Needle head filter

Abstract

The utility model discloses a needle filter which comprises a first shell, a second shell and a filter membrane, the outer edges of the first shell and the second shell are in sealed connection, at least one layer of pre-filtering membrane is stacked on the upstream side of the filter membrane, and the aperture of the pre-filtering membrane is larger than that of the filter membrane; the pre-filtering membrane comprises a pre-filtering area and an annular acting area integrally formed on the periphery of the pre-filtering area; an extrusion area is arranged at the position, corresponding to the annular action area, of the inner surface of the first shell and extrudes the annular action area towards the direction where the filter membrane is located so as to position the pre-filter membrane. The pre-filtering membrane is arranged at the upstream of the filtering membrane, so that the pollutant holding capacity of the filter is increased, the problem that the filtering membrane is blocked too early is solved, the service life of the filtering membrane is prolonged, and the service life of the filter is further prolonged; and the annular acting area of the pre-filtering membrane not only plays a role in positioning and mounting the pre-filtering membrane, but also plays a role in holding dirt, so that all the areas of the pre-filtering membrane can play a role in filtering, and the overall dirt holding capacity of the pre-filtering membrane is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of filters, in particular to a needle filter. Background Art

[0002] The existing utility model patent CN213555703U provides a butterfly filter, including a first shell, a second shell and a filter membrane sealed and fixed between the first shell and the second shell. The first shell and the second shell form a sealed connection at the outer edge. Usually, the filter membrane is sealed and fixed to the first shell by welding or bonding. The liquid to be filtered flows into the inlet of the second shell, is filtered through the filter membrane, and the filtrate is discharged from the outlet of the first shell.

[0003] The butterfly filter is small in size and contains only one filter membrane. Its service life is usually short, and users need to replace the filter frequently. Moreover, for some liquids with high particle content and high processing volume requirements, the filter replacement frequency is even higher. To solve this problem, it is usually practiced to weld or bond a pre-filter membrane with a larger pore size on the upstream side of the filter membrane to initially intercept large particle pollutants to extend the service life of the filter membrane. However, the pre-filter membrane is fixed by welding or bonding, which, on the one hand, complicates the manufacturing process of the filter, and on the other hand, the welding or bonding area of ​​the pre-filter membrane can no longer intercept particles, resulting in this part of the filtration area being wasted.

[0004] The internal structure of the filter needs to be improved to increase the area of ​​the pre-filter membrane that can actually be used for filtration, increase the dirt holding capacity of the pre-filter membrane, extend the service life of the filter, and simplify the manufacturing process of the filter. Summary of the invention

[0005] In order to overcome the shortcomings of the prior art, the utility model provides a syringe filter, which has a pre-filter membrane upstream of the filter membrane. The pre-filter membrane is positioned only by squeezing the shell, so that the entire area of ​​the pre-filter membrane can play a role in absorbing dirt, greatly increasing the dirt-absorbing capacity of the filter and extending the service life of the filter membrane.

[0006] The technical solution adopted by the utility model to solve the technical problem is: a syringe filter, including a first shell and a second shell formed in a sealed connection at the outer edge, and a filter membrane sealed and fixed between the first shell and the second shell.

[0007] At least one layer of pre-filter membrane is stacked on the upstream side of the filter membrane, and the pore size of the pre-filter membrane is larger than the pore size of the filter membrane;

[0008] The pre-filtration membrane comprises a pre-filtration area and an annular action area integrally formed on the periphery of the pre-filtration area;

[0009] The inner surface of the first shell has a pressing area at a position corresponding to the annular action area, and the pressing area presses the annular action area toward the direction where the filter membrane is located to form the positioning of the pre-filter membrane.

[0010] The syringe filter of the utility model is provided with at least one pre-filter membrane upstream of the filter membrane, and the annular action area of ​​the pre-filter membrane is squeezed by the squeezing area of ​​the first shell to realize positioning. During the filtering process, the liquid to be filtered tends to first pass through the pre-filter area of ​​the pre-filter membrane, so that the larger particles are intercepted by the pre-filter area; because the pre-filter membrane is not welded and fixed to the second shell, nor is it welded and fixed to the filter membrane, the liquid to be filtered can also flow radially outward to the surface of the annular action area and pass through the annular action area, and the large particle pollutants are intercepted by the annular action area, and the pre-filter liquid continues to flow downward to reach the upstream surface of the filter membrane, that is, the annular action area of ​​the pre-filter membrane can also play a role in receiving pollutants, thereby improving the overall pollutant receiving capacity of the pre-filter membrane, and the annular action area not only plays a role in positioning and installing the pre-filter membrane, but also plays a role in filtering. Therefore, the entire area of ​​the pre-filter membrane can play a filtering role, and because the welding operation is omitted, the manufacturing process of the filter is simplified, and the filtering area of ​​the pre-filter membrane is avoided from being sacrificed, and the service life of the pre-filter membrane and the filter membrane is extended, thereby greatly extending the service life of the filter.

