Filter element, preparation method thereof and vehicle

Abstract

The invention discloses a filter element, a preparation method thereof and a vehicle, and relates to the technical field of automobiles. Comprising a first filter fiber layer, a second filter fiber layer and a third filter fiber layer, wherein the second filter fiber layer is arranged between the first filter fiber layer and the third filter fiber layer; the thickness of the first filter fiber layer is greater than that of the third filter fiber layer; the micropore size of the first filter fiber layer is smaller than that of the second filter fiber layer; the micropore size of the second filter fiber layer is smaller than that of the third filter fiber layer. The filter element has the functions of filtering dust and improving the filtering precision, so that finer dust is filtered out, the flow and the pollutant holding amount are increased, the filter element is not easy to block, and the service life of the filter element is prolonged.

Description

Technical Field

[0001] The present application relates to the technical field of exhaust gas treatment, and in particular to a filter element, a preparation method thereof, and a vehicle. Background Art

[0002] When the ammonia diesel engine is working, the high-pressure combustible mixture and exhaust gas in the combustion chamber may leak into the crankcase through the gap between the piston ring and the cylinder, causing blowby. The blowby mixture contains unburned ammonia, which enters the engine oil, reduces the oil performance, accelerates the oxidation and deterioration of the oil, forms sludge, and blocks the oil circuit. At the same time, the oil enters the oil filter again for circulation. At present, the material of oil filter materials generally ranges from low-end wood pulp materials to mid-range materials doped with synthetic fibers, mainly PET and fine glass fiber materials, to fully synthetic materials without wood pulp materials, which are high-end products. Not only does the dust holding capacity increase, but the aging resistance also continues to increase. However, these traditional oil filter materials are not resistant to ammonia, and there is currently no mass-produced oil filter material specifically for ammonia diesel engine oil filtration, especially ammonia water resistance, in the world. In particular, during the bench test of the ammonia-diesel engine, the ammonia-diesel engine oil coarse filter was damaged after 100 hours of performance test, leaking the nylon lining; the engine oil pressure was low, and the engine was disassembled: broken fibers were distributed on the top of the cylinder head; the oil collector filter was clogged; the oil pump housing was cracked; it was judged that ammonia formed ammonia water or ammonia's nitration products caused corrosion to the oil filter material.

[0003] However, although the existing ammonia-resistant filter elements have improved ammonia resistance, it is difficult to balance the filtration dust holding capacity and filtration accuracy. Summary of the invention

[0004] The present application provides a filter element and a preparation method thereof and a vehicle to solve the problem that it is difficult for existing filter elements to balance the filtering dust holding capacity and filtering accuracy.

[0005] In a first aspect, the present application provides a filter element, comprising a first filter fiber layer, a second filter fiber layer and a third filter fiber layer, wherein:

[0006] The second filter fiber layer is disposed between the first filter fiber layer and the third filter fiber layer;

[0007] The thickness of the first filter fiber layer is greater than the thickness of the third filter fiber layer;

[0008] The micropore size of the first filter fiber layer is smaller than the micropore size of the second filter fiber layer;

[0009] The pore size of the second filter fiber layer is smaller than the pore size of the third filter fiber layer.

[0010] It should be noted that, in the present application, the third filter fiber layer is in contact with the exhaust gas to be filtered, and the exhaust gas after filtering is discharged from the first filter fiber layer. That is, in the exhaust gas filtration process, the arrangement from outside to inside is the third filter fiber layer, the second filter fiber layer, and the first filter fiber layer.

[0011] The present application divides the filter element into a first filter fiber layer, a second filter fiber layer and a third filter fiber layer, wherein the thickness of the first filter fiber layer is greater than the thickness of the third filter fiber layer, the micropore size of the first filter fiber layer is smaller than the micropore size of the second filter fiber layer, and the micropore size of the second filter fiber layer is smaller than the micropore size of the third filter fiber layer, so that the pores of the filter layer of the entire filter element on the exhaust gas movement path of the exhaust gas treatment are smaller and smaller, the micropore size of the outer third filter fiber layer is the largest, and mainly plays the role of accommodating the filtered dust, the micropore size of the middle second filter fiber layer is smaller than the micropore size of the outer third filter fiber layer, and plays the role of further intercepting dust, and the micropore size of the inner first filter fiber layer is the smallest, which plays the role of improving the filtering accuracy, so that finer dust is filtered out, the flow rate and the amount of dirt holding are increased, the filter element is not easy to be blocked, and the service life is extended. At the same time, the thickness of the inner first filter fiber layer is greater than the thickness of the outer third filter fiber layer, so that fine dust has a longer path to pass through when passing through the filter element, and is intercepted in a longer movement distance, thereby improving the filtering accuracy, while retaining the dust holding capacity of the third filter fiber layer, the filter element is not easy to be blocked, and the service life is extended.

[0012] The material of the filter element may include at least one of nylon, polyester, polyethylene, polytetrafluoroethylene, polystyrene, and PBT, wherein the filter element made of nylon has high cleanliness, no pollution to engine oil, and is resistant to acid, alkali, organic solvents, and ammonia corrosion.

[0013] It should be noted that the micropore size of the filter fiber layer refers to the size of the tiny holes in the filter material, which directly affects the filtering effect and filtering speed of the filter material. The smaller the micropore size of the filter fiber, the higher the filtering accuracy, and it can filter out smaller particles and impurities, but at the same time it will reduce the filtering speed.

[0014] It should be noted that, in some embodiments of the present application, each of the first filter fiber layer, the second filter fiber layer and the third filter fiber layer may include multiple fiber layers, and the fibers in the multiple fiber layers may be interlaced in opposite spiral directions to form a labyrinth filter pore structure, thereby further improving the filtering accuracy.

[0015] In some embodiments, the thickness of the first filter fiber layer is H1, the thickness of the second filter fiber layer is H2, and the thickness of the third filter fiber layer is H3, wherein:

[0016] 1.5H3≤H1≤3H3, the thickness of the first filter fiber layer is 1.5 to 3 times the thickness of the third filter fiber layer, which can make the fine dust pass through the first filter fiber layer for a longer distance, and the fine dust is more difficult to capture. By extending its passing path, the filter element's ability to remove fine dust can be improved, and the filter element's filtering accuracy can be improved. At the same time, the third filter layer mainly captures large dust particles, and large dust particles occupy more volume. Therefore, the micropores in the third filter fiber layer provide the filter element with sufficient dust holding capacity, and increase the total amount of filtration. Preferably, the thickness of the first filter fiber layer is twice the thickness of the third filter fiber layer, which can further balance the filtering accuracy and dust holding capacity, is not easy to block the filter element, and extends the service life; and / or,

[0017] 10mm≤H1≤14mm. The thickness of the first filter fiber layer is within this range, which can improve the filter element's ability to remove fine dust and improve the filter element's filtering accuracy; and / or,

[0018] 6mm≤H2≤14mm, the thickness of the second filter fiber layer is within this range, so that the unique gradient design forms a three-dimensional filter residue effect, while improving the filtration accuracy and dust holding capacity to meet the filtration requirements; and / or,

[0019] 5mm≤H3≤7mm. The thickness of the third filter fiber layer is within this range, which can provide sufficient dust holding capacity for the filter element and increase the total amount of filtered dust.

