structure that utilizes a flexible and optimized combination of a single-stage brush seal and a labyrinth seal in a megapascal ultra-high pressure differential sealing environment to meet the ultra-high pressure differential sealing requirements. The structure can be widely used in air systems, wheel rim seals, and bearing cavity seals of impeller rotating machinery such as turbine-based combined cycle engines, rocket-based combined cycle engines, air-turbine-rocket combined power engines, aircraft engines, gas turbines, steam turbines, and the like. Background Art

[0002] Brush seal is a contact dynamic sealing technology with excellent sealing performance. Its leakage is only 1 / 5 to 1 / 10 of that of traditional labyrinth seal. Due to the existence of inherent gap, the sealing performance of traditional labyrinth seal is limited. When controlling leakage, it will generate airflow excitation force, which is easy to induce rotor vortex instability. There will be friction between the traditional labyrinth seal and the rotor, which will permanently increase the sealing gap and cause leakage loss to increase. Brush seal is mainly composed of front baffle, rear baffle and brush bundle. The front baffle mainly plays the role of protecting the brush bundle, and the rear baffle mainly supports the brush bundle to prevent the brush from being greatly deformed under the action of high-speed airflow. The brush bundle has a certain inclination along the circumference of the rotor, which can reduce the wear between the brush bundle and the rotor. At the same time, when the rotor jumps, the flexible brush can move with the rotor to reduce gas leakage.

[0003] Brush seals are mainly divided into two types: single-stage and multi-stage. Single-stage brush seals have limited pressure bearing capacity due to their structure, and it is difficult to meet the sealing requirements under high pressure difference conditions, resulting in seal failure and reduced service life. In order to extend the service life of brush seals under large pressure difference conditions, multi-stage brush seals are required. However, in actual applications, it is found that there is an imbalance in the pressure drop of each stage of multi-stage brush seals. The main reason is that the volume flow rate increases unevenly at each stage, and the pressure drop at each stage increases with the uneven increase in volume flow rate; a certain stage of brush wire fails prematurely due to the increase in load due to bearing most of the pressure drop, which directly affects its sealing characteristics and service life.

[0004] At present, there are three main measures to solve the uneven pressure drop between the stages of multi-stage brush seals. The first is to increase the cross-sectional area of ​​the downstream flow channel, the second is to change the radial gap between the brush wire bundle and the rotor surface, and the third is to change the gap between the brush wires. The basic principle of these three measures is to increase the flow area of ​​the brush wire bundle area, so that the increase in the volume flow of this stage is reduced, resulting in a decrease in the inlet and outlet volume flow and pressure drop, which can improve the distribution of pressure drop and increase the service life of the brush seal. Although these three methods balance the pressure drop between the stages of the multi-stage brush seal, they also sacrifice the sealing performance and increase the leakage.

[0005] In addition, the current multi-stage brush seal is realized by simply connecting multiple single-stage brush seals in series. The rear baffle of the upstream single-stage brush seal is installed in conjunction with the front baffle of the downstream single-stage brush seal, resulting in two baffle structures between the two adjacent brush wires, thereby increasing the axial distance of the entire multi-stage brush seal structure. At the same time, this multi-stage brush seal structure, which is simply connected in series by multiple single-stage brush seals, will produce radial leakage flow on the contact mating surface between each adjacent two single-stage brush seals under a large sealing pressure difference, further reducing the sealing effect. Summary of the invention

