Low-flow-resistance filter

Abstract

The low-flow-resistance filter comprises an end cover, a filter cup and a filter element assembly, the end cover and the filter cup are buckled in a sealed mode, the filter element assembly is arranged in the filter cup, an axial liquid outlet flow channel is formed in the middle of the end cover, and an annular limiting groove is formed in the portion, on the outer side of the liquid inlet end of the liquid outlet flow channel, of the end cover; a plurality of liquid inlet flow channels of spiral gradually-expanding structures are evenly distributed in the position, on the outer side of the liquid outlet end of the liquid outlet flow channel, of the end cover in the circumferential direction, the liquid inlet flow channels are communicated with an annular flow channel formed between the filter cup and the filter element assembly, and the filter element assembly is composed of a middle framework and a filter element arranged on the middle framework in a sleeving mode. One end of the filter element assembly is hermetically mounted in the annular limiting groove of the end cover, the other end of the filter element assembly is hermetically mounted in the annular mounting groove in one side of the bottom cover, the other side of the bottom cover is in abutting fit with the bottom of the filter cup, and the liquid outlet runner is communicated with a backflow cavity formed between the filter element assembly and the bottom cover. The filter is simple in structure and small in material consumption, the overall light weight of the filter is achieved, the production cost is reduced, and the production procedures are reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of filter structure improvement, and in particular relates to a low flow resistance filter. Background Art

[0002] As a critical component in fluid power systems (such as internal combustion engines, fuel systems, and hydraulic systems), filters' core function is to intercept and remove impurities from the fluid, protecting the delicate components within the system and ensuring reliable operation and extended service life. However, conventional filter designs, particularly those of the inlet end cap and center tube, often prioritize structural strength and lightweighting over flow path optimization. This leads to increased flow resistance, limited performance, and a series of technical issues. First, inappropriate inlet end cap design can cause unnecessary eddy currents, impacts, and localized resistance upon inlet flow, resulting in significant inlet flow losses. Second, the center tube structure and its aperture design are inherently flawed. These factors increase flow resistance and, under high pressure differentials, can easily cause structural deformation, compromising filtration accuracy and potentially leading to filter element rupture and failure. Furthermore, inappropriate aperture design can generate localized microjets, creating low-pressure zones that can easily induce bubble formation and accumulation. These bubbles can then enter downstream systems and potentially cause cavitation, noise, measurement inaccuracies, and poor lubrication. The combined consequences of these filter structural defects are: excessive initial differential pressure upon activation of a new filter, increasing the pumping load and energy consumption of the fluid power system; At the same time, the high initial differential pressure and potential risk of structural failure significantly shorten the filter's effective service life. Therefore, optimizing the filter structure, particularly redesigning the inlet end cap and center tube structure to effectively reduce flow resistance, minimize initial differential pressure, enhance center tube structural stability, and inhibit internal bubble formation, has become a key technical challenge for improving overall filter performance, reducing system energy consumption, and extending component life, and innovative solutions are urgently needed.

[0003] Patent document CN201922292403.9 discloses a liquid filter center tube and a liquid filter, wherein the liquid filter center tube includes a support tube and a reinforcing rib. The support tube is hollow cylindrical and is provided with mounting rings at both axial ends. The mounting rings are radially protruding from the support tube. The reinforcing ribs are provided on the outer wall of the support tube and include a transverse section parallel to the end of the support tube connected to the guide section of another reinforcing rib to form a combined reinforcing rib. On the one hand, this patent can enhance the rupture resistance of the liquid filter center tube and prevent the filter element supported on the outside of the liquid filter center tube from collapsing prematurely. On the other hand, it reduces the weight of the liquid filter center tube, which is conducive to achieving the lightweight of the liquid filter as a whole. However, it has the following shortcomings: (1) It is made of traditional rolled steel plates and has reinforcement ribs, which places high demands on the forming process of the filter center tube; (2) holes are opened around the annular reinforcement ribs to allow liquid to enter the interior of the filter center tube, but there is still a large flow resistance; (3) The position of the center tube opening is arranged in a spiral shape along with the reinforcement ribs, which will cause vortices inside the center tube, resulting in large flow losses.