[0020] It should be noted that the thickness in the present application refers to the thickness in the filtering direction, that is, the thickness on the exhaust gas passing path.

[0021] In some embodiments, the fiber diameter of the first filter fiber layer is D1, the fiber diameter of the second filter fiber layer is D2, and the fiber diameter of the third filter fiber layer is D3; wherein:

[0022] 1μm≤D1≤4μm, the fiber diameter of the first filter fiber layer is within this range, which can increase the density of the filter material and improve the filtering effect; and / or,

[0023] 4μm≤D2≤8μm, the fiber diameter of the second filter fiber layer is within this range, which can play a balancing role between the filtering effect and the filtering resistance; and / or,

[0024] 8μm≤D3≤10μm. The fiber diameter of the third filter fiber layer is within this range, which can reduce the filtration resistance of the filter material.

[0025] In some embodiments, the micropore size of the first filter fiber layer is R1, the micropore size of the second filter fiber layer is R2, and the micropore size of the third filter fiber layer is R3; wherein:

[0026] 0.1μm≤R1≤15μm, the size of the micropores determines the dust retention, the smaller the size of the micropores, the smaller the dust particles that can be retained, the higher the filtration accuracy, the micropore size of the first filter fiber layer is within this range, the filtration accuracy can be improved; and / or,

[0027] 10μm≤R2≤30μm. The size of the micropores determines the dust retention. The smaller the size of the micropores, the smaller the dust particles that can be retained, and the higher the filtration accuracy. The micropore size of the second filter fiber layer is within this range, which can balance the filtration accuracy and filtration resistance; and / or,

[0028] 25μm≤R3≤60μm. The size of the micropores determines the retention of dust. The smaller the size of the micropores, the smaller the dust particles that can be throttled and the higher the filtration accuracy. At the same time, the micropores provide dust holding space for dust. The micropore size of the third filter fiber layer is within this range, which can reduce the filtration resistance.

[0029] In some embodiments, the material of the filter element also includes carbon tubes. Due to the high strength and light weight of the carbon tubes themselves, the strength of the filter fiber layer can be increased, and the strength and rigidity of the filter element material, especially the filter element made of nylon material, can be significantly improved. The one-dimensional structure between the carbon tubes can effectively absorb and disperse stress concentration, thereby improving the strength and durability of the material. At the same time, the electrostatic effect of the carbon tubes can capture fine dust, which can improve the filtration efficiency and reduce the filtration resistance.

[0030] In some embodiments, the carbon tubes include carbon tubes modified with hydroxyl and / or carboxyl groups. Since carbon tubes are non-polar materials and the filter element substrate, especially nylon, is a polar material, the dispersion degree of carbon tubes in nylon determines the improvement effect of carbon tubes on the filter element. By introducing strong polar groups such as hydroxyl and carboxyl groups, carbon nanotubes and polyamide solvents are compatible due to similar polarity, thereby improving the dispersion degree of carbon nanotubes in the solution and improving the dispersion uniformity of carbon nanotubes in nylon, the filtration efficiency of the filter element can be further improved and the filtration resistance can be reduced; and / or,

[0031] The mass proportion of the carbon tubes in the material of the filter element is 2.5% to 5%. Within this range, the electrostatic effect can be used to capture fine dust, improve filtration efficiency and reduce filtration resistance, while reducing the impact on the performance of the filter material itself; and / or,

[0032] The diameter of the carbon tube is D4, 1 μm≤D4≤4 μm. The diameter of the carbon tube is within this range, which is conducive to the dispersion of the carbon tube and improves the distribution density of the carbon tube.

[0033] In a second aspect, the present application provides a method for preparing a filter element, which is used to prepare the filter element of the first aspect, comprising the following steps:

[0034] The nylon is sequentially formed into a first filter fiber layer, a second filter fiber layer and a third filter fiber layer by a melt-blowing method, wherein:

[0035] The thickness of the first filter fiber layer is greater than the thickness of the third filter fiber layer;

[0036] The micropore size of the first filter fiber layer is smaller than the micropore size of the second filter fiber layer;

[0037] The pore size of the second filter fiber layer is smaller than the pore size of the third filter fiber layer.

[0038] The melt-blowing process is used to sequentially form the first filter fiber layer, the second filter fiber layer, and the third filter fiber layer. The diameter and pore size of the filter fiber layer can be controlled by controlling the airflow pressure, extrusion amount, and receiving distance of the melt-blowing, thereby achieving continuous operation and simplifying the process. Specifically, the nylon substrate melt can be extruded from the spinneret hole of the detachable melt-blowing die head, stretched by high-speed hot air flow on both sides of the spinneret hole to form a fan-shaped waterfall-like fiber jet, and continuously wound and formed by the core rod on the receiving device. During the melt-blowing process, the high-temperature air flow also plays a role in carrying and transferring heat to the fibers, and has a compacting effect on the fiber filaments reaching the core rod, so that the fiber nodes of the first filter fiber layer, the second filter fiber layer, and the third filter fiber layer have good fusion welding.

[0039] In some embodiments, the air flow pressure of the first filter fiber layer formed by melt-blowing is 0.4-0.6 MPa. When the air flow pressure of the first filter fiber layer is within this range, the fiber diameter of the first filter fiber layer can be within a suitable range; and / or,

[0040] The extrusion rate of the first filter fiber layer formed by melt-blowing is 0.01-0.03 g / min. The extrusion rate of the first filter fiber layer is within this range, so that the fiber diameter of the first filter fiber layer is within a suitable range; and / or,

[0041] The receiving distance of the first filter fiber layer formed by melt-blowing is 4 to 6 cm. When the receiving distance of the first filter fiber layer is within this range, the fiber thermal bonding effect can be improved, the relative strength of the filter material can be improved, and the stratification can be reduced; and / or,

[0042] The air flow pressure of the second filter fiber layer formed by melt-blowing is 0.3-0.4 MPa. The air flow pressure of the second filter fiber layer formed by melt-blowing is within this range, so that the fiber diameter of the second filter fiber layer is within a suitable range; and / or,

[0043] The extrusion rate of the second filter fiber layer formed by melt-blowing is 0.03-0.05 g / min. The extrusion rate of the second filter fiber layer is within this range, so that the fiber diameter of the second filter fiber layer is within a suitable range; and / or,

[0044] The receiving distance of the second filter fiber layer formed by melt-blowing is 7 to 9 cm. When the receiving distance of the second filter fiber layer is within this range, the fiber thermal bonding effect can be improved, the relative strength of the filter material can be improved, and the stratification can be reduced; and / or,

[0045] The air flow pressure of the third filter fiber layer formed by melt-blowing is 0.1-0.3 MPa, and the extrusion amount of the third filter fiber layer is within this range, so that the fiber diameter of the third filter fiber layer can be within a suitable range; and / or,

[0046] The extrusion amount of the third filter fiber layer formed by melt-blowing is 0.08-0.12 g / min. The extrusion amount of the third filter fiber layer formed within this range can make the fiber diameter of the third filter fiber layer within a suitable range; and / or,

[0047] The receiving distance of the third filter fiber layer formed by the melt-blowing method is 12 to 18 cm. The receiving distance of the third filter fiber layer formed within this range can improve the fiber thermal bonding effect, improve the relative strength of the filter material, and reduce stratification.

