A micro centrifugal compressor sealing device

Abstract

The present application relates to the field of rotary mechanical seal, and discloses a micro centrifugal compressor sealing device for being arranged between a shell and a rotating shaft, comprising: a micro centrifugal compressor and a plurality of stages of non-contact seal members arranged in the axial direction, an inter-stage interval is formed between any two adjacent stages of non-contact seal members, at least one inter-stage interval is provided with the micro centrifugal compressor, the micro centrifugal compressor is arranged close to the low-pressure side, and the micro centrifugal compressor comprises a wheel disc and a plurality of moving blades arranged on the outer sidewall of the wheel disc in the circumferential direction of the wheel disc, and the wheel disc is used for being fixedly sleeved on the outer side of the rotating shaft. The left-high and right-low shape of the micro centrifugal compressor can block the airflow from directly rushing from the high-pressure side to the low-pressure side, and can also suck the gas on the low-pressure side into the blade channel of the compressor for pressurization and balance the pressure of the gas on the high-pressure side. The micro centrifugal compressor sealing device can realize sealing in a shorter axial interval by cooperation of the micro centrifugal compressor and the non-contact seal member.

Description

Technical Field

[0001] The invention relates to the field of rotary mechanical seals, in particular to a sealing device for a micro centrifugal compressor. Background Art

[0002] Bearing cavity sealing devices play a crucial role in the maintenance costs and operational reliability of rotating machinery. For example, aircraft engines operate under harsh operating conditions such as high pressure, high temperature, and high speed. Their sealing devices are primarily designed to prevent medium leakage, thereby protecting the bearings. These devices protect the working environment of the bearing cavity by isolating the engine's air flow, and sealing plays a crucial role in this process. However, due to the harsh working environment of current sealing devices, wear and high-temperature deformation often occur, resulting in the sealing effect and service life of the sealing devices falling short of expectations. To increase the sealing effect, the most commonly used method is to increase the number of non-contact seals. However, the greater the number of non-contact seals, the longer the required axial distance. The axial length of the bearing cavity is limited, and the number of non-contact seals cannot be increased indefinitely.

[0003] Therefore, how to achieve sealing within a short axial distance has become a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a micro centrifugal compressor sealing device to achieve sealing within a shorter axial spacing.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention provides a micro centrifugal compressor sealing device, which is used to be arranged between a casing and a rotating shaft and is arranged near the low-pressure side. The device comprises: a micro centrifugal compressor and a multi-stage non-contact seal arranged along the axial direction. A stage gap is formed between any two adjacent stages of the non-contact seals. The micro centrifugal compressor is arranged in at least one of the stage gaps. The micro centrifugal compressor is arranged near the low-pressure side. The micro centrifugal compressor comprises a wheel disc and a plurality of large moving blades. The wheel disc is used to be fixedly mounted on the outer side of the rotating shaft. The outer side wall of the wheel disc is a conical structure, and the outer diameter of the end of the wheel disc close to the high-pressure side is larger than the outer diameter of the end of the wheel disc away from the high-pressure side. All the large moving blades are arranged on the outer side wall of the wheel disc and are arranged along the circumference of the wheel disc. The large moving blades can suck the airflow on the low-pressure side into between the casing and the rotating shaft and can compress the airflow to perform work, and the end of the wheel disc close to the high-pressure side can shield all the large moving blades.

[0007] Optionally, the micro centrifugal compressor also includes a plurality of small moving blades, all of which are arranged on the outer side wall of the wheel disc, all of which are arranged along the circumference of the wheel disc, and the large moving blades and the small moving blades are arranged alternately in the circumference of the wheel disc, the small moving blades can suck the airflow on the low-pressure side into between the casing and the rotating shaft, and can perform work on compressing the airflow, and the end of the wheel disc close to the high-pressure side can cover all of the small moving blades.

[0008] Optionally, the large moving blades are large rotating blades, and the small moving blades are small rotating blades.

