Engine oil filter for small-sized compressor

Abstract

The invention relates to the technical field of engine oil filters, and provides an engine oil filter for a small compressor, the engine oil filter comprises a screwed joint, an inner filter assembly and an outer filter assembly, the screwed joint is provided with an inner hole along the axial direction; the inner filter assembly comprises an inner barrel and an inner filter screen, the outer filter assembly comprises an outer barrel and an outer filter screen, and the inner barrel and the outer barrel are coaxially arranged on the threaded connector; a plurality of inner filter holes are formed in the inner cylinder body, the inner filter screen is arranged on the outer side of the inner filter holes of the inner cylinder body, a plurality of outer filter holes are formed in the outer cylinder body, and the outer filter screen is arranged on the outer side of the outer filter holes of the outer cylinder body. The inner filter assembly and the outer filter assembly are coaxially nested, so that the radial space utilization is greatly optimized, and the defect of large occupied space of a traditional parallel filter is overcome; meanwhile, the engine oil is sequentially filtered step by step through rough filtration and fine filtration, so that the overall filtration precision and efficiency are remarkably improved, the pollutant load of a filter material is effectively dispersed, and the service life of the engine oil filter is remarkably prolonged.

Description

Technical Field

[0001] This invention relates to the field of oil filter technology, and more particularly to an oil filter for a small compressor. Background Technology

[0002] Currently, most oil filtration solutions for small compressors on the market are simply miniaturized versions of traditional oil filters. However, this approach has several problems. Firstly, simply reducing the size reduces the filter's filtration area, making it difficult to meet the oil flow requirements of small compressors without compromising filtration accuracy. This can lead to insufficient oil supply and affect the compressor's normal operation. Secondly, because small compressors operate in complex and variable environments, their oil filtration requirements are more stringent. Simply miniaturized filters cannot effectively handle impurities under complex operating conditions, impacting the reliability and stability of small compressors. For example, in high-temperature and high-humidity environments, sludge formed by the combination of impurities and moisture is even more difficult to filter out with simply miniaturized filters, thus damaging the small compressor.

[0003] Furthermore, most existing oil filters focus solely on filtration precision while neglecting the issue of clogging. Once a high-precision filter becomes clogged with impurities, frequent replacements are necessary, increasing operating costs and maintenance workload. Moreover, frequent filter replacements can lead to prolonged downtime for small compressors, impacting production efficiency. In conclusion, existing oil filters fail to meet the actual needs of small compressors in terms of size, filtration performance, and clogging management, necessitating a new type of oil filter specifically designed for small compressors to address these problems. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention aims to provide an oil filter for small compressors. By coaxially nesting the inner and outer filter components, a highly integrated two-stage filtration structure is constructed, greatly optimizing radial space utilization and overcoming the space-consuming shortcomings of traditional parallel filters. This perfectly adapts to the compact installation environment of small compressors. Simultaneously, the gradient filtration mechanism formed by the inner and outer filter components allows the oil to undergo step-by-step filtration through coarse and fine filters, significantly improving overall filtration accuracy and efficiency. It also effectively disperses the dirt-holding load of the filter media, slowing down the clogging rate of the core fine filter layer, thereby significantly extending the service life of the oil filter.

[0005] To achieve the above objectives, the present invention provides an oil filter for a small compressor, comprising a threaded joint, an inner filter assembly, and an outer filter assembly. The threaded joint has an axially extending inner hole, and the inner filter assembly and the outer filter assembly are coaxially arranged and installed on the threaded joint. The inner filter assembly includes an inner cylinder and an inner filter screen, and the outer filter assembly includes an outer cylinder and an outer filter screen. The inner cylinder and the outer cylinder are coaxially arranged on the threaded joint. The inner cylinder has a plurality of inner filter holes, and the inner filter screen is disposed outside the inner filter holes of the inner cylinder. The outer cylinder has a plurality of outer filter holes, and the outer filter screen is disposed outside the outer filter holes of the outer cylinder.

