A fuel double filter

Abstract

The present invention discloses a fuel double filter, which comprises an oil filter seat, a stop valve, an inlet pipeline, a check valve I and a filter element. An upper flow channel and a lower flow channel are arranged inside the oil filter seat. The lower flow channel comprises a filter element installation inner cavity, a check valve cavity and an outlet cavity. The filter element installation inner cavities are symmetrically arranged. The check valve cavity is arranged below the filter element installation inner cavity and communicated with the filter element installation inner cavity. The outlet cavity is arranged between the check valve cavities, and both ends of the outlet cavity are respectively communicated with the check valve cavities. The lower flow channel is a cross oil channel. Stop valve cavities are respectively arranged at the left and right ends of the cross oil channel. The stop valve cavities are communicated with the filter element installation inner cavity through connection holes. The stop valve is installed in the stop valve cavity. Through a completely new design of the filter structure, compared with the same filtering structure arranged in parallel, it has the advantages of small occupied space and convenient disassembly and assembly of the filter element, and realizes the integration of filtration and control, realizes the multi-channel oil circuit circulation, and realizes the non-stop switching of the oil circuit.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel system filtration, and particularly to a fuel double filter. Background Art

[0002] The fuel system provides fuel power for the engine and keeps working during the operation of the machine. Therefore, the oil filter is always in operation, and the filter element needs to be replaced and maintained due to blockage after long-term work; in the conventional fuel system pipeline, two identical oil filters are arranged in parallel, and stop valves are used to realize the oil circuit commutation before and after, and shutdown is required for disassembly and replacement; this design has a large space occupation for the installation and maintenance of the oil filter, and the disassembly and replacement are time-consuming and laborious; moreover, this kind of oil filter has a simple structure and single function, and cannot adjust the oil flow rate and flow direction for different power systems, and the overall integration function is poor; Chinese Patent Application No. 201410306283.2 discloses a double fuel filter, which consists of a switching valve core and two left and right chambers, and an operating handle is arranged on the top of the switching valve core; a filter body and a filter cartridge are arranged in each chamber, and the filter can be cleaned or replaced without shutdown. This structure is a conventional parallel connection of two oil filters, and the switching valve core is switched by operating the handle, which requires manual operation and cannot meet the requirements on the aircraft, and it has a large volume and cannot adjust the oil flow rate and flow direction; similarly, Chinese Patent Application No. 202011522364.8 discloses a fuel double filter, which includes: a body, a filtering device, an exhaust valve and a quick connector. There are at least two filtering devices, and the filtering devices are arranged in parallel. The filtering device includes a cylindrical filter element; the exhaust valve is arranged on the body; the quick connector has a connecting part for external connection, and the quick connector is used for sampling or on-line detection of oil product parameters. This structure is also a conventional parallel filter element structure, which requires manual operation and cannot meet the requirements of the power adjustment system; it cannot meet the requirements in actual use, so there is an urgent need for improved technology in the market to solve the above problems. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the existing defects and provide a fuel double filter. This structure has a completely new design of the filter structure, realizes the integration of filtration and control, has a small structure volume, realizes the non-stop switching of the oil circuit, can adjust the oil circuit and flow rate, integrates various valves on the oil filter seat, and sets pressure and temperature measurement points to realize the real-time monitoring of the oil liquid, and can effectively solve the problems in the background art.

[0004] To achieve the above object, the present invention provides the following technical solution: A fuel double filter, comprising an oil filter seat, a stop valve, an inlet pipe, a check valve I and a filter element. An upper flow channel and a lower flow channel are provided inside the oil filter seat. The lower flow channel includes a filter element installation inner cavity, a check valve cavity and an outlet cavity. The filter element installation inner cavities are symmetrically arranged. The check valve cavity is arranged below the filter element installation inner cavity and communicates with the filter element installation inner cavity. The outlet cavity is arranged between the check valve cavities, and both ends of the outlet cavity communicate with the check valve cavities respectively. The lower flow channel is a cross oil channel. Stop valve cavities are respectively arranged at the left and right ends of the cross oil channel. The stop valve cavities communicate with the filter element installation inner cavity through connection holes. The stop valve is installed in the stop valve cavity. The upper and lower ends of the cross oil channel are respectively connected with inlet pipes. The filter element is arranged in the filter element installation inner cavity. The check valve I is installed in the check valve cavity and is connected to the lower end of the filter element. A check valve II is arranged at the upper end of the filter element.