[0009] Optionally, the thickness of the wheel disc gradually decreases from an end of the wheel disc close to the high-pressure side to an end of the wheel disc away from the high-pressure side, so that the outer side wall of the wheel disc is a tapered structure.

[0010] Optionally, there are multiple micro centrifugal compressors, and all of the micro centrifugal compressors are respectively arranged in the stage intervals at different positions.

[0011] Optionally, the outer side wall of the wheel disc is a curved structure.

[0012] Optionally, a plurality of annular grooves are axially arranged on the inner wall of the shell, and the non-contact seals correspond to the annular grooves one by one. Each of the non-contact seals is partially embedded in the corresponding annular groove, and a gasket for positioning the two adjacent levels of the non-contact seals is provided between any two adjacent annular grooves.

[0013] Optionally, there is a gap between the outer side wall of one end of the wheel disc close to the high-pressure side and the gasket.

[0014] Optionally, the non-contact seal and the gasket adjacent thereto are detachably connected.

[0015] Compared with the prior art, the present invention has achieved the following technical effects:

[0016] The micro centrifugal compressor sealing device provided by the present invention is used to be arranged between a casing and a rotating shaft and is arranged near the low-pressure side. It includes: a micro centrifugal compressor and a multi-stage non-contact seal arranged along the axial direction. A stage gap is formed between any two adjacent non-contact seals. A micro centrifugal compressor is arranged in at least one stage gap. The micro centrifugal compressor is arranged near the low-pressure side. The micro centrifugal compressor includes a wheel and a plurality of large moving blades. The wheel is used to be fixedly mounted on the outside of the rotating shaft. The outer wall of the wheel is a conical structure, and the outer diameter of the end of the wheel close to the high-pressure side is larger than the outer diameter of the end of the wheel away from the high-pressure side. All large moving blades are arranged on the outer wall of the wheel, and all large moving blades are arranged along the circumference of the wheel. The large moving blades can suck the airflow on the low-pressure side into between the casing and the rotating shaft, and can compress the airflow and perform work, and the end of the wheel close to the high-pressure side can cover all large moving blades.

[0017] During specific use, the wheel rotates synchronously with the shaft, and the large rotor blades rotate synchronously with the wheel. When the large rotor blades rotate, they can draw the airflow on the low-pressure side into the space between the housing and the shaft, and compress the airflow to increase the pressure of the airflow. The low-pressure side airflow that has completed the compression work can collide with the airflow entering the space between the housing and the shaft from the high-pressure side, thereby causing the airflow pressure entering the space between the housing and the shaft from the high-pressure side to drop rapidly within a short wheelbase. The pressure of the airflow entering the space between the housing and the shaft from the high-pressure side is reduced to the same level as the pressure of the airflow entering the space between the housing and the shaft from the low-pressure side, thus achieving sealing. In addition, during specific use, the end of the wheel close to the high-pressure side can hinder the flow of airflow, preventing the airflow from rushing straight from the high-pressure side to the low-pressure side. In this way, compared with sealing using multi-stage non-contact seals, the micro-centrifugal compressor sealing device provided by the present invention can achieve sealing within a shorter axial spacing by adding a micro-centrifugal compressor and using the micro-centrifugal compressor in conjunction with the non-contact seal. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 A cross-sectional view of a micro centrifugal compressor sealing device provided in an embodiment of the present invention;

[0020] Figure 2 for Figure 1 An enlarged view of part I;

[0021] Figure 3Schematic diagram of the arrangement of a micro centrifugal compressor in a micro centrifugal compressor sealing device provided in an embodiment of the present invention;

[0022] Figure 4 A schematic diagram of the velocity triangle of a large rotor blade of a micro centrifugal compressor sealing device provided in an embodiment of the present invention;

[0023] Figure 5 A comparison diagram of the sealing effects of the micro centrifugal compressor sealing device provided in an embodiment of the present invention and a conventional sealing method;

[0024] Figure 6 A sealing principle diagram of a micro centrifugal compressor sealing device provided in an embodiment of the present invention;

[0025] Figure 7 The sealing principle diagram of the non-contact seal mentioned in the background technology.