[0011] Furthermore, the extrusion zone is a curved surface, which at least includes a first zone and a second zone, the second zone is integrally formed on the radially outer side of the first zone, and at least the first zone is pressed against the annular action zone.

[0012] The extrusion zone is designed as a curved structure, which contacts and squeezes the annular action zone over a larger area. The force exerted by the extrusion zone on the annular action zone includes components in various directions, forming a pressing effect on the annular action zone in various directions, making the positioning and installation of the pre-filtration membrane more stable. At the same time, the extrusion strength between the extrusion zone and the annular action zone is prevented from being too large, which would cause the annular action zone to be too dense and the filtered liquid could not pass through smoothly.

[0013] Furthermore, the extrusion zone also includes a third zone, which is integrally formed on the radial inner side of the first zone, the first zone protrudes inwardly toward the inner side of the first shell, and the second zone and the third zone are recessed outwardly toward the outer side of the first shell.

[0014] Such arrangement enables the first zone to better exert its holding effect on the annular action zone, and the second zone and the third zone can provide space to accommodate the deformation of the annular action zone after being squeezed, thereby avoiding the inability to effectively position and install due to the squeezing deformation of the annular action zone, and at the same time avoiding excessive squeezing of the annular action zone, so that the annular action zone can smoothly permeate liquid, and form a gap for liquid to flow through within the range corresponding to the second zone and the third zone and the annular action zone.

[0015] Furthermore, the first area, the second area and the third area are all arc-shaped surfaces, and two sides of the first area are smoothly connected to the second area and the third area respectively.

[0016] The first zone, the second zone and the third zone are smoothly connected arc surfaces, so that the squeezing effect on the pre-filter membrane will not be too sharp, avoiding damage to the pre-filter membrane after being compressed. The design of the arc surface enables the liquid to be filtered to quickly reach the surface of the annular action area, thereby improving the filtration efficiency of the filter.

[0017] Furthermore, the pre-filter membrane includes at least a first pre-filter membrane and a second pre-filter membrane, the first pre-filter membrane is located upstream of the second pre-filter membrane, the outer edge of the first pre-filter membrane protrudes radially outward relative to the outer edge of the second pre-filter membrane, and the extrusion area is at least pressed on the annular action area of ​​the first pre-filter membrane.

[0018] With such arrangement, on the one hand, the extrusion area directly contacts and squeezes the annular action area of ​​the first pre-filter membrane, thereby achieving a good positioning and installation effect on the first pre-filter membrane and the second pre-filter membrane. On the other hand, the extrusion intensity on the annular action area of ​​the second pre-filter membrane is reduced, which is beneficial to the realization of the filtering function of the annular action area of ​​the second pre-filter membrane.

[0019] Furthermore, the pore size of the first pre-filter membrane is larger than that of the second pre-filter membrane, and the radial width of the annular action area of ​​the first pre-filter membrane is larger than that of the second pre-filter membrane.

[0020] Such arrangement enables the annular action zone of the first pre-filter membrane to be larger than the annular action zone of the second pre-filter membrane, ensuring that after the extrusion zone can form an extrusion positioning for the first pre-filter membrane, a good extrusion positioning effect is formed on the second pre-filter membrane through the first pre-filter membrane; in addition, it is ensured that the to-be-filtered liquid reaching the annular action zone of the second pre-filter membrane must first pass through the annular action zone of the first pre-filter membrane, thereby achieving graded retention of particulate pollutants of different sizes.

[0021] Furthermore, the inner surface of the first shell also has a limiting area located radially outside the extrusion area, and the limiting area extends axially to form a radial limit for at least a part of the pre-filter membrane.

[0022] The limiting area can assist the squeezing area in forming radial positioning for the pre-filter membrane, thereby preventing the pre-filter membrane from shifting in the radial direction.

[0023] Furthermore, a flow gap is formed between the outer peripheral wall of the annular action area of ​​the second pre-filter membrane and the limiting area for the liquid to be filtered to pass through;

[0024] and / or,

[0025] The extrusion zone includes at least a first zone and a second zone integrally formed on the outside thereof, the limiting zone is integrally formed on the radial outside of the second zone, a portion of the second zone is pressed against the outer edge area of ​​the annular action zone of the second pre-filter membrane, and a flow gap is formed between another portion of the second zone and the outer peripheral wall of the annular action zone of the second pre-filter membrane for the passage of the filtered liquid.

[0026] The second pre-filter membrane can be squeezed with different areas of the extrusion zone to form a positioning fit, and the assembly flexibility is high; when the filtration is approaching the middle and late stages, most of the pores of the pre-filter membrane are blocked, the flow resistance increases, and part of the liquid to be filtered can directly pass through the extrusion area of ​​the first shell and the annular action area of ​​the pre-filter membrane, and then flow to the filter membrane through the flow gap, avoiding the problem of the filter membrane's pollution capacity not being fully utilized due to the blockage of the pre-filter membrane.

