A two-stage filter for oil which can be quickly serviced

Abstract

The utility model relates to oil liquid filtration field especially is pointed to a kind of two-stage filtration oil liquid filter of quick maintenance, and the filter is constituted by five big core components of filter main body, filter core, end cap, coarse filter cartridge, gasket. Filter main body is integrally formed with installation groove by outlet pipe. Filter core adopts detachable structure, and it is matched with filter core cylinder, realizes oil liquid fine filter, and upper plate and lower plate are closely attached with installation groove, avoid oil liquid short circuit. End cap is installed with coaxial fixing ring by thread, and it is convenient to install and coarse filter cartridge positioning accuracy, and limiting ring can also guarantee gasket accurate sealing. Gasket adopts elastic material, and multiple sealing is realized by cooperating end cap compression force. When working, oil liquid enters coarse filter cartridge pretreatment through oil inlet pipe, and then is fine filtered through filter core cylinder, and flows out from installation groove gap through outlet pipe. The overall structure realizes "coarse filter+fine filter" fractional filtration, and detachable design reduces maintenance difficulty, multiple sealing guarantees stable operation, effectively solves traditional filter pain point.

Description

Technical Field

[0001] This utility model relates to the field of oil filtration, and in particular to a two-stage oil filter that can be quickly maintained. Background Technology

[0002] In industrial production and machinery maintenance, oil is a key medium for power transmission, lubrication, and cooling; its cleanliness directly determines the operational accuracy and service life of the equipment. Currently, most mainstream oil filters on the market suffer from insufficient ease of installation and disassembly. Many filters use multiple bolts or welded structures, requiring various tools for filter element replacement, making the process cumbersome and time-consuming, especially in the confined spaces of large equipment, resulting in extremely low maintenance efficiency. Utility Model Content

[0003] In view of the shortcomings mentioned above, this utility model provides a two-stage oil filter that can be quickly maintained.

[0004] The present invention adopts the following technical solution: A quick-maintainable two-stage oil filter, characterized in that the oil filter comprises: The filter body has a downwardly recessed mounting groove on its upper surface and a liquid outlet pipe communicating with the mounting groove on its outer circumference. The filter element is detachably placed in the mounting groove. The filter element includes a filter element cylinder and an upper plate and a lower plate respectively disposed on the upper and lower surfaces of the filter element cylinder. The upper plate and the lower plate are adapted to the mounting groove. The upper plate has a through hole communicating with the oil passage inside the filter element cylinder. When the filter element is placed in the mounting groove, a gap is formed between the outer peripheral surface of the filter element cylinder and the inner wall of the mounting groove. An end cap has a mounting ring that protrudes downward from the bottom edge of the end cap. The mounting ring is threadedly connected to the filter body to open or close the mounting groove. A fixing ring is coaxially provided on the bottom surface of the end cap, and an oil inlet pipe is coaxially provided on the upper surface of the end cap. The coarse filter cartridge has an outwardly protruding mounting protrusion at the edge of its opening. The mounting protrusion is threadedly connected to the fixing ring. After the end cap is assembled with the filter body, the coarse filter cartridge passes through the through hole and is inserted into the oil passage. The sealing gasket is made of elastic material and its shape is adapted to the mounting ring. The sealing gasket has a through mounting hole adapted to the fixing ring. When the sealing gasket is placed into the mounting ring, the mounting hole is fitted on the outside of the fixing ring. After the end cap and the filter body are assembled, the sealing gasket is pressed against the upper plate of the filter element to achieve a seal. As a further improvement, both the inner ring surface of the mounting ring and the outer ring surface of the fixing ring are provided with limiting rings, and both the outer ring surface of the sealing gasket and the wall of the mounting hole are provided with limiting grooves. When the sealing gasket and the end cap are assembled, the limiting rings are embedded in the corresponding limiting grooves.

[0005] As a further improvement, each of the liquid outlet pipe and the oil inlet pipe is detachably connected to a conduit.

[0006] As a further improvement, the outer side of the conduit is slidably and rotatably fitted with a threaded sleeve, and the edge of the conduit opening protrudes outward to form a connecting ring for axially limiting the threaded sleeve. The threaded sleeve is threadedly connected to the liquid outlet pipe or the oil inlet pipe.