[0026] Figures 1-6 Explanation of the accompanying reference numerals: 100, micro centrifugal compressor sealing device; 1, housing; 2, rotating shaft; 3, non-contact seal; 4, micro centrifugal compressor; 401, wheel; 402, large moving blade; 403, small moving blade; 5, gasket; 6, gap; 7, space; 8, positioning pin.

[0027] Figure 7 Description of reference numerals: 1', rotating shaft; 2', non-contact seal. DETAILED DESCRIPTION

[0028] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0029] The object of the present invention is to provide a micro centrifugal compressor sealing device capable of achieving sealing within a shorter axial distance.

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] refer to Figures 1-6 As shown, the micro centrifugal compressor sealing device 100 provided in this embodiment is used to be arranged between the housing 1 and the rotating shaft 2, and includes: a micro centrifugal compressor 4 and a multi-stage non-contact seal 3 arranged along the axial direction.

[0032] Specifically, a stage gap is formed between any two adjacent stages of non-contact seals 3, and a micro centrifugal compressor 4 is provided in at least one stage gap, and the micro centrifugal compressor 4 is provided between the high-pressure side and the low-pressure side and closer to the low-pressure side. It should be noted that one side of the two sides of the micro centrifugal compressor sealing device 100 has a high pressure and the other side has a low pressure. The side with high pressure is the high-pressure side, and the side with low pressure is the low-pressure side. The micro centrifugal compressor sealing device 100 provided in this embodiment is in accordance with Figure 1 When arranged in the manner shown, the left side is the high-pressure side and the right side is the low-pressure side. Figure 1 The arrow in the middle indicates the direction of air flow.

[0033] like Figure 3 As shown, the micro centrifugal compressor 4 includes a wheel 401 and a plurality of large moving blades 402. The wheel 401 is used to be fixedly mounted on the outside of the rotating shaft 2. The outer wall of the wheel 401 is a conical structure, and the outer diameter of the end of the wheel 401 close to the high-pressure side is larger than the outer diameter of the end of the wheel 401 away from the high-pressure side. All large moving blades 402 are arranged on the outer wall of the wheel 401, and all large moving blades 402 are arranged along the circumference of the wheel 401. For example, all large moving blades 402 are evenly arranged along the circumference of the wheel 401. The large moving blades 402 can suck the airflow on the low-pressure side into between the shell 1 and the rotating shaft 2, and can compress the airflow to do work, and the end of the wheel 401 close to the high-pressure side can simultaneously block all the large moving blades 402. It should be noted that, taking one of the large moving blades 402 as an example, the blocking here refers to the entire blocking or partial blocking of the large moving blade 402 by the end of the wheel 401 close to the high-pressure side. Figure 3 The middle one is fully blocked.

[0034] During specific use, the micro centrifugal compressor 4 can draw the low-pressure side gas into the compressor blade channel between two adjacent large moving blades 402 to pressurize it to counteract the high-pressure side gas pressure, thereby causing the airflow pressure entering from the high-pressure side between the shell 1 and the rotating shaft 2 to drop rapidly within a short wheelbase. The airflow pressure entering between the shell 1 and the rotating shaft 2 from the high-pressure side is reduced to the same level as the airflow pressure entering between the shell 1 and the rotating shaft 2 from the low-pressure side, thereby achieving sealing. In addition, during specific use, the end of the wheel 401 close to the high-pressure side can hinder the flow of airflow. In this way, compared with sealing using a multi-stage non-contact seal 3, the micro centrifugal compressor sealing device 100 provided by the present invention can achieve sealing within a shorter axial spacing by adding a micro centrifugal compressor 4 and using the micro centrifugal compressor 4 in conjunction with the non-contact seal 3.