[0006] In some embodiments, the inner filter screen is a coarse filter screen and the outer filter screen is a fine filter screen. During operation, the oil flows in from the inner hole of the threaded joint, first passes radially through the inner filter assembly for coarse filtration, enters the gap between the outer cylinder and the inner cylinder, then passes radially through the outer filter assembly for fine filtration, and finally flows out and enters the oil tank. Alternatively, the inner filter screen is a fine filter screen, and the outer filter screen is a coarse filter screen. During operation, the oil first passes radially through the outer filter assembly for coarse filtration, enters the outer cylinder, then passes radially through the inner filter assembly for fine filtration, enters the inner cylinder, and finally flows out from the inner hole of the threaded joint into the lubrication system.

[0007] In some embodiments, the end of the outer cylinder away from the threaded joint is closed by an outer cover plate, and the end of the inner cylinder away from the threaded joint is closed by an inner cover plate. The inner cover plate and the outer cover plate together form a sealed space between the inner cylinder and the outer cylinder.

[0008] In some embodiments, the inner cylinder end is disposed inside the outer cylinder end, and both the inner cover plate and the outer cover plate are circular, with the inner cover plate concentrically disposed inside the outer cover plate and maintaining a distance between them; Alternatively, the inner cylinder end extends through the outer cylinder end, the inner cover plate is circular, the outer cover plate is annular, and the inner cover plate is concentrically arranged outside the outer cover plate and spaced apart.

[0009] In some embodiments, the end of the outer cylinder away from the threaded joint is closed by an outer cover plate, the inner side of which is provided with a sealing groove, and the end of the inner cylinder is adapted to be inserted into the sealing groove so that the outer periphery of the end of the inner cylinder is sealed with the groove wall of the sealing groove.

[0010] In some embodiments, the inner filter hole and the outer filter hole are arranged opposite each other, the inner filter hole and the outer filter hole have equal axial lengths, and the width of the inner filter hole in the circumferential direction of the inner cylinder is reduced by a constant proportional coefficient according to the width of the outer filter hole in the circumferential direction of the outer cylinder, thereby forming a specific flow distribution and filtration gradient.

[0011] In some embodiments, the outer filter holes are spaced apart around the outer cylinder, and the inner filter holes are spaced apart around the inner cylinder. And / or, the outer filter holes are spaced apart axially around the outer cylinder, and the inner filter holes are spaced apart axially around the inner cylinder.

[0012] In some embodiments, the inner filter and / or the outer filter are coated with an adsorption layer to adsorb small particles and organic impurities in the engine oil.

[0013] In some embodiments, the inner filter assembly and / or the outer filter assembly are fitted with an annular magnetic adsorption structure for adsorbing metallic impurities.

[0014] Compared with the prior art, the oil filter for a small compressor provided by the present invention has at least one of the following beneficial effects: 1. By coaxially nesting the internal and external filter components, a highly integrated two-stage filtration structure is constructed, which greatly optimizes the use of radial space and overcomes the shortcomings of traditional parallel filters that occupy a large amount of space, thus perfectly adapting to the compact installation environment of small compressors. At the same time, the gradient filtration mechanism formed by the internal and external filter components allows the oil to pass through coarse and fine filters in stages, which not only significantly improves the overall filtration accuracy and efficiency, but also effectively disperses the dirt-holding load of the filter media and slows down the clogging speed of the core fine filter layer, thereby significantly extending the service life of the oil filter.

[0015] 2. The outer and inner cover plates ensure that the oil passage from the outer filter to the inner filter is a completely closed annular channel, eliminating the risk of unfiltered oil leaking directly from the end.

[0016] 3. The inner filter holes on the inner cylinder and the outer filter holes on the outer cylinder are arranged opposite each other in radial projection, so as to achieve precise flow distribution and controllable pressure drop gradient, build and strengthen gradient filtration mechanism, and significantly improve dirt holding capacity and anti-clogging performance.

[0017] 4. Coating the surface of the inner and / or outer filter screen with an adsorption layer can enhance the adsorption capacity for some organic impurities and tiny particles, further improving the cleanliness of the engine oil.

[0018] 5. A ring-shaped magnetic adsorption structure is fitted on the outside of the internal filter assembly and / or the external filter assembly to adsorb metal shavings in the engine oil and improve the filtration effect. Attached Figure Description

[0019] The preferred embodiments will now be described in a clear and easy-to-understand manner, in conjunction with the accompanying drawings, to further explain the above-mentioned characteristics, technical features, advantages, and implementation methods of the present invention.

