Two-stage filtering air filter with automatic drain valve
By designing a dual-stage air filter, combined with swirl vanes and a mechanical automatic drain valve, the problems of water-air separation and solid impurity filtration in civil aircraft inerting systems are solved, achieving automatic drainage and efficient air purification, while reducing maintenance and space requirements.
Patent Information
- Application Number
- CN202511470058.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-15
- Publication Date
- 2025-12-26
AI Technical Summary
Air filters in civil aircraft inerting systems need to achieve water-air separation and solid impurity filtration. However, existing filters are large in size and heavy, and require manual drainage periodically, which can easily lead to inerting system failure.
It adopts a two-stage air filter, which includes a cylindrical shell and two-layer filter structure. The outer layer is an anaerobic filter element and the inner layer is a high-precision filter element. Combined with swirl vanes and a mechanical automatic drain valve, it realizes water-air separation and automatic drainage functions.
It achieves automatic drainage without adding electrical controls, reducing maintenance costs, saving installation space and weight, while ensuring air cleanliness.
Smart Images
Figure CN121197947A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the technical field of air filter for civil aircraft inerting systems, and relates to a two-stage air filter with an automatic drain valve, particularly to the field of separating water and drain in air filters for civil aircraft inerting systems. Background Technology
[0002] Air filters in civil aircraft inerting systems need to separate water and air, drain water, and filter solid impurities. To achieve these functions, two filter cups, each with a filter element connected in series, are typically used. These filters are bulky and heavy. Since the separated water must be drained out of the filter, otherwise it will accumulate and enter the downstream of the inerting system, causing damage to the ozone and nitrogen-oxygen separation membranes and ultimately rendering the inerting system ineffective, manual drainage is usually required periodically. Summary of the Invention
[0003] To address the aforementioned problems, this invention provides a two-stage air filter with an automatic drain valve, which can achieve functions such as water-air separation and collection, automatic drainage, filtration of solid impurities, and filter element differential pressure detection, thus improving maintainability.
[0004] The technical solution of the present invention is as follows: A two-stage air filter with an automatic drain valve includes a cylindrical housing, a gas inlet and a gas outlet on the top two sides of the housing. The gas inlet connects to the outer ring channel inside the housing, and the gas outlet connects to the central circle inside the housing. The outer ring channel and the central circle inside the housing are separated by a cylindrical surface. The outer ring channel and the central circle are provided with two coaxially fitted cylindrical filter structures at the bottom inside the housing. Below the filter structures is a drain valve assembly.
[0005] Furthermore, it also includes swirl vanes, which are located in the outer ring channel above the two-layer filter structure.
[0006] Furthermore, the two-layer filter structure is connected to the housing via the lower end cap assembly.
[0007] Furthermore, the two-layer filtration structure includes an outer anaerobic filter element and an inner high-precision filter element. The anaerobic filter element and the high-precision filter element are identical in structure except for their diameter, filter screen, and end cap structure.
[0008] Furthermore, the anaerobic filter element includes an upper end cap, a frame, a filter screen, and a lower end cap. The filter screen is located on the outer surface of the cylindrical frame. The upper end cap with a ring structure and the lower end cap with a disc structure fix the frame and the filter screen. The cylindrical surface of the frame is evenly distributed with through holes. The lower end cap has an installation structure that matches the upper part of the end cap assembly.
[0009] Furthermore, the lower end cap has a flared opening below it, and a sleeve that matches the flared opening is located at the center of the upper end cap assembly. A spring is installed inside the sleeve, and the top of the spring is connected to a spring seat. The top of the sleeve has an upper limit limit for the spring seat.
[0010] Furthermore, the outer layer of the anaerobic filter element is coated with an anaerobic material, and the density of the high-precision filter element's filter screen is at least an order of magnitude higher than that of the anaerobic filter element's filter screen.
[0011] Furthermore, the drain valve assembly is located on the bottom side wall of the housing and includes a valve core assembly, a drain valve spring, a drain valve housing, and a drain valve spring seat. The drain valve housing has a drain hole at its center. One end of the drain valve spring is located at the protrusion at the outlet of the drain hole, and the other end of the drain valve spring is connected to the valve core assembly. The bottom of the valve core assembly has an annular sealing structure, and the top of the valve core assembly is limited by the drain valve spring seat located at the inlet of the drain hole in the drain valve housing.
