A fuel filter

Abstract

The present invention discloses a fuel filter, which relates to the technical field of vehicle fuel filtration systems and includes a main housing and a filter cartridge. An oil inlet and an oil outlet are provided on the main housing; a filtering assembly is arranged inside the filter cartridge, and the filtering assembly includes a first filtering assembly and a second filtering assembly; a first cavity is formed between the first filtering assembly and the inner wall of the main housing, and the first cavity is communicated with the oil inlet. The first filtering assembly can filter particulate matter in the fuel; a drain port is further provided on the main housing. A second cavity is formed between the first filtering assembly and the second filtering assembly, and the second cavity is communicated with the drain port. The second filtering assembly can filter water in the fuel; a third cavity is arranged inside the second filtering assembly, and the third cavity is communicated with the oil outlet. The present invention can achieve the effects of impurity filtration and oil-water separation, and effectively solve the problem of corrosion of components in the fuel system during the use of vehicles.

Description

Technical Field

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

[0002] With the popularization of vehicle component lightweighting and the achievement of low fuel consumption goals, and to further reduce vehicle failures caused by fuel system problems, lightweight fuel filters under positive pressure conditions are gradually being applied to small and medium power engines.

[0003] However, existing fuel filters can usually only filter particulate matter and large-diameter water droplets in fuel, and cannot filter fine and tiny water droplets in fuel to achieve high-precision and long-term oil-water separation; the unfiltered fine and tiny water droplets in fuel enter the interior of the fuel system, which easily causes component corrosion and further leads to faults such as engine stalling and difficult starting.

[0004] Therefore, a new type of fuel filter is provided to solve the above problems existing in the prior art. Summary of the Invention

[0005] The object of the present invention is to provide a fuel filter to solve the above problems existing in the prior art, which can achieve more efficient impurity filtration and oil-water separation effects, and effectively solve the problem of component corrosion in the fuel system during vehicle use.

[0006] To achieve the above object, the present invention provides the following solution:

[0007] The present invention provides a fuel filter, including a main housing and a filter cartridge. A filter chamber is provided inside the main housing, and the filter cartridge is installed in the filter chamber. An oil inlet and an oil outlet are provided on the main housing; a filter assembly is provided inside the filter cartridge, and the filter assembly includes a first filter assembly and a second filter assembly. The first filter assembly is located outside the second filter assembly; a first cavity is formed between the first filter assembly and the inner wall of the main housing, and the first cavity is communicated with the oil inlet. The first filter assembly can filter particulate matter in fuel; a drain port is further provided on the main housing. A second cavity is formed between the first filter assembly and the second filter assembly, and the second cavity is communicated with the drain port. The second filter assembly can filter water in fuel; a third cavity is provided inside the second filter assembly, and the third cavity is communicated with the oil outlet.

[0008] Preferably, the first filtering component includes a first filtering layer and a second filtering layer, the second filtering component includes a third filtering layer, the outer side of the first filtering layer is radial, the inner side thereof is attached to the outer side of the second filtering layer, and the inner side of the second filtering layer is installed in the filtering cylinder through a first support member; the third filtering layer is installed in the filtering cylinder through a second support member, and a second cavity is formed between the inner side of the second filtering layer and the outer side of the third filtering layer.

[0009] Preferably, the first filtering layer, the second filtering layer, and the third filtering layer are made of fiber materials of different media; the first filtering layer is used to intercept particulate matters in the fuel and allow the emulsified water in the fuel to pass through, the second filtering layer can coalesce the emulsified water passing through the first filtering layer, and the coalesced emulsified water slides down along the inner side of the second filtering layer into the second cavity; the third filtering layer is a hydrophobic net that can intercept the coalesced emulsified water.

[0010] Preferably, an upper end cover is provided at the top of the filtering cylinder, and a lower end cover is provided at the bottom, and the filtering component is located between the upper end cover and the lower end cover.

[0011] Preferably, the main housing includes an upper housing and a lower housing, the upper housing is hermetically connected to the lower housing, the upper end cover is hermetically connected to the upper housing, and the lower end cover is hermetically connected to the lower housing; the fuel inlet and the fuel outlet are both installed on the upper housing, and the drain outlet is installed on the lower housing.