[0048] In some embodiments, the melt-blowing temperature is 180-270° C. When the melt-blowing temperature is within this range, the fiber diameter of each filter fiber layer can be within a suitable range.

[0049] In a third aspect, the present application provides a vehicle comprising the filter element of the first aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0051] Figure 1 Schematic diagram of the structure of a filter element according to an embodiment of the present application.

[0052] Figure 2 This is a schematic diagram of the cross-sectional structure of a filter element according to an embodiment of the present application.

[0053] Description of Figure Numbers:

[0054] 100 filter element; 1 first filter fiber layer; 2 second filter fiber layer; 3 third filter fiber layer. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical solution and advantages of the present application clearer, the technical solution of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present application.

[0056] It is necessary to develop zero-carbon or low-carbon fuel internal combustion engines to meet the needs of different application scenarios. Ammonia is used as a zero-carbon fuel and a hydrogen-rich carrier. Without changing the engine structure, it is a more feasible technical solution to combine ammonia fuel with other highly active fuels and use highly active fuels to ignite the internal combustion engine. Oil filtration is a sub-application with lower filtration accuracy requirements and the highest aging resistance requirements among various automotive or mechanical oil filtration.

[0057] The main function of automotive oil filters is to remove pollutants such as metal particles, carbon deposits and dust from the oil, and prevent pollutants in the oil from adversely affecting the movement of parts and damaging the engine and other parts. For oil filter materials alone, the requirements for heavy-duty engines are generally higher than those for passenger cars. The main reason is that the materials required for different replacement mileages have different dirt holding capacity and aging resistance. For example, the general host of passenger cars recommends replacing the oil and oil filter every 5,000 to 10,000 kilometers, while commercial vehicles have increased from 50,000 kilometers in the National IV and National V standards to the current National VI standards, which can replace the oil and oil filter at 100,000 kilometers or even 150,000 kilometers. In addition, due to the higher average operating temperature of diesel engines, the aging of high-power diesel engine oil is faster than that of gasoline engines, and the aging resistance requirements of filter materials are also higher.

[0058] The filtration accuracy of the National VI ammonia diesel engine filter often reaches 4μm 99.5% or even higher requirements because it needs to protect the precise gap as small as 1.5μm high-pressure common rail system. At the same time, when the ammonia diesel engine is working, the high-pressure combustible mixture and exhaust gas in the combustion chamber may leak into the crankcase through the gap between the piston ring and the cylinder, causing blowby. The blowby mixture contains unburned ammonia, which enters the engine oil, reduces the oil performance, accelerates the oxidation and deterioration of the oil, forms sludge, and blocks the oil circuit. At the same time, the oil enters the oil filter again for circulation. At present, the material of oil filter materials generally ranges from low-end wood pulp materials to mid-range materials doped with synthetic fibers, mainly PET and fine glass fiber materials, to fully synthetic materials without wood pulp materials, which are high-end products. However, these traditional oil filter materials are not resistant to ammonia, and there are few mass-produced oil filter materials that are specifically designed for ammonia diesel engine oil filtration, especially those with ammonia water resistance. In particular, during the bench test of the ammonia-diesel engine, the ammonia-diesel engine oil coarse filter was damaged after 100 hours of performance test, leaking the nylon lining; the engine oil pressure was low, and the engine was disassembled and broken fibers were found on the top of the cylinder head; the oil collector filter was clogged; the oil pump housing was cracked; it was judged that the ammonia formed ammonia water or the nitration products of ammonia corroded the oil filter material.

[0059] Although the existing ammonia-resistant filter element can improve the ammonia resistance of the filter element, its filtering accuracy, dust holding capacity and service life are difficult to guarantee.

[0060] In view of this, the present application provides a filter element and a preparation method thereof and a vehicle to solve the problem that it is difficult for existing filter elements to balance the filtering dust holding capacity and filtering accuracy.

[0061] First, as Figure 1 and Figure 2 As shown, the present application provides a filter element 100, comprising a first filter fiber layer 1, a second filter fiber layer 2 and a third filter fiber layer 3, wherein:

[0062] The second filter fiber layer 2 is provided between the first filter fiber layer 1 and the third filter fiber layer 3;

[0063] The thickness of the first filter fiber layer 1 is greater than the thickness of the third filter fiber layer 3;

[0064] The micropore size of the first filter fiber layer 1 is smaller than the micropore size of the second filter fiber layer 2;

[0065] The pore size of the second filter fiber layer 2 is smaller than the pore size of the third filter fiber layer 3 .

[0066] It should be noted that, in the present application, the third filter fiber layer 3 is in contact with the exhaust gas to be filtered, and the exhaust gas after filtering is discharged from the first filter fiber layer 1, that is, in the exhaust gas filtration process, the arrangement from outside to inside is the third filter fiber layer 3, the second filter fiber layer 2, and the first filter fiber layer 1.

[0067] The present application divides the filter element 100 into a first filter fiber layer 1, a second filter fiber layer 2 and a third filter fiber layer 3, wherein the thickness of the first filter fiber layer 1 is greater than that of the third filter fiber layer 3, the micropore size of the first filter fiber layer 1 is smaller than that of the second filter fiber layer 2, and the micropore size of the second filter fiber layer 2 is smaller than that of the third filter fiber layer 3. This allows the entire filter element 100 to have smaller and smaller pores on the exhaust gas movement path of the exhaust gas treatment. The outer third filter fiber layer 3 has the largest micropore size, which mainly serves to accommodate filtered dust. The middle second filter fiber layer 2 has a smaller micropore size than the outer third filter fiber layer 3, which serves to further intercept dust. The inner first filter fiber layer 1 has the smallest micropore size, which serves to improve the filtering accuracy, so that finer dust is filtered out, thereby increasing the flow rate and the amount of dirt holding. The filter element 100 is not easily blocked, thereby extending the service life. At the same time, the thickness of the inner first filter fiber layer 1 is greater than the thickness of the outer third filter fiber layer 3, which allows fine dust to have a longer path to pass through when passing through the filter element 100 and be intercepted during a longer movement distance, thereby improving the filtration accuracy while retaining the dust holding capacity of the third filter fiber layer 3, making the filter element 100 less prone to clogging and extending its service life.