[0007] As a further improvement, an elastic gasket is provided between the threaded sleeve and the connecting ring. The elastic gasket is slidably sleeved on the outside of the conduit. When the threaded sleeve is threadedly connected to the outlet pipe or the inlet pipe and tightened, the elastic gasket is compressed to achieve a seal.

[0008] As a further improvement, the outer ring of the threaded sleeve is symmetrically provided with an outwardly protruding push handle to facilitate tightening the threaded sleeve.

[0009] As a further improvement, the outer ring of the threaded sleeve is symmetrically provided with two operating planes to facilitate tightening the threaded sleeve.

[0010] As described above, this utility model has the following advantages compared to existing technologies: The filter consists of five core components: a filter body, a filter element, an end cap, a coarse filter cartridge, and a sealing gasket. The filter body is integrated with an outlet pipe and an installation groove. The filter element has a detachable structure, which, combined with the filter cartridge, enables fine filtration of the oil. The upper and lower plates fit tightly into the installation groove to prevent short circuits. The end cap, with its threaded mounting ring and coaxial fixing ring, balances ease of installation with the positioning accuracy of the coarse filter cartridge. The limiting ring also ensures precise sealing of the sealing gasket. The sealing gasket is made of elastic material, which, combined with the clamping force of the end cap, achieves multiple seals. During operation, the oil enters the coarse filter cartridge for pretreatment through the inlet pipe, then undergoes fine filtration through the filter cartridge, and finally flows out through the outlet pipe from the gap in the installation groove. The overall structure achieves graded filtration of "coarse filtration + fine filtration," the detachable design reduces maintenance difficulty, and the multiple seals ensure stable operation, effectively solving the pain points of traditional filters. Attached Figure Description

[0011] Figure 1 This is a three-dimensional structural diagram of the present invention.

[0012] Figure 2 This is a cross-sectional structural diagram of the present invention.

[0013] Figure 3This is a schematic diagram of the three-dimensional structure of the filter body.

[0014] Figure 4 This is a schematic diagram of the three-dimensional structure of the filter element.

[0015] Figure 5 This is a three-dimensional structural diagram of the end cap and coarse filter cartridge.

[0016] Figure 6 This is an exploded structural diagram of the end cap, coarse filter cartridge, and sealing gasket.

[0017] Figure 7 This is a schematic diagram showing the exploded structure of the end cap and the conduit. Detailed Implementation

[0018] The specific embodiments of this utility model are described below with reference to the accompanying drawings.

[0019] As attached Figure 1 and Figure 2 As shown, a quick-maintaining two-stage oil filter is provided. The oil filter is mainly composed of five core components: filter body 1, filter element 2, end cap 3, coarse filter cartridge 4, and sealing gasket 5. The components work together to complete the oil filtration. It is also equipped with auxiliary components such as conduit 6 to further improve the practicality and adaptability of the filter.

[0020] As attached Figure 2 and 3 As shown, the filter body 1, as the basic framework of the entire filter, not only needs to provide stable installation support for other components, but also plays a role in guiding the flow of oil during the filtration process. Its structural design directly affects the overall stability and filtration efficiency of the filter. The upper surface of the filter body 1 is precision-machined and has a downwardly recessed mounting groove 11. This mounting groove 11 is not a simple recessed structure; its inner wall is treated with high-precision polishing. On the one hand, it ensures a good fit with the filter element 2, reducing the resistance of oil flow; on the other hand, it facilitates subsequent cleaning and maintenance of the inside of the mounting groove 11. The dimensions of the mounting groove 11 are strictly calculated to ensure that the filter element 2 can be accurately placed within it, while reserving reasonable space for the flow of oil between the filter element 2 and the mounting groove 11.