[0012] Preferably, an internal thread is provided at the bottom end of the upper housing, an external thread is provided at the top end of the lower housing, the upper housing is threadedly connected to the lower housing, and a sealing member is provided at the connection; a reinforcing ring is provided at the bottom end of the outer wall of the upper housing, and the reinforcing ring is located outside the internal thread;

[0013] A limit anti - detachment structure is also provided at the connection between the upper housing and the lower housing.

[0014] Preferably, a fuel heating socket is provided on the upper housing, a fuel heater is installed in the fuel heating socket, an installation structure is provided on the outer wall of the upper housing for connecting to a vehicle, an installation hole is provided on the installation structure, and a metal lining ring is embedded in the installation hole; an oil temperature sensor is also installed on the upper housing.

[0015] Preferably, the drain outlet is located at the bottom of the lower housing, a drain cock is installed on the drain outlet, a screwing part is provided on the drain cock, and a water level sensor is also installed on the bottom of the lower housing; and sealing members are provided at the connections of the drain cock and the water level sensor with the lower housing;

[0016] An integrated component is also installed on the outer wall of the lower housing. The integrated component includes a first integrated component and a second integrated component. The first integrated component is used for installing and fixing accessory components, and an electrostatic discharge device is provided on the second integrated component; an edge is also provided at the bottom of the outer wall of the lower housing.

[0017] Preferably, an upper central cylinder is provided in the middle of the upper housing, and the upper central cylinder communicates with the oil outlet; an upper connecting cylindrical cavity is provided at the top of the upper end cover, and the upper connecting cylindrical cavity communicates with the third cavity; sealing members are provided between the outer wall of the upper connecting cylindrical cavity and the inner wall of the upper central cylinder and between the bottom surface of the upper central cylinder and the top surface of the upper end cover.

[0018] Preferably, two raised rings are provided on the circumference of the bottom of the lower end cover, and a sealing member is provided between the outer wall between the two raised rings on the lower end cover and the inner wall of the lower housing;

[0019] A lower connecting cylindrical cavity is provided at the bottom of the lower end cover, and a claw structure is further provided on the outer wall of the lower connecting cylindrical cavity. A lower central cylinder is provided in the middle of the lower housing, and a lock catch is correspondingly provided on the inner wall of the lower central cylinder; when the lower end cover is connected to the lower housing, the claw structure and the lock catch can cooperate to perform self-locking, and when the lower housing is disassembled, the claw structure and the lock catch can be disengaged.

[0020] The present invention has achieved the following technical effects compared with the prior art:

[0021] Through the simultaneous action of the first filtration component and the second filtration component, the present invention makes the product impurity filtration performance more efficient and the water separation efficiency more stable, effectively solving problems such as engine flameout and difficult starting caused by gas accumulation inside the fuel system and component rust.

[0022] The present invention has also achieved the following technical effects in other technical solutions compared with the prior art:

[0023] 1. The product of the present invention is small in volume, effectively solving the problem that the product cannot be installed due to insufficient vehicle layout space, and making the product applicable to various vehicle loading scenarios;

[0024] 2. The product of the present invention adopts a fully plastic lightweight design in terms of structure, and the components are installed modularly, making the self-weight of the product smaller, meeting the development requirements of vehicle weight reduction and low power consumption in the industry regulations;

[0025] 3. In terms of sealing reliability, the present invention introduces special structure designs that meet high-pressure environments, such as anti-deformation design, component structure strength design, multiple sealing design, etc., meeting the sealing requirements in various complex environments;

[0026] 4. All the electrical components integrated in the present invention adopt a modular design, which can be increased or decreased according to actual usage requirements, realizing the standardized and platform-based development of the product structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0028] Figure 1 is the overall external shape structure diagram of the present invention;

[0029] Figure 2 is the cross-sectional view of the internal structure assembly relationship of the present invention;

[0030] Figure 3 is the composition diagram of the upper housing assembly of the present invention;

[0031] Figure 4 is the composition diagram of the filter cartridge of the present invention;

[0032] Figure 5 is the composition diagram of the lower housing assembly of the present invention.