[0027] Furthermore, the radial width of one side of the annular action zone is 0.1%-4% of the outer diameter of the pre-filtration membrane.

[0028] If the above ratio is too small, the mutual contact area between the extrusion zone and the annular action zone is too small, and the positioning effect of the pre-filtration membrane is not stable enough. If the above ratio is too large, the filtration area loss of the pre-filtration zone is too large, the pre-filtration effect is not good, and the pollution holding capacity of the pre-filtration membrane is small. Under the above ratio, a stable extrusion effect can be guaranteed, and the maximum effectiveness of the pre-filtration membrane can be exerted as much as possible.

[0029] Furthermore, the inner surface of the first shell has a plurality of extrusion ribs located radially inward of the extrusion zone, whose end faces contact and abut against the upstream surface of the pre-filter membrane, and cavities for the flow of the filtered liquid are formed between adjacent extrusion ribs.

[0030] The extrusion ribs can form a stable axial positioning effect on the pre-filter membrane, and cavities are formed between adjacent extrusion ribs, so that the extrusion ribs can also guide the flow of the filtered liquid. The flow distribution of the filtered liquid in various parts of the inner surface area of ​​the first shell is relatively balanced, avoiding local failure of the pre-filter membrane due to a large amount of local filtered liquid, thereby extending the service life of the pre-filter membrane.

[0031] The utility model has the following beneficial effects: 1) at least one pre-filtering membrane is arranged upstream of the filter membrane, which greatly increases the dirt holding capacity of the filter. The combination of the pre-filtering membrane and the filter membrane solves the problem of premature clogging of the filter membrane, prolongs the service life of the filter membrane, and then prolongs the service life of the filter; 2) the annular action area of ​​the pre-filtering membrane not only plays a role in positioning and installing the pre-filtering membrane, but also plays a role in absorbing dirt, so that the entire area of ​​the pre-filtering membrane can play a filtering role, thereby improving the overall dirt holding capacity of the pre-filtering membrane; 3) the pre-filtering membrane is positioned only by extrusion of the shell, and the welding operation is omitted, the manufacturing process of the filter is simplified, and the filtering area of ​​the pre-filtering membrane is also avoided from being sacrificed; 4) the extrusion area is designed as a curved surface structure, and the area of ​​mutual contact and extrusion between the extrusion area and the annular action area is larger, and the positioning and installation of the pre-filtering membrane is more stable. At the same time, the extrusion strength between the extrusion area and the annular action area is avoided to be too large, which causes the annular action area to be too dense and the filtered liquid cannot pass smoothly; 5) the first area, the second area and the third area are smoothly connected to the arc surface, so that the extrusion effect on the pre-filtering membrane will not be too sharp, avoiding the pre-filtering membrane from being affected The first pre-filter membrane and the second pre-filter membrane are used in a superimposed manner, and the outer edge of the first pre-filter membrane protrudes radially outward relative to the outer edge of the second pre-filter membrane, and directly contacts and squeezes the annular action area of ​​the first pre-filter membrane through the squeezing area, so as to achieve a good positioning and installation effect on the first pre-filter membrane and the second pre-filter membrane, reduce the squeezing effect strength on the annular action area of ​​the second pre-filter membrane, and facilitate the filtering function of the annular action area of ​​the second pre-filter membrane, and ensure that the filtered liquid reaching the annular action area of ​​the second pre-filter membrane must first pass through the annular action area of ​​the first pre-filter membrane, that is, to achieve graded retention of particulate pollutants of different sizes; 7) The setting of the flow gap, when the filtration is close to the middle and late stages, most of the pores of the pre-filter membrane are blocked, the flow resistance increases, and part of the filtered liquid can pass directly between the first shell and the annular action area of ​​the pre-filter membrane, and then flow to the filter membrane through the flow gap, avoiding the problem that the pollution capacity of the filter membrane cannot be fully utilized due to the blockage of the pre-filter membrane. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the exploded structure of the utility model.

[0033] Figure 2 It is a cross-sectional view of the utility model.

[0034] Figure 3 for Figure 2 A magnified view of the structure in Figure 2.

[0035] Figure 4 It is a top view of the pre-filtration membrane in the utility model.

[0036] Figure 5 It is a cross-sectional view of the first shell in the utility model.

[0037] Figure 6 for Figure 5 Enlarged view of the structure at B in the figure.

[0038] Figure 7 It is a bottom view of the first shell in the utility model.

[0039] Figure 8 It is a three-dimensional diagram of the second shell in the utility model.

[0040] Fig. 9 It is a cross-sectional view of the second shell in the utility model.