[0068] The material of the filter element 100 may include at least one of nylon (polyamide), polyester, polyethylene, polytetrafluoroethylene, polystyrene, and PBT. Among them, the filter element 100 made of nylon has high cleanliness, no pollution to engine oil, and is resistant to acid, alkali, organic solvents, and ammonia corrosion.

[0069] It should be noted that the micropore size of the filter fiber layer refers to the size of the tiny holes in the filter material, which directly affects the filtering effect and filtering speed of the filter material. The smaller the micropore size of the filter fiber, the higher the filtering accuracy, and it can filter out smaller particles and impurities, but at the same time it will reduce the filtering speed.

[0070] It should be noted that, in some embodiments of the present application, each of the first filter fiber layer 1, the second filter fiber layer 2 and the third filter fiber layer 3 may include multiple fiber layers, and the fibers in the multiple fiber layers may be interlaced in opposite spiral directions to form a labyrinth filter pore structure, thereby further improving the filtering accuracy.

[0071] In combination with the first aspect, in some embodiments provided in the present application, the thickness of the first filter fiber layer 1 is H1, the thickness of the second filter fiber layer 2 is H2, and the thickness of the third filter fiber layer 3 is H3, wherein: 1.5H3≤H1≤3H3, the thickness of the first filter fiber layer 1 is 1.5 to 3 times the thickness of the third filter fiber layer 3, which can make the distance that fine dust passes through the first filter fiber layer 1 longer, and fine dust is more difficult to capture, and the filter element 1 can be improved by extending its passage path. 00 has the ability to remove fine dust, improves the filtering accuracy of the filter element 100, and at the same time, the third filter layer mainly captures large dust particles, which occupy more volume. Therefore, the micropores in the third filter fiber layer 3 provide sufficient dust holding capacity for the filter element 100, and improve the total amount of filtration. H1 / H3 includes but is not limited to 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9 or 3.0. Preferably, the thickness of the first filter fiber layer 1 is twice the thickness of the third filter fiber layer 3, which can further balance the filtering accuracy and dust holding capacity, is not easy to block the filter element 100, and prolongs the service life.

[0072] In combination with the first aspect, in some embodiments provided in the present application, the thickness of the first filter fiber layer 1 is H1, the thickness of the second filter fiber layer 2 is H2, and the thickness of the third filter fiber layer 3 is H3, wherein: 10mm≤H1≤14mm, the thickness of the first filter fiber layer 1 within this range can improve the ability of the filter element 100 to remove fine dust and improve the filtering accuracy of the filter element 100. The value of H1 includes but is not limited to 10mm, 10.5mm, 11mm, 11.5mm, 12mm, 12.5mm, 13mm, 13.5mm or 14mm.

[0073] In combination with the first aspect, in some embodiments provided in the present application, the thickness of the first filter fiber layer 1 is H1, the thickness of the second filter fiber layer 2 is H2, and the thickness of the third filter fiber layer 3 is H3, wherein: 6mm≤H2≤14mm, the thickness of the second filter fiber layer 2 is within this range, which can make the unique gradient design form a three-dimensional filter residue effect, and at the same time can improve the filtering accuracy and dust holding capacity to meet the filtering requirements. The value of H2 includes but is not limited to 6mm, 7.5mm, 8mm, 9.5mm, 10mm, 11.5mm, 12mm, 13mm or 14mm.

[0074] In combination with the first aspect, in some embodiments provided in the present application, the thickness of the first filter fiber layer 1 is H1, the thickness of the second filter fiber layer 2 is H2, and the thickness of the third filter fiber layer 3 is H3, wherein: 5mm≤H3≤7mm, and the thickness of the third filter fiber layer 3 within this range can provide sufficient dust holding capacity for the filter element 100 and increase the total amount of filtration. The value of H3 includes but is not limited to 5mm, 5.5mm, 6mm, 6.5mm or 7mm.

[0075] It should be noted that the thickness in the present application refers to the thickness in the filtering direction, that is, the thickness in the direction of the exhaust gas passing path.

[0076] In combination with the first aspect, in some embodiments provided in the present application, the fiber diameter of the first filter fiber layer 1 is D1, the fiber diameter of the second filter fiber layer 2 is D2, and the fiber diameter of the third filter fiber layer 3 is D3; wherein: 1μm≤D1≤4μm, the fiber diameter of the first filter fiber layer 1 is within this range, the density of the filter material is increased, and the filtering effect is improved. The value of D1 includes but is not limited to 1μm, 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm or 4μm.

[0077] In combination with the first aspect, in some embodiments provided in the present application, the fiber diameter of the first filter fiber layer 1 is D1, the fiber diameter of the second filter fiber layer 2 is D2, and the fiber diameter of the third filter fiber layer 3 is D3; wherein: 4μm≤D2≤8μm, the fiber diameter of the first filter fiber layer 1 within this range can balance the filtering effect and filtering resistance. The value of D2 includes but is not limited to 4μm, 4.5μm, 5μm, 5.5μm, 6μm, 6.5μm, 7μm, 7.5μm or 8μm.

[0078] In combination with the first aspect, in some embodiments provided in the present application, the fiber diameter of the first filter fiber layer 1 is D1, the fiber diameter of the second filter fiber layer 2 is D2, and the fiber diameter of the third filter fiber layer 3 is D3; wherein: 8μm≤D3≤10μm, the fiber diameter of the first filter fiber layer 1 within this range can reduce the filter resistance of the filter material. The value of D2 includes but is not limited to 8μm, 8.5μm, 9μm, 9.5μm or 10μm.

[0079] In combination with the first aspect, in some embodiments provided in the present application, the micropore size of the first filter fiber layer 1 is R1, the micropore size of the second filter fiber layer 2 is R2, and the micropore size of the third filter fiber layer 3 is R3; wherein: 0.1μm≤R1≤15μm, the size of the micropore determines the retention of dust, the smaller the size of the micropore, the smaller the dust particles that can be throttled, and the higher the filtering accuracy. The micropore size of the first filter fiber layer 1 is within this range, which can improve the filtering accuracy. The value of R1 includes but is not limited to 0.1μm, 0.5μm, 1μm, 3μm, 5μm, 8μm, 10μm, 12μm or 15μm.

[0080] In combination with the first aspect, in some embodiments provided in the present application, the micropore size of the first filter fiber layer 1 is R1, the micropore size of the second filter fiber layer 2 is R2, and the micropore size of the third filter fiber layer 3 is R3; wherein: 10μm≤R2≤30μm, the size of the micropore determines the retention of dust, the smaller the size of the micropore, the smaller the dust particles that can be throttled, and the higher the filtering accuracy. The micropore size of the second filter fiber layer 2 is within this range, which can balance the filtering accuracy and filtering resistance. The value of R2 includes but is not limited to 10μm, 12μm, 15μm, 17μm, 20μm, 23μm, 25μm, 28μm or 30μm.