[0033] Description of the reference numerals in the drawings: 1. Upper housing assembly; 101. Upper housing; 102. Mounting bracket; 103. Inlet oil pipe joint; 104. Outlet oil pipe joint; 105. Fuel heater; 106. Oil temperature sensor; 2. Filter cartridge; 201. Upper end cover; 202. First filter layer; 203. Second filter layer; 204. Third filter layer; 205. Lower end cover; 3. Lower housing assembly; 301. Lower housing; 302. Integrated component; 303. Electrostatic discharge device; 304. Polygonal edge structure; 305. Water level signaler; 306. Drain cock; 4. First sealing point; 5. Second sealing point; 6. Third sealing point; 7. Fourth sealing point. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0035] The object of the present invention is to provide a fuel filter to solve the above problems in the prior art, which can achieve more efficient impurity filtration and oil-water separation effects, and effectively solve the problem of corrosion of components in the fuel system during the use of vehicles.

[0036] To make the above objects, features and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] As Figures 1 - 5 shown, this embodiment provides a fuel filter, which mainly includes a main housing and a filter cartridge 2. A filter cavity is provided inside the main housing, and the filter cartridge 2 is installed in the filter cavity. An oil inlet and an oil outlet are provided on the main housing; a filter assembly is provided inside the filter cartridge 2, and the filter assembly includes a first filter assembly and a second filter assembly. The first filter assembly is located outside the second filter assembly; a first cavity is formed between the first filter assembly and the inner wall of the main housing, and the first cavity is communicated with the oil inlet. The first filter assembly can filter the particulate matter in the fuel; a drain port is also provided on the main housing. A second cavity is formed between the first filter assembly and the second filter assembly, and the second cavity is communicated with the drain port. The second filter assembly can filter the water in the fuel; a third cavity is provided inside the second filter assembly, and the third cavity is communicated with the oil outlet.

[0038] Among them, as <* Figure 1 shown, the main housing mainly includes an upper housing assembly 1 and a lower housing assembly 3. The upper housing assembly 1 is located above the lower housing assembly 3, and the filter cartridge 2 is located inside the upper housing assembly 1 and the lower housing assembly 3. Further, the upper housing assembly 1, the lower housing assembly 3 and the filter cartridge 2 are all preferably of a circular structure. In this embodiment, the fuel filter mainly includes three parts: an upper housing assembly 1, a lower housing assembly 3 and a filter cartridge 2. The structure is compact and detachable. The overall volume of the product is small, effectively solving the problem that the product cannot be installed due to insufficient layout space of the whole vehicle, making the product applicable to various vehicle loading scenarios. Moreover, the fuel filter is designed with full-plastic lightweight in structure, and the components are installed modularly, making the self-weight of the product smaller, meeting the development requirements of vehicle weight reduction and low power consumption in the industry regulations.

[0039] In this embodiment, as Figure 4 shown, the top of the filter cartridge 2 is provided with an upper end cover 201, and the bottom is provided with a lower end cover 205. The filter assembly is located between the upper end cover 201 and the lower end cover 205. Among them, after the upper part of the upper end cover 201 of the filter cartridge 2 is installed with the upper central cylinder of the upper housing 101, seals are provided between the outer wall of the upper connecting cylindrical cavity and the inner wall of the upper central cylinder and between the bottom surface of the upper central cylinder and the top surface of the upper end cover 201, forming a circumferential seal and a planar seal arranged one above the other. The two seals form the first seal 4.

[0040] In this embodiment, the upper housing assembly 1 and the lower housing assembly 3 are connected by threads, and a sealing ring is installed between the two threaded joints. After being installed in place, a circumferential seal is formed, as shown in Figure 2 the second sealing position 5 in the figure. Specifically, an internal thread structure is arranged at the lower port part of the inner cavity of the upper housing 101, and an external thread structure is correspondingly arranged at the upper port part of the lower housing 301. A sealing ring fixing structure is also arranged on the circumference of the upper port part of the lower housing 301 for fixing the sealing ring and connecting and sealing with the upper half body. Among them, the sealing ring fixing structure is selected according to specific working requirements, and preferably an annular sealing groove is adopted. A reinforcing ring for preventing deformation is added to the entire outer circumference of the internal thread structure of the upper housing 101.

[0041] In this embodiment, a limit and anti-disengagement structure is also provided at the connection between the upper housing 101 and the lower housing 301, and the direction is unique after being assembled in place. Specifically, a 1 / 4 circumferential groove is provided on the first reinforcing ring in contact with the lower housing on the circumference of the upper housing mouth. A triangular boss with a guide is provided on the plane of the groove. The triangular boss is located at the edge of the arc of the groove. The guiding angle is smaller for the assembly entry surface and has a gentler slope, and the guiding angle is larger for the exit surface and has a steeper slope. An elastic thin plate structure is provided at the position on the lower housing corresponding to the boss of the upper housing, and a raised limit baffle is provided on the thin plate in the direction towards the triangular boss.