[0041] Among them, 1-first shell, 11-extrusion rib, 2-second shell, 3-filter membrane, 4-pre-filter membrane, 41-first pre-filter membrane, 42-second pre-filter membrane, 43-pre-filter area, 44-annular action area, 5-extrusion area, 51-first area, 52-second area, 53-third area, 6-limiting area, 7, 8-flow gap, 81-inlet, 82-outlet. DETAILED DESCRIPTION

[0042] In order to enable those skilled in the art to better understand the solution of the utility model, the following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the utility model.

[0043] like Figure 1-Figure 3 As shown, a syringe filter includes a first shell 1, a second shell 2, and a filter membrane 3. The outer edges of the first shell 1 and the second shell 2 form a sealed connection, and the filter membrane 3 is sealed and fixed between the first shell 1 and the second shell 2. Specifically, in this embodiment, the filter membrane 3 is welded and fixed to the inner surface of the second shell 2. At the same time, the first shell 1 presses down on the outer periphery of the filter membrane 3. Of course, it is not a necessary structure for the first shell 1 to press the filter membrane 3 downward, and it is also possible not to press the outer periphery of the filter membrane 3. Of course, in other embodiments, the filter membrane 3 can also be fixedly connected to the inner surface of the second shell 2 in other forms. The filter membrane 3 can also be sealed and fixed to the inner surface of the first shell 2, without specific limitation.

[0044] At least one layer of pre-filter membrane 4 is stacked on the upstream side of the filter membrane 3. The materials of the filter membrane 3 and the pre-filter membrane 4 can be different. There is no need to consider the sealing bonding or welding between the two during the assembly process, which simplifies the assembly process. In a specific embodiment, the material of the pre-filter membrane 4 can be glass fiber, and the material of the filter membrane 3 can be at least one of PP and PE. The pore size of the pre-filter membrane 4 is larger than that of the filter membrane 3. In other words, the pre-filter membrane 4 first intercepts larger particles upstream of the filter membrane 3. Figure 4 As shown, the pre-filtering membrane 4 includes a pre-filtering area 43 and an annular action area 44 integrally formed on the periphery of the pre-filtering area 43. Specifically, the radial width L2 of the annular action area 44 on one side is 0.1-4% of the outer diameter L1 of the pre-filtering membrane 4, that is, L2 / L1=0.1-4%. If the ratio of L2 to L1 is too small, the mutual contact area between the squeezing area 5 and the annular action area 44 is too small, and the positioning effect on the pre-filtering membrane 4 is not stable enough; because the filtering effect of the annular action area 44 is relatively slightly worse than that of the pre-filtering area 43, if the ratio of L2 to L1 is too large, the filtering area loss of the pre-filtering area 43 is too large, the pre-filtering effect is not good, and the pollution holding capacity of the pre-filtering membrane 4 is small. When L2 / L1 is less than 0.1%, the squeezing area 5 cannot play a stable positioning role on the pre-filtering membrane 4, and when L2 / L1 is greater than 4%, the annular action area 44 occupies too large an area, and the overall pollution holding capacity of the pre-filtering membrane 4 is reduced to a certain extent. At a ratio of L2 / L1=0.1-4%, a stable squeezing effect can be ensured, while the maximum effect of the pre-filtration membrane 4 can be brought into play as much as possible.

[0045] like Figure 3 , Figure 5 , Figure 7 As shown, the inner surface of the first shell 1 has a squeezing area 5 at a position corresponding to the annular action area 44, which squeezes the annular action area 44 toward the filter membrane 3 to position the pre-filter membrane 4 and prevent the pre-filter membrane 4 from moving radially.

[0046] In the syringe filter of the present invention, at least one pre-filter membrane 4 is arranged upstream of the filter membrane 3, the pore size of the pre-filter membrane 4 is larger than the pore size of the filter membrane 3, and the annular action area 44 of the pre-filter membrane 4 is squeezed and positioned by the squeezing area 5 of the first shell 1; during the filtering process, the material to be filtered flowing in from the inlet 81 will tend to first pass through the pre-filter area 43 of the pre-filter membrane 4, so that larger particles are retained by the pre-filter area 43; it should be emphasized that the positioning connection method of the pre-filter membrane 4 is different from that of the filter membrane 3, the pre-filter membrane 4 is not welded and fixed to the second shell 2, nor is it welded and fixed to the filter membrane 3, so that part of the material to be filtered will also flow radially outward to the surface of the annular action area 44, and roughly along the surface of the pre-filter area 44. Figure 3The direction indicated by the middle arrow passes through the annular action area 44, and the large particle pollutants are intercepted by the annular action area 44. The pre-filtrate continues to flow downward to reach the upstream surface of the filter membrane 3, that is, the annular action area 44 of the pre-filter membrane 4 can also play a role in receiving pollutants, thereby increasing the pollutant receiving capacity of the pre-filter membrane 4. In other words, the annular action area 44 not only plays a role in positioning and installing the pre-filter membrane 4, but also plays a filtering role. Therefore, the entire area of ​​the pre-filter membrane 4 can play a filtering role. Since the welding operation is omitted, the manufacturing process of the filter is simplified, and the filtering area of ​​the pre-filter membrane 4 is also avoided. By using the combination of the pre-filter membrane 4 and the filter membrane 3, both large particles and small particles can be intercepted at the same time, which greatly increases the pollutant receiving capacity of the filter. Moreover, the entire area of ​​the pre-filter membrane 4 plays a filtering role, and there is no partial area that cannot play a filtering role due to welding, thereby avoiding the problem of premature clogging caused by the use of the filter membrane 3 alone, extending the service life of the filter membrane 3, and then greatly extending the service life of the filter.