[0020] Figure 1 This is a cross-sectional view of an oil filter used in small compressors.

[0021] Explanation of icon numbers: Threaded connector 1, inner cylinder 2, inner filter hole 21, inner filter screen 3, inner cover plate 4, outer cylinder 5, outer filter hole 51, outer filter screen 6, outer cover plate 7. Detailed Implementation

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without any creative effort.

[0023] To keep the drawings concise, each figure only schematically shows the parts relevant to the invention, and these do not represent the actual structure of the product. Furthermore, to facilitate understanding, in some figures, only one of components with the same structure or function is schematically depicted, or only one is labeled. In this document, "one" not only means "only one," but can also mean "more than one."

[0024] It should also be further understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0025] In this document, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0026] Furthermore, in the description of this application, the terms "first," "second," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance. It should be noted that the above embodiments can be freely combined as needed. The above are merely preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, several improvements and modifications can be made without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

[0027] refer to Figure 1This invention provides an oil filter for a small compressor, comprising a threaded connector 1, an inner filter assembly, and an outer filter assembly. The threaded connector 1 has an axially extending inner hole. The inner filter assembly and the outer filter assembly are coaxially arranged and installed on the threaded connector 1. The inner filter assembly includes an inner cylinder 2 and an inner filter screen 3, and the outer filter assembly includes an outer cylinder 5 and an outer filter screen 6. The inner cylinder 2 and the outer cylinder 5 are coaxially arranged on the threaded connector 1. The inner cylinder 2 has a plurality of inner filter holes 21, and the inner filter screen 3 is disposed outside the inner filter holes 21 of the inner cylinder 2. The outer cylinder 5 has a plurality of outer filter holes 51, and the outer filter screen 6 is disposed outside the outer filter holes 51 of the outer cylinder 5.

[0028] In this embodiment, a highly integrated two-stage filtration structure is constructed by coaxially nesting the inner and outer filter components. This greatly optimizes the radial space utilization and overcomes the shortcomings of traditional parallel filters that occupy a large amount of space, thus perfectly adapting to the compact installation environment of small compressors. At the same time, the gradient filtration mechanism formed by the inner and outer filter components allows the oil to pass through coarse and fine filters in sequence. This not only significantly improves the overall filtration accuracy and efficiency but also effectively disperses the dirt-holding load of the filter media, slows down the clogging speed of the core fine filter layer, and thus significantly extends the service life of the oil filter.

[0029] Specifically, in the research of underwater power systems using hot air engines, a small exhaust compressor is needed to discharge exhaust gases outside the ship. Due to the extremely limited internal space in the underwater environment, the size of the exhaust compressor is significantly restricted. During the development of this small exhaust compressor, it was found that traditional compressors mostly use external filter paper type oil filters. These filters are suitable for larger spaces and higher flow requirements, resulting in a large filter size that affects the overall size of the compressor and cannot meet the compact spatial layout requirements of small compressors. The purpose of this invention is to provide a composite oil filter for small compressors, solving the problems of existing oil filters being too large to fit the space of small compressors, as well as their poor filtration performance and susceptibility to clogging. Moreover, it can perfectly fit the compact internal space of small compressors, solving the long-standing problem of ineffective installation caused by filter size issues, and greatly expanding the application range of small compressors in various space-constrained devices. For example, in small refrigeration equipment, previously, due to space limitations, only small filters with poor filtration effects could be used. However, the filter structure of this invention can improve filtration performance without changing the overall size of the equipment.

[0030] The oil filter is cylindrical in shape, and the fine filter assembly and the coarse filter assembly are fixed to the threaded connector 1 by welding. The threaded connector 1 serves as the base and mounting interface of the entire filter, and it has an axially extending inner hole. This inner hole serves two purposes: firstly, it allows the entire filter to be installed to the corresponding oil passage of the compressor via a threaded connection; secondly, it constitutes the only channel for oil to enter the internal cavity of the filter, and is the starting point for oil flow. Specifically, the threaded connector 1 has a cylindrical structure, with threads machined at one end and a wrench face machined at the other end, and a hole drilled along the axis to serve as the channel for oil outflow.