[0042] When the upper housing and the lower housing are assembled close to the limit and anti-disengagement structure, the limit baffle on the lower housing slowly slides into the upper housing through the entry surface of the triangle and enters the limit area through the exit surface of the triangular boss. When the limit baffle reaches the retaining wall of the arc groove of the upper housing, the assembly stops to achieve the limit function. When the limit baffle is forced to rotate in the reverse direction, due to the relatively large angular limit of the exit surface of the triangular boss on the upper housing relative to the assembly guiding surface, it prevents the limit baffle on the lower housing from rotating out of the limit space of the upper housing, thus realizing the anti-disengagement function. When it is necessary to replace the filter element for maintenance, a special disassembly tool can be used to normally disassemble the upper and lower housings.

[0043] In this embodiment, two raised rings are provided on the bottom circumference of the lower end cover 205. A sealing member, preferably a circular sealing ring, is provided between the outer wall between the two raised rings on the lower end cover 205 and the inner wall of the lower housing 301. After the filter cartridge 2 is installed in place from top to bottom, a circumferential compression seal is formed with the inner wall of the lower housing assembly 3, as shown in Figure 2 the third sealing position 6 in the figure.

[0044] Further, a lower connection cylindrical cavity is provided at the bottom of the lower end cover 205, and a ring with a flanging is further provided on the outer wall of the lower connection cylindrical cavity as a claw structure. A lower central tube is provided in the middle of the lower housing 301, and a lock catch is correspondingly provided on the inner wall of the lower central tube. When the lower end cover 205 is connected to the lower housing 301, the claw structure and the lock catch can cooperate to perform self-locking. When disassembling the lower housing, the claw structure and the lock catch can be disengaged to realize the function that the filter cartridge 2 automatically exits when the lower housing 301 is disassembled.

[0045] In this embodiment, two outwardly protruding platforms are provided at the bottom of the lower housing 301. The inner holes of the protruding platforms are threaded structures. The inner hole of one protruding platform is communicated with the drain hole for connecting the drain cock 306, and the other is for connecting the water level sensor 305. The water level sensor 305 can also be connected to a controller, and the controller is connected to an alarm to realize the functions of detecting the water volume inside the product, alarming, and regularly discharging sewage; there are flat gaskets between the water level sensor 305 and the drain cock 306 and the protruding platforms to form a planar seal when the parts are tightened, as Figure 2 in the fourth seal 7. Among them, a screwing part is further provided on the drain cock 306 for easy manual disassembly. Preferably, two screwing parts are provided, and the shape of the screwing part can be selected according to specific working needs, preferably a disc-shaped structure.

[0046] In this embodiment, the above four seals form three independent spaces. The middle area between the inner wall of the upper housing 101 and the outer side surface of the first filter layer 202 (the first cavity) is the upstream of filtration. The area from the back of the first filter layer 202 to the outside of the third filter layer 204 (the second cavity) is the middle stream. The area from the back of the third filter layer 204 to the space of the oil outlet pipe joint 104 (the third cavity) is the downstream of filtration.

[0047] In this embodiment, as Figure 3 shown, the upper housing assembly 1 mainly includes an upper housing 101, an oil inlet pipe joint 103, an oil outlet pipe joint 104, an oil temperature sensor 106, and a fuel heater 105. Among them, the oil inlet and the oil outlet are both installed on the upper housing 101. Preferably, two oil inlets and two oil outlets are provided, which are respectively installed on both sides of the upper housing 101; further, an oil inlet pipe joint 103 is provided on the oil inlet for connecting with the oil inlet pipe of the vehicle, and an oil outlet pipe joint 104 is provided on the oil outlet for connecting with the oil outlet pipe of the vehicle; and fuel data acquisition components can also be installed on the oil inlet and the oil outlet for acquiring fuel data. The fuel data acquisition components can include an oil temperature sensor 106 or other sensors, etc.

[0048] In this embodiment, the assembly directions of the oil inlet pipe, the oil outlet pipe, and the temperature sensor with respect to the oil inlet and the oil outlet can be freely adjusted according to the usage requirements, and can be set in the horizontal direction or the vertical direction; the assembly methods can be welding structure, ferrule structure, and threaded structure, and the welding method is preferably adopted.