[0081] In combination with the first aspect, in some embodiments provided in the present application, the micropore size of the first filter fiber layer 1 is R1, the micropore size of the second filter fiber layer 2 is R2, and the micropore size of the third filter fiber layer 3 is R3; wherein: 25μm≤R3≤60μm, the size of the micropore determines the retention of dust, the smaller the size of the micropore, the smaller the dust particles that can be throttled, the higher the filtration accuracy, and the micropore provides dust holding space for dust, and the micropore size of the third filter fiber layer 3 is within this range, which can reduce the filtration resistance. The value of R3 includes but is not limited to 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm or 60μm.

[0082] In combination with the first aspect, in some embodiments provided in the present application, the material of the filter element 100 also includes carbon tubes. Due to the high strength and light weight of the carbon tubes themselves, the strength of the filter fiber layer can be increased, and the material of the filter element 100 can be significantly improved, especially the strength and rigidity of the filter element 100 made of nylon material. The one-dimensional structure between the carbon tubes can effectively absorb and disperse stress concentration, thereby improving the strength and durability of the material. At the same time, the electrostatic effect of the carbon tubes can capture fine dust, which can improve the filtration efficiency and reduce the filtration resistance.

[0083] In combination with the first aspect, in some embodiments provided in the present application, the carbon tubes include hydroxyl and / or carboxyl modified carbon tubes. Since the carbon tubes are non-polar materials and the filter element 100 substrate, especially nylon, is a polar material, the dispersion degree of the carbon tubes in nylon determines the improvement effect of the carbon tubes on the filter element 100. The introduction of strong polar groups such as hydroxyl and carboxyl groups makes the carbon nanotubes and polyamide solvents compatible due to similar polarity, thereby improving the dispersion degree of the carbon nanotubes in the solution and improving the dispersion uniformity of the carbon nanotubes in nylon, which can further improve the filtration efficiency of the filter element 100 and reduce the filtration resistance. Specifically, the carbon tube fiber powder can be weighed, added to a mixed acid (for example, VHNO3: VH2SO4 = 1: 1), ultrasonically dispersed and oxidized for 2 hours, filtered after the oxidation is completed, washed with water until the pH is neutral, and dried at 80°C for 2 hours to obtain carboxyl modified carbon tubes.

[0084] In combination with the first aspect, in some embodiments provided in the present application, the mass proportion of the carbon tube in the material of the filter element 100 is 2.5% to 5%. When the mass proportion of the carbon tube in the material of the filter element 100 is within this range, the electrostatic effect can be relied on to capture fine dust, improve filtration efficiency and reduce filtration resistance, while reducing the impact on the performance of the filter material itself. The mass proportion of the carbon tube in the material of the filter element 100 includes but is not limited to 2.5%, 3%, 3.5%, 4%, 4.5% or 5%.

[0085] In combination with the first aspect, in some embodiments provided in the present application, the diameter of the carbon tube is D4, 1μm≤D4≤4μm, and the diameter of the carbon tube within this range is conducive to the dispersion of the carbon tube and improves the distribution density of the carbon tube. The diameter of the carbon tube includes but is not limited to 1μm, 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm or 4μm.

[0086] In a second aspect, the present application provides a method for preparing a filter element 100, which is used to prepare the filter element 100 of the first aspect, and comprises the following steps:

[0087] The nylon is sequentially formed into a first filter fiber layer 1, a second filter fiber layer 2 and a third filter fiber layer 3 by melt-blowing method, wherein:

[0088] The thickness of the first filter fiber layer 1 is greater than the thickness of the third filter fiber layer 3;

[0089] The micropore size of the first filter fiber layer 1 is smaller than the micropore size of the second filter fiber layer 2;

[0090] The pore size of the second filter fiber layer 2 is smaller than the pore size of the third filter fiber layer 3 .

[0091] The melt-blowing process is used to sequentially form the first filter fiber layer 1, the second filter fiber layer 2 and the third filter fiber layer 3. The diameter and pore size of the filter fiber layer can be controlled by controlling the airflow pressure, extrusion amount and receiving distance of the melt-blowing, so as to realize continuous operation and simplify the process. Specifically, the nylon substrate melt can be extruded from the spinneret hole of the detachable melt-blowing die head, and the high-speed hot air flow on both sides of the spinneret hole is stretched to form a fan-shaped waterfall-like fiber jet, and the core rod on the receiving device is continuously wound and formed. During the melt-blowing process, the high-temperature air flow also plays a role in carrying and heat transfer to the fibers, and has a compacting effect on the fiber filaments reaching the core rod, so that the first filter fiber layer 1, the second filter fiber layer 2 and the third filter fiber layer 3 have good fusion welding at the fiber nodes. The filter element 100 obtained by the preparation method of the present application does not require fixed folding distance glue and folding equipment, and the process is simple, which can reduce costs.

[0092] In conjunction with the second aspect, in some embodiments provided in the present application, the airflow pressure for forming the first filter fiber layer 1 by meltblowing is 0.4-0.6 MPa. The airflow pressure for forming the first filter fiber layer 1 is within this range, so that the fiber diameter of the first filter fiber layer is within a suitable range. The airflow pressure for forming the first filter fiber layer 1 includes, but is not limited to, 0.4 MPa, 0.45 MPa, 0.5 MPa, 0.55 MPa or 0.6 MPa.

[0093] In combination with the second aspect, in some embodiments provided in the present application, the extrusion amount of the first filter fiber layer 1 formed by the melt-blowing method is 0.01 to 0.03 g / min. The extrusion amount of the first filter fiber layer 1 is within this range, so that the fiber diameter of the first filter fiber layer is within a suitable range. The extrusion amount of the first filter fiber layer 1 includes but is not limited to 0.01 g / min, 0.015 g / min, 0.02 g / min, 0.025 g / min or 0.03 g / min.

[0094] In conjunction with the second aspect, in some embodiments provided in the present application, the receiving distance of the first filter fiber layer 1 formed by the melt-blowing method is 4 to 6 cm. The receiving distance of the first filter fiber layer 1 formed within this range can improve the fiber thermal bonding effect, improve the relative strength of the filter material, and reduce stratification. The receiving distance of the first filter fiber layer 1 includes but is not limited to 4 cm, 4.2 cm, 4.5 cm, 4.7 cm, 5.0 cm, 5.3 cm, 5.5 cm, 5.8 cm or 6.0 cm.

[0095] In conjunction with the second aspect, in some embodiments provided in the present application, the air flow pressure for forming the second filter fiber layer 2 by melt-blowing is 0.3-0.4 MPa. The air flow pressure for forming the second filter fiber layer 2 is within this range, so that the fiber diameter of the second filter fiber layer is within a suitable range. The air flow pressure for forming the second filter fiber layer 2 includes, but is not limited to, 0.3 MPa, 0.31 MPa, 0.32 MPa, 0.33 MPa, 0.34 MPa, 0.35 MPa, 0.36 MPa, 0.37 MPa, 0.38 MPa, 0.39 MPa or 0.4 MPa.