[0031] The core filtration function of the entire filter is achieved by a two-stage filtration system consisting of an inner filter assembly and an outer filter assembly, coaxially mounted on threaded connector 1, arranged in a nested layout. The inner filter assembly constitutes the first stage of filtration. It includes an inner cylinder 2 and an inner filter screen 3 covering it. The inner cylinder 2 is a circular tubular structure, and the inner filter screen 3 is a metal mesh structure, evenly covering the outer surface of the inner cylinder 2 and fixed to it by welding. It is used to filter smaller impurities. The number of inner filter screen layers 3 can be adjusted according to actual needs. The inner cylinder 2 has several internal filter holes 21, and the inner filter screen 3 is located outside these holes. When engine oil flows through the inner filter assembly, it must first pass through the inner filter screen 3 before entering the inner cylinder 2. The external filter assembly constitutes the second stage of filtration. It includes an outer cylinder 5 and an outer filter screen 6 covering it. The outer cylinder 5 is a circular tubular structure, and the outer filter screen 6 is a metal mesh structure, evenly covering the outer wall of the outer cylinder 5 and fixed to it by welding. It is used to filter larger impurities. The number of layers of the outer filter screen 6 can be adjusted according to actual needs. The outer cylinder 5 has several external filter holes 51. Similarly, the outer filter screen 6 is located outside the external filter holes 51 of the outer cylinder 5. When engine oil flows through the external filter assembly, it must first pass through the outer filter screen 6 before entering the annular space between the outer cylinder 5 and the inner cylinder 2. By integrating the inner and outer filter assemblies in a coaxial nested manner, the traditional transverse or longitudinal series layout required for two-stage filtration is transformed into a radially stacked layout. This greatly reduces the overall size of the filter in the axial and longitudinal directions, perfectly overcoming the inherent drawback of large space occupation in traditional parallel or series filters. This allows the filter to be easily installed inside small compressors with extremely limited space, meeting the development needs of modern compressors for miniaturization and compactness.

[0032] In this embodiment, the inner filter 3 is a coarse filter, and the outer filter 6 is a fine filter. During operation, the engine oil flows in from the inner hole of the threaded joint 1, first passing radially through the inner filter assembly for coarse filtration, then entering the gap between the outer cylinder 5 and the inner cylinder 2, and subsequently passing radially through the outer filter assembly for fine filtration, finally flowing out and into the oil tank. Specifically, the engine oil enters from the inner hole of the threaded joint 1, first reaching the space formed by the outer filter 6 and the outer cylinder 5. The engine oil first passes through the outer filter 6 for the first stage of filtration. The filtered engine oil passes through the outer filter hole 51 on the outer cylinder 5 and enters the annular cavity between the outer cylinder 5 and the inner filter 3. Subsequently, the engine oil flows inward, passes through the inner filter 3 for the second stage of filtration, and the filtered engine oil passes through the inner filter hole 21 on the inner cylinder 2, finally entering the central clean oil chamber of the inner cylinder 2. The clean engine oil flows out from the inner hole of the threaded joint 1, completing the entire filtration process.

[0033] In another embodiment, the inner filter 3 is a fine filter, and the outer filter 6 is a coarse filter. During operation, the oil first passes radially through the outer filter assembly for coarse filtration, then enters the outer cylinder 5. Subsequently, it passes radially through the inner filter assembly for fine filtration, then enters the inner cylinder 2, and finally flows out from the inner hole of the threaded joint 1 into the lubrication system. The coarse filter of the inner cylinder 2 intercepts larger particles of impurities, greatly reducing the quantity and size of impurities entering the fine filter of the outer cylinder 5. In practical applications, traditional single-stage high-precision filters may become clogged quickly due to impurity accumulation, requiring frequent replacement. The dual-stage gradient filtration structure of this invention significantly extends the clogging cycle of the fine filter, reducing the frequency of filter replacement. This not only reduces operating costs but also reduces downtime caused by filter replacement for small compressor equipment requiring continuous operation, improving equipment operating efficiency and stability.