[0006] (I) Technical Problem Solved by the Invention

[0007] In order to realize high reliability and long life sealing of impeller rotating machinery under ultra-high sealing pressure difference environment, solve the problem that the existing multi-stage brush seal structure cannot simultaneously realize balanced distribution of pressure drop between stages to improve service life and further improve its sealing performance, and overcome the problem that the existing single-stage series multi-stage brush seal structure has large axial dimensions and radial leakage of adjacent single-stage brush seal contact mating surfaces under large sealing pressure difference, the present invention provides a labyrinth combined multi-stage brush seal structure, which is particularly suitable for the air system, rim seal and bearing cavity seal of impeller rotating machinery such as turbine-based combined cycle engines, rocket-based combined cycle engines, air-turbine rocket combined power engines, aviation engines, gas turbines or steam turbines, etc., and can simultaneously realize the sealing capacity of ultra-high aerodynamic flow resistance and the high reliability and long life of balanced distribution of pressure drop between stages of multi-stage brush seals under ultra-high pressure difference sealing environment of megapascal level. In addition, the axial length of the multi-stage brush seal structure can be effectively reduced and the radial leakage flow between two adjacent single-stage brush seal structures can be effectively suppressed.

[0008] (II) Technical solution adopted by the present invention to solve its technical problem

[0009] A labyrinth combined multi-stage brush seal structure comprises a mounting sleeve and a plurality of seals arranged axially in the mounting sleeve, wherein the seals comprise a plurality of brush seal units, a plurality of labyrinth sealing rings, a distance ring and a compression nut, wherein:

[0010] The mounting sleeve is a hollow cylindrical body as a whole, including a front end located at the upstream high-pressure side, a rear end located at the downstream low-pressure side, and a main body mounting section located between the front end and the rear end, and an annular baffle extending radially inward is provided on the inner wall of the rear end of the mounting sleeve, and the clamping nut is fixedly arranged at the front end of the mounting sleeve;

[0011] The brush seal units of each stage have the same structure, and all include an annular front baffle, an annular rear baffle, and an annular brush bundle clamped between the front baffle and the rear baffle. The outer diameters of the front baffle, the rear baffle, and the brush bundle are the same as the inner diameter of the mounting sleeve. The inner diameter of the front baffle is larger than that of the rear baffle, and the inner diameter of the rear baffle is larger than that of the brush bundle, so that the brush bundle extends out of the rear baffle in the inner diameter direction. The front baffle, the rear baffle, and the brush bundle are arranged in close contact with each other. After the three are arranged in close contact, the three are fixedly connected at least near the outer diameter to form a whole.

[0012] The labyrinth sealing ring has an outer diameter that is the same as the inner diameter of the mounting sleeve, and an inner diameter that is substantially the same as the inner diameter of the rear baffle. The inner wall surface of the labyrinth sealing ring is provided with at least one annular inclined comb tooth extending in the inner diameter direction, and the front end surface of the labyrinth sealing ring is provided with a plurality of annular inclined labyrinth sealing grooves, wherein the inclined comb tooth is inclined toward the upstream high pressure front side, and the labyrinth sealing groove is inclined toward the inner diameter direction;

[0013] Several levels of brush seal units are arranged in an axially spaced manner in the main body installation section of the installation sleeve, at least one labyrinth sealing ring is arranged between two adjacent levels of brush seal units, and the number of labyrinth sealing rings arranged between two adjacent levels of brush seal units is different;

[0014] The first-stage brush seal unit is installed near the front end of the mounting sleeve, and the last-stage brush seal unit is arranged at the rear end of the mounting sleeve, and the rear end face of the rear baffle of the last-stage brush seal unit is pressed against the annular baffle on the rear end inner wall of the mounting sleeve, and the clamping nut is pressed against the front end face of the front baffle of the first-stage brush seal unit through the distance ring, so that the brush seal units and labyrinth sealing rings of each stage are pressed and arranged in the mounting sleeve.

[0015] Preferably, a plurality of arc-shaped grooves arranged along the axial direction are provided on the inner wall of the installation sleeve, so that the radial leakage flow between the matching surfaces of two adjacent sealing members in the installation sleeve generates flow resistance, thereby reducing and suppressing the leakage flow.