[0049] In this embodiment, a fuel heating socket is provided in the direction perpendicular to the upper housing 101 (radial direction). The outside of the fuel heating socket is connected to the vehicle circuit, and the inside is connected to the fuel heater 105 to realize the auxiliary heating function of the fuel; among them, the fuel heater 105 can be selected according to specific working needs, and an electric heater is preferably adopted. Further, the fuel heater 105 is inserted into the bottom opening of the upper housing 101 and is fixedly combined with the upper housing 101 through screw connection. The fuel heater 105 is equipped with two groups of metal connection terminals (posts). One group of connection terminals (posts) is inserted from the outside to the inside through the fuel heating socket, and the other group of connection terminals (posts) passes through the heater fixing hole from the bottom of the lower housing 301 and penetrates the inside of the upper housing 101 from the inside to the outside to be connected to the first group of connection terminals (posts) of the fuel heating socket, so as to realize the conduction of the circuit and the heating function. Among them, the direction of the fuel heating socket can also be adjusted by rotation in the circumferential direction according to the installation requirements.

[0050] In this embodiment, an installation structure for connecting to the vehicle is provided on another side surface perpendicular to the upper housing 101. There are two installation holes on the installation structure, and metal lining rings are embedded in the holes for releasing the internal static electricity of the diesel; among them, the installation bracket 102 is preferably adopted for the installation structure, or other installation structures can also be selected according to specific working needs.

[0051] In this embodiment, the filter cartridge 2 mainly includes an upper seal ring of the filter cartridge, an upper end cover 201, a seal ring, a first filter layer 202, a second filter layer 203, a third filter layer 204, a lower end cover 205, and a lower seal ring of the filter cartridge. An upper end cover 201 is provided at the top of the filter cartridge 2. There are two sealing structures on the upper end cover 201. These sealing structures are connected to the inner wall and the bottom surface of the upper central cylinder of the upper housing 101 through the upper seal ring of the filter cartridge and the seal ring to form a seal. A lower end cover 205 is provided at the bottom of the filter cartridge 2. There is one sealing structure on the lower end cover 205. This sealing structure is directly connected to the inside of the lower housing 301 through the lower seal ring of the filter cartridge to form a seal.

[0052] In this embodiment, the filter cartridge 2 is generally cylindrical in shape. Its middle part mainly includes a first filter layer 202, a second filter layer 203, and a third filter layer 204 arranged successively from outside to inside. The three filter layers are composed of hollow cylindrical fiber materials of different media. Among them, the first filter layer 202 is circular when surrounding inward and radially outward. The second filter layer 203 is flaky when surrounding inward. The outer side surface of the second filter layer 203 is closely attached to the inner side surface of the first filter layer 202 to form a first filter assembly. The inner side surface of the second filter layer 203 is supported by a separate plastic support cylinder. The third filter layer 204 is made of a semi-transparent material and is wrapped and fixed on the support frame to form a single part. A channel gap with a fixed width is formed between the third filter layer 204 and the second filter layer 203. The upper part of the filter cartridge 2 contacts the upper end cover 201, and the bottom contacts the lower end cover 205, and they are combined into a whole after being filled with glue.

[0053] Specifically, the first filter layer 202 is made of a fully synthetic fiber material and mainly consists of four layers of materials. From the fuel inflow surface to the inside, they are a protective layer, a coarse fiberglass layer, a fine fiberglass layer, and a support layer in sequence. The outermost protective layer and the innermost support layer are the structural layers of the entire first filter layer, mainly realizing the structural support and performance protection functions of the first filter layer during the manufacturing process. The fibers of the middle coarse fiberglass layer and the fine fiberglass layer are superimposed and compounded with each other to form a reticular structure with a front-leaning and rear-dense gradient layer, which is called the filter penetration layer. In this layer, impurity particles in the fuel are intercepted by the front-leaning and rear-dense reticular structure layer to form a filtering function. Combining with the hydrophobic characteristics of the glass fiber material in the fiberglass layer, the emulsified water in the fuel penetrates through the reticular structure layer and seeps to the next layer. Thus, while impurities are intercepted and filtered, fine moisture is coalesced and then seeps to the next stage, that is, it reaches the outer surface of the second filter layer.