[0004] The patent document CN202123039171.X discloses a cyclone-type oil-gas separator, which includes a filter element assembly, a housing, a baffle, a cyclone plate, a sealing ring seal, an air inlet pipe and an air outlet. The upper end of the air inlet pipe is connected to the housing through a sealing ring seal, and an air outlet is provided on the right side of the upper end of the housing. The end cross-section of the sealing ring seal is a multi-channel continuous bending structure, and the housing is located at the outermost bending part of the sealing ring seal. The inner bending part of the sealing ring seal is connected to the filter cartridge in the filter element assembly through a connecting plate. A cyclone plate is provided in the filter cartridge in the filter element assembly, and the middle part of the cyclone plate is connected to the oil flow plate in the filter element assembly, and the lower end of the outer filter layer in the filter element assembly is connected to the baffle. This patented technology allows the oil and gas mixture to be separated three times, overcoming the problem of low equipment service life caused by low oil and gas separation rate, thereby extending the equipment service life, improving equipment working efficiency, and reducing equipment manufacturing cost and operating cost. However, a swirl plate is provided in the filter cartridge of the filter element assembly, which uses the swirl plate to perform preliminary separation of the oil-gas mixture under the action of centrifugal force. It is not an improvement on the swirl structure of the filter end cover, nor is it the oblique downward spiral gradually expanding flow channel structure on the filter end cover. Summary of the Invention

[0005] The technical problem solved by the present invention is to provide a low flow resistance filter with a simple structure and reasonable design. The filter can effectively solve the technical problems of traditional filters such as large flow loss at the inlet and center tube due to unreasonable structure, excessively high initial pressure difference of the filter, easy deformation of the center tube, and easy generation of bubbles inside the center tube.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solution: a low flow resistance filter, which includes a sealed end cover and a filter cup, and a filter element assembly arranged inside the filter cup and fixed between the end cover and the bottom cover, wherein an axial liquid outlet channel is provided in the middle of the end cover, and an annular limiting groove for installing the filter element assembly is provided on the end cover outside the liquid inlet end of the liquid outlet channel, and a plurality of spirally expanding liquid inlet channels are evenly distributed along the circumferential direction on the end cover outside the liquid outlet end of the liquid outlet channel, the liquid inlet channel is communicated with the annular flow channel formed between the filter cup and the filter element assembly, the filter element assembly consists of an intermediate frame and a filter element sleeved on the intermediate frame, one end of the filter element assembly is sealed and installed in the annular limiting groove of the end cover, and the other end of the filter element assembly is sealed and installed in the annular installation groove on one side of the bottom cover, the other side of the bottom cover is tightly fitted with the bottom of the filter cup, and the liquid outlet channel is communicated with the reflux chamber formed between the filter element assembly and the bottom cover.

[0007] It is further defined that the liquid inlet flow channel is used for the axial inflow and radial outflow of oil, and there are 6 groups of liquid inlet flow channels evenly distributed along the circumferential direction, and the liquid inlet flow channel is designed with cast fillets at the position where the oil flows, which is used to greatly reduce the resistance of the oil during the flow process. At the same time, the spiral expansion structure of the liquid inlet flow channel can prevent the generation of inlet vortexes to the greatest extent, and can significantly increase the uniformity of oil distribution on the outer edge of the filter element assembly.

[0008] It is further defined that the intermediate skeleton is a cylindrical skeleton formed by integrally forming columns and annular ribs, wherein a plurality of groups of parallel and oppositely arranged annular ribs are sequentially connected and fixed through a plurality of axially arranged columns.

[0009] It is further defined that the columns and annular ribs in the intermediate skeleton all adopt a conical structure with a larger inner side and a smaller outer side. The conical structure is used to effectively increase the strength of the intermediate skeleton and the flow area of ​​the fluid entering the filter element assembly, thereby reducing the fluid flow resistance and the process requirements.

[0010] It is further defined that the intermediate frame and the bottom cover are fixed by welding or bonding, wherein the intermediate frame is formed by casting, injection molding or die-casting, and the bottom cover is formed by stamping, and the inner side of the annular mounting groove of the bottom cover forms a bottom cover protrusion through a transition slope, and the inner edge of the connecting end of the intermediate frame and the bottom cover forms a wedge-shaped structure that matches the transition slope of the bottom cover. The transition slope of the bottom cover and the wedge-shaped structure at the end of the intermediate frame are effectively increased by the welding or bonding fixing area of ​​the intermediate frame and the bottom cover, thereby increasing the connection strength and connection reliability of the intermediate frame and the bottom cover.