[0034] It is worth noting that the core of this invention lies in the coaxial nesting and gradient filtration of the inner and outer filter components. Whether the inner filter 3 is a coarse filter and the outer filter 6 is a fine filter, or vice versa, does not affect the core idea of ​​this application. Gradient filtration forces the oil through two stages of inner filter 3 and outer filter 6 with different precision. This step-by-step filtration method first intercepts most of the larger particulate contaminants with the coarse filter, and then the fine filter removes the fine particles, greatly slowing down the clogging rate of the core fine filter. This allows the filter to hold more contaminants while maintaining high filtration precision, thus significantly extending its maintenance cycle and service life, and reducing the frequency and cost of equipment maintenance. This not only significantly improves the overall filtration precision and ensures the cleanliness of the lubricating oil, but also reduces the burden on the fine filter because large particles have been pre-removed, thereby improving the overall filtration efficiency and ensuring smooth oil flow. In contrast, in traditional single-stage filters, all contaminants are concentrated on a single filter media, leading to rapid clogging.

[0035] Preferably, the coarse filter screen aperture can be adjusted within the range of 0.2mm-1mm according to the oil flow rate and operating environment. The fine filter screen aperture can be adjusted within the range of 0.01mm-0.1mm according to the oil flow rate and operating environment. This application can form a gradient filtration mechanism by setting inner filter screen 3 and outer filter screen 6 with different precision. During the process of oil flowing through the coarse and fine filter screens, impurities are intercepted step by step, which not only significantly improves the overall filtration precision and efficiency, but also reasonably distributes the dirt-holding load of inner filter screen 3 and outer filter screen 6, effectively delaying the clogging speed of the core fine filter screen. Thus, while ensuring filtration performance, it greatly extends the service life of the oil filter and reduces the maintenance frequency.

[0036] Furthermore, the end of the outer cylinder 5 away from the threaded joint 1 is sealed by the outer cover plate 7, and the end of the inner cylinder 2 away from the threaded joint 1 is sealed by the inner cover plate 4. The inner cover plate 4 and the outer cover plate 7 together form a sealed space between the inner cylinder 2 and the outer cylinder 5.

[0037] In this embodiment, the outer cover plate 7 and the inner cover plate 4 ensure that the oil passage from the outer filter screen 6 to the inner filter screen 3 is a completely closed annular channel, eliminating the risk of unfiltered oil leaking directly from the end.

[0038] Specifically, the outer cylinder 5 is closed at one end to the outer cover plate 7, and the inner cylinder 2 is closed at one end to the inner cover plate 4, together forming a closed annular oil chamber. The core purpose is to ensure that the oil flows strictly along the path of the outer filter 6, the annular chamber, and the inner filter 3. This helps reduce pressure loss when the oil passes through the filter, ensuring that the compressor lubrication system maintains sufficient oil pressure, which is beneficial for the stable operation and energy efficiency improvement of small compressors. The end seals of the inner cover plate 4 and the outer cover plate 7 completely prevent oil from flowing between the two stages of filtration or bypassing a particular filter, thus ensuring the absolute effectiveness of the gradient filtration mechanism and allowing the aforementioned improvement in filtration accuracy and efficiency to be stably achieved. It is worth noting that in this embodiment, the outer cover plate 7 can be part of the outer cylinder 5, and the inner cover plate 4 can be part of the inner cylinder 2; that is, both the outer cylinder 5 and the inner cylinder 2 are closed at one end and open at the other.

[0039] In one embodiment, the inner cylinder 2 is located inside the end of the outer cylinder 5. Both the inner cover plate 4 and the outer cover plate 7 are circular, with the inner cover plate 4 concentrically positioned inside the outer cover plate 7 and spaced apart. This spacing provides a clear and smooth flow path for the oil to flow from the outer stage to the inner stage. The inner filter assembly is completely enclosed by the outer filter assembly; that is, the inner cylinder 2, inner filter screen 3, outer cylinder 5, and outer filter screen 6 are arranged coaxially and nested sequentially from the inside out. This layout maximizes the use of radial space, achieving a compact structure. Integrating the inner cylinder 2 and outer cylinder 5 into a compact unit reduces additional connecting pipes and sealing points. This not only simplifies the installation process but also reduces the risk of leakage due to excessive joints, improving the structural rigidity and operational reliability of the entire oil filtration system.