[0005] Further, the stop valve includes a valve stem and a valve seat I. The valve seat I is inserted into the oil filter seat by means of a thread. The valve stem is threadedly connected to the valve seat I, and a seal ring I is arranged between the valve stem and the valve seat I. The valve stem is provided with a conical head and corresponds to the cross oil channel. The other end of the valve stem is provided with a handle I. The handle I is installed on the valve stem through an anti-loosening nut. A limit piece is arranged on the valve stem.

[0006] Further, a rotary valve is arranged on the oil filter seat. The rotary valve is composed of a valve I, a handle II, a spring seat I, a valve seat I, a rotary joint I and a seal ring II. The lower end of the valve seat I is threadedly connected to the oil filter seat, and the lower end of the valve seat I communicates with the check valve cavity. The lower end of the valve I passes through the valve seat I. The rotary joint I is arranged at the lower part of the valve seat I, and a seal ring II is arranged between the rotary joint I and the valve seat I. The spring seat I is threadedly connected to the valve seat I. The handle II is installed at the outer end of the valve I. An outer spring is arranged between the valve I and the spring seat I. An inner spring is arranged between the valve I and the valve seat I.

[0007] Further, a monitoring joint is arranged on one side of the rotary valve. The monitoring joint is composed of a plug, a seal ring V, a rotary joint II and a seal ring VI. The plug is threadedly connected to the oil filter seat, and a seal ring VI is arranged between the plug and the oil filter seat. The internal oil path of the plug communicates with another check valve cavity. The rotary joint II communicates with the internal oil path of the plug, and a seal ring V is arranged between the rotary joint II and the plug.

[0008] Further, an outlet pipe is arranged at the bottom of the oil filter seat. The outlet pipe communicates with the outlet cavity. Flange holes are arranged on the lower surface of the oil filter seat.

[0009] Furthermore, the one-way valve I includes a valve seat II, a valve II, a one-way spring, and a spring seat II. The valve seat II is arranged in the one-way valve cavity, and the upper end of the valve seat II contacts the lower end cover of the filter element. A sealing ring III is arranged between the valve seat II and the lower end cover of the filter element. The valve II is arranged in the valve seat II. The spring seat II is threadedly connected to the oil filter seat, and a sealing ring IV is arranged at the connection. The one-way spring is arranged between the spring seat II and the valve II.

[0010] Furthermore, the one-way valve II is composed of a valve housing, a steel ball, a limiting spring, a spring seat III, and a valve seat II. The valve seat II is threadedly connected to the oil filter seat, and a sealing ring VII is arranged at the connection. The inner cavity of the valve seat II communicates with the upper part of the inner cavity for installing the filter element through an inclined channel. The lower part of the valve housing is threadedly connected to the valve seat II. The spring seat III is threadedly connected to the lower end of the valve housing. The steel ball is arranged in the valve housing, and the limiting spring is arranged between the steel ball and the spring seat III. A sealing cover is arranged at the upper end of the valve housing.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0012] 1. By newly designing the filter structure, compared with the same parallel filter structure, it has the advantages of small occupied space and convenient disassembly and assembly of the filter element, and realizes the integration of filtration and control. A variety of valves are integrated on the oil filter seat to realize the multi-channel oil circuit circulation, realize the non-stop machine switching of the oil circuit, and can adjust the oil flow and flow direction for different power systems.

[0013] 2. The one-way valve I is integrated at the filter element outlet to realize the one-way conduction of the oil circuit, close and isolate the parallel oil circuits. When replacing the filter element, it can be used as a self-sealing valve to achieve the purpose of dual use of one valve, seal the outlet oil fluid, and prevent oil leakage; the one-way valve II is integrated at the filter element inlet end, and the oil fluid flows unidirectionally during operation; when replacing the filter element, it can be used as an oil drain valve to drain all the fuel in the inner cavity of the oil filter, eliminating the need for a separate oil drain structure, and the design of this structure makes full use of the space.