[0021] A liquid outlet pipe 12, connected to the mounting groove 11, is carefully installed on the outer circumference of the filter body 1. The liquid outlet pipe 12 and the filter body 1 are manufactured using an integrated molding process. This manufacturing method effectively avoids gaps that may occur due to welding or other connection methods, thereby greatly reducing the risk of oil leakage. The inner diameter of the liquid outlet pipe 12 is matched according to the design flow rate of the filter to ensure that the filtered oil can flow smoothly out of the liquid outlet pipe 12 without problems such as oil retention or excessive pressure loss due to an insufficient pipe diameter. In addition, the outer wall of the liquid outlet pipe 12 is provided with a standard thread structure, which facilitates the subsequent connection with the conduit 6. At the same time, the precision and surface roughness of the thread are strictly controlled to ensure the sealing and reliability of the connection.

[0022] As attached Figure 3 and Figure 4 As shown, filter element 2 is the core component for achieving fine oil filtration. Its performance directly determines the filtration accuracy and effect of the oil. Furthermore, for ease of maintenance and replacement, filter element 2 is designed with a detachable structure, allowing it to be easily removed or installed from the mounting slot 11. Filter element 2 mainly consists of three parts: filter element cylinder 21, upper plate 23, and lower plate 22. These three parts are assembled together using a special connection process, ensuring the overall structural strength and sealing of filter element 2.

[0023] Filter cartridge 21 is the core filtration element of filter cartridge 2. It contains precision filter media, which can be made of various materials such as glass fiber, metal mesh, and filter paper, depending on different filtration requirements. The pore size of the filter media is also strictly selected to effectively trap impurities in the oil, such as metal shavings, dust, and colloids, thereby ensuring the oil meets the specified cleanliness standards. The filter cartridge 21 features a porous structure design on its wall, ensuring both sufficient contact between the filter media and the oil, and smooth flow of the filtered oil.

[0024] The upper plate 23 and the lower plate 22 are fixedly mounted on the upper and lower surfaces of the filter element cylinder 21, respectively. They not only serve to fix and protect the filter element cylinder 21, but also form a good fit with the mounting groove 11. The size and shape of the upper plate 23 and the lower plate 22 perfectly match the inner wall contour of the mounting groove 11. When the filter element 2 is placed in the mounting groove 11, the upper plate 23 and the lower plate 22 can fit tightly against the inner wall of the mounting groove 11, effectively preventing unfiltered oil from bypassing the filter element 2 and directly entering the outlet pipe 12, ensuring that all oil must be filtered by the filter element cylinder 21. At the center of the upper plate 23, there is a through hole 24 that communicates with the oil passage 2a inside the filter element cylinder 21. The diameter of this through hole 24 has been precisely calculated to ensure that the oil can smoothly enter the interior of the filter element cylinder 21 without causing excessive pressure inside the filter element cylinder 21 due to an excessively large diameter. When the filter element 2 is accurately placed into the mounting groove 11, a uniform gap will be formed between the outer circumferential surface of the filter element cylinder 21 and the inner wall of the mounting groove 11. This gap provides a flow channel for the filtered oil, allowing the filtered oil to collect in this gap and then flow smoothly to the outlet pipe 12.

[0025] As attached Figure 2 , Figure 5 and Figure 6 As shown, the end cap 3 plays a crucial role in the entire filter. It not only allows for the opening and closing of the mounting groove 11 but also provides a stable mounting platform for components such as the coarse filter cartridge 4. Its structural design fully considers ease of operation and reliable connection. The bottom edge of the end cap 3 protrudes downwards, forming a ring-shaped mounting ring 31. The inner surface of the mounting ring 31 has a standard internal thread, while the filter body 1 has an external thread at the corresponding position. The mounting ring 31 and the filter body 1 are fixed together by a threaded connection. This threaded connection method has advantages such as simple structure, reliable connection, and convenient assembly and disassembly. Operators can easily open or close the mounting groove 11 by simply rotating the end cap 3, facilitating the inspection, maintenance, and replacement of internal components such as the filter element 2.

[0026] On the bottom surface of the end cap 3, a retaining ring 32 is coaxially arranged with the end cap 3. The inner ring surface of the retaining ring 32 is also provided with a threaded structure, which is mainly used for connection with the coarse filter cartridge 4. The retaining ring 32 and the end cap 3 are manufactured using an integrated molding process, which ensures the connection strength and coaxiality between the retaining ring 32 and the end cap 3, and avoids inaccurate installation position of the coarse filter cartridge 4 due to the misalignment of the retaining ring 32, thereby affecting the filtration effect of the oil.