[0016] Preferably, the inner wall of the front end of the mounting sleeve is provided with an internal thread, and the side wall of the clamping nut is provided with an external thread. The clamping nut is fixedly arranged on the internal thread at the front end of the mounting sleeve through the external thread on its side wall, and the clamping force is transmitted through the distance ring to press and fit the seals in the mounting sleeve to reduce and suppress the radial leakage flow between the mating surfaces of two adjacent seals under large pressure difference.

[0017] Preferably, the number of labyrinth sealing rings between two adjacent stages of brush seal units increases sequentially from the upstream high-pressure side to the downstream low-pressure side.

[0018] Preferably, in each of the brush seal units, the front baffle plate, the rear baffle plate, and the brush bundle are fixed as a whole at the outer diameter by welding.

[0019] Preferably, each of the oblique labyrinth sealing grooves on the front end surface of the labyrinth sealing ring is inclined at about 45° toward the inner diameter direction.

[0020] Preferably, in each of the brush-type sealing units, an annular groove is formed on the front end surface of the rear baffle near its inner diameter, so as to reduce the contact area between the brush wire bundle and the rear baffle, reduce the friction between the brush wire and the baffle, improve the brush wire follow-up and reduce the brush wire hysteresis effect.

[0021] Further, in each of the brush seal units, a first annular protrusion protruding backwards is formed on the rear end face of the rear baffle near its inner diameter, and the annular groove is radially located between the inner diameter and the outer diameter of the first annular protrusion; a second annular protrusion protruding backwards is formed on the rear end face of the labyrinth sealing ring near its inner diameter, and each of the oblique labyrinth sealing grooves on the front end face of the labyrinth sealing ring is radially located between the inner diameter and the outer diameter of the second annular protrusion, and a third annular protrusion protruding forwards is formed on the front end face of the labyrinth sealing ring near its outer diameter; the inner diameter of the first annular protrusion is the same as the inner diameter of the rear baffle, and the outer diameter is the same as that of the front baffle. and the inner diameter of the annular baffle at the rear end of the mounting sleeve, the inner diameter of the second annular protrusion is the same as the inner diameter of the labyrinth sealing ring, and the outer diameter is the same as the inner diameter of the front baffle and the inner diameter of the third annular protrusion, the inner diameter of the third annular protrusion is the same as the outer diameters of the first and second annular protrusions, and the outer diameter is the same as the inner diameter of the mounting sleeve, so that when each of the brush sealing units and the labyrinth sealing rings are assembled into the mounting sleeve, mutually overlapping assembly structures are formed between adjacent two labyrinth sealing rings, between adjacent labyrinth sealing rings and brush sealing units, and between the brush sealing unit and the annular baffle at the rear end of the mounting sleeve.

[0022] Furthermore, when in the assembled state, there is an axial gap between the first annular protrusion of the rear baffle of the brush sealing unit and the front end face of the adjacent labyrinth sealing ring, between the second annular protrusion of the labyrinth sealing ring and the adjacent front baffle of the brush sealing unit, and between two adjacent labyrinth sealing rings at the position of the second annular protrusion.

[0023] (III) Compared with the prior art, the present invention has significant technical effects

[0024] (1) The labyrinth-combined multi-stage brush seal structure of the present invention is particularly suitable for the air system, wheel rim seal and bearing cavity seal of impeller rotating machinery such as turbine-based combined cycle engines, rocket-based combined cycle engines, air-turbine-rocket combined power engines, aircraft engines, gas turbines or steam turbines, and can simultaneously achieve the sealing capability of ultra-high aerodynamic flow resistance and the high reliability and long life of the multi-stage brush seal with balanced distribution of pressure drop between stages in a megapascal ultra-high pressure difference sealing environment.

[0025] (2) The labyrinth-combined multi-stage brush seal structure of the present invention can effectively reduce the axial length of the multi-stage brush seal structure and effectively suppress the radial leakage flow between two adjacent single-stage brush seal structures.