[0096] In conjunction with the second aspect, in some embodiments provided in the present application, the extrusion amount of the second filter fiber layer 2 formed by the melt-blowing method is 0.03 to 0.05 g / min. The extrusion amount of the second filter fiber layer 2 is within this range, so that the fiber diameter of the second filter fiber layer is within a suitable range. The extrusion amount of the second filter fiber layer 2 includes but is not limited to 0.03 g / min, 0.035 g / min, 0.04 g / min, 0.045 g / min or 0.05 g / min.

[0097] In conjunction with the second aspect, in some embodiments provided in the present application, the receiving distance of the second filter fiber layer 2 formed by the melt-blowing method is 7 to 9 cm. The receiving distance of the second filter fiber layer 2 formed within this range can improve the fiber thermal bonding effect, improve the relative strength of the filter material, and reduce stratification. The receiving distance of the second filter fiber layer 2 includes but is not limited to 7 cm, 7.5 cm, 8 cm, 8.5 cm or 9 cm.

[0098] In combination with the second aspect, in some embodiments provided in the present application, the air flow pressure for forming the third filter fiber layer 3 by melt-blowing is 0.1-0.3 MPa, and the extrusion amount for forming the third filter fiber layer 3 is within this range, so that the fiber diameter of the third filter fiber layer can be within a suitable range. The air flow pressure for forming the third filter fiber layer 3 includes but is not limited to 0.1 MPa, 0.15 MPa, 0.2 MPa, 0.25 MPa or 0.3 MPa.

[0099] In combination with the second aspect, in some embodiments provided in the present application, the extrusion amount of the third filter fiber layer 3 formed by the melt-blowing method is 0.08 to 0.12 g / min. The extrusion amount of the third filter fiber layer 3 formed within this range can make the fiber diameter of the third filter fiber layer within a suitable range. The extrusion amount of the third filter fiber layer 3 includes but is not limited to 0.08 g / min, 0.09 g / min, 0.10 g / min, 0.11 g / min or 0.12 g / min.

[0100] In combination with the second aspect, in some embodiments provided in the present application, the receiving distance of the third filter fiber layer 3 formed by the melt-blowing method is 12 to 18 cm. The receiving distance of the third filter fiber layer 3 formed within this range can improve the fiber thermal bonding effect, improve the relative strength of the filter material, and reduce stratification. The receiving distance of the third filter fiber layer 3 includes but is not limited to 12 cm, 13.5 cm, 14 cm, 15 cm, 16.5 cm, 17 cm or 18 cm.

[0101] In conjunction with the second aspect, in some embodiments provided in the present application, the temperature of the melt-blowing is 180-270° C. Within this range, the fiber diameter of each filter fiber layer can be within a suitable range. The temperature of the melt-blowing includes, but is not limited to, 180° C., 190° C., 205° C., 210° C., 220° C., 230° C., 245° C., 255° C., 260° C., or 270° C.

[0102] It should be noted that when the material of the filter element 100 includes nylon and carbon tubes, the twin-screw extruder adopts a double feed port, and the modified carbon tubes are added to the molten polyamide for uniform mixing, and then melt-blown to form the filter element 100. The first filter fiber layer 1, the second filter fiber layer 2, and the third filter fiber layer 3 may all contain carbon tubes.

[0103] In a third aspect, the present application provides a vehicle, comprising the filter element 100 of the first aspect. The vehicle comprises all technical solutions of the filter element 100, and thus has all beneficial effects of the filter element 100, which will not be described in detail in this application.

[0104] The technical solution provided in this application is described in detail below in conjunction with embodiments.

[0105] Example 1

[0106] Embodiment 1 of the present application provides a filter element, comprising a first filter fiber layer, a second filter fiber layer and a third filter fiber layer arranged in sequence from the inside to the outside, wherein:

[0107] The first filter fiber layer has a thickness of 10 mm, a fiber diameter of 1 μm, and a micropore size of 0.1 to 5 μm;

[0108] The thickness of the second filter fiber layer is 12 mm, the fiber diameter is 4 μm, and the micropore size is 10-15 μm;

[0109] The third filter fiber layer has a thickness of 6 mm, a fiber diameter of 8 μm, and a micropore size of 25 to 35 μm;

[0110] The materials of the first filter fiber layer, the second filter fiber layer and the third filter fiber layer are nylon PA6.

[0111] Example 2

[0112] Embodiment 2 of the present application provides a filter element, comprising a first filter fiber layer, a second filter fiber layer, and a third filter fiber layer arranged in sequence from the inside to the outside, wherein:

[0113] The first filter fiber layer has a thickness of 10 mm, a fiber diameter of 1 μm, and a micropore size of 0.1 to 5 μm;

[0114] The thickness of the second filter fiber layer is 13 mm, the fiber diameter is 4 μm, and the micropore size is 10-15 μm;

[0115] The third filter fiber layer has a thickness of 5 mm, a fiber diameter of 8 μm, and a micropore size of 25 to 35 μm;

[0116] The materials of the first filter fiber layer, the second filter fiber layer and the third filter fiber layer are nylon PA6, to which 2.5% by mass of carboxyl-modified carbon tubes are added.

[0117] Example 3

[0118] Embodiment 3 of the present application provides a filter element, comprising a first filter fiber layer, a second filter fiber layer and a third filter fiber layer arranged in sequence from the inside to the outside, wherein:

[0119] The thickness of the first filter fiber layer is 14 mm, the fiber diameter is 4 μm, and the micropore size is 10-15 μm;

[0120] The second filter fiber layer has a thickness of 7 mm, a fiber diameter of 8 μm, and a micropore size of 20 to 30 μm;

[0121] The third filter fiber layer has a thickness of 7 mm, a fiber diameter of 10 μm, and a micropore size of 45 to 60 μm;

[0122] The materials of the first filter fiber layer, the second filter fiber layer and the third filter fiber layer are nylon PA6, to which 5% by mass of carboxyl-modified carbon tubes are added.

[0123] Example 4

[0124] Embodiment 4 of the present application provides a filter element, comprising a first filter fiber layer, a second filter fiber layer, and a third filter fiber layer arranged in sequence from the inside to the outside, wherein:

[0125] The first filter fiber layer has a thickness of 8 mm, a fiber diameter of 0.8 μm, and a micropore size of 0.1 to 5 μm;

[0126] The thickness of the second filter fiber layer is 16 mm, the fiber diameter is 3 μm, and the micropore size is 10-15 μm;

[0127] The third filter fiber layer has a thickness of 4 mm, a fiber diameter of 7 μm, and a micropore size of 25 to 35 μm;

[0128] The materials of the first filter fiber layer, the second filter fiber layer and the third filter fiber layer are nylon PA6, to which 2% by mass of carboxyl-modified carbon tubes are added.