[0012] Furthermore, when the dual-stage air filter is working, high-pressure gas enters the housing, and the pressure generated by the high-pressure gas pushes the valve core assembly to overcome the elastic force of the drain valve spring, causing the sealing structure at the bottom of the valve core assembly to block the drain hole; when the dual-stage air filter is not working, the valve core assembly moves to the drain valve spring seat under the elastic force of the drain valve spring, and the drain hole opens.
[0013] Technical effects of the present invention: 1. This invention adds two filter elements connected in series, similar to placing them in a "matryoshka doll" in a filter cup, which saves installation space and reduces product weight.
[0014] 2. The mechanical automatic drain valve of this invention achieves automatic drainage function at low cost without increasing the electrical control of the inerting system, thus saving maintenance costs.
[0015] 3. The end cap assembly of the present invention is provided with a spring, firstly to press the anaerobic filter element to prevent it from moving axially, and secondly to allow the end cap assembly to pop out for easy disassembly. Attached Figure Description
[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0017] Figure 1 This is a general diagram of a two-stage air filter with an automatic drain valve according to the present invention.
[0018] Among them, 1—drain valve assembly, 2—housing, 3—anaerobic filter element, 4—high-precision filter element, 5—cyclone vane, 6—differential pressure indicator, 7—electric plug, 8—tail accessory, 9—end cap assembly, 10—sealing ring, 11—screw, 12—plate joint overlap piece, 13—screw, 14—washer, 15—first plug cap, 16—second plug cap, 17—locking screw.
[0019] Figure 2 This is a schematic diagram of the drain valve assembly and valve core assembly of the present invention.
[0020] 1-1—Valve core assembly; 1-2—Drain valve spring; 1-3—Drain valve housing; 1-4—Drain valve sealing ring; 1-5—Drain valve spring seat; 1-1-1—Valve core; 1-1-2—Rubber.
[0021] Figure 3 This is a schematic diagram of the swirl blade structure of the present invention.
[0022] Figure 4 This is a schematic diagram of the end cap assembly structure of the present invention.
[0023] Among them, 9-1—end cap; 9-2—sleeve; 9-3—end cap spring; 9-4—end cap spring seat.
[0024] Figure 5 This is a schematic diagram of the hydrophobic filter element structure of the present invention.
[0025] Among them, 3-1—upper end cover; 3-2—frame; 3-3—filter screen; 3-4—lower end cover Figure 6 This is a schematic diagram of the product installation according to the present invention. Detailed Implementation
[0026] This section describes embodiments of the present invention, used to explain and illustrate the technical solutions of the present invention. Unless otherwise specified, the embodiments and features described herein can be combined with each other.
[0027] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating directions or positional relationships, are given in the accompanying drawings and are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or device referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include more than one of those features. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.
[0028] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integrated connections; they can refer to mechanical connections or point connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.
[0029] Example 1: A two-stage air filter with an automatic drain valve includes a cylindrical housing 2, a gas inlet and a gas outlet on the top sides of the housing 2. The gas inlet connects to the outer ring channel inside the housing 2, and the gas outlet connects to the central circle inside the housing 2. The outer ring channel and the central circle inside the housing 2 are separated by a cylindrical surface. The outer ring channel and the central circle are provided with two coaxially fitted cylindrical filter structures at the bottom inside the housing 2. Below the filter structures is a drain valve assembly 1.
[0030] It also includes swirl vanes 5, which are located in the outer ring channel above the two-layer filter structure.
[0031] The two-layer filter structure is connected to the housing 2 via the lower end cap assembly 9.
[0032] The two-layer filtration structure includes an outer anaerobic filter element 3 and an inner high-precision filter element 4. The anaerobic filter element 3 and the high-precision filter element 4 are identical except for their diameter, filter screen and end cap structure.