[0054] The second filter layer 203 is made of artificial synthetic chemical fiber and has a special adsorption effect on moisture. The fine water droplets permeated by the first filter layer 202 and some water droplets wrapped by oil droplets are gradually adsorbed and intercepted in this layer, forming a physical manifestation of water molecules combining into fine water droplets and the fine water droplets condensing into large water beads. And the chemical fiber of this layer has no such physical characteristic effect on the filtered clean fuel and directly penetrates through the second filter layer to reach the third filter layer.

[0055] The third filter layer is made of PET polyester material and has strong water repellency. It is a dense filter grid formed by the interweaving of ultra-fine fibers, and the shape of the formed part is a semi-transparent yarn-like appearance. The condensed large water beads are completely separated and intercepted from the oil-water mixture state under the water repellency of the PET polyester material of the third filter layer. The separated water beads enter the product water accumulation cavity, and the separated clean fuel enters the downstream. The relatively dirty fuel before filtration completes efficient filtration of impurities and long-term oil-water separation through the filtration, condensation, and separation effects of the three filter layers in sequence, and provides sufficiently clean fuel to enter the engine fuel injection system.

[0056] In this embodiment, the separation principle is that while the first filter layer intercepts particulate matter, the emulsified water in the fuel penetrates through the filter media; the second filter layer coalesces the emulsified water that has passed through (i.e., water molecules combine into small water droplets, the small water droplets coalesce into large water beads, and the relatively large water beads slide down along the surface of the filter media to the water accumulation cavity under the action of gravity); the third filter layer uses a hydrophobic mesh as the last stage of separation to intercept all the coalesced small water droplets. Each of the three layers of filtration plays a separation role, and different filter media are used for different water droplet diameters to achieve a high oil-water separation efficiency.

[0057] In this embodiment, as Figure 5 shown, the lower housing assembly 3 is generally funnel-shaped as a whole, with a larger mouth at the upper section of the lower housing 301 and a smaller lower part; the lower housing assembly 3 mainly includes functional components such as the lower housing 301, the water level sensor 305, and the drain cock 306. Three integrations are reserved on the circumference at the middle position of the lower housing 301. The three integrations include two first integrations, which can play a role in installing and fixing accessory components, and the second integration contains an electrostatic discharge device 303, preferably a metal insert, which can be connected to the negative electrode of the water level sensor 305 to achieve the electrostatic discharge function between the tank body and the oil. Regular edges are provided on the outer circumferential surface at the bottom of the lower housing 301 to form a polygonal edge structure 304, which facilitates users to use tools to improve the maintenance efficiency of product disassembly and assembly and enhance the user experience.

[0058] Specific examples are used in this specification to elaborate on the principles and implementation manners of the present invention. The descriptions of the above embodiments are only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A fuel filter, comprising a main housing and a filter cartridge. A filter chamber is provided inside the main housing, and the filter cartridge is installed in the filter chamber. An oil inlet and an oil outlet are provided on the main housing; characterized in that, A filter element is provided inside the filter cartridge. The filter element includes a first filter element and a second filter element. The first filter element is located outside the second filter element. A first cavity is formed between the first filter element and the inner wall of the main housing. The first cavity is in communication with the oil inlet. The first filter element can filter particulate matter in the fuel. A drain port is further provided on the main housing. A second cavity is formed between the first filter element and the second filter element. The second cavity is in communication with the drain port. The second filter element can filter water in the fuel. A third cavity is provided inside the second filter element. The third cavity is in communication with the oil outlet. The first filter element includes a first filter layer and a second filter layer. The second filter element includes a third filter layer. The inner side of the first filter layer is attached to the outer side of the second filter layer. The first filter layer is made of a fully synthetic fiber material and includes a protective layer, a coarse fiberglass layer, a fine fiberglass layer, and a support layer that are sequentially distributed from the fuel inflow surface inward. The fibers of the coarse fiberglass layer and the fibers of the fine fiberglass layer are superposed and compounded with each other to form a mesh structure with a gradient layer that is sparse in the front and dense in the back. Impurity particles in the fuel are intercepted by the mesh structure that is sparse in the front and dense in the back to form a filtering function. Combining with the hydrophobic property of the fiberglass material in the fiberglass layer itself, the emulsified water in the fuel penetrates the mesh structure layer and penetrates to the next layer. The main housing includes an upper housing and a lower housing. The upper housing is threadedly connected to the lower housing. A limit and anti-disconnection structure is further provided at the connection between the upper housing and the lower housing. Specifically, a 1 / 4 circumferential groove is provided on the first reinforcing ring in contact with the lower housing on the circumferential edge of the mouth of the upper housing. A triangular boss with a guide is provided on the plane of the groove. The triangular boss is located at the edge of the arc of the groove. The guiding angle is smaller for the assembly entry surface and larger for the exit surface. And an elastic thin plate is provided at the position on the lower housing corresponding to the boss of the upper housing. A protruding limit baffle is provided on the thin plate in the direction towards the triangular boss.