[0026] (3) The labyrinth-combined multi-stage brush seal structure of the present invention is based on a modular design and can be flexibly assembled into multi-stage brush seals of different numbers according to different sealing pressure difference requirements. By changing the number of labyrinth sealing rings installed between two adjacent single-stage brush seals, the pressure drop between each stage can be flexibly adjusted and matched. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a partially enlarged schematic diagram of the cross section of the labyrinth combined multi-stage brush seal structure of the present invention;

[0028] Figure 2 It is a cross-sectional schematic diagram of the labyrinth combined multi-stage brush seal structure of the present invention.

[0029] Description of reference numerals:

[0030] Brush seal unit 1, labyrinth sealing ring 2, mounting sleeve 3, distance ring 4, compression nut 5, front baffle 6, brush wire bundle 7, rear baffle 8, annular groove 9, helical grate teeth 10, oblique labyrinth sealing groove 11, arc groove 12, radial rectangular groove 13. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical scheme and advantages of the implementation of the present invention clearer, the technical scheme in the embodiment of the present invention will be described in more detail below in conjunction with the drawings in the embodiment of the present invention. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described embodiments are part of the embodiments of the present invention, not all of the embodiments, and are intended to be used to explain the present invention, but should not be understood as limitations on the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0032] like Figure 1As shown, the labyrinth combined multi-stage brush seal structure of the present invention includes a mounting sleeve 3 and a plurality of seals arranged axially in the mounting sleeve 3, wherein the seals include a plurality of brush seal units 1, a plurality of labyrinth sealing rings 2, a certain distance ring 4 and a clamping nut 5.

[0033] The mounting sleeve 3 is a hollow cylindrical body as a whole, including a front end located at the upstream high-pressure side, a rear end located at the downstream low-pressure side, and a main mounting section located between the front end and the rear end. The inner wall of the rear end of the mounting sleeve 3 is provided with an annular baffle extending radially inward, and the clamping nut 5 is fixedly arranged at the front end of the mounting sleeve 3. As a preferred example, the inner wall of the mounting sleeve 3 is provided with a plurality of arc-shaped grooves 12 arranged along the axial direction, so that the radial leakage flow between the mating surfaces of two adjacent seals in the mounting sleeve 3 generates flow resistance, thereby reducing and suppressing the leakage flow. The inner wall of the front end of the mounting sleeve 3 is provided with an internal thread, and the side wall of the clamping nut 5 is provided with an external thread. The clamping nut 5 is fixedly arranged on the internal thread of the front end of the mounting sleeve 3 through the external thread on its side wall, and the clamping force is transmitted through the distance ring 4, so that the various seals in the mounting sleeve 3 are pressed and fitted to reduce and suppress the radial leakage flow between the mating surfaces of two adjacent seals under large pressure difference.

[0034] Each level of brush seal unit 1 has the same structure, including an annular front baffle 6, an annular rear baffle 8, and an annular brush bundle 7 clamped between the front baffle 6 and the rear baffle 8. The outer diameters of the front baffle 6, the rear baffle 8, and the brush bundle 7 are the same as the inner diameter of the mounting sleeve 3. The inner diameter of the front baffle 6 is larger than that of the rear baffle 8, and the inner diameter of the rear baffle 8 is larger than that of the brush bundle 7, so that the brush bundle 7 extends out of the rear baffle 8 in the inner diameter direction. The front baffle 6, the rear baffle 8, and the brush bundle 7 are arranged in close contact with each other. After the three are arranged in close contact, they are fixedly connected to form a whole at least near the outer diameter. The front baffle 6, the rear baffle 8, and the brush bundle 7 are preferably fixed as a whole by welding at the outer diameter. An annular groove 9 is formed on the front end surface of the rear baffle 8 near its inner diameter to reduce the contact area between the brush bundle 7 and the rear baffle 8, reduce the friction between the brush and the baffle, improve the brush follow-up and reduce the brush hysteresis effect.