[0014] 3. The oil filter can be used for dual-system operation. Multiple inlets are arranged on the oil filter seat. When the small power system is used, the cut-off valve can be used for manual control of the system. When the large power system is used, the interface of the one-way valve II can be connected to increase the system flow. A rotary joint is arranged on the oil filter seat and can be used for the split fuel system to connect to the pressurized fuel tank for secondary pressurization. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a three-dimensional structure schematic diagram of the present invention;

[0016] Figure 2 is a schematic diagram of the upper-layer oil circuit structure of the oil filter seat of the present invention;

[0017] Figure 3 is a schematic diagram of the upper-layer oil circuit structure of the oil filter seat of the present invention;

[0018] Figure 4 Schematic diagram of the internal structure of the present invention;

[0019] Figure 5 Schematic diagram of the enlarged structure at I of the present invention;

[0020] Figure 6 Schematic diagram of the imported oil fluid commutation structure of the present invention;

[0021] Figure 7 Schematic diagram of the monitoring interface and rotary valve interface of the present invention.

[0022] In the figure: 1 oil filter seat, 2 stop valve, 3 inlet pipeline, 4 rotary valve, 5 check valve I, 6 outlet pipeline, 7 monitoring joint, 8 check valve II, 9 filter element, 10 outlet cavity, 11 filter element installation inner cavity, 12 check valve cavity, 13 cross oil passage, 14 connecting hole, 15 stop valve cavity, 201 anti-loosening nut, 202 valve stem, 203 handle I, 204 sealing ring I, 205 valve seat I, 206 limit piece, 401 valve I, 402 handle II, 403 spring seat I, 404 valve seat I, 405 rotary joint I, 406 sealing ring II, 407 outer spring, 408 inner spring, 501 sealing ring III, 502 valve seat II, 503 valve II, 504 one-way spring, 505 spring seat II, 506 sealing ring IV, 701 plug, 702 sealing ring V, 703 rotary joint II, 704 sealing ring VI, 801 valve housing, 802 steel ball, 803 limit spring, 804 spring seat III, 805 valve seat II, 806 sealing ring VII, 807 inclined passage, 808 sealing cover. Specific embodiments

[0023] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0024] Please refer to Figures 1-7, the present invention provides a technical solution: a fuel double filter, including an oil filter base 1, a stop valve 2, an inlet pipe 3, a check valve I 5, and a filter element 9. An upper flow channel and a lower flow channel are provided inside the oil filter base 1. The lower flow channel includes a filter element installation inner cavity 11, a check valve cavity 12, and an outlet cavity 10. The filter element installation inner cavity 11 and the check valve cavity 12 are each provided in two. The filter element installation inner cavities 11 are symmetrically arranged. The check valve cavity 12 is arranged below the filter element installation inner cavity 11 and is communicated with the filter element installation inner cavity 11. The outlet cavity 10 is arranged between the check valve cavities 12, and both ends of the outlet cavity 10 are communicated with the check valve cavities 12 respectively. The lower flow channel is a cross oil channel 13. Stop valve cavities 15 are respectively arranged at the left and right ends of the cross oil channel 13. The stop valve cavities 15 are communicated with the filter element installation inner cavity 11 through connection holes 14. The stop valve 2 is installed in the stop valve cavity 15. By adjusting the handle I 203 of the stop valve 2, it can be sealed or separated from the oil filter base 1 to achieve communication with the two filter element installation inner cavities 11. The upper and lower ends of the cross oil channel 13 are respectively connected with the inlet pipe 3. The filter element 9 is arranged in the filter element installation inner cavity 11. The check valve I 5 is installed in the check valve cavity 12, and the check valve I 5 is connected to the lower end of the filter element 9. The outlet of the filter element 9 integrates the check valve I 5 to achieve one-way conduction of the oil circuit and closed isolation of the parallel oil circuits. When replacing the check valve I 5, it can be used as a self-sealing valve to seal the outlet oil and prevent oil leakage. A check valve II 8 is arranged at the upper end of the filter element 9. The oil filter can be used for dual-system operation. Multiple inlets can be arranged on the oil filter base 1. When the small power system is in use, the stop valve 2 can be used to control the system manually. When the large power system is in use, the interface of the check valve II 8 can be connected to increase the system flow rate.