[0027] An oil inlet pipe 33 is coaxially mounted on the upper surface of end cap 3. The oil inlet pipe 33 serves as the channel for oil to enter the filter. Its structural design is similar to that of the outlet pipe 12, also employing an integrated molding process to connect with end cap 3. The outer wall has a standard threaded structure for easy connection to another conduit 6. The inner diameter of the oil inlet pipe 33 is determined based on the filter's design flow rate to ensure smooth oil flow into the filter. Furthermore, the interior of the oil inlet pipe 33 is smoothed to reduce resistance and turbulence during oil flow, preventing pressure loss due to poor oil flow.

[0028] As attached Figure 6 As shown, in addition, a limiting ring 34 is provided on the inner ring surface of the mounting ring 31 and the outer ring surface of the fixing ring 32. The limiting ring 34 is integrally molded with the mounting ring 31 and the fixing ring 32. Its main function is to position and fix the sealing gasket 5, preventing the sealing gasket 5 from shifting during the assembly of the filter, thereby ensuring that the sealing gasket 5 can accurately perform its sealing function. The size and height of the limiting ring 34 are precisely calculated to ensure that after the sealing gasket 5 is installed in place, it can form a perfect fit with the limiting groove 52 on the sealing gasket 5, achieving reliable positioning.

[0029] As attached Figure 2 and Figure 6 As shown, the coarse filter cartridge 4 serves as the first line of filtration after the oil enters the filter. It is mainly responsible for coarse filtration of the oil. By intercepting larger particles of impurities in the oil, such as large metal blocks and impurity clumps, it can effectively reduce the filtration burden of the subsequent filter element 2, extend the service life of the filter element 2, and prevent larger particles of impurities from damaging the filter element 2, thus ensuring the overall filtration performance of the filter.

[0030] The edge of the coarse filter cartridge 4 protrudes outward, forming an annular mounting protrusion 41. The outer annular surface of the mounting protrusion 41 is provided with external threads, which match the internal threads of the fixing ring 32 on the end cover 3. Through this threaded connection, the coarse filter cartridge 4 can be securely installed on the end cover 3. This threaded connection method not only facilitates disassembly and assembly but also ensures the coaxiality between the coarse filter cartridge 4 and the end cover 3, ensuring that the coarse filter cartridge 4 will not shake or shift during operation.

[0031] The wall of the coarse filter cartridge 4 is made of porous metal material. The size of these holes is carefully designed to effectively trap larger impurity particles in the oil without causing excessive resistance to the oil flow. The length and outer diameter of the coarse filter cartridge 4 are determined according to the internal structure of the filter element 2. After the end cap 3 is assembled with the filter body 1, the coarse filter cartridge 4 can accurately pass through the through hole 24 of the upper plate 23 of the filter element 2 and be inserted into the oil passage 2a of the filter element cartridge 21. An appropriate gap is maintained between the outer wall of the coarse filter cartridge 4 and the inner wall of the through hole 24, which ensures that the oil can flow smoothly from the coarse filter cartridge 4 into the oil passage 2a, while preventing unfiltered oil from directly entering the oil passage 2a.

[0032] As attached Figure 2 and Figure 6 As shown, the sealing gasket 5 plays a crucial sealing role in the filter. It effectively prevents oil leakage during the filtration process, ensuring that all oil is filtered along the predetermined filtration path. It also prevents external impurities from entering the filter and contaminating the oil. The sealing gasket 5 is made of elastic materials, such as nitrile rubber and fluororubber. These materials possess excellent elasticity, oil resistance, and aging resistance, maintaining good sealing performance over long-term use and adapting to changes in temperature, pressure, and other working environments during oil filtration.