[0035] In this embodiment, if Figure 3As shown, the micro centrifugal compressor 4 also includes a plurality of small rotor blades 403, all of which are disposed on the outer side wall of the wheel disc 401. All of the small rotor blades 403 are arranged along the circumference of the wheel disc 401, and the large rotor blades 402 and the small rotor blades 403 are alternately arranged circumferentially of the wheel disc 401. The small rotor blades 403 can draw the airflow on the low-pressure side into between the housing 1 and the rotating shaft 2 and perform work on compressing the airflow. The end of the wheel disc 401 close to the high-pressure side can shield all of the small rotor blades 403. By adding the small rotor blades 403, the airflow can be better compressed.

[0036] In this embodiment, the large moving blades 402 are large rotating blades, and the small moving blades 403 are small rotating blades.

[0037] Furthermore, the length of the large rotor blade 402 is greater than the length of the small rotor blade 403 , and the thickness of the large rotor blade 402 is greater than the thickness of the small rotor blade 403 .

[0038] Furthermore, if Figure 3 As shown, the large moving blades 402 and the small moving blades 403 are both arranged at an angle, and the ends of the large moving blades 402 and the small moving blades 403 close to the low pressure side are both leading edges, and the ends away from the low pressure side are both trailing edges. The leading edge of the large moving blade 402 is flush with the end of the wheel disc 401 close to the low pressure side, and the trailing edge of the large moving blade 402 is flush with the end of the wheel disc 401 away from the low pressure side.

[0039] In this embodiment, the distance between the top end of the small rotor blade 403 and the axis of the rotating shaft 2 is smaller than the distance between the top end of the large rotor blade 402 and the axis of the rotating shaft 2, and the outer diameter of the end of the wheel 401 close to the high pressure side is larger than the distance between the top end of the large rotor blade 402 and the axis of the rotating shaft 2, so that the end of the wheel 401 close to the high pressure side can block all the large rotor blades 402 and all the small rotor blades 403. In this way, the wheel 401 can block the large rotor blades 402 and the small rotor blades 403 as a whole. Figure 4 The middle is the overall occlusion.

[0040] In this embodiment, the thickness of the wheel disc 401 gradually decreases from the end of the wheel disc 401 close to the high pressure side to the end of the wheel disc 401 away from the high pressure side, so that the outer wall of the wheel disc 401 has a tapered structure.

[0041] In this embodiment, there are multiple micro-centrifugal compressors 4, all of which are arranged in different stage intervals. The number of micro-centrifugal compressors 4 and the specific stage intervals in which they are arranged are determined according to actual needs. For example, the number of micro-centrifugal compressors 4 can be increased starting from the stage interval closest to the low-pressure side, and in a direction from the low-pressure side to the high-pressure side.

[0042] In this embodiment, the outer wall of the wheel disc 401 is a curved structure.

[0043] In this embodiment, if Figure 1 As shown, a plurality of annular grooves are provided on the inner wall of the housing 1 along the axial direction, and the non-contact seals 3 correspond to the annular grooves one by one. Each non-contact seal 3 is partially embedded in its corresponding annular groove, and a gasket 5 for positioning the adjacent two-stage non-contact seals 3 is provided between any two adjacent annular grooves.

[0044] Furthermore, if Figure 1 As shown, at least part of the gaskets 5 is an inverted L-shaped structure, a mounting cavity is provided on the inner wall of the housing 1 , all the L-shaped gaskets 5 are arranged side by side, and an annular groove is formed between any two adjacent gaskets 5 .

[0045] Furthermore, if Figure 1 As shown, there is a gap 6 between the outer wall of one end of the wheel disc 401 close to the high-pressure side and the gasket 5. Specifically, in this embodiment, the size of the gap 6 is 0.1 mm to 0.2 mm.

[0046] Furthermore, the non-contact seal 3 and the adjacent gasket 5 are detachably connected. For example, the non-contact seal 3 and the gasket 5 are connected via a locating pin. It should be noted that there are two gaskets 5 adjacent to the non-contact seal 3, and the non-contact seal 3 is detachably connected to at least one of the gaskets 5.