[0035] The labyrinth sealing ring 2 has an outer diameter that is the same as the inner diameter of the mounting sleeve 3, and an inner diameter that is substantially the same as the inner diameter of the rear baffle 8. The inner wall surface thereof is provided with at least one annular inclined comb tooth 10 extending in the inner diameter direction, and the front end surface thereof is provided with a plurality of annular oblique labyrinth sealing grooves 11, the inclined comb teeth 10 are inclined toward the upstream high pressure front side, and the labyrinth sealing grooves 11 are inclined toward the inner diameter direction, preferably inclined at about 45°; a plurality of brush seal units 1 are arranged in the main body mounting section of the mounting sleeve 3 at intervals along the axial direction, at least one labyrinth sealing ring 2 is provided between two adjacent brush seal units 1, and a plurality of brush seal units 1 are provided between each adjacent brush seal unit 1. The number of labyrinth sealing rings 2 installed is different, and the number of labyrinth sealing rings 2 between two adjacent brush sealing units 1 increases from the upstream high-pressure side to the downstream low-pressure side; the first-stage brush sealing unit 1 is installed near the front end of the mounting sleeve 3, and the last-stage brush sealing unit 1 is arranged at the rear end of the mounting sleeve 3, and the rear end face of the rear baffle of the last-stage brush sealing unit 1 is pressed against the annular baffle on the inner wall of the rear end of the mounting sleeve 3, and the clamping nut 5 is pressed against the front end face of the front baffle 6 of the first-stage brush sealing unit 1 through the distance ring 4, so that the brush sealing units 1 and the labyrinth sealing rings 2 of each stage are compressed and arranged in the mounting sleeve 3.

[0036] As a preferred example, in each brush seal unit 1, a first annular protrusion protruding backwards is formed on the rear end face of the rear baffle 8 near its inner diameter, and the annular groove is radially located between the inner diameter and the outer diameter of the first annular protrusion; a second annular protrusion protruding backwards is formed on the rear end face of the labyrinth sealing ring 2 near its inner diameter, and each oblique labyrinth sealing groove 11 on the front end face of the labyrinth sealing ring 2 is radially located between the inner diameter and the outer diameter of the second annular protrusion, and a third annular protrusion protruding forwards is formed on the front end face of the labyrinth sealing ring 2 near its outer diameter; the inner diameter of the first annular protrusion is the same as the inner diameter of the rear baffle 8, and the outer diameter is the same as the outer diameter of the front baffle 6. and the inner diameter of the annular baffle at the rear end of the mounting sleeve 3, the inner diameter of the second annular protrusion is the same as the inner diameter of the labyrinth sealing ring 2, the outer diameter is the same as the inner diameter of the front baffle 6 and the inner diameter of the third annular protrusion, the inner diameter of the third annular protrusion is the same as the outer diameter of the first annular protrusion and the second annular protrusion, and the outer diameter is the same as the inner diameter of the mounting sleeve 3, so that when each brush seal unit 1 and the labyrinth sealing ring 2 are assembled into the mounting sleeve 3, a mutually overlapping assembly structure is formed between the adjacent two labyrinth sealing rings 2, between the adjacent labyrinth sealing rings 2 and the brush seal unit 1, and between the brush seal unit 1 and the annular baffle at the rear end of the mounting sleeve 3. Further, when in the assembled state, there is an axial gap between the first annular protrusion of the rear baffle 8 of the brush seal unit 1 and the front end face of the adjacent labyrinth sealing ring 2, between the second annular protrusion of the labyrinth sealing ring 2 and the front baffle 6 of the adjacent brush seal unit 1, and between the adjacent two labyrinth sealing rings 2 at the position of the second annular protrusion.