[0033] The shape of the sealing gasket 5 is adapted to the shape of the mounting ring 31, and its outer diameter is exactly the same as the inner diameter of the mounting ring 31, ensuring that the sealing gasket 5 can be accurately placed into the mounting ring 31 and fit tightly against the inner wall of the mounting ring 31. At the center of the sealing gasket 5, a mounting hole 51 adapted to the fixing ring 32 is opened. The diameter of the mounting hole 51 matches the outer diameter of the fixing ring 32. When the sealing gasket 5 is placed into the mounting ring 31, the mounting hole 51 can be accurately fitted onto the outside of the fixing ring 32 and fit tightly against the outer wall of the fixing ring 32, thereby achieving the radial positioning of the sealing gasket 5.

[0034] To further ensure the positioning accuracy and stability of the sealing gasket 5 during assembly, limiting grooves 52 adapted to the limiting ring 34 are respectively provided on the outer annular surface of the sealing gasket 5 and the wall of the mounting hole 51. When the sealing gasket 5 is assembled with the end cap 3, the limiting ring 34 on the inner annular surface of the mounting ring 31 will be embedded in the limiting groove 52 on the outer annular surface of the sealing gasket 5, and the limiting ring 34 on the outer annular surface of the fixing ring 32 will be embedded in the limiting groove 52 on the wall of the mounting hole 51. Through this limiting fit structure, the sealing gasket 5 can be effectively prevented from rotating or shifting during the assembly and use of the filter, ensuring that the sealing gasket 5 is always in the correct sealing position.

[0035] After the end cap 3 is assembled with the filter body 1, the end cap 3 will exert a certain pressure on the sealing gasket 5, so that the sealing gasket 5 is tightly pressed onto the upper plate 23 of the filter element 2. At this time, the sealing gasket 5 will undergo a certain elastic deformation. This elastic deformation can fill the tiny gaps that may exist between the sealing gasket 5 and the upper plate 23, the mounting ring 31, and the fixing ring 32, thereby achieving a reliable sealing effect and effectively preventing oil leakage from these gaps.

[0036] As attached Figure 2 and Figure 7 As shown, the conduit 6 is an important component connecting the filter to the external oil system. Its main function is to transport the oil to be filtered from the external system into the filter, and simultaneously transport the filtered clean oil back to the external system. To meet the connection requirements of different scenarios, a conduit 6 is detachably connected to both the outlet pipe 12 and the inlet pipe 33. This detachable connection method not only facilitates the replacement and maintenance of the conduit 6, but also allows for the selection of conduits 6 of different lengths and materials according to actual installation requirements, improving the adaptability and flexibility of the filter.

[0037] The structural design of the conduit 6 fully considers the sealing performance of the connection and the ease of operation. A threaded sleeve 63 is slidably and rotatably fitted onto the outside of the conduit 6. The inner wall of the threaded sleeve 63 has an internal thread that matches the external thread of the outlet pipe 12 or the inlet pipe 33. This threaded connection allows for a fixed connection between the conduit 6 and the outlet pipe 12 or the inlet pipe 33. The edge of the conduit 6's opening protrudes outwards, forming an annular connecting ring 61. The outer diameter of the connecting ring 61 is larger than the inner diameter of the opening 66 on the threaded sleeve 63 through which the conduit 6 passes. Its main function is to axially limit the threaded sleeve 63, preventing it from detaching from the opening of the conduit 6 during sliding. Simultaneously, when the threaded sleeve 63 is tightened, the connecting ring 61, in conjunction with the threaded sleeve 63, applies pressure to the elastic gasket 62, ensuring that the elastic gasket 62 can fully perform its sealing function.

[0038] An elastic gasket 62 is provided between the threaded sleeve 63 and the connecting ring 61. The elastic gasket 62 is made of a material with good elasticity and oil resistance, such as a rubber gasket or a silicone gasket. The elastic gasket 62 is slidably fitted on the outside of the conduit 6. When the threaded sleeve 63 is threadedly connected to the outlet pipe 12 or the inlet pipe 33 and tightened, the threaded sleeve 63 will move towards the connecting ring 61, exerting a squeezing effect on the elastic gasket 62, causing the elastic gasket 62 to deform elastically. The elastic deformation of the elastic gasket 62 can fill the gap between the threaded sleeve 63, the connecting ring 61 and the conduit 6, thereby achieving a reliable sealing effect and effectively preventing oil leakage at the connection point.