[0025] The stop valve 2 includes a valve stem 202 and a valve seat I 205. The valve seat I 205 is inserted into the oil filter base 1 through threads. The valve stem 202 is threadedly connected to the valve seat I 205, and a sealing ring I 204 is arranged between the valve stem 202 and the valve seat I 205. The sealing ring I 204 prevents oil leakage and ensures stable operation of the system. The valve stem 202 is provided with a conical head and corresponds to the cross oil channel 13. The other end of the valve stem 202 is provided with a handle I 203. The handle I 203 is installed on the valve stem 202 through an anti-loosening nut 201. By rotating the handle I 203, the valve stem 202 can be moved left and right to achieve sealing and circulation with the oil filter base 1. A limit piece 206 is arranged on the valve stem 202. The other end of the limit piece 206 corresponds to a fixed block on the oil filter base 1. When the valve stem 202 moves to the right to seal with the oil filter base 1, the limit piece 206 reaching the specified position indicates that the valve is installed in place.

[0026] A rotary valve 4 is provided on the oil filter base 1. The rotary valve 4 is composed of a valve I 401, a handle II 402, a spring seat I 403, a valve seat I 404, a rotary joint I 405, and a sealing ring II 406. The lower end of the valve seat I 404 is threadedly connected to the oil filter base 1, and the lower end of the valve seat I 404 is communicated with the check valve chamber 12. The lower end of the valve I 401 passes through the valve seat I 404. The rotary joint I 405 is arranged at the lower part of the valve seat I 404, and a sealing ring II 406 is arranged between the rotary joint I 405 and the valve seat I 404. The spring seat I 403 is threadedly connected to the valve seat I 404. The handle II 402 is installed at the outer end of the valve I 401. The rotary valve 4 is communicated with the check valve chamber 12. The handle II 402 and the valve I 401 are fastened together. The valve I 401 can be moved up and down by the handle II 402 to control the on and off of the oil fluid. This pipeline can be used in the fuel sub-system, connected to the pressurized fuel tank for secondary pressurization work. The connection joint can rotate, providing great flexibility for the operation space. An outer spring 407 is arranged between the valve I 401 and the spring seat I 403, and an inner spring 408 is arranged between the valve I 401 and the valve seat I 404. The inner spring 408 and the outer spring 407 keep the valve I 401 in a balanced state.

[0027] A monitoring joint 7 is arranged on one side of the rotary valve 4. The monitoring joint 7 is composed of a plug 701, a sealing ring V 702, a rotary joint II 703, and a sealing ring VI 704. The plug 701 is threadedly connected to the oil filter base 1, and a sealing ring VI 704 is arranged between the plug 701 and the oil filter base 1. The internal oil circuit of the plug 701 is communicated with another check valve chamber 12. The rotary joint II 703 is communicated with the internal oil circuit of the plug 701, and a sealing ring V 702 is arranged between the rotary joint II 703 and the plug 701. A sensor can be connected through the rotary joint II 703 to monitor the pressure and temperature of the oil fluid in real time. The rotary joint II 703 can rotate, providing great flexibility for the operation space.

[0028] An outlet pipe 6 is arranged at the bottom of the oil filter base 1. The outlet pipe 6 is communicated with the outlet chamber 10. Flange holes are arranged on the lower surface of the oil filter base 1 for the fixation of the oil filter, which is convenient for installation. The oil filter base 1 is of an integral structure, different from the conventional filter with upper and lower shells connected. This structure is designed in layers, saving space and having complex internal oil circuit channels, and can integrate multiple components.

[0029] The one-way valve Ⅰ5 includes a valve seat Ⅱ502, a valve Ⅱ503, a one-way spring 504 and a spring seat Ⅱ505. The valve seat Ⅱ502 is arranged in the one-way valve cavity 12, and the upper end of the valve seat Ⅱ502 contacts the lower end cover of the filter element 9. A sealing ring Ⅲ501 is arranged between the valve seat Ⅱ502 and the lower end cover of the filter element 9. The valve Ⅱ503 is arranged in the valve seat Ⅱ502. The spring seat Ⅱ505 is threadedly connected to the oil filter seat 1, and a sealing ring Ⅳ506 is arranged at the connection. The one-way spring 504 is arranged between the spring seat Ⅱ505 and the valve Ⅱ503. When the oil fluid flows to the one-way valve Ⅰ5, the valve Ⅱ503 moves downward to open, and the oil fluid flows through the one-way valve Ⅰ5 to the outlet cavity 10 and flows out through the outlet pipe 6. When the left filter element 9 works, the left one-way valve Ⅰ5 opens, and the right one-way valve Ⅰ5 closes under the action of the outlet oil fluid, isolating the two cavities of the one-way valve cavity 12. When replacing the filter element 9, the one-way valve Ⅰ5 closes and can be used as a self-sealing valve to seal the outlet oil fluid, preventing the outlet oil fluid from leaking when replacing the filter element 9.