[0040] In a modified embodiment, the end of the inner cylinder 2 penetrates the end of the outer cylinder 5. The inner cover plate 4 is circular, and the outer cover plate 7 is annular. The inner cover plate 4 is concentrically disposed outside the outer cover plate 7 and is spaced apart. In this case, the end of the inner cylinder 2 penetrates the end of the outer cylinder 5, and the outer cover plate 7 is annular, sealing the outer cylinder 5 itself and its connection with the inner cylinder 2; while the inner cover plate 4 is circular, sealing the inner cylinder 2 and located outside the annular outer cover plate 7. Of course, how to seal between the outer periphery of the inner cylinder 2 and the inner edge of the outer cover plate 7 is prior art in this application, and will not be further described here.

[0041] In another modified embodiment, the end of the outer cylinder 5 furthest from the threaded joint 1 is sealed by an outer cover plate 7. The outer cover plate 7 has a sealing groove on its inner side, and the end of the inner cylinder 2 is adapted to be inserted into the sealing groove, thus sealing the outer periphery of the end of the inner cylinder 2 with the groove wall. In this case, the end of the inner cylinder 2 is directly inserted and sealed within the sealing groove. This greatly simplifies the assembly process, eliminating the need for an inner cover plate 4, reducing the number of independent parts, and further reducing potential leakage points due to the reduced connection interfaces. It also improves the overall integrity and rigidity of the structure, and allows for better alignment of the inner filter hole 21 and the outer filter hole 51.

[0042] It is worth noting that this application provides a variety of feasible end sealing solutions, which provides manufacturers with diverse options based on their own production processes and cost control objectives, and has greater industrialization and adaptability, meeting the needs of different customers and product lines.

[0043] Furthermore, the inner filter hole 21 and the outer filter hole 51 are arranged opposite each other, the inner filter hole 21 and the outer filter hole 51 have equal axial lengths, and the width of the inner filter hole 21 in the circumferential direction of the inner cylinder 2 is reduced by a constant proportional coefficient according to the width of the outer filter hole 51 in the circumferential direction of the outer cylinder 5, thereby forming a specific flow distribution and filtration gradient.

[0044] In this embodiment, the inner filter hole 21 on the inner cylinder 2 and the outer filter hole 51 on the outer cylinder 5 are arranged opposite each other in radial projection, so as to achieve precise flow distribution and controllable pressure drop gradient, construct and strengthen gradient filtration mechanism, and significantly improve dirt holding capacity and anti-clogging performance.

[0045] Specifically, each opposing inner filter hole 21 and outer filter hole 51 have exactly the same length in the axial direction. The width of each inner filter hole 21 in the circumferential direction of the inner cylinder 2 is reduced by a constant proportional coefficient compared to the width of its opposing outer filter hole 51 in the circumferential direction of the outer cylinder 5. Since the inner filter holes 21 and outer filter holes 51 are opposite each other and have the same axial length, but the width of the inner filter hole 21 in the circumferential direction of the inner cylinder 2 is reduced proportionally to the width of the outer filter hole 51 in the circumferential direction of the outer cylinder 5, the flow area of ​​the inner filter hole 21 is proportionally smaller than that of the outer filter hole 51. This establishes a controllable and stable pressure drop distribution between the inner and outer filter components, ensuring that the oil can pass evenly through the entire filtration area, avoiding eddies or dead zones caused by sudden changes in local flow area, thereby optimizing the overall flow field and achieving the best balance between flow capacity and filtration efficiency. Preferably, both the external filter hole 51 and the internal filter hole 21 are elongated holes with equal major axis lengths but decreasing minor axis lengths. Of course, the external filter hole 51 and the internal filter hole 21 can also be oval, elliptical, or other shapes, which are not further limited here.

[0046] Furthermore, the larger flow area of ​​the external filter orifice 51 corresponds to a lower initial resistance, making it suitable as a coarse filtration stage, while the smaller flow area of ​​the internal filter orifice 21 corresponds to a higher subsequent resistance, making it suitable as a fine filtration stage. This forces the fluid to undergo a physically rigorously defined filtration process, progressing from easy to difficult and from coarse to fine, as it passes through both stages. This not only improves the accuracy of the results but also ensures the strict execution of the filtration logic, making the filtration effect more stable and predictable.