[0047] In this embodiment, the non-contact seal 3 is an annular non-contact seal, such as a carbon ring. It should be noted that the non-contact seal 3 is not limited to a carbon ring, and other structures that can achieve non-contact sealing can also be selected.

[0048] During specific use, the micro centrifugal compressor 4 is designed and matched according to the rotation direction of the shaft 2, the pressure conditions before and after the micro centrifugal compressor sealing device 100, and the working conditions of the gap 7 between the non-contact seal 3 and the shaft 2. The design contents include: the size of the large moving blades 402, the density of the large moving blades 402, the size of the small moving blades 403, the density of the small moving blades 403, and the gap 6 between the wheel 401 and the gasket 5.

[0049] The following combination Figure 4 The pressure reduction and flow diversion principles of the micro centrifugal compressor 4 provided in this embodiment are described in detail:

[0050] Figure 4The velocity triangle for the large rotor blades 402 of a micro centrifugal compressor is shown. The rotating shaft 2 rotates counterclockwise. Gas enters the blade passageway at an absolute velocity V1, between two adjacent large rotor blades 402. The large rotor blades 402 rotate along the rotating shaft 2 at a circumferential velocity U. Therefore, the gas moves at a relative velocity W1 relative to the large rotor blades 402, where the relative velocity plus the circumferential velocity equals the absolute velocity. As the gas flows toward the outlet of the large rotor blades 402 at velocity W1, the direction and magnitude of the outlet relative velocity W2 and the absolute velocity V2 change due to the compression work performed by the rotating large rotor blades 402. The pressure of the gas flowing toward the tail of the large rotor blades 402 increases. The increased pressure of the low-pressure gas offsets the high-pressure gas, preventing leakage of the high-pressure gas and improving sealing performance. Furthermore, the end of the impeller 401 near the high-pressure side also blocks the high-pressure gas flow, reducing the flow of high-pressure gas to the low-pressure side. Figure 4 Where W1 is the relative velocity at the inlet of the large moving blade 402, W2 is the relative velocity at the outlet of the large moving blade 402, V1 is the absolute velocity at the inlet of the large moving blade 402, V2 is the absolute velocity at the outlet of the large moving blade 402, and U is the circumferential velocity.

[0051] The following combination Figure 5-Figure 7 The advantages of the micro centrifugal compressor sealing device 100 provided in this embodiment are described in detail below:

[0052] Figure 5 A schematic diagram comparing the sealing effects of the micro centrifugal compressor sealing device 100 provided in this embodiment and a conventional sealing method is provided. Figure 5 The placement position of the mid-axial non-contact seal 3 corresponds to the line diagram. The micro centrifugal compressor sealing device 100 provided in this embodiment takes a one-stage micro centrifugal compressor 4 coupled with a five-stage carbon ring as an example, and the conventional sealing method takes a multi-stage carbon ring as an example. For the convenience of description, the one-stage micro centrifugal compressor coupled with a five-stage carbon ring is referred to as a micro centrifugal compressor sealing method, and the conventional multi-stage carbon ring sealing method is referred to as a micro centrifugal compressor sealing method. Figure 7 As shown, in the sealing mode without micro centrifugal compressor, since the micro centrifugal compressor 4 is not provided, a cavity is formed between the gasket 5 and the rotating shaft 2 . Figure 5 The horizontal axis is the axis from high pressure inlet to low pressure outlet, and the vertical axis is the total pressure and leakage respectively. Figure 5As can be seen from the figure, at the same inlet pressure and the same shaft speed, the seal method with a micro-centrifugal compressor can reach the outlet low pressure value more quickly than the method without a micro-centrifugal compressor seal. Furthermore, the seal method with a micro-centrifugal compressor requires fewer carbon ring stages, thus requiring a shorter axial spacing. Furthermore, the seal method provided in this embodiment prevents a significant pressure drop in the last carbon ring stage at the outlet of the micro-centrifugal compressor, thereby reducing damage to the carbon rings.