[0037] More specifically, Figure 1As shown, the labyrinth combined multi-stage brush seal structure of the present invention is mainly composed of a single-stage brush seal unit 1, a labyrinth sealing ring 2, a mounting sleeve 3, a distance ring 4 and a compression nut 5. The labyrinth combined multi-stage brush seal structure of the present invention is based on a modular design and can be assembled into multi-stage brush seals of different levels according to different sealing pressure difference requirements. Figure 1 The three-stage brush seal is shown in Figure . Figure 1 As shown, the single-stage brush seal unit 1 is composed of a rectangular cross-section front baffle 6, a brush bundle 7 and a cylindrical step rear baffle 8, which are fixed as a whole at their outer diameters by vacuum electron beam welding. An annular groove 9 is provided on the inner wall of the cylindrical step rear baffle 8 to reduce the contact area between the brush bundle 7 and the cylindrical step rear baffle 8, reduce the friction between the brush wires and the baffle, improve the brush wire follow-up and reduce the brush wire hysteresis effect. The labyrinth sealing ring 2 adopts a cylindrical step form with the same structure as the single-stage brush seal rear baffle 8, which can realize the mutual overlap installation between the single-stage brush seal unit 1 and the labyrinth sealing ring 2. An inverted helical tooth comb 10 is provided on the bottom surface of the labyrinth sealing ring 2 to realize throttling and pressure reduction between two adjacent single-stage brush seal units 1. Three 45° inclined labyrinth sealing grooves 11 are provided on the inner wall of the labyrinth sealing ring 2, which also play a throttling and pressure reduction role on the upstream high-pressure airflow.

[0038] The labyrinth combined multi-stage brush seal structure of the present invention adopts a modular design, and different numbers of labyrinth sealing rings 2 can be installed between two adjacent single-stage brush seal units 1 to form differentiated flow resistance between stages, further improving the sealing capacity of the entire multi-stage brush seal while realizing the pressure drop distribution and regulation between each stage of the multi-stage brush seal. Since the brush wire bundle of the last stage of the multi-stage brush seal is subjected to a greater pressure drop, a first-stage labyrinth sealing ring 2 is installed between the upstream single-stage brush seal unit 1 and the middle-stage single-stage brush seal unit 1, and a two-stage labyrinth sealing ring 2 is installed between the middle-stage single-stage brush seal unit 1 and the downstream single-stage brush seal unit 1. After the upstream high-pressure gas passes through the upstream single-stage brush seal unit 1, the speed increases, the static pressure decreases, and the total pressure decreases. This part of gas continues to pass through the first-stage labyrinth sealing ring 2. The flow resistance loss generated by the inverted helical teeth 10 and the three 45° inclined labyrinth sealing grooves 11 further reduces the total pressure of the gas downstream of the labyrinth sealing ring 2 (i.e., the gas upstream of the intermediate single-stage brush seal unit 1). At the same time, the volume flow of this part of gas is further increased, resulting in an increase in the sealing pressure difference of the upstream single-stage brush seal unit 1 and a decrease in the sealing pressure difference of the intermediate single-stage brush seal unit 1. This achieves the balance of the sealing pressure drop between the two adjacent single-stage brush seal units 1 while further increasing the flow resistance loss. The principle of pressure drop balance between the intermediate single-stage brush seal unit 1 and the downstream single-stage brush seal unit 1 is similar to the above, except that the pressure drop to be balanced is larger. Therefore, two levels of labyrinth sealing rings 2 are required between the intermediate single-stage brush seal unit 1 and the downstream single-stage brush seal unit 1, which will not be repeated here.