[0011] It is further defined that at least three groups of limiting angles are evenly distributed along the circumferential direction on the outer side wall of the annular mounting groove of the bottom cover, and the limiting angles have a conical structure with a larger inner side and a smaller outer side, and the conical ends of the limiting angles are tightly fitted with the inner wall of the filter bowl, so as to realize the installation guidance of the bottom cover and the filter bowl and the radial positioning of the bottom cover in the filter bowl.

[0012] It is further defined that a step stop fitting structure matching the inner side wall of the annular limit groove is formed inside the connecting end of the intermediate skeleton and the end cover annular limit groove, the intermediate skeleton is nested and installed on the inner side wall of the annular limit groove and the intermediate skeleton and the annular limit groove are aligned through the step stop fitting structure, and the formed stop fitting structure is used to effectively ensure the centering and installation strength of the intermediate skeleton.

[0013] It is further defined that the filter element is a radial pleated filter element, which is sleeve-mounted on the middle frame, one end of the filter element is fixed in the annular mounting groove of the bottom cover by adhesive sealing, and the other end of the filter element is fixed in the annular limiting groove of the end cover by adhesive sealing.

[0014] It is further defined that the liquid outlet channel of the end cover is a full-length internal thread structure, through which the end cover and the outer component are sealed and installed. The length of the internal thread on the inner wall of the liquid outlet channel can effectively ensure the installation strength and installation sealing of the filter and the outer component.

[0015] It is further defined that an annular groove is provided on the end cover on the outer side of the liquid inlet channel, and an installation sealing ring is installed in the annular groove, and a sealed installation connection between the filter and the outer component is realized through the installation sealing ring, thereby effectively ensuring the installation accuracy and sealing of the filter; an annular groove is provided on the end cover on the outer side of the installation sealing ring, and an integral sealing ring is installed in the annular groove, and a sealed installation connection between the filter cup and the end cover is realized through the integral sealing ring; the filter cup is a cylindrical structure with an open end, and after the open end of the filter cup is nested and installed with the filter element assembly and the end cover, the open end of the filter cup is bent inwardly by a sheet metal machine to form an inner flange structure, and the integral sealing ring is pressed and fixed by the inner flange structure to realize the sealed connection installation between the filter cup and the end cover, thereby simultaneously ensuring the overall installation firmness and the overall sealing of the filter.

[0016] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. The present invention optimizes the filter's liquid inlet flow channel without changing the filter's installation dimensions. The filter end cap's liquid inlet flow channel adopts a unique spiral expansion structure, which directly introduces the oil entering the filter end cap into the annular flow channel between the filter bowl and the filter element assembly. This effectively controls the filter's pressure loss, protects and improves the safety of the filter and related equipment, and the test results are highly reliable.

[0017] 2. Without changing the installation dimensions of the filter, the present invention adopts an intermediate filter frame to replace the traditional filter center tube, thereby increasing the fluid flow area. While ensuring that the support effect on the filter element remains unchanged, the flow resistance at the filter element outlet is significantly reduced, the filtering effect of the filter is improved, and the service life of the filter can be significantly extended.

[0018] 3. In traditional filters, oil flowing out of the filter element must flow through the micropores in the center tube. These microjets easily form low-pressure areas, which can easily induce the formation and accumulation of bubbles. These bubbles enter the downstream system with the oil, potentially causing cavitation, noise, measurement inaccuracies, and poor lubrication. The filter proposed in this invention completely solves this problem by replacing the center tube with an intermediate frame. While supporting the filter element, the intermediate frame hardly interferes with the oil outflow, and the oil flow inside the intermediate frame is very stable.

[0019] 4. The filter's central framework effectively utilizes the structural stability of a simple beam and a triangular structure, with the number and placement of circular rings rationally arranged to disperse edge stress. The outer edge of the filter's central framework adopts a tapered structure with a larger inner edge and a smaller outer edge. This reduces flow resistance while also lowering process requirements, lowering production costs and improving efficiency.

[0020] 5. The present invention can increase the liquid inlet area without changing the installation dimensions, effectively improving the filtration performance of the filter. The present invention has a simple structure and uses less material, achieving overall lightweighting of the filter, reducing production costs and simplifying the production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the low flow resistance filter of the present invention.

[0022] Figure 2 It is a structural schematic diagram of the end cover of the low flow resistance filter of the present invention.