[0047] like Figure 6 As shown, the extrusion area 5 is a curved surface, which includes at least a first area 51 and a second area 52, and the second area 52 is integrally formed on the radially outer side of the first area 51. The extrusion area 5 extrudes the annular action area 44 toward the direction where the filter membrane 3 is located, which means that at least the first area 51 is pressed against the annular action area 44. Specifically, the first area 51 may be pressed against the annular action area 44, or both the first area 51 and the second area 52 may be pressed against the annular action area 44, or part of the first area 51 and part of the second area 52 may be pressed against the annular action area 44. The curved surface of the extrusion area 5 is relative to a flat surface, and is specifically an arc curved surface, or an irregular curved surface, without limitation.

[0048] The squeezing area 5 is designed to be a curved structure, which contacts and squeezes the annular action area 44 over a larger area. The force exerted by the squeezing area 5 on the annular action area 44 includes components in various directions, forming a pressing effect on the annular action area 44 in various directions, making the positioning and installation of the pre-filtration membrane 4 more stable. At the same time, it avoids excessive squeezing strength between the squeezing area 5 and the annular action area 44, which would cause the annular action area 44 to be too dense and the filtered liquid to be unable to pass through smoothly.

[0049] In this embodiment, the extrusion zone 5 further includes a third zone 53, which is integrally formed on the radial inner side of the first zone 51. Figure 6Taking the direction shown as an example, the second area 52, the first area 51 and the third area 53 are arranged successively from the outside to the inside. Specifically, the first area 51 protrudes inward toward the inside of the first shell 1, and the second area 52 and the third area 53 are recessed outward toward the outside of the first shell 1. In this way, the first area 51 can better exert the pressing and holding effect on the annular action area 44, and the second area 52 and the third area 53 can provide space to accommodate the deformation of the annular action area 44 after being squeezed, so as to avoid the inability to effectively position and install the annular action area 44 due to the squeezing and deformation, and at the same time avoid the annular action area 44 from being squeezed excessively, so that the annular action area 44 can smoothly permeate liquid, and form a gap for liquid to flow through in the range corresponding to the second area 52 and the third area 53 and the annular action area 44.

[0050] Here, it should be noted that the first zone 51 bulging inwardly toward the inner side of the first shell 1 means that the first zone 51 bulges toward the interior of the first shell 1, and the second zone 52 and the third zone 53 are recessed outwardly toward the outer side of the first shell 1 means that the second zone 52 and the third zone 53 are recessed toward the outer surface of the first shell 1.

[0051] In this embodiment, the first area 51, the second area 52 and the third area 53 are all arc-shaped surfaces, and the two sides of the first area 51 are smoothly connected to the second area 52 and the third area 53, respectively. In other words, in this embodiment, the squeezing area 5 is a concave-convex structure. The first area 51, the second area 52 and the third area 53 are smoothly connected arc-shaped surfaces, and their squeezing effect on the pre-filter membrane 4 is not too sharp, so as to avoid damage to the pre-filter membrane 4 after being pressed, and the design of the arc-shaped surface enables the liquid to be filtered to quickly reach the surface of the annular action area 44; in addition, the smooth transition arc-shaped surface also makes the flow resistance of the liquid to be filtered relatively small.

[0052] like Figure 5 , Figure 7 As shown, the inner surface of the first shell 1 has a plurality of extrusion ribs 11 located radially inside the extrusion zone 5, and the extrusion ribs 11 extend radially, and the end faces of the extrusion ribs 11 contact and abut against the upstream surface of the pre-filter membrane 4, thereby forming a stable axial positioning effect on the pre-filter membrane 4, and a cavity for the flow of the filtered liquid is formed between adjacent extrusion ribs 11, so that the extrusion ribs 11 play a role in guiding the flow of the filtered liquid, and the flow distribution of the filtered liquid at various locations on the inner surface area of ​​the first shell 1 is relatively balanced, thereby avoiding local failure of the pre-filter membrane 4 due to a large amount of local filtered liquid, and extending the service life of the pre-filter membrane 4.