[0039] At present, most single-stage brush seals and multi-stage brush seals are axially fixed by means of retaining rings or installing end covers to prevent the brush seals from axial movement. These structures cannot provide a large axial clamping force, so for multi-stage brush seals that are simply connected in series with single-stage brush seals, radial leakage flow will occur on the mating end faces of the adjacent two stages under a large sealing pressure difference, resulting in a sharp decline in sealing characteristics. The modular labyrinth combined multi-stage brush seal structure of the present invention has an outer diameter that is installed in cooperation with the inner diameter of the installation sleeve 3, which mainly produces two effects: first, a closed sealing surface (the inner diameter surface of the installation sleeve 3) is added to the outer ring surface of the labyrinth combined multi-stage brush seal, and the inner diameter surface of the installation sleeve 3 is provided with 8 semicircular grooves 12, which generates flow resistance for the radial leakage flow between the mating surfaces of two adjacent seals, thereby reducing and suppressing the leakage flow; second, the clamping nut 5 is matched with the internal thread provided in the installation sleeve 3, and the clamping force generated when the clamping nut 5 is screwed in is transmitted through the distance ring 4, which compresses the single-stage brush seal units 1 and the labyrinth sealing ring 2 that are mutually installed in the labyrinth combined multi-stage brush seal, further reducing and suppressing the radial leakage flow between the mating surfaces of two adjacent seals under large pressure difference. Six radial rectangular grooves 13 are provided on the end surface of the clamping nut to facilitate screwing in and applying force.

[0040] Through the above embodiments, the purpose of the present invention is fully and effectively achieved. Those skilled in the art can understand that the present invention includes but is not limited to the contents described in the drawings and the above specific embodiments. Although the present invention has been described with respect to the most practical and preferred embodiments currently considered, it should be understood that the present invention is not limited to the disclosed embodiments, and any modification that does not deviate from the functional and structural principles of the present invention will be included in the scope of the claims.

[0041] The present invention does not elaborate on some of the well-known technologies that belong to those skilled in the art.

Claims

1. A labyrinth combined multi-stage brush seal structure, comprising a mounting sleeve and a plurality of seals arranged axially in the mounting sleeve, wherein the seals comprise a plurality of brush seal units, a plurality of labyrinth sealing rings, a distance ring and a compression nut, characterized in that: The mounting sleeve is a hollow cylindrical body as a whole, including a front end located at the upstream high-pressure side, a rear end located at the downstream low-pressure side, and a main body mounting section located between the front end and the rear end, and an annular baffle extending radially inward is provided on the inner wall of the rear end of the mounting sleeve, and the clamping nut is fixedly arranged at the front end of the mounting sleeve; The brush seal units of each stage have the same structure, and all include an annular front baffle, an annular rear baffle, and an annular brush bundle clamped between the front baffle and the rear baffle. The outer diameters of the front baffle, the rear baffle, and the brush bundle are the same as the inner diameter of the mounting sleeve. The inner diameter of the front baffle is larger than that of the rear baffle, and the inner diameter of the rear baffle is larger than that of the brush bundle, so that the brush bundle extends out of the rear baffle in the inner diameter direction. The front baffle, the rear baffle, and the brush bundle are arranged in close contact with each other. After the three are arranged in close contact, the three are fixedly connected at least near the outer diameter to form a whole. The labyrinth sealing ring has an outer diameter that is the same as the inner diameter of the mounting sleeve, and an inner diameter that is substantially the same as the inner diameter of the rear baffle. The inner wall surface of the labyrinth sealing ring is provided with at least one annular inclined comb tooth extending in the inner diameter direction, and the front end surface of the labyrinth sealing ring is provided with a plurality of annular inclined labyrinth sealing grooves, wherein the inclined comb tooth is inclined toward the upstream high pressure front side, and the labyrinth sealing groove is inclined toward the inner diameter direction; Several stages of brush seal units are arranged in an axially spaced manner in the main body installation section of the installation sleeve, at least one labyrinth sealing ring is arranged between two adjacent stages of the brush seal units, and the number of labyrinth sealing rings arranged between two adjacent stages of the brush seal units is different, and the number of labyrinth sealing rings between two adjacent stages of the brush seal units increases from the upstream high-pressure side to the downstream low-pressure side; The first-stage brush seal unit is installed near the front end of the mounting sleeve, and the last-stage brush seal unit is arranged at the rear end of the mounting sleeve, and the rear end face of the rear baffle of the last-stage brush seal unit is pressed against the annular baffle on the rear end inner wall of the mounting sleeve, and the clamping nut is pressed against the front end face of the front baffle of the first-stage brush seal unit through the distance ring, so that the brush seal units and labyrinth sealing rings of each stage are pressed and arranged in the mounting sleeve.