[0047] It is worth noting that the outer filter holes 51 are spaced apart circumferentially around the outer cylinder 5, and the inner filter holes 21 are spaced apart circumferentially around the inner cylinder 2; and / or, the outer filter holes 51 are spaced apart axially around the outer cylinder 5, and the inner filter holes 21 are spaced apart axially around the inner cylinder 2. Specifically, the outer filter holes 51 are distributed in an array on the outer cylinder 5, and the inner filter holes 21 are distributed in a corresponding array on the inner cylinder 2. The distribution method includes, but is not limited to, circumferentially spaced and axially spaced, so that the outer filter holes 51 and the inner filter holes 21 are distributed in one or more rows in the circumferential direction of the outer cylinder 5 and the inner cylinder 2. The outer filter holes 51 and the inner filter holes 21 are distributed in one or more columns in the axial direction of the outer cylinder 5 and the inner cylinder 2. These two distribution modes can be implemented individually or in combination to form a filter hole matrix covering most of the cylinder area.

[0048] Furthermore, the inner filter screen 3 and / or the outer filter screen 6 are coated with an adsorption layer to adsorb tiny particles and organic impurities in the engine oil.

[0049] In this embodiment, an adsorption layer with adsorption function is coated on the surface of the inner filter screen 3 and / or the outer filter screen 6, which can enhance the adsorption capacity for some organic impurities and tiny particles, and further improve the cleanliness of the engine oil.

[0050] Specifically, a functional adsorption layer is coated on the fiber surface of the inner filter screen 3 and / or the outer filter screen 6. This adsorption layer is composed of materials with high specific surface area and strong adsorption capacity. Its core function is to capture dissolved or suspended fine particles such as carbon soot and sludge, as well as organic impurities such as acidic substances and oxidation products in the engine oil through physical adsorption or chemical bonding. The adsorption layer is preferably made of materials such as activated carbon, diatomaceous earth, or special synthetic adsorption resin. This application does not further limit its application.

[0051] Furthermore, the outer side of the inner filter assembly and / or the outer filter assembly is fitted with a ring-shaped magnetic adsorption structure for adsorbing metallic impurities.

[0052] In this embodiment, a ring-shaped magnetic adsorption structure is sleeved on the outside of the inner filter assembly and / or the outer filter assembly to adsorb metal shavings in the engine oil and improve the filtration effect.

[0053] Specifically, one or more annular magnetic adsorption structures are fitted onto the outside of the inner filter assembly and / or the outer filter assembly. More specifically, the annular magnetic adsorption structure can be fitted onto the outside of the outer filter screen 6, or located within the annular cavity between the outer filter screen 6 and the inner filter screen 3. The annular magnetic adsorption structure is typically made of a permanent magnet in a ring shape, or formed by embedding magnetic material within a non-magnetic annular support. Its function is to generate a magnetic field surrounding the filter assembly, strongly adsorbing metal shavings such as iron and steel particles from the engine oil.

[0054] Preferably, the annular magnetic adsorption structure is disposed on the outside of the coarse filter screen, and the adsorption layer is disposed on the surface of the fine filter screen. In this configuration, the annular magnetic adsorption structure acts as the vanguard, strongly adsorbing iron filings first, reducing the cutting and clogging of the fibers of the inner filter screen 3 and outer filter screen 6 by the iron filings, preventing these hard particles from wearing down subsequent filter screens and the adsorption layer during oil circulation, thus protecting the core filtration unit. The inner filter screen 3 and outer filter screen 6 act as the backbone, continuing to intercept solid particles from coarse to fine, removing large particulate contaminants in advance and reducing the physical burden on the adsorption layer. The adsorption layer acts as the rearguard, finally adsorbing the tiny contaminants and chemical impurities that have penetrated the first two stages of defense, achieving precise final purification. The adsorption layer can also capture colloidal substances, preventing them from sticking to the filter screen and increasing the pressure drop, all of which delay filter screen clogging and extend the filter element replacement cycle.