[0053] like Figure 1-Figure 3As shown, the pre-filter membrane 4 at least includes a first pre-filter membrane 41 and a second pre-filter membrane 42. The first pre-filter membrane 41 is located upstream of the second pre-filter membrane 42, that is, the first pre-filter membrane 41 is closer to the inlet 81, and the second pre-filter membrane 42 is adjacent to the filter membrane 3. The pore size of the first pre-filter membrane 41 may be larger than the pore size of the second pre-filter membrane 42, and the outer edge of the first pre-filter membrane 41 protrudes radially outward relative to the outer edge of the second pre-filter membrane 42. In other words, the first pre-filter membrane 41 and the second pre-filter membrane 42 are centered and stacked axially up and down, and the outer diameter of the first pre-filter membrane 41 is larger than the outer diameter of the second pre-filter membrane 42.

[0054] In addition, the thickness of the first pre-filter membrane 41 is smaller than that of the second pre-filter membrane 42, so that the first pre-filter membrane 41 can fully intercept large particles of pollutants, and the second pre-filter membrane 42 can fully intercept medium particles of pollutants. In practice, the number of large particles of pollutants is less than the number of medium particles of pollutants, so it is more reasonable that the thickness of the first pre-filter membrane 41 is smaller than that of the second pre-filter membrane 42, which is adapted to the particle distribution in the liquid to be filtered, and avoids the waste of the pre-filter membrane 4.

[0055] The squeezing area 5 of the above structure at least presses the annular action area 44 of the first pre-filter membrane 41, specifically, the squeezing area 5 only directly presses the annular action area 44 of the first pre-filter membrane 41, and indirectly presses the annular action area 44 of the second pre-filter membrane 42 through the first pre-filter membrane 41; or, the squeezing area 5 not only directly presses the annular action area 44 of the first pre-filter membrane 41, but also directly presses the annular action area 44 of the second pre-filter membrane 42. Figure 3 As shown, in this embodiment, part of the squeezing area 5 is pressed on the annular action area 44 of the first pre-filter membrane 41, and indirectly presses the annular action area 44 of the second pre-filter membrane 42 through the first pre-filter membrane 41, and part of the squeezing area 5 is directly pressed on the annular action area 44 of the second pre-filter membrane 41. Whether the squeezing area 5 is pressed on the annular action area 44 of the first pre-filter membrane 41 and the annular action area 44 of the second pre-filter membrane 42 respectively, or the squeezing area 5 is directly pressed on the annular action area of ​​the first pre-filter membrane 41, it can not only achieve a good positioning and installation effect on the first pre-filter membrane 41 and the second pre-filter membrane 42, but also reduce the squeezing effect strength on the annular action area 44 of the second pre-filter membrane 42, which is conducive to the filtering function of the annular action area 44 of the second pre-filter membrane 42.

[0056] The radial width of the annular action area of ​​the first pre-filter membrane 41 is greater than the radial width of the annular action area 44 of the second pre-filter membrane 42, that is, Figure 3, the radial width of the annular action area 44 of the first pre-filter membrane 41 is L3, and the radial width of the annular action area 44 of the second pre-filter membrane 42 is L4, then L3>L4. In other words, the radial starting ends of the annular action area 44 of the first pre-filter membrane 41 and the annular action area 44 of the second pre-filter membrane 42 are located in the same vertical plane, and the radial terminal end of the annular action area 44 of the first pre-filter membrane 41 is located outside the radial terminal end of the annular action area 44 of the second pre-filter membrane 42. With such arrangement, on the one hand, the extrusion area 5 directly contacts and squeezes the annular action area 44 of the first pre-filter membrane 41, thereby achieving a good positioning and installation effect on the first pre-filter membrane 41 and the second pre-filter membrane 42; on the other hand, the extrusion intensity on the annular action area 44 of the second pre-filter membrane 42 is reduced, which is beneficial to the realization of the filtering function of the annular action area 44 of the second pre-filter membrane 42. In addition, it ensures that the material to be filtered must first pass through the annular action area 44 of the first pre-filter membrane 41 with a larger pore size, and then pass through the annular action area 44 of the second pre-filter membrane 42 with a slightly smaller pore size, that is, to achieve graded retention of particulate pollutants of different sizes, thereby ensuring the filtering effect of the material.

[0057] Specifically, in this embodiment, Figure 3 As shown, the end face and the outer peripheral wall of the annular action area 44 of the first pre-filter membrane 41 are squeezed and matched with the first area 51, the second area 52, and the third area 53, and part of the end face and part of the outer peripheral wall of the annular action area 44 of the second pre-filter membrane 42 are squeezed and matched with the second area 52.

[0058] like Figure 5-Figure 7 As shown, the inner surface of the first shell 1 also has a limiting area 6 located radially outside the extrusion area 5, and the limiting area 6 extends axially to form a radial limitation on at least part of the pre-filter membrane 4. Specifically, according to the direction shown in the figure, the limiting area 6 is located axially below the extrusion area 5, so that the auxiliary extrusion area 5 further prevents the pre-filter membrane 4 from shifting radially.