2. The labyrinth combined multi-stage brush seal structure according to claim 1, characterized in that: The inner wall of the installation sleeve is provided with a plurality of arc-shaped grooves arranged along the axial direction, so that the radial leakage flow between the matching surfaces of two adjacent sealing members in the installation sleeve generates flow resistance, thereby reducing and suppressing the leakage flow.

3. The labyrinth combined multi-stage brush seal structure according to claim 1, characterized in that: The front end inner wall of the mounting sleeve is provided with an internal thread, and the side wall of the clamping nut is provided with an external thread. The clamping nut is fixedly arranged on the internal thread at the front end of the mounting sleeve through the external thread on its side wall, and the clamping force is transmitted through the distance ring to press and fit the seals in the mounting sleeve to reduce and suppress the radial leakage flow between the mating surfaces of two adjacent seals under large pressure difference.

4. The labyrinth combined multi-stage brush seal structure according to claim 1, characterized in that: In each of the brush seal units, the front baffle plate, the rear baffle plate, and the brush bundle are fixed as a whole at the outer diameter by welding.

5. The labyrinth combined multi-stage brush seal structure according to claim 1, characterized in that: Each of the oblique labyrinth sealing grooves on the front end surface of the labyrinth sealing ring is inclined at about 45° toward the inner diameter direction.

6. The labyrinth combined multi-stage brush seal structure according to claim 1, characterized in that: In each of the brush-type sealing units, an annular groove is formed on the front end surface of the rear baffle near its inner diameter to reduce the contact area between the brush wire bundle and the rear baffle, reduce the friction between the brush wire and the baffle, improve the brush wire follow-up and reduce the brush wire hysteresis effect.

7. The labyrinth combined multi-stage brush seal structure according to claim 6, characterized in that: In each of the brush seal units, a first annular protrusion protruding backwards is formed on the rear end surface of the rear baffle near its inner diameter, and the annular groove is radially located between the inner diameter and the outer diameter of the first annular protrusion; a second annular protrusion protruding backwards is formed on the rear end surface of the labyrinth sealing ring near its inner diameter, and each of the oblique labyrinth sealing grooves on the front end surface of the labyrinth sealing ring is radially located between the inner diameter and the outer diameter of the second annular protrusion, and a third annular protrusion protruding forwards is formed on the front end surface of the labyrinth sealing ring near its outer diameter; the inner diameter of the first annular protrusion is the same as the inner diameter of the rear baffle, and the outer diameter is the same as that of the front baffle and the The inner diameters of the annular baffles at the rear end of the mounting sleeve are the same, the inner diameter of the second annular protrusion is the same as the inner diameter of the labyrinth sealing ring, and the outer diameter is the same as the inner diameter of the front baffle and the inner diameter of the third annular protrusion; the inner diameter of the third annular protrusion is the same as the outer diameters of the first and second annular protrusions, and the outer diameter is the same as the inner diameter of the mounting sleeve, so that when each of the brush sealing units and the labyrinth sealing rings are assembled into the mounting sleeve, mutually overlapping assembly structures are formed between adjacent two labyrinth sealing rings, between adjacent labyrinth sealing rings and brush sealing units, and between the brush sealing unit and the annular baffle at the rear end of the mounting sleeve.

8. The labyrinth combined multi-stage brush seal structure according to claim 7, characterized in that: When in the assembled state, there is an axial gap between the first annular protrusion of the rear baffle of the brush seal unit and the front end face of the adjacent labyrinth sealing ring, between the second annular protrusion of the labyrinth sealing ring and the adjacent front baffle of the brush seal unit, and between the two adjacent labyrinth sealing rings at the position of the second annular protrusion.

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