[0023] Figure 3 This is a schematic diagram of the partially cutaway structure of the low flow resistance filter of the present invention.

[0024] Figure 4 It is a three-dimensional structural diagram of the low flow resistance filter of the present invention.

[0025] Figure 5 It is a schematic diagram of the partial structure of the middle skeleton of the low flow resistance filter of the present invention.

[0026] Figure 6 This is a three-dimensional exploded view of the low flow resistance filter of the present invention.

[0027] Figure 7 Schematic diagram of the structure of a traditional filter.

[0028] Figure 8 This is a 3D exploded view of a traditional filter.

[0029] Figure 9 It is a two-dimensional streamline diagram of the middle section of the low flow resistance filter of the present invention.

[0030] Figure 10This is the pressure cloud diagram of the middle section of the low flow resistance filter of the present invention.

[0031] Figure 11 This is a two-dimensional streamline diagram of the middle section of a traditional filter.

[0032] Figure 12 This is the pressure cloud diagram of the middle section of the traditional filter.

[0033] In the figure: 1-installation sealing ring, 2-integral sealing ring, 3-end cover, 4-filter cup, 5-filter element, 6-middle skeleton, 7-bottom cover, 8-bottom cover protrusion, 9-annular mounting groove, 10-limiting angle, 11-annular limiting groove, 12-liquid inlet channel, 13-annular flow channel, 14-reflux chamber, 15-liquid outlet channel. DETAILED DESCRIPTION

[0034] The specific embodiments of the present invention will be further described with reference to the accompanying drawings.

[0035] like Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 、 Figure 6 As shown, a low flow resistance filter comprises a sealed end cap 3 and a filter cup 4, and a filter element assembly disposed inside the filter cup 4 and fixed between the end cap 3 and the bottom cover 7. An axial liquid outlet channel 15 is provided in the middle of the end cap 3. An annular limiting groove 11 for mounting the filter element assembly is provided on the end cap 3 outside the liquid inlet end of the liquid outlet channel 15. Multiple liquid inlet channels 12 with a spirally expanding structure are evenly distributed along the circumferential direction on the end cap 3 outside the liquid outlet end of the liquid outlet channel 15. The liquid inlet channel 12 is communicated with the annular flow channel 13 formed between the filter cup 4 and the filter element assembly. The filter element assembly is composed of an intermediate skeleton 6 and a filter element 5 sleeved on the intermediate skeleton 6. One end of the filter element assembly is sealed and installed in the annular limiting groove 11 of the end cover 3, and the other end of the filter element assembly is sealed and installed in the annular mounting groove 9 on one side of the bottom cover 7. The other side of the bottom cover 7 is tightly fitted with the bottom of the filter cup 4. The liquid outlet channel 15 is communicated with the reflux chamber 14 formed between the filter element assembly and the bottom cover 7.

[0036] like Figure 1 、 Figure 2 、 Figure 6As shown, the liquid outlet channel 15 of the end cap 3 of the present invention has a full-length internal thread structure, which achieves a sealed installation connection between the end cap 3 and the external component. The length of the internal thread on the inner wall of the liquid outlet channel 15 effectively ensures the installation strength and sealing between the filter and the external component. The liquid inlet end of the liquid outlet channel 15 of the end cap 3, i.e., the outer wall of the annular retaining groove 11, is nested and installed with the intermediate frame 6 on which the filter element assembly is installed. The resulting stopper structure effectively ensures the centering and installation strength of the intermediate frame 6. The full-length internal thread structure of the liquid outlet channel 16 also effectively ensures the installation strength between the external component and the end cap 3. The filter element 5 and the intermediate skeleton 6 are installed in the annular mounting groove 9 of the bottom cover 7, wherein the filter element 5 is sealed and fixed to the annular mounting groove 9 of the bottom cover 7 by using sealant, and the intermediate skeleton 6 is fixed to the annular mounting groove of the bottom cover 7 by welding or bonding with strong sealant to form a whole. The intermediate skeleton 6 is formed by casting, injection molding or die-casting, and the bottom cover 7 is formed by stamping. The inner side of the annular mounting groove 9 of the bottom cover 7 is formed by a transition slope to form a bottom cover protrusion 8, and the inner edge of the connecting end of the intermediate skeleton 6 and the bottom cover 7 forms a wedge-shaped structure matching the transition slope of the bottom cover 7. The transition slope of the bottom cover 7 and the wedge-shaped structure at the end of the intermediate skeleton 6 are effectively increased. The welding or bonding fixing area of ​​the intermediate skeleton 6 and the bottom cover 7 is thereby increased, thereby increasing the connection strength and connection reliability of the intermediate skeleton 6 and the bottom cover 7. The other end of the filter element assembly with the filter element 9 and the intermediate skeleton 6 installed is inserted into the annular limit groove 18 of the end cover 3 and sealed and fixed using sealant.