[0059] Preferably, a flow gap 7 is formed between the outer peripheral wall of the annular action area 44 of the second pre-filter membrane 42 and the limiting area 6, and the flow gap 7 is for the filtered liquid to pass through, that is, after a part of the filtered liquid passes through the annular action area 44 of the first pre-filter membrane 41, it flows into the flow gap 7 and directly flows downward to reach the upstream surface of the filter membrane 3 without passing through the filtering action of the second pre-filter membrane 42; or, when the annular action area 44 of the first pre-filter membrane 41 is blocked, the filtered liquid can pass through the extrusion area 5 and the annular action area 44 of the first pre-filter membrane 41, flow into the flow gap 7 to reach the annular action area 44 of the second pre-filter membrane 42 or the upstream surface of the filter membrane 3.

[0060] When the extrusion zone 5 includes at least a first zone 51 and a second zone 52 integrally formed on the outside of the first zone 51, the limiting zone 6 is integrally formed on the radial outside of the second zone 52, and a portion of the second zone 52 is pressed against the outer edge area of ​​the annular action zone 44 of the second pre-filter membrane 42, and a flow gap 8 for the filtered liquid to pass through is formed between another portion of the second zone 52 and the outer peripheral wall of the annular action zone 44 of the second pre-filter membrane 42, and the flow gap 8 is located axially above the flow gap 7, and the two are integrated.

[0061] The arrangement of the above-mentioned flow gaps 8 and 7 allows the filtered liquid to flow radially through the extrusion zone 5 and the annular action zone 44 of the first pre-filter membrane 41, and flow directly and quickly to the filter membrane 3 through the flow gaps 8 and 7 for filtration when the annular action zone 44 of the first pre-filter membrane 41 is blocked by large particle pollutants, or when the annular action zone 44 of the first pre-filter membrane 41 and the annular action zone 44 of the second pre-filter membrane 42 are both blocked by large particle pollutants. The filter liquid can be further utilized.

[0062] The above description mentioned that since the pre-filter membrane 4 is not welded and fixed to the second shell 2, nor is it welded and fixed to the filter membrane 3, the liquid to be filtered can pass through the annular action area 44 of the pre-filter membrane 4, and the entire area of ​​the pre-filter membrane 4 can play a role in absorbing pollutants. It is not ruled out that after the overall pores of the pre-filter membrane 4 are occupied by pollutants, the flow resistance formed by the pre-filter membrane 4 on the liquid to be filtered is greater than the flow resistance formed by the extrusion effect between the extrusion area 5 of the first shell 1 and the annular action area 44 of the pre-filter membrane 4. As a result, the liquid to be filtered may flow through between the extrusion area 5 of the first shell 1 and the annular action area 44 of the pre-filter membrane 4. At this time, the liquid to be filtered that flows through can directly enter the flow gaps 8 and 7, and then be filtered by the filter membrane 3.

[0063] Combined with the curved structure of the extrusion zone 5, when the first pre-filter membrane 41 and the second pre-filter membrane 42 are blocked, when the filtered liquid flows through the extrusion zone 5, it can flow along the third zone 53 to the first zone 51. Under the accumulation effect of the third zone 53 and the blocking effect of the first zone 51, the filtered liquid can more easily flow through the extrusion zone 5 of the first shell 1 and the annular action zone 44 of the first pre-filter membrane 41, and then flow to the flow gaps 8 and 7 more quickly, thereby improving the filtering efficiency of the filter.

[0064] The working process of the utility model is described by taking the pre-filter membrane 4 including the first pre-filter membrane 41 and the second pre-filter membrane 42 as an example. Of course, in other embodiments, the pre-filter membrane 4 can be provided with more numbers, and there is no specific limitation. In the early stage of filtration, a large amount of the material to be filtered tends to first pass through the pre-filter area 43 of the first pre-filter membrane 41 and the second pre-filter membrane 42. At this time, the annular action area 44 plays a greater role in positioning and installation. Of course, part of the material to be filtered can also penetrate from the annular action area 44. A small amount of the material to be filtered flows through between the extrusion area 5 of the first shell 1 and the annular action area 44 of the first pre-filter membrane 41. That is to say, most of the material to be filtered flowing to the filter membrane 3 has been preliminarily filtered by the pre-filter membrane 4. The first pre-filter membrane 41 and the second pre-filter membrane 42 share the filtration pressure of the filter membrane 3, so that the filter membrane 3 can be more fully utilized.