[0039] To facilitate tightening of the threaded sleeve 63, symmetrically protruding push handles 64 are provided on the outer ring surface of the threaded sleeve 63. Operators can easily rotate the threaded sleeve 63 by pressing against the push handles 64, reducing operational difficulty and improving work efficiency. Simultaneously, two symmetrically arranged operating surfaces 65 are also provided on the outer ring surface of the threaded sleeve 63. The arrangement of the operating surfaces 65 facilitates the use of tools (such as wrenches) to tighten the threaded sleeve 63. When a larger tightening torque is required, the operator can use a wrench to engage the operating surfaces 65 to easily tighten the threaded sleeve 63, ensuring the reliability and sealing of the threaded connection. Furthermore, the arrangement of the operating surfaces 65 also prevents the threaded sleeve 63 from rolling during storage or transportation, improving the stability of the threaded sleeve 63.

[0040] The oil to be filtered first flows out from the external oil system and smoothly enters the oil inlet pipe 33 on the end cover 3 through the conduit 6 connected to the oil inlet pipe 33. The oil entering the oil inlet pipe 33 continues to flow downwards under its own pressure, entering the coarse filter cartridge 4 installed on the end cover 3. During the flow of the oil in the coarse filter cartridge 4, the porous structure on the wall of the cartridge performs coarse filtration, trapping larger impurity particles such as large metal fragments and impurity clumps, thus initially purifying the oil and reducing the filtration burden on the subsequent filter element 2.

[0041] After being coarsely filtered by the coarse filter cartridge 4, the oil flows out through the pores in the cartridge wall and enters the oil passage 2a of the filter element cartridge 21. The oil entering the oil passage 2a, under the influence of pressure difference, gradually permeates into the filter medium of the filter element cartridge 21. The filter medium inside the filter element cartridge 21 has a precise pore structure, enabling further fine filtration of the oil, trapping smaller impurities, colloids, moisture, and other harmful substances, thus ensuring the oil's cleanliness meets the specified standards.

[0042] The clean oil, after being finely filtered by the filter cartridge 21, seeps out from the outer circumference of the filter cartridge 21 and enters the gap between the filter cartridge 21 and the mounting groove 11. In this gap, the clean oil gradually accumulates. As the oil continues to flow in, the oil pressure within the gap gradually increases. When the pressure reaches a certain level, the clean oil, under the action of pressure, flows towards the outlet pipe 12 and finally flows back to the external oil system through the conduit 6 connected to the outlet pipe 12, completing the entire oil filtration process.

[0043] Throughout the filtration process, the components work in close coordination, and sealing elements such as the sealing gasket 5 and elastic gasket 62 fully perform their sealing functions, ensuring that no oil leakage occurs. All oil is filtered according to the predetermined filtration path, guaranteeing the reliability and stability of the filtration effect. Simultaneously, the filter's detachable design allows operators to easily remove the end cap 3, coarse filter cartridge 4, and filter element 2 after a period of use. The coarse filter cartridge 4 and filter element 2 can be cleaned or replaced, and the filter can then be reassembled to restore its filtration performance. This significantly reduces maintenance costs and difficulty, and extends the filter's service life.

[0044] In summary, this utility model filter is designed with "high-efficiency filtration + convenient maintenance" as its core design goal. It consists of five core components: filter body 1, filter element 2, end cap 3, coarse filter cartridge 4, and sealing gasket 5, as well as auxiliary components such as conduit 6. The filter body 1 ensures stable flow and component compatibility through an integrated molded liquid outlet pipe 12 and mounting groove 11. The filter element 2 adopts a detachable structure and can be equipped with precision filter media of various materials to achieve fine filtration of oil. The upper and lower plates fit tightly with the mounting groove to prevent oil short circuits. The end cap 3, with the help of a threaded mounting ring 31 and a coaxial fixing ring 32, balances ease of installation with the positioning accuracy of the coarse filter cartridge 4. The limiting ring 34 also ensures precise sealing of the sealing gasket 5. The sealing gasket 5 is made of elastic material and achieves multiple seals in conjunction with the clamping force of the end cap. During operation, the oil enters the coarse filter cartridge 4 for pretreatment via conduit 6 and inlet pipe 33, then undergoes fine filtration via filter cartridge 21, and finally flows out through the outlet pipe 12 from the gap in the mounting groove. The overall structure achieves staged filtration of "coarse filtration + fine filtration," the detachable design reduces maintenance difficulty, multiple seals ensure stable operation, and it is adaptable to different installation requirements, effectively solving the pain points of traditional filters and combining practicality and economy.