[0030] The one-way valve Ⅱ8 is composed of a valve housing 801, a steel ball 802, a limiting spring 803, a spring seat Ⅲ804 and a valve seat Ⅱ805. The valve seat Ⅱ805 is threadedly connected to the oil filter seat 1, and a sealing ring Ⅶ806 is arranged at the connection. The inner cavity of the valve seat Ⅱ805 is communicated with the upper part of the filter element installation inner cavity 11 through an inclined channel 807. The lower part of the valve housing 801 is threadedly connected to the valve seat Ⅱ805. The spring seat Ⅲ804 is threadedly connected to the lower end of the valve housing 801. The steel ball 802 is arranged in the valve housing 801, and the limiting spring 803 is arranged between the steel ball 802 and the spring seat Ⅲ804. A sealing cover 808 is arranged at the upper end of the valve housing 801. As shown in the appendix Figure 5 When the oil fluid flows in from the upper end to push the steel ball 802 to move downward, the one-way valve Ⅱ8 opens. When the small power system works, this oil path is not connected, and the oil fluid acts on the steel ball 802 to seal the oil path. When the large power system works, this pipeline is connected to the second oil pump, and the oil fluid is connected to increase the flow rate of the system and provide large-flow fuel for the system. When the small power system works, this one-way valve Ⅱ8 closes. When the filter element 9 is replaced, the one-way valve Ⅱ8 can be used as a drain valve to drain all the oil fluid in the inner cavity, facilitating the maintenance of the filter element 9.

[0031] This device is different from the conventional filter with the upper and lower shells connected to provide an installation space for the filter element. The oil filter seat 1 of this structure is not only a supporting structural member, but also has complex oil path channels inside, can integrate multiple components, and has flange holes at the bottom for fixing the oil filter seat 1.

[0032] During operation, the oil fluid enters the inner cavity of the oil filter base 1 through the inlet pipeline 3, is filtered by the filter element 9, then flows out through the check valve I 5 via the outlet cavity 10 and through the outlet pipeline 6 to the system power unit; the upper end of the filter element 9 is fixed by the check valve II 8, and the lower end is fixed by the check valve I 5. When the left oil circuit works until the filter element 9 is blocked, open the right stop valve 2 to make the other oil fluid conduct, tighten the left stop valve 2, unscrew the check valve II 8, and remove the filter element 9, then the filter element 9 can be replaced without shutting down the machine, which is convenient and fast for maintenance and does not affect the normal operation of the machine.