[0033] The anaerobic filter element 3 includes an upper end cover 3-1, a frame 3-2, a filter screen 3-3, and a lower end cover 3-4. The filter screen 3-3 is located on the outer surface of the cylindrical frame 3-2. The upper end cover 3-1 with a ring structure and the lower end cover 3-4 with a disc structure fix the frame 3-2 and the filter screen 3-3. The cylindrical surface of the frame 3-2 is evenly distributed with through holes. The lower end cover 3-4 is provided with an installation structure that cooperates with the upper part of the end cover assembly 9.
[0034] The lower end cap 3-4 has a flared opening below it. The upper center of the end cap assembly 9 has a sleeve 9-2 that matches the flared opening. A spring 9-3 is installed inside the sleeve 9-2. The top of the spring 9-3 is connected to the spring seat 9-4. The top of the sleeve 9-2 has an upper limit limit for the spring seat 9-4.
[0035] The outer layer of the filter screen 3-3 of the anaerobic filter element 3 is coated with anaerobic material, and the density of the filter screen of the high-precision filter element 4 is at least an order of magnitude higher than that of the filter screen 3-3 of the anaerobic filter element 3.
[0036] The drain valve assembly 1 is located on the bottom side wall of the housing 2, and includes a valve core assembly 1-1, a drain valve spring 1-2, a drain valve housing 1-3, and a drain valve spring seat 1-5. The drain valve housing 1-3 has a drain hole at its center. One end of the drain valve spring 1-2 is located at the protrusion at the outlet of the drain hole, and the other end of the drain valve spring 1-2 is connected to the valve core assembly 1-1. The bottom of the valve core assembly 1-1 has an annular sealing structure, and the top of the valve core assembly 1-1 is limited by the drain valve spring seat 1-5 located at the inlet of the drain hole in the drain valve housing 1-3.
[0037] When the dual-stage air filter is working, high-pressure gas enters the housing 2. The pressure generated by the high-pressure gas pushes the valve core assembly 1-1 to overcome the elastic force of the drain valve spring 1-2, causing the sealing structure at the bottom of the valve core assembly 1-1 to block the drain hole. When the dual-stage air filter is not working, the valve core assembly 1-1 moves to the drain valve spring seat 1-5 under the elastic force of the drain valve spring 1-2, and the drain hole opens.
[0038] Example 2: This invention provides a high-precision air filter for civil aircraft inerting systems, featuring water-air separation and automatic drainage functions, enabling dual-stage filtration. It aims to separate moisture from the air, filter impurities, provide clean air to the aircraft inerting system, and automatically discharge collected moisture as needed. Our proposed dual-filter series configuration, similar to a "nested doll" structure, houses them in a single filter cup, saving space and weight. Furthermore, a mechanical automatic drain valve enables automatic drainage when the product is not in operation. This achieves automatic drainage at extremely low cost without increasing the electrical control of the inerting system.
[0039] When the product is working normally, the air of the inerting system enters the lower housing through the product inlet. After passing through the swirl vane 5, the air forms a rotating airflow. Under the influence of centrifugal force, the moisture in the air adheres to the inner wall of the upper housing 2. The moisture flows along the inner wall of the housing 2 and flows to the area above the drain valve assembly 1. After the air passes through the anaerobic filter element 3, the moisture it contains is blocked by the anaerobic coating layer on the anaerobic filter element and similarly gathers above the drain valve assembly 1. The anaerobic filter element 3 can also intercept larger solid particles. Then the air enters the high-precision filter element 4 to remove smaller solid particles. The clean air then enters the downstream of the system through the outlet.
[0040] As the working time increases, the pressure difference between the anaerobic filter element 3 and the high-pressure filter element 4 gradually increases. When the pressure difference between the two filter elements reaches 25kPa±10kPa, the differential pressure indicator 6 sends a blockage signal, reminding the filter element to be replaced in time.