[0053] It should be noted that, compared with conventional centrifugal compressors, the centrifugal compressor provided in the embodiment of the present invention is arranged between the housing 1 and the rotating shaft 2. The size of the centrifugal compressor in the present invention is much smaller than that of conventional centrifugal compressors. Therefore, the centrifugal compressor in the present invention is referred to as a micro centrifugal compressor. The "micro" here does not mean that the size of the micro centrifugal compressor is smaller than a certain value. The size of the micro centrifugal compressor is adjusted according to the sealing requirements. It should also be pointed out that the structure of the micro centrifugal compressor provided in the embodiment of the present invention is essentially the same as that of a conventional centrifugal compressor, and the micro centrifugal compressor sealing device 100 provided in this embodiment is not only suitable for bearing cavities, but also suitable for other non-contact sealing occasions.

[0054] This specification uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A micro centrifugal compressor sealing device, characterized in that: It is used to be arranged between the housing and the rotating shaft, including: a micro centrifugal compressor and a multi-stage non-contact seal arranged along the axial direction, a stage gap is formed between any two adjacent stages of the non-contact seals, the micro centrifugal compressor is arranged in at least one stage gap, the micro centrifugal compressor is arranged close to the low-pressure side, the micro centrifugal compressor includes a wheel and a plurality of large moving blades, the wheel is used to be fixedly sleeved on the outside of the rotating shaft, the outer wall of the wheel is a conical structure, and the outer diameter of the end of the wheel close to the high-pressure side is greater than the outer diameter of the end of the wheel away from the high-pressure side, all the large moving blades are arranged on the outer wall of the wheel, and all the large moving blades are along the circumference of the wheel. The large moving blades are arranged in a directional manner, the large moving blades can suck the airflow on the low-pressure side into between the casing and the rotating shaft, and can compress the airflow, and the end of the wheel close to the high-pressure side can cover all the large moving blades; the micro centrifugal compressor also includes a plurality of small moving blades, all of the small moving blades are arranged on the outer side wall of the wheel, all of the small moving blades are arranged along the circumference of the wheel, and the large moving blades and the small moving blades are alternately arranged in the circumference of the wheel, the small moving blades can suck the airflow on the low-pressure side into between the casing and the rotating shaft, and can compress the airflow, and the end of the wheel close to the high-pressure side can cover all the small moving blades.

2. The micro centrifugal compressor sealing device according to claim 1, characterized in that: The large moving blades are large rotating blades, and the small moving blades are small rotating blades.

3. The micro centrifugal compressor sealing device according to claim 1, characterized in that: The thickness of the wheel disc gradually decreases from one end of the wheel disc close to the high-pressure side to the other end of the wheel disc away from the high-pressure side, so that the outer side wall of the wheel disc is a tapered structure.

4. The micro centrifugal compressor sealing device according to claim 1, characterized in that: There are multiple micro centrifugal compressors, and all of the micro centrifugal compressors are respectively arranged in the stage intervals at different positions.

5. The micro centrifugal compressor sealing device according to claim 1, characterized in that: The outer side wall of the wheel disc is a curved structure.

6. The micro centrifugal compressor sealing device according to claim 1, characterized in that: A plurality of annular grooves are axially arranged on the inner wall of the shell, and the non-contact seals correspond to the annular grooves one by one. Each of the non-contact seals is partially embedded in the corresponding annular groove, and a gasket for positioning the two adjacent levels of the non-contact seals is provided between any two adjacent annular grooves.

7. The micro centrifugal compressor sealing device according to claim 6, characterized in that: A gap is formed between an outer side wall of one end of the wheel disc close to the high-pressure side and the gasket.

8. The micro centrifugal compressor sealing device according to claim 6, characterized in that: The non-contact seal and the gasket adjacent thereto are detachably connected.

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