Filtration equipment, especially small filtration equipment for the manufacture of biopharmaceuticals.

Abstract

A filtration device (10), particularly a small filtration device for the manufacture of biopharmaceuticals, comprises a housing including an upper cover (12) having an unfiltered liquid inlet (18) and a lower cover (14) having a filtrate outlet (22), and one or more filter supports (16) stacked vertically between the upper cover (12) and the lower cover (14), with the upper side of each filter support (16) facing the upper cover (12) and the lower side of each filter support (16) facing the lower cover (14). Each filter support (16) is fitted with a flat upper filter (40) and a flat lower filter (42), and each filter (40, 42) has a filtrate side and an unfiltered liquid side on the opposite side. The upper and lower filters (40, 42) are sealed to the upper and lower sides of the filter support (16), respectively, such that the filtrate side faces the filter support (16) and the unfiltered liquid side faces away from the filter support (16). The unfiltered liquid flow path extends from the unfiltered liquid inlet of the upper cover (12) to the unfiltered liquid side of the upper filter (40) and the unfiltered liquid side of the lower filter (42), and the blocking means prevents the unfiltered liquid from flowing directly from the unfiltered liquid inlet of the upper cover (12) to the filtrate outlet (22) of the lower cover (14). The filtrate flow path extends from the filtrate sides of the upper and lower filters (40, 42) to the filtrate outlet (22) of the lower cover (14) via at least one filtrate guide flow path (48a, 48b) formed on the upper side of the filter support (16) and at least one filtrate guide flow path (48a, 48b) formed on the lower side of the filter support (16). The upper filter (40) and the lower filter (42) have the same shape.

Description

Technical Field

[0001] The present invention relates to a filtration device, particularly a small-scale filtration device for the production of biopharmaceuticals.

[0002] In the context of the present invention, a small-scale filtration device means a device used for extremely small batches ranging from a few milliliters to a few liters, and the effective filtration area is about 5 to 100 square centimeters. For example, such a small amount of intravenous pharmaceuticals may be filtered by a small-scale filtration device immediately before being administered to a patient. However, the concept of the present invention is also applicable to larger filtration devices with an effective filtration area of up to about 300 square centimeters or more.

Background Art

[0003] From European Patent Application Publication No. 2363197 (EP 2363197 A2), a filtration cartridge having a fluid inlet and a fluid outlet is known. This filtration cartridge includes an upper end cap, a lower end cap, and a vent provided in at least one of these caps. One or more filtration units are provided, and each filtration unit has two filter plates. Each filter plate includes a membrane support plate having at least one filtration membrane, and the filtration membranes are respectively joined to the lower and upper surfaces of the membrane support plate. The membrane support plates of the two filter plates are joined to each other at their outer peripheral surfaces to form a seal, whereby fluid supply cannot enter the fluid outlet unless it passes through at least one filtration membrane. A fluid flow path is provided from the fluid inlet through the filtration membrane and further through the fluid outlet. This fluid flow path prevents the fluid supply from bypassing the filtration membrane from the inlet and provides a single filtrate passage including a row of holes for the filtrate to flow to the fluid outlet. The filtration membranes joined to the lower and upper surfaces of the membrane support plate have different dimensions respectively. Since they must not be confused with each other, the assembly of the filtration cartridge becomes complicated and misassembly is likely to occur.

Summary of the Invention

[0004] The present invention aims to provide a compact filtration device that is easy to assemble and can increase the effective filtration area per membrane, particularly a compact filtration device for the production of biopharmaceuticals.

[0005] The above problems are solved by the filtration device described in claim 1 and the filter support for the filtration device described in claim 17. Preferred advantageous embodiments of the present invention are evident from the respective dependent claims.

[0006] The present invention provides a filtration device, particularly a small filtration device for the manufacture of biopharmaceuticals. The filtration device comprises a housing including an upper cover having an unfiltered liquid inlet and a lower cover having a filtrate outlet, and one or more filter supports stacked vertically between the upper and lower covers, with the upper side of each filter support facing the upper cover and the lower side of each filter support facing the lower cover. Each filter support is fitted with a flat upper filter and a flat lower filter (e.g., a membrane). Each filter has a filtrate side and an unfiltered liquid side on the opposite side. The upper and lower filters are sealed to the upper and lower sides of the filter support, respectively, such that the filtrate side faces the filter support and the unfiltered liquid side faces away from the filter support. An unfiltered liquid flow path extends from the unfiltered liquid inlet of the upper cover to the unfiltered liquid side of the upper filter and the unfiltered liquid side of the lower filter, and a blocking means prevents the unfiltered liquid from flowing directly from the unfiltered liquid inlet of the upper cover to the filtrate outlet of the lower cover. The filtrate flow path extends from the filtrate side of the upper and lower filters to the filtrate outlet of the lower cover, via at least one filtrate guide flow path formed on the upper side of the filter support and at least one filtrate guide flow path formed on the lower side of the filter support. The upper and lower filters have the same shape.

[0007] In its assembled state, the filtration device forms a single, integrated structure. That is, the upper cover, lower cover, and filter support(s), and the filter provided on and sealed on the filter support, are connected to each other, preferably by welding. Alternative connection methods include mechanical assembly methods such as clamping, bonding, joining, overmolding, and screwing (with seals as needed). In any case, the housing is a fluid-sealed enclosure and may include at least a separate component or part surrounding the filter support, or it may be formed by the upper and lower covers and the outer portion of the filter support, as will be further described below.