[0041] Figure 2 These are drawings of drain valve assembly 1 and valve core assembly 1-1. Through a vulcanization process, rubber 1-1-2 is bonded to the valve core 1-1-1 of drain valve assembly 1-1, with the top of the rubber being semi-circular. When the product is in operation, the air pressure inside the product cavity is approximately 0.4 MPa. At this time, valve core assembly 1-1 is pressed against drain valve housing 1-3 under pressure, and drain valve assembly 1 is closed. When the product is not in operation, the air pressure inside the product cavity is zero. At this time, valve core assembly 1-1 is disengaged from drain valve housing 1-3 under the preload of spring 1-2, and drain valve assembly 1 is opened to achieve drainage.
[0042] Figure 3 This is a schematic diagram of the structure of the swirl vane 5. Air passing through the swirl vane 5 will form an optional airflow. Under the action of centrifugal force, water will be collected on the inner wall of the housing 2. The water will flow along the inner wall of the housing 2 to the top of the drain valve assembly 1.
[0043] This invention integrates an air cyclone device, an anaerobic filter element, a high-precision filter element, and an automatic drain valve into a single cavity, achieving efficient use of space. The automatic drain valve can automatically close to prevent drainage when the product is in operation and automatically open to drain water when the product is not in operation. This invention uses a vulcanization process to attach a rubber ring to the valve core of a drain valve, with the top of the rubber ring being semi-circular. When the product is in operation, the air pressure inside the product cavity is approximately 0.4 MPa. At this pressure, the drain valve core adheres to the drain valve seat, closing the drain valve. When the product is not in operation, the air pressure inside the product cavity is zero. At this pressure, the drain valve core detaches from the drain valve seat under the action of a spring, opening the drain valve and achieving drainage.
[0044] The product is equipped with swirl vanes. When water-containing air flows in from the product inlet, it forms a rotating airflow after passing through the swirl vanes. Under the influence of centrifugal force, the water adheres to the shell and flows along the shell into the drain valve. The product is equipped with a differential pressure indicator. When the differential pressure between the anaerobic filter cartridge and the high-precision filter cartridge reaches a certain value, it sends a discrete signal to the system to remind maintenance personnel to replace the filter cartridge. The product end cap is equipped with a clamping component to clamp the filter element and prevent the filter element from moving axially. At the same time, it provides a thrust to the end cap when removing the filter element, making it easy to remove. The product end cap has a threaded hole in the center. When replacing the filter element, the bolt can be screwed into the threaded hole. The bolt acts as a "handle" to make it easy to remove the end cap.
[0045] The bottom cover of the anaerobic filter element has a ring of small holes, and a certain gap is reserved between the bottom cover of the anaerobic filter element and the housing. This is to allow water to accumulate along the small holes and gaps to the drain valve.
[0046] The lower end cap of the anaerobic filter cartridge has a "flared opening" to facilitate easy insertion of the end cap clamping assembly. This ensures the coaxiality of the anaerobic filter cartridge and the housing while reducing the difficulty of replacing the filter cartridge.
[0047] The product end cap has a pressure device with a drain outlet, allowing water to flow directly to the drain valve.
[0048] The drain valve is installed at the lowest position of the product to facilitate water collection and gravity drainage.
[0049] Figure 4 This is a schematic diagram of the end cap assembly 9. The end cap assembly 9 is equipped with a spring 9-3, which serves two purposes: first, to press the anaerobic filter element 3 to prevent it from moving axially; and second, to allow the lower end cap assembly 9 to pop out for easy disassembly.
[0050] Figure 5 This is a schematic diagram of the anaerobic filter element 5. The outer layer of the filter screen 5-3 is coated with an anaerobic material to remove larger solid particles while intercepting moisture from the air. The lower end cap 5-4 of the anaerobic filter element 5 has a flared opening to facilitate easy insertion of the spring seat 9-4 in the end cap assembly 9. This flared opening ensures the coaxiality of the anaerobic filter element 5 and the housing 2, while also reducing the difficulty of replacing the anaerobic filter element 3 and the high-precision filter element 4.
[0051] Figure 6The product is installed in such a way that the drain valve assembly 1 is placed at the lowest point of the product. Because a ring of small holes is arranged on the lower end cover 3-4 of the anaerobic filter element 3, and a certain gap is reserved between the lower end cover 3-4 of the anaerobic filter element 3 and the housing 2, water collects above the drain valve assembly 1 at the bottom of the product under the action of gravity.