[0045] The above are merely specific embodiments of this utility model, but the design concept of this utility model is not limited thereto. Any non-substantial modifications made to this utility model using this concept shall be considered as an infringement of the protection scope of this utility model.

Claims

1. A two-stage oil filter with quick maintenance, characterized in that, The oil filter includes: The filter body has a downwardly recessed mounting groove on its upper surface and a liquid outlet pipe communicating with the mounting groove on its outer circumference. The filter element is detachably placed in the mounting groove. The filter element includes a filter element cylinder and an upper plate and a lower plate respectively disposed on the upper and lower surfaces of the filter element cylinder. The upper plate and the lower plate are adapted to the mounting groove. The upper plate has a through hole communicating with the oil passage inside the filter element cylinder. When the filter element is placed in the mounting groove, a gap is formed between the outer peripheral surface of the filter element cylinder and the inner wall of the mounting groove. An end cap has a mounting ring that protrudes downward from the bottom edge of the end cap. The mounting ring is threadedly connected to the filter body to open or close the mounting groove. A fixing ring is coaxially provided on the bottom surface of the end cap, and an oil inlet pipe is coaxially provided on the upper surface of the end cap. The coarse filter cartridge has an outwardly protruding mounting protrusion at the edge of its opening. The mounting protrusion is threadedly connected to the fixing ring. After the end cap is assembled with the filter body, the coarse filter cartridge passes through the through hole and is inserted into the oil passage. The sealing gasket is made of elastic material and its shape is adapted to the mounting ring. The sealing gasket has a through mounting hole adapted to the fixing ring. When the sealing gasket is placed into the mounting ring, the mounting hole is fitted on the outside of the fixing ring. After the end cap and the filter body are assembled, the sealing gasket is pressed against the upper plate of the filter element to achieve a seal.

2. The quick-maintainable two-stage oil filter as described in claim 1, characterized in that: Both the inner ring surface of the mounting ring and the outer ring surface of the fixing ring are provided with limiting rings, and both the outer ring surface of the sealing gasket and the wall of the mounting hole are provided with limiting grooves. When the sealing gasket and the end cap are assembled, the limiting rings are embedded in the corresponding limiting grooves.

3. The quick-maintainable two-stage oil filter as described in claim 1, characterized in that: The liquid outlet pipe and the oil inlet pipe are each detachably connected to a conduit.

4. The quick-maintainable two-stage oil filter as described in claim 3, characterized in that: The outer side of the conduit is slidably and rotatably fitted with a threaded sleeve. The edge of the conduit opening protrudes outward to form a connecting ring for axially limiting the threaded sleeve. The threaded sleeve is threadedly connected to the liquid outlet pipe or the oil inlet pipe.

5. A quick-maintainable two-stage oil filter as described in claim 4, characterized in that: An elastic gasket is provided between the threaded sleeve and the connecting ring. The elastic gasket is slidably sleeved on the outside of the conduit. When the threaded sleeve is threadedly connected to the liquid outlet pipe or the oil inlet pipe and tightened, the elastic gasket is compressed to achieve a seal.

6. A quick-maintainable two-stage oil filter as described in claim 5, characterized in that: The outer ring of the threaded sleeve is symmetrically provided with an outwardly protruding push handle to facilitate tightening the threaded sleeve.

7. A quick-maintainable two-stage oil filter as described in claim 5, characterized in that: The outer ring of the threaded sleeve is symmetrically provided with two operating planes to facilitate tightening the threaded sleeve.

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