[0037] like Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 、 Figure 6 As shown, the oil flow pattern inside the liquid inlet channel 12 of the end cover 3 of the present invention is designed to be spiral while retaining the fluid flow area, and the liquid inlet channel 12 gradually increases from the liquid inlet end to the liquid outlet end to form a spiral expansion structure. The oil flow direction in the liquid inlet channel 12 is axial inflow and radial outflow. There are 6 groups of liquid inlet channels 12 evenly distributed along the circumferential direction on the end cover 3, and the liquid inlet channel 12 is designed with cast fillets at the position where the oil flows, which greatly reduces the resistance of the oil during the flow process. At the same time, its spiral expansion structure can prevent the generation of inlet vortexes to the greatest extent and can significantly increase the uniformity of oil distribution on the outer edge of the filter element assembly.

[0038] like Figure 1 、 Figure 3 、 Figure 6 As shown, the spirally expanding structure of the liquid inlet channel 12 of the end cover 3 of the present invention can effectively reduce the thickness of the filter compared to the traditional filter liquid inlet channel structure. The end cover 3 is formed by integral casting and then undergoes related structural processing, which greatly reduces the traditional filter end cover that requires multiple complex molding methods to pass the process.

[0039] like Figure 1 、 Figure 3 、 Figure 6 As shown, the intermediate frame 6 and bottom cover 7 of the present invention are both made of aluminum alloy, effectively preventing filter damage caused by fluid corrosion or rust. The bottom cover 7 and intermediate frame 6 are connected using continuous laser welding or a more advanced welding method to ensure weld strength and post-weld polishing to reduce stress concentration. The intermediate frame 6 can also be formed by injection molding or die casting. After casting, the intermediate frame 6 undergoes stress relief treatment to ensure material strength, and annealing can also be performed to ensure strength.

[0040] like Figure 1 、 Figure 3 、 Figure 6 As shown, after one end of the intermediate frame 6 is secured to the annular mounting groove 9 of the bottom cover 7, the filter element 5 is sleeved and mounted on the intermediate frame 6 and inserted into the annular mounting groove 9 of the bottom cover 7. The end of the filter element 5 is then sealed and bonded to the intermediate frame 6 and bottom cover 7 using sealant to form a single unit and prevent leakage. The other end of the filter element 5 and intermediate frame 6 assembly is then inserted into the annular retaining groove 11 of the end cover 3. The connection 9 between the filter element 5 and the annular retaining groove 11 of the end cover 3 is sealed and secured using sealant to ensure a tight seal. Finally, the filter cup 4 is sealed and installed (the filter cup is secured via a snap-fit ​​connection), completing the filter assembly.

[0041] like Figure 3 、 Figure 5 、 Figure 6 As shown, compared to conventional frame structures that use rolled iron sheets or welded rings for fixing, the intermediate frame 6 of the present invention adopts a triangular cross-section, with the triangles arranged with the inside larger and the outside smaller. This reduces flow resistance while also lowering process requirements. This intermediate frame 6 structure can be formed by casting, injection molding, or die-casting. It can also be mass-cast and then the stamped bottom cover 7 is connected to the intermediate frame 6 to secure it. This effectively prevents filter damage caused by excessive internal filter pressure, which can lead to filter frame deformation.

[0042] like Figure 3 、 Figure 5 、 Figure 6As shown, the intermediate skeleton 6 of the present invention is formed by 6 columns fixed by unequal numbers of ring ribs (the cross-section of the circular ring and the cross-section of the outer edge of the column are both conical structures with the inner side larger and the outer side smaller). The intermediate skeleton 6 is a cylindrical skeleton formed by the columns and the ring ribs as one piece, wherein a plurality of groups of parallel and oppositely arranged ring ribs are connected and fixed in sequence through a plurality of axially arranged columns, and the axial position distance of the ring ribs is reasonably and effectively arranged to disperse the edge stress, thereby improving the filtering effect of the filter to the optimal state.