2. The fuel filter according to claim 1, characterized in that, The outer side of the first filter layer is radial. The inner side of the second filter layer is installed inside the filter cartridge through a first support member. The third filter layer is installed inside the filter cartridge through a second support member. The second cavity is formed between the inner side of the second filter layer and the outer side of the third filter layer.

3. The fuel filter according to claim 2, wherein The first filter layer, the second filter layer, and the third filter layer are made of fiber materials with different media. The second filter layer can coalesce the emulsified water that has passed through the first filter layer, so that the coalesced emulsified water slides down along the inner side of the second filter layer into the second cavity. The third filter layer is a hydrophobic net that can intercept the coalesced emulsified water.

4. The fuel filter according to any one of claims 1 to 3, characterized in that, An upper end cover is provided at the top of the filter cartridge, and a lower end cover is provided at the bottom. The filter element is located between the upper end cover and the lower end cover.

5. The fuel filter according to claim 4, wherein, The upper housing is hermetically connected to the lower housing, the upper end cover is hermetically connected to the upper housing, and the lower end cover is hermetically connected to the lower housing; the oil inlet and the oil outlet are both installed on the upper housing, and the drain port is installed on the lower housing.

6. The fuel filter according to claim 5, characterized in that, The bottom end of the upper housing is provided with internal threads, the top end of the lower housing is provided with external threads, and a seal is provided at the connection between the upper housing and the lower housing; a reinforcing ring is provided at the bottom end of the outer wall of the upper housing, and the reinforcing ring is located outside the internal threads.

7. The fuel filter according to claim 5, characterized in that, A fuel heating socket is provided on the upper housing, a fuel heater is installed in the fuel heating socket, an installation structure is provided on the outer wall of the upper housing for connecting to a vehicle, an installation hole is provided on the installation structure, and an electrostatic discharge device is installed in the installation hole; an oil temperature sensor is also installed on the upper housing.

8. The fuel filter according to claim 5, characterized in that, The drain port is located at the bottom of the lower housing, a drain cock is installed on the drain port, a screwing part is provided on the drain cock, and a water level sensor is also installed on the bottom of the lower housing; and seals are provided at the connections between the drain cock and the water level sensor and the lower housing. An integrated component is also installed on the outer wall of the lower housing. The integrated component includes a first integrated component and a second integrated component. The first integrated component is used for installing and fixing accessory components, and an electrostatic discharge device is provided on the second integrated component; a rib is also provided at the bottom of the outer wall of the lower housing.

9. The fuel filter according to claim 5, characterized in that A central upper cylinder is provided in the middle of the upper housing, and the central upper cylinder communicates with the oil outlet; an upper connecting cylindrical cavity is provided at the top of the upper end cover, and the upper connecting cylindrical cavity communicates with the third cavity; seals are provided between the outer wall of the upper connecting cylindrical cavity and the inner wall of the central upper cylinder and between the bottom surface of the central upper cylinder and the top surface of the upper end cover.

10. The fuel filter according to claim 5, characterized in that, Two raised rings are provided on the circumferential bottom of the lower end cover, and a seal is provided between the outer wall between the two raised rings on the lower end cover and the inner wall of the lower housing. A lower connecting cylindrical cavity is provided at the bottom of the lower end cover, and a claw structure is further provided on the outer wall of the lower connecting cylindrical cavity. A central lower cylinder is provided in the middle of the lower housing, and a lock catch is correspondingly provided on the inner wall of the central lower cylinder; when the lower end cover is connected to the lower housing, the claw structure and the lock catch can cooperate to perform self-locking, and when the lower housing is disassembled, the claw structure and the lock catch can be disengaged.

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