[0033] The above shows and describes the basic principles, main features and advantages of the present invention. Without departing from the spirit and scope of the present invention, there are various changes and improvements to the present invention, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. A fuel double filter, comprising an oil filter seat (1), a stop valve (2), an inlet pipe (3), a one-way valve I (5) and a filter element (9), characterized in that: The oil filter seat (1) is provided with an upper flow channel and a lower flow channel inside. The lower flow channel comprises a filter element installation cavity (11), a one-way valve cavity (12) and an outlet cavity (10). The filter element installation cavity (11) is symmetrically arranged. The one-way valve cavity (12) is arranged below the filter element installation cavity (11) and is communicated with the filter element installation cavity (11). The outlet cavity (10) is arranged between the one-way valve cavities (12), and both ends of the outlet cavity (10) are communicated with the one-way valve cavities (12). The lower flow channel is a cross oil channel (13). The left and right ends of the cross oil channel (13) are respectively provided with The stop valve chamber (15) is connected to the filter element installation chamber (11) through a connecting hole (14). The stop valve (2) is installed in the stop valve chamber (15). The upper and lower ends of the cross oil passage (13) are respectively connected to the inlet pipe (3). The filter element (9) is arranged in the filter element installation chamber (11). The check valve I (5) is installed in the check valve chamber (12). The check valve I (5) is connected to the lower end of the filter element (9). The filter element (9) outlet is integrated with the check valve I (5), so as to realize one-way conduction of the oil circuit and seal and isolate the parallel oil circuit. When the check valve Ⅰ (5) is in the oil filter seat (1), it can be used as a self-sealing valve. The upper end of the filter element (9) is provided with a check valve Ⅱ (8). The oil filter seat (1) is provided with a rotary valve (4). The rotary valve (4) is composed of a valve Ⅰ (401), a handle Ⅱ (402), a spring seat Ⅰ (403), a valve seat Ⅰ (404), a rotary joint Ⅰ (405), and a sealing ring Ⅱ (406). The lower end of the valve seat Ⅰ (404) is threadedly connected to the oil filter seat (1), and the lower end of the valve seat Ⅰ (404) is connected to the check valve chamber (12). The lower end of the valve Ⅰ (401) is inserted into the valve seat Ⅰ (401). 4), the rotary joint I (405) is arranged at the lower part of the valve seat I (404), and a sealing ring II (406) is arranged between the rotary joint I (405) and the valve seat I (404), the spring seat I (403) is threadedly connected to the valve seat I (404), the handle II (402) is installed at the outer end of the valve I (401), the rotary valve (4) is communicated with the one-way valve chamber (12), the handle II (402) and the valve I (401) are fastened together, and the valve I (401) can be moved up and down by the handle II (402) to control the on and off of the oil;An outer spring (407) is provided between the valve I (401) and the spring seat I (403), an inner spring (408) is provided between the valve I (401) and the valve seat I (404), a monitoring joint (7) is provided on one side of the rotary valve (4), the monitoring joint (7) is composed of a plug (701), a sealing ring V (702), a rotary joint II (703), and a sealing ring VI (704), the plug (701) is threadedly connected to the oil filter seat (1), the plug (701) is threadedly connected to the oil filter seat (1), and the plug (701) is threadedly connected to the oil filter seat (1). A sealing ring VI (704) is arranged between the seats (1), the internal oil circuit of the plug (701) is communicated with another one-way valve chamber (12), the rotary joint II (703) is communicated with the internal oil circuit of the plug (701), and a sealing ring V (702) is arranged between the rotary joint II (703) and the plug (701); an outlet pipe (6) is arranged at the bottom of the oil filter seat (1), the outlet pipe (6) is communicated with the outlet chamber (10), and a flange hole is arranged on the lower surface of the oil filter seat (1). ; 2. A fuel double filter according to claim 1, characterized in that: The stop valve (2) comprises a valve rod (202) and a valve seat I (205). The valve seat I (205) is threadedly inserted on the oil filter seat (1). The valve rod (202) is threadedly connected to the valve seat I (205). A sealing ring I (204) is provided between the valve rod (202) and the valve seat I (205). The valve rod (202) is configured as a conical head and corresponds to the cross oil passage (13). A handle I (203) is provided at the other end of the valve rod (202). The handle I (203) is mounted on the valve rod (202) through an anti-drop nut (201). A limit plate (206) is provided on the valve rod (202).

3. A fuel double filter according to claim 1, characterized in that: The one-way valve I (5) comprises a valve seat II (502), a valve II (503), a one-way spring (504) and a spring seat II (505). The valve seat II (502) is arranged in the one-way valve chamber (12), and the upper end of the valve seat II (502) contacts the lower end cover of the filter element (9). A sealing ring III (501) is arranged between the valve seat II (502) and the lower end cover of the filter element (9). The valve II (503) is arranged in the valve seat II (502). The spring seat II (505) is threadedly connected to the oil filter seat (1), and a sealing ring IV (506) is arranged at the connection. The one-way spring (504) is arranged between the spring seat II (505) and the valve II (503).

4. A fuel dual filter according to claim 1, characterized in that: The one-way valve II (8) is composed of a valve housing (801), a steel ball (802), a limit spring (803), a spring seat III (804) and a valve seat II (805). The valve seat II (805) is threadedly connected to the oil filter seat (1), and a sealing ring VII (806) is provided at the connection. The inner cavity of the valve seat II (805) is communicated with the upper part of the filter element installation inner cavity (11) through an inclined channel (807). The lower part of the valve housing (801) is threadedly connected to the valve seat II (805), and the spring seat III (804) is threadedly connected to the lower end of the valve housing (801). The steel ball (802) is arranged in the valve housing (801), and the limit spring (803) is arranged between the steel ball (802) and the spring seat III (804). A sealing cover (808) is provided at the upper end of the valve housing (801).

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