[0129] Example 5

[0130] Embodiment 5 of the present application provides a filter element, comprising a first filter fiber layer, a second filter fiber layer and a third filter fiber layer arranged in sequence from the inside to the outside, wherein:

[0131] The first filter fiber layer has a thickness of 18 mm, a fiber diameter of 5 μm, and a micropore size of 0.1 to 5 μm;

[0132] The second filter fiber layer has a thickness of 2 mm, a fiber diameter of 10 μm, and a micropore size of 10 to 15 μm;

[0133] The third filter fiber layer has a thickness of 8 mm, a fiber diameter of 12 μm, and a micropore size of 25 to 35 μm;

[0134] The materials of the first filter fiber layer, the second filter fiber layer and the third filter fiber layer are nylon PA6, to which 6% by mass of carboxyl-modified carbon tubes are added.

[0135] Example 6

[0136] Embodiment 6 of the present application provides a filter element, comprising a first filter fiber layer, a second filter fiber layer, and a third filter fiber layer arranged in sequence from the inside to the outside, wherein:

[0137] The first filter fiber layer has a thickness of 12 mm, a fiber diameter of 3 μm, and a micropore size of 5 to 10 μm;

[0138] The second filter fiber layer has a thickness of 10 mm, a fiber diameter of 6 μm, and a micropore size of 15 to 20 μm;

[0139] The third filter fiber layer has a thickness of 6 mm, a fiber diameter of 9 μm, and a micropore size of 35 to 45 μm;

[0140] The materials of the first filter fiber layer, the second filter fiber layer and the third filter fiber layer are nylon PA6, to which 4% by mass of carboxyl-modified carbon tubes are added.

[0141] Example 7

[0142] Embodiment 7 of the present application provides a method for preparing a filter element, comprising the following steps:

[0143] The raw material used in the melt-blowing process is nylon PA6, to which 4% by mass of carboxyl-modified carbon tubes are added. The twin-screw extruder adopts a double feed port, and the modified carbon tubes are added into the molten polyamide for uniform mixing. The temperature of the melt-blowing die is 240°C.

[0144] The air flow pressure of the first filter fiber layer is 0.5 MPa, the melt extrusion rate is 0.02 g / min, and the receiving distance is 5 cm;

[0145] The air flow pressure of the second filter fiber layer is 0.35 MPa, the melt extrusion rate is 0.04 g / min, and the receiving distance is 8 cm;

[0146] The air flow pressure of the third filter fiber layer is 0.2 MPa, the melt extrusion amount is 0.1 g / min, and the receiving distance is 15 cm.

[0147] Comparative Example 1

[0148] Comparative Example 1 of the present application provides a filter element, comprising a first filter fiber layer, a second filter fiber layer and a third filter fiber layer arranged in sequence from the inside to the outside, wherein:

[0149] The first filter fiber layer has a thickness of 12 mm, a fiber diameter of 5 μm, and a micropore size of 0.1 to 5 μm;

[0150] The second filter fiber layer has a thickness of 4 mm, a fiber diameter of 10 μm, and a micropore size of 10 to 15 μm;

[0151] The third filter fiber layer has a thickness of 12 mm, a fiber diameter of 12 μm, and a micropore size of 25 to 35 μm;

[0152] The materials of the first filter fiber layer, the second filter fiber layer and the third filter fiber layer are nylon PA6.

[0153] Comparative Example 2

[0154] Comparative Example 2 of the present application provides a filter element, comprising a first filter fiber layer, a second filter fiber layer and a third filter fiber layer arranged in sequence from the inside to the outside, wherein:

[0155] The first filter fiber layer has a thickness of 6 mm, a fiber diameter of 5 μm, and a micropore size of 0.1 to 5 μm;

[0156] The thickness of the second filter fiber layer is 16 mm, the fiber diameter is 10 μm, and the micropore size is 10-15 μm;

[0157] The third filter fiber layer has a thickness of 6 mm, a fiber diameter of 12 μm, and a micropore size of 25 to 35 μm;

[0158] The materials of the first filter fiber layer, the second filter fiber layer and the third filter fiber layer are nylon PA6.

[0159] Comparative Example 3

[0160] Comparative Example 1 of the present application provides a filter element, comprising a first filter fiber layer, a second filter fiber layer and a third filter fiber layer arranged in sequence from the inside to the outside, wherein:

[0161] The first filter fiber layer has a thickness of 12 mm, a fiber diameter of 5 μm, and a micropore size of 10 to 15 μm;

[0162] The second filter fiber layer has a thickness of 4 mm, a fiber diameter of 10 μm, and a micropore size of 10 to 15 μm;

[0163] The third filter fiber layer has a thickness of 12 mm, a fiber diameter of 12 μm, and a micropore size of 10 to 15 μm;

[0164] The materials of the first filter fiber layer, the second filter fiber layer and the third filter fiber layer are nylon PA6.

[0165] Comparative Example 4

[0166] Comparative Example 1 of the present application provides a filter element, comprising a first filter fiber layer, a second filter fiber layer and a third filter fiber layer arranged in sequence from the inside to the outside, wherein:

[0167] The first filter fiber layer has a thickness of 9.3 mm, a fiber diameter of 5 μm, and a micropore size of 0.1 to 5 μm;

[0168] The thickness of the second filter fiber layer is 9.3 mm, the fiber diameter is 10 μm, and the micropore size is 10 to 15 μm;

[0169] The third filter fiber layer has a thickness of 9.3 mm, a fiber diameter of 12 μm, and a micropore size of 25 to 35 μm;

[0170] The materials of the first filter fiber layer, the second filter fiber layer and the third filter fiber layer are nylon PA6.

[0171] Performance Testing

[0172] The filter elements of Examples 1 to 6 and Comparative Examples 1 to 4 were subjected to performance tests to test their filtration efficiency, resistance and dust holding capacity. The results are shown in Table 1, where:

[0173] The test method for filtration efficiency is: ISO4548-12.

[0174] The test method for filtration resistance is: ISO 4548-1.

[0175] The test method for dust holding capacity is: ISO4548-12.

[0176] Table 1 Performance of filter elements of Examples 1 to 6 and Comparative Examples 1 to 4

[0177] Filtration efficiency (%) Filtration resistance (kPa) Dust holding capacity (g) Example 1 83.66 3.68 57.15 Example 2 99.95 2.41 82.31 Example 3 99.97 2.87 80.67 Example 4 93.58 2.14 69.28 Example 5 99.97 12.7 72.08 Example 6 99.99 3.68 92.78 Comparative Example 1 71.54 4.75 49.56 Comparative Example 2 67.21 3.97 50.34 Comparative Example 3 57.23 8.35 32.53 Comparative Example 4 64.75 3.97 52.86

[0178] It can be seen from Table 1 that the filter elements of Examples 1 to 6 have higher dust holding capacity and filtration accuracy, wherein Examples 2 to 6 add carbon tubes, and their filtration effects are further improved on the basis of Example 1.