[0055] The oil filter of this application meets the oil filtration requirements of small compressors while significantly reducing its overall size, making it perfectly suited to the compact space layout of small compressors. It also adopts a two-stage gradient filtration mode, which effectively delays the clogging of the fine filter layer, reduces the frequency of filter replacement, reduces maintenance costs and downtime, and improves the efficiency of small compressors.

[0056] It should be noted that the above embodiments can be freely combined as needed. The above are merely preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An oil filter for a small compressor, characterized in that, It includes a threaded joint, an inner filter assembly, and an outer filter assembly. The threaded joint has an axially penetrating inner hole. The inner filter assembly and the outer filter assembly are coaxially arranged and installed on the threaded joint. The inner filter assembly includes an inner cylinder and an inner filter screen, and the outer filter assembly includes an outer cylinder and an outer filter screen. The inner cylinder and the outer cylinder are coaxially arranged on the threaded joint. The inner cylinder has a plurality of inner filter holes, and the inner filter screen is disposed outside the inner filter holes of the inner cylinder. The outer cylinder has a plurality of outer filter holes, and the outer filter screen is disposed outside the outer filter holes of the outer cylinder.

2. An oil filter for a small compressor according to claim 1, characterized in that, The inner filter screen is a coarse filter screen, and the outer filter screen is a fine filter screen. During operation, the oil flows in from the inner hole of the threaded joint, first passes radially through the inner filter assembly for coarse filtration, enters the gap between the outer cylinder and the inner cylinder, then passes radially through the outer filter assembly for fine filtration, and finally flows out and enters the oil tank. Alternatively, the inner filter screen is a fine filter screen, and the outer filter screen is a coarse filter screen. During operation, the oil first passes radially through the outer filter assembly for coarse filtration, enters the outer cylinder, then passes radially through the inner filter assembly for fine filtration, enters the inner cylinder, and finally flows out from the inner hole of the threaded joint into the lubrication system.

3. An oil filter for a small compressor according to claim 1, characterized in that, The outer cylinder is closed at the end away from the threaded joint by an outer cover plate, and the inner cylinder is closed at the end away from the threaded joint by an inner cover plate. The inner cover plate and the outer cover plate together form a sealed space between the inner cylinder and the outer cylinder.

4. An oil filter for a small compressor according to claim 3, characterized in that, The inner cylinder end is located inside the outer cylinder end. Both the inner cover plate and the outer cover plate are circular. The inner cover plate is concentrically located inside the outer cover plate and is spaced apart. Alternatively, the inner cylinder end extends through the outer cylinder end, the inner cover plate is circular, the outer cover plate is annular, and the inner cover plate is concentrically arranged outside the outer cover plate and spaced apart.

5. An oil filter for a small compressor according to claim 1, characterized in that, The end of the outer cylinder away from the threaded joint is closed by an outer cover plate. The inner side of the outer cover plate is provided with a sealing groove. The end of the inner cylinder is adapted to be inserted into the sealing groove so that the outer periphery of the end of the inner cylinder is sealed with the groove wall of the sealing groove.

6. An oil filter for a small compressor according to claim 1, characterized in that, The inner filter hole and the outer filter hole are arranged opposite each other, and the inner filter hole and the outer filter hole have equal axial lengths. The width of the inner filter hole in the circumferential direction of the inner cylinder is reduced by a constant proportional coefficient according to the width of the outer filter hole in the circumferential direction of the outer cylinder, thereby forming a specific flow distribution and filtration gradient.

7. An oil filter for a small compressor according to claim 6, characterized in that, The outer filter holes are spaced apart around the outer cylinder, and the inner filter holes are spaced apart around the inner cylinder. And / or, the outer filter holes are spaced apart axially around the outer cylinder, and the inner filter holes are spaced apart axially around the inner cylinder.

8. An oil filter for a small compressor according to claim 1, characterized in that, The inner filter and / or the outer filter are covered with an adsorption layer to adsorb tiny particles and organic impurities in the engine oil.

9. An oil filter for a small compressor according to claim 7, characterized in that, The inner filter assembly and / or the outer filter assembly are fitted with an annular magnetic adsorption structure for adsorbing metallic impurities.

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