[0065] In the middle of filtration, the pores of the pre-filtration area 43 of the first pre-filtration membrane 41 and the second pre-filtration membrane 42 are occupied by pollutants, and at this time the filter membrane 3 has not yet reached its maximum service life, and the filtrate to be filtered can continue to penetrate from the annular action area 44 of the first pre-filtration membrane 41 and the second pre-filtration membrane 42, and then flow to the filter membrane 3, and the filter membrane 3 can continue to filter while intercepting larger and smaller particles. At this time, the filtering effect of the annular action area 44 is greater than the positioning and installation effect, and the annular action area 44 of the first pre-filtration membrane 41 and the second pre-filtration membrane 42 both play the maximum filtering effect. Compared with the welding and fixing of the pre-filtration membrane and the second shell 2 and the filter membrane 3, the welding area cannot play the filtering effect, and the extrusion area 5 of the first shell 1 is used to realize the extrusion positioning and installation of the annular action area 44. On the premise of playing the positioning and installation effect, the annular action area 44 can also play the filtering effect, so that the filtering area of ​​the pre-filtration membrane 4 is increased, the pollution holding capacity of the pre-filtration membrane 4 is improved, and the filtering pressure of the filter membrane 3 is greatly reduced. As the flow resistance of the pre-filter membrane 4 to the liquid to be filtered increases, more liquid to be filtered flows through between the squeezing area 5 of the first housing 1 and the annular action area 44 of the first pre-filter membrane 41, enters the flow gaps 8 and 7, and flows directly to the filter membrane 3;

[0066] In the later stage of filtration, the pores in the pre-filtration area 43 and the annular action area 44 of the first pre-filtration membrane 41 and the second pre-filtration membrane 42 are occupied by pollutants, and the filtered liquid can flow through between the extrusion area 5 of the first shell 1 and the annular action area 44 of the first pre-filtration membrane 41, enter the flow gaps 8 and 7, and finally flow directly to the filter membrane 3, which greatly extends the service life of the filter membrane 3, and then extends the service life of the filter.

[0067] The above specific implementation modes are used to explain the present invention rather than to limit the present invention. Any modification and change made to the present invention within the spirit of the present invention and the protection scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A syringe filter, comprising a first shell and a second shell formed in a sealed connection at the outer edges, and a filter membrane sealed and fixed between the first shell and the second shell, characterized in that: At least one layer of pre-filter membrane is stacked on the upstream side of the filter membrane, and the pore size of the pre-filter membrane is larger than the pore size of the filter membrane; The pre-filtration membrane comprises a pre-filtration area and an annular action area integrally formed on the periphery of the pre-filtration area; The inner surface of the first shell has a pressing area at a position corresponding to the annular action area, and the pressing area presses the annular action area toward the direction where the filter membrane is located to form the positioning of the pre-filter membrane.

2. The syringe filter according to claim 1, characterized in that: The extrusion zone is a curved surface, which includes at least a first zone and a second zone, wherein the second zone is integrally formed on the radially outer side of the first zone, and at least the first zone is pressed against the annular action zone.

3. The syringe filter according to claim 2, characterized in that: The extrusion zone further includes a third zone which is integrally formed radially inside the first zone, the first zone protrudes inwardly toward the inside of the first shell, and the second zone and the third zone are recessed outwardly toward the outside of the first shell.

4. The syringe filter according to claim 3, characterized in that: The first area, the second area and the third area are all arc-shaped surfaces, and two sides of the first area are smoothly connected to the second area and the third area respectively.

5. The syringe filter according to claim 1, characterized in that: The pre-filter membrane comprises at least a first pre-filter membrane and a second pre-filter membrane, wherein the first pre-filter membrane is located upstream of the second pre-filter membrane, an outer edge of the first pre-filter membrane protrudes radially outward relative to an outer edge of the second pre-filter membrane, and the extrusion zone is at least pressed on an annular action area of ​​the first pre-filter membrane.

6. The syringe filter according to claim 5, characterized in that: The pore size of the first pre-filter membrane is larger than that of the second pre-filter membrane, and the radial width of the annular action area of ​​the first pre-filter membrane is larger than that of the second pre-filter membrane.

7. The syringe filter according to claim 5, characterized in that: The inner surface of the first shell further comprises a limiting area located radially outside the squeezing area, and the limiting area extends axially to form radial limiting for at least part of the pre-filter membrane.

8. The syringe filter according to claim 7, characterized in that: A flow gap is formed between the outer peripheral wall of the annular action area of ​​the second pre-filter membrane and the limiting area for the liquid to be filtered to pass through; and / or, The extrusion zone includes at least a first zone and a second zone integrally formed on the outside thereof, the limiting zone is integrally formed on the radial outside of the second zone, a portion of the second zone is pressed against the outer edge area of ​​the annular action zone of the second pre-filter membrane, and a flow gap is formed between another portion of the second zone and the outer peripheral wall of the annular action zone of the second pre-filter membrane for the passage of the filtered liquid.

9. The syringe filter according to claim 1, characterized in that: The radial width of one side of the annular action zone is 0.1%-4% of the outer diameter of the pre-filtration membrane.

10. The syringe filter according to claim 1, characterized in that: The inner surface of the first shell has a plurality of extrusion ribs located radially inward of the extrusion zone, whose end faces contact and abut against the upstream surface of the pre-filter membrane, and cavities for the flow of the filtered liquid are formed between adjacent extrusion ribs.

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