[0179] Since Comparative Example 1 does not contain modified carbon tubes and the thickness of the first filter layer is equal to the thickness of the third filter layer, the filtration efficiency and dust holding capacity are relatively low.

[0180] Since Comparative Example 2 does not contain modified carbon tubes, the thickness of the first filter layer is equal to the thickness of the third filter layer, and the thickness of the second filter fiber layer is greater than the thickness of the first filter layer and the thickness of the third filter layer, the filtration efficiency and dust holding capacity are both low.

[0181] Since Comparative Example 3 does not contain modified carbon tubes and the micropores have uniform sizes, a gradient pore size distribution cannot be formed, so the filtration efficiency and dust holding capacity are relatively low.

[0182] Since Comparative Example 4 does not contain modified carbon tubes and the three layers have the same thickness, the filtration efficiency and dust holding capacity are relatively low.

[0183] In summary, by dividing the filter element into a first filter fiber layer, a second filter fiber layer and a third filter fiber layer, the thickness of the first filter fiber layer is greater than the thickness of the third filter fiber layer, the micropore size of the first filter fiber layer is smaller than the micropore size of the second filter fiber layer, and the micropore size of the second filter fiber layer is smaller than the micropore size of the third filter fiber layer. This allows the entire filter element to have smaller and smaller pores on the exhaust gas movement path of the exhaust gas treatment. The outer third filter fiber layer has the largest micropore size, which mainly serves to accommodate filtered dust. The middle second filter fiber layer has a smaller micropore size than the outer third filter fiber layer, which further intercepts dust. The inner first filter fiber layer has the smallest micropore size, which improves the filtration accuracy, allowing finer dust to be filtered out, increasing the flow rate and pollution holding capacity, making the filter element less prone to blockage and extending its service life. At the same time, the thickness of the inner first filter fiber layer is greater than the thickness of the outer third filter fiber layer, which allows fine dust to have a longer path to pass through the filter element and be intercepted over a longer movement distance, thereby improving the filtration accuracy while retaining the dust holding capacity of the third filter fiber layer, making the filter element less likely to be blocked and extending its service life.

[0184] In the description of this specification, the description with reference to the terms "one embodiment / method", "some embodiments / methods", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment / method or example are included in at least one embodiment / method or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment / method or example. Moreover, the specific features, structures, materials or characteristics described may be combined in a suitable manner in any one or more embodiments / methods or examples. In addition, those skilled in the art may combine and combine the different embodiments / methods or examples described in this specification and the features of the different embodiments / methods or examples, unless they are contradictory.

[0185] It should be noted that, in the present application, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of more restrictions, the elements defined by the sentence "comprise one..." do not exclude the existence of other identical elements in the process, method, article or equipment including the elements. In the present application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically stipulated.

[0186] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A filter element, characterized in that: The invention comprises a first filter fiber layer, a second filter fiber layer and a third filter fiber layer, wherein: The second filter fiber layer is disposed between the first filter fiber layer and the third filter fiber layer; The thickness of the first filter fiber layer is greater than the thickness of the third filter fiber layer; The micropore size of the first filter fiber layer is smaller than the micropore size of the second filter fiber layer; The pore size of the second filter fiber layer is smaller than the pore size of the third filter fiber layer.

2. The filter element according to claim 1, characterized in that: The thickness of the first filter fiber layer is H1, the thickness of the third filter fiber layer is H3, 1.5H3≤H1≤3H3; and / or, The thickness of the first filter fiber layer is H1, 10 mm ≤ H1 ≤ 14 mm; and / or, The thickness of the second filter fiber layer is H2, 6mm≤H2≤14mm; and / or, The thickness of the third filter fiber layer is H3, 5mm≤H3≤7mm.

3. The filter element according to claim 1, characterized in that: The fiber diameter of the first filter fiber layer is D1, 1 μm≤D1≤4 μm; and / or, The fiber diameter of the second filter fiber layer is D2, 4 μm≤D2≤8 μm; and / or, The fiber diameter of the third filter fiber layer is D3, 8 μm≤D3≤10 μm.

4. The filter element according to claim 1, characterized in that: The micropore size of the first filter fiber layer is R1, 0.1 μm≤R1≤15 μm; and / or, The micropore size of the second filter fiber layer is R2, 10 μm ≤ R2 ≤ 30 μm; and / or, The micropore size of the third filter fiber layer is R3, 25 μm≤R3≤60 μm.

5. The filter element according to claim 1, characterized in that: The material of the filter element also includes carbon tubes.

6. The filter element according to claim 5, characterized in that: The carbon tubes include hydroxyl- and / or carboxyl-modified carbon tubes; and / or, The mass proportion of the carbon tubes in the material of the filter element is 2.5% to 5%; and / or, The diameter of the carbon tube is D4, 1 μm≤D4≤4 μm.

7. A method for preparing a filter element according to any one of claims 1 to 6, characterized in that: The following steps are involved: The nylon is sequentially formed into a first filter fiber layer, a second filter fiber layer and a third filter fiber layer by a melt-blowing method, wherein: The thickness of the first filter fiber layer is greater than the thickness of the third filter fiber layer; The micropore size of the first filter fiber layer is smaller than the micropore size of the second filter fiber layer; The pore size of the second filter fiber layer is smaller than the pore size of the third filter fiber layer.

8. The method for preparing the filter element according to claim 7, characterized in that: The air flow pressure of the first filter fiber layer formed by melt-blowing is 0.4-0.6 MPa; and / or, The extrusion rate of the first filter fiber layer formed by melt-blowing is 0.01 to 0.03 g / min; and / or, The receiving distance of the first filter fiber layer formed by melt-blowing is 4 to 6 cm; and / or, The air flow pressure of the second filter fiber layer formed by melt-blowing is 0.3-0.4 MPa; and / or, The extrusion rate of the second filter fiber layer formed by melt-blowing is 0.03-0.05 g / min; and / or, The receiving distance of the second filter fiber layer formed by melt-blowing is 7 to 9 cm; and / or, The air flow pressure of the third filter fiber layer formed by melt-blowing is 0.1-0.3 MPa; and / or, The extrusion rate of the third filter fiber layer formed by melt-blowing is 0.08-0.12 g / min; and / or, The receiving distance of the third filter fiber layer formed by melt-blowing is 12 to 18 cm.

9. The method for preparing a filter element according to claim 7, characterized in that: The temperature of melt blowing is 180-270°C.

10. A vehicle, characterized in that: A filter element comprising the filter element as described in any one of claims 1 to 6, or a filter element made by the preparation method of the filter element as described in any one of claims 7 to 9.

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