[0043] like Figure 4 As shown, in the low-resistance filter of the present invention, after the end cap 3, filter element 5, intermediate frame 6, and bottom cap 7 are installed, the integral sealing ring 2 is installed in the annular groove on the outside of the end cap 3. The open end of the filter bowl 4 is then bent inward using a sheet metal machine to form an inner flange structure. This inner flange structure compresses and secures the integral sealing ring 2, thereby achieving a sealed connection between the filter bowl 4 and the end cap 3, thereby simultaneously ensuring the overall installation security and overall filter sealing. An annular groove is provided on the end cap 3 outside the liquid inlet channel 12, and the installation sealing ring 1 is installed in this annular groove. This installation sealing ring 1 realizes the sealed installation connection between the filter and the outer components, thereby effectively ensuring the installation accuracy and sealing of the filter.

[0044] The following describes the assembly and working process of the present invention in detail with reference to the accompanying drawings.

[0045] The specific assembly process of the low flow resistance filter described in the present invention is: the intermediate skeleton 6 and the bottom cover 7 are first welded and bonded to be sealed and installed, and then the filter element 5 is sleeved and installed on the intermediate skeleton 6. At the same time, the end of the filter element 5 is sealed and fixed in the annular installation groove 9 of the bottom cover 7 by bonding. The other end of the filter element assembly formed by the filter element 5 and the intermediate skeleton 6 is installed in the annular limiting groove 11 of the end cover 3 by bonding and sealing. Both ends of the filter element are sealed and bonded with sealant to effectively ensure good sealing. Finally, the filter cup 4 is installed (the filter cup is fixed by a snap connection) to complete the assembly of the entire filter.

[0046] The present invention reduces the filter flow resistance and achieves the optimal flow area of ​​the fluid in the low flow resistance filter as follows: First, the inlet channel 12 of the end cap 3 is a spirally expanding structure that slopes downward. Compared to conventional filters, this inlet channel 12 structure better conforms to the laws of liquid flow, avoids the large local resistance losses caused by sudden changes in the inlet channel 12, and significantly reduces the filter inlet flow resistance. Through the inlet channel 12 of the end cap 3, the oil spirals into the annular channel 13 between the filter element assembly and the filter cup 4. The oil's downward spiraling direction facilitates the uniform distribution of impurities within the annular channel. This prevents sedimentation and ensures uniform oil entry into the filter element 5, effectively preventing problems such as uneven force and severe deformation of the filter element 5 due to severe local blockage, thereby extending the service life of the filter element 5. Once the oil fills the annular channel 13 between the filter element assembly and the filter cup 4, it is filtered through the filter element 5 and enters the intermediate frame 6. The filter element 5 is radially pleated and rolled into a cylindrical shape to increase the filtration area. Finally, it is mounted on the outside of the intermediate frame 6 for secure installation. The traditional center tube is formed by punching and rolling a steel mesh or iron sheet, which will reduce the fluid flow area. When the pressure at a local position of the center tube is high, it will cause the center tube to deform. The intermediate skeleton 6 proposed in the present invention adopts a steel simple beam structure (taking advantage of the stability of the triangle, the cross-sectional area is designed to be an equilateral triangle), and the number and position of the crossbeams and longitudinal beams of the intermediate skeleton can be judged by the flow area of ​​the oil entering the intermediate bracket 6 to judge the actual fluid flow state and pressure concentration position of the fluid flowing into the filter, so as to arrange them reasonably and effectively, thereby improving the filtering effect of the filter to the optimal state. Finally, when the fluid inside the intermediate skeleton 6 is full, it flows out from the liquid outlet channel 15 of the end cover 3 and proceeds to the next link.

[0047] The above embodiments describe the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for illustrating the principles of the present invention. Without departing from the scope of the principles of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of protection of the present invention.

Claims

1. A low flow resistance filter, characterized in that The filter element assembly is composed of an intermediate frame and a filter element sleeved on the intermediate frame. One end of the filter element assembly is sealed and mounted in the annular limiting groove of the end cover, and the other end of the filter element assembly is sealed and mounted in the annular mounting groove on one side of the bottom cover. The other side of the bottom cover is tightly fitted with the bottom of the filter cup. The liquid outlet channel is connected to the reflux chamber formed between the filter element assembly and the bottom cover.