[0052] The above description is merely a specific embodiment of the present invention, providing a detailed description of the invention. Parts not covered herein are conventional techniques. However, the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. The scope of protection of the present invention should be determined by the scope of the claims.
Claims
1. A two-stage air filter with an automatic drain valve, characterized in that, The shell (2) includes a cylindrical structure, a gas inlet and a gas outlet on the top two sides of the shell (2). The gas inlet is connected to the outer ring channel inside the shell (2), and the gas outlet is connected to the central circle inside the shell (2). The outer ring channel and the central circle inside the shell (2) are separated by a cylindrical surface. The outer ring channel and the central circle are provided with a two-layer filter structure in a cylindrical coaxial fit inside the shell (2). Below the filter structure is a drain valve assembly (1).
2. A two-stage air filter with an automatic drain valve according to claim 1, characterized in that, It also includes swirl vanes (5), which are located in the outer ring channel above the two-layer filter structure.
3. A two-stage air filter with an automatic drain valve according to claim 1, characterized in that, The two-layer filter structure is connected to the housing (2) via the lower end cap assembly (9).
4. A two-stage air filter with an automatic drain valve according to claim 3, characterized in that, The two-layer filtration structure includes an outer anaerobic filter element (3) and an inner high-precision filter element (4). The anaerobic filter element (3) and the high-precision filter element (4) are identical except for their diameter, filter screen and end cap structure.
5. A two-stage air filter with an automatic drain valve according to claim 4, characterized in that, The anaerobic filter element (3) includes an upper end cap (3-1), a frame (3-2), a filter screen (3-3), and a lower end cap (3-4). The filter screen (3-3) is located on the outer surface of the cylindrical frame (3-2). The upper end cap (3-1) with a ring structure and the lower end cap (3-4) with a disc structure fix the frame (3-2) and the filter screen (3-3). The cylindrical surface of the frame (3-2) is evenly distributed with through holes. The lower end cap (3-4) is provided with an installation structure that cooperates with the upper part of the end cap assembly (9).
6. A two-stage air filter with an automatic drain valve according to claim 5, characterized in that, The lower end cap (3-4) has a flared opening below it. The upper center of the end cap assembly (9) is provided with a sleeve (9-2) that matches the flared opening. A spring (9-3) is provided inside the sleeve (9-2). The top of the spring (9-3) is connected to the spring seat (9-4). The top of the sleeve (9-2) is provided with an upper limit limit for the spring seat (9-4).
7. A two-stage air filter with an automatic drain valve according to claim 5, characterized in that, The outer layer of the filter screen (3-3) of the anaerobic filter element (3) is coated with anaerobic material, and the density of the filter screen of the high-precision filter element (4) is at least one order of magnitude higher than that of the filter screen (3-3) of the anaerobic filter element (3).
8. A two-stage air filter with an automatic drain valve according to claim 1, characterized in that, The drain valve assembly (1) is located on the bottom side wall of the housing (2) and includes a valve core assembly (1-1), a drain valve spring (1-2), a drain valve housing (1-3), and a drain valve spring seat (1-5). The drain valve housing (1-3) has a drain hole in the center. One end of the drain valve spring (1-2) is located at the protrusion at the outlet of the drain hole, and the other end of the drain valve spring (1-2) is connected to the valve core assembly (1-1). The bottom of the valve core assembly (1-1) is provided with an annular sealing structure, and the top of the valve core assembly (1-1) is limited by the drain valve spring seat (1-5) located at the inlet of the drain hole of the drain valve housing (1-3).
9. A two-stage air filter with an automatic drain valve according to claim 8, characterized in that, When the dual-stage air filter is working, high-pressure gas enters the housing (2). The pressure generated by the high-pressure gas pushes the valve core assembly (1-1) to overcome the elastic force of the drain valve spring (1-2), causing the sealing structure at the bottom of the valve core assembly (1-1) to block the drain hole. When the dual-stage air filter is not working, the valve core assembly (1-1) moves to the drain valve spring seat (1-5) under the elastic force of the drain valve spring (1-2), and the drain hole opens.