2. The low flow resistance filter according to claim 1, characterized in that: The liquid inlet flow channel is used for the axial inflow and radial outflow of oil. There are 6 groups of liquid inlet flow channels evenly distributed along the circumferential direction, and the position where the oil flows in the liquid inlet flow channel is designed with cast fillets, which is used to greatly reduce the resistance of the oil during the flow process. At the same time, the spiral expansion structure of the liquid inlet flow channel can prevent the generation of inlet vortex to the greatest extent and can significantly increase the uniformity of oil distribution on the outer edge of the filter element assembly.

3. The low flow resistance filter according to claim 1, characterized in that: The intermediate frame is a cylindrical frame formed by integrally forming columns and annular ribs, wherein a plurality of groups of parallel and oppositely arranged annular ribs are sequentially connected and fixed through a plurality of axially arranged columns.

4. The low flow resistance filter according to claim 3, characterized in that: The columns and annular ribs in the intermediate frame all adopt a tapered structure with a larger inner portion and a smaller outer portion. The tapered structure is used to effectively increase the strength of the intermediate frame and the flow area of ​​the fluid entering the filter element assembly, thereby reducing the fluid flow resistance and the process requirements.

5. The low flow resistance filter according to claim 1, characterized in that: The intermediate frame and the bottom cover are fixed by welding or bonding, wherein the intermediate frame is formed by casting, injection molding or die-casting, and the bottom cover is formed by stamping. The inner side of the annular mounting groove of the bottom cover forms a bottom cover protrusion through a transition slope, and the inner edge of the connecting end of the intermediate frame and the bottom cover forms a wedge-shaped structure that matches the transition slope of the bottom cover. The transition slope of the bottom cover and the wedge-shaped structure at the end of the intermediate frame effectively increase the welding or bonding fixing area of ​​the intermediate frame and the bottom cover, thereby increasing the connection strength and connection reliability between the intermediate frame and the bottom cover.

6. The low flow resistance filter according to claim 1, characterized in that: At least three groups of limiting angles are evenly distributed along the circumferential direction on the outer side wall of the annular mounting groove of the bottom cover. The limiting angles have a conical structure with a larger inner side and a smaller outer side, and the conical ends of the limiting angles are tightly fitted with the inner wall of the filter bowl, so as to realize the installation guidance of the bottom cover and the filter bowl and the radial positioning of the bottom cover in the filter bowl.

7. The low flow resistance filter according to claim 1, characterized in that: A step stop matching structure that matches the inner side wall of the annular limit groove is formed inside the connecting end of the intermediate frame and the end cover annular limit groove. The intermediate frame is nested and installed on the inner side wall of the annular limit groove, and the intermediate frame and the annular limit groove are aligned through the step stop matching structure. The formed stop matching structure is used to effectively ensure the centering and installation strength of the intermediate frame installation.

8. The low flow resistance filter according to claim 1, characterized in that: The filter element is a radial pleated filter element, which is sleeve-mounted on the middle frame. One end of the filter element is fixed in the annular mounting groove of the bottom cover by adhesive sealing, and the other end of the filter element is fixed in the annular limiting groove of the end cover by adhesive sealing.

9. The low flow resistance filter according to claim 1, characterized in that: The liquid outlet channel of the end cover is a full-length internal thread structure, through which the end cover and the outer component are sealed and installed. The length of the internal thread on the inner wall of the liquid outlet channel can effectively ensure the installation strength and installation sealing of the filter and the outer component.

10. The low flow resistance filter according to claim 1, characterized in that: An annular groove is provided on the end cover on the outer side of the liquid inlet channel, and an installation sealing ring is installed in the annular groove, and a sealing installation connection between the filter and the outer component is realized through the installation sealing ring, thereby effectively ensuring the installation accuracy and sealing of the filter; an annular groove is provided on the end cover on the outer side of the installation sealing ring, and an integral sealing ring is installed in the annular groove, and a sealing installation connection between the filter cup and the end cover is realized through the integral sealing ring; the filter cup is a cylindrical structure with an open end, and the open end of the filter cup is nested and installed with the filter element assembly and the end cover, and the open end of the filter cup is bent inwardly by a sheet metal machine to form an inner flange structure, and the integral sealing ring is pressed and fixed by the inner flange structure to realize the sealing connection and installation of the filter cup and the end cover, thereby simultaneously ensuring the overall installation firmness and overall sealing of the filter.

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