[0008] Regarding the term "vertical direction," it should be understood that the filtration device is designed so that the fluid flow from the unfiltered liquid inlet to the filtrate outlet is at least assisted by gravity. Therefore, the orientation of the filtration device when in use is upright, with the upper cover positioned above the filter support(s) and the lower cover. Of course, the "vertical direction" does not need to be perfectly vertical.

[0009] The filters used in filtration devices are preferably flat filter membranes. However, depending on the application, other types of filters, such as nonwoven fabric filters or woven fabric filters, can also be used. The filters may consist of a single layer of filter media with a thickness of approximately 100 μm, but it is also possible to use multiple layers of filter media or fibrous materials with a maximum thickness of about 1000 μm (i.e., 10 times the thickness of single-layer filter media), such as PP / PET meltblown, spunbond, or short-fiber wet-molded bodies.

[0010] In the context of the present invention, "sealed" preferably means that a tight connection is formed, particularly to prevent bacteria and / or viruses from passing through. "Sealed" should not be interpreted narrowly and may also include connections formed by methods such as welding, joining, clamping, bonding, and overmolding.

[0011] A key aspect of the present invention lies in the use of filters of the same shape. That is, at least the upper and lower filters sealed on the same filter support are of the same shape. Preferably, all filters in the filtration device are of the same shape, so that all filters used in the device have the same geometric design. In this context, "identically shaped" refers to the geometric shape, particularly the shape in a plane perpendicular to the vertical direction. Therefore, even if the filter properties differ, such as material, pore size, and vertical thickness, they are considered "identical" as long as the horizontal dimensions and shape, especially the contour, are the same. In other words, it is required that the filters are congruent when viewed from above or below.

[0012] This invention is based on the finding that the assembly of a filtration device can be significantly simplified by using filters of the same shape. Since filters of the same shape can be fitted to either side of the filter support, there is no risk of attaching the filter to the wrong side of the filter support.

[0013] The filtrate guide channels formed on the upper and lower sides of the filter support should be distinguished, on the one hand, from mere protrusions on which the filter membrane is placed. On the other hand, the filtrate guide channels should also be distinguished from irregularly distributed pores in a porous or perforated filter support. Rather, the filtrate guide channels are dedicated structures that define a channel for directly guiding the filtrate to the area connected to the filtrate outlet of the filtration device.

[0014] According to a preferred embodiment, the filtrate guide channel extends substantially horizontally and opens into a discharge port that extends vertically through the entire filter support. This discharge port is fluidly connected to the filtrate outlet of the lower cover. Of course, the filtrate guide channel may be slightly inclined toward the discharge port to ensure effective discharge of the filtrate.

[0015] In a preferred embodiment of the filtration device, an upper structure and a lower structure are formed on the upper and lower sides of each filter support, respectively, both of which form an inner structure, preferably a central structure, surrounding the outer periphery of the discharge hole. Each inner structure includes an inner welded region, which is liquid-tightly welded to a corresponding inner welded region of an adjacent filter support, or to a corresponding inner welded region of the upper cover, or to a corresponding inner welded region of the lower cover. This inner welded region enables mechanical connection of the upper cover, lower cover, and multiple filter supports stacked in between within the inner region of the filtration device, greatly contributing to the overall stability of the filtration device.

[0016] In general, the term "welding area" should not be understood restrictively. As mentioned above, the upper cover, lower cover, filter support, and / or annular wall of the housing of the filtration device can be connected to each other, preferably by welding. For this reason, the term "welding area" is used herein. However, as mentioned above, welding areas can also be connected by other connection techniques. This applies to both inner and outer welding areas (outer welding areas will be discussed later).

[0017] To enable the filter to be sealed in a position directly adjacent to the inner weld region, the inner structure further includes an inner sealing region, which surrounds and is adjacent to the inner weld region. The inner sealing region is sealed to the inner region of the corresponding filter, either the upper or lower filter. To form a fluid space accessible to unfiltered liquid between adjacent filter supports and to prevent the inner sealing region from interfering with the inner weld region, the inner sealing region is offset vertically from the inner weld region.

[0018] In a preferred design, both the inner welded area and the inner sealing area have multiple bulges and multiple intermediate sections, the bulges being substantially identical in shape to each other, the intermediate sections being substantially identical in shape to each other, the bulges and intermediate sections being alternately arranged around the discharge port, and the bulges extending horizontally from the discharge port. Depending on the number and specific shape of the bulges and intermediate sections, the internal structure may appear clover-shaped, triangular, cross-shaped, or star-shaped. Such a configuration allows the fluid, after being filtered, to be guided to a specific area of ​​the intermediate section and from there to reach the discharge port.

[0019] Preferably, the number of bulges and intermediate sections in the upper and lower structures is the same, and the shape and dimensions of the bulges and intermediate sections of the internal structure are also substantially the same. This means that the overall shape of the upper and lower internal structures of the filter support is basically the same. Considering the size of the filtration device, the total number of bulges on both sides is preferably equal to the total number of intermediate sections and does not exceed 7, preferably 3, 4, or 5.

[0020] As a further improvement to this preferred design, the internal structure of the upper structure is positioned such that it is rotationally offset with respect to the internal structure of the lower structure in the vertical direction. This causes the bulge of the upper structure to face, preferably exactly, the middle section of the lower structure, and vice versa.

[0021] In a preferred design, the filtrate guide channels on the upper and lower sides of the filter support are spaced apart from each other in the circumferential direction and preferably alternately lead to the bulging and intermediate portions of the upper and lower structures. The most effective arrangement is when the filtrate guide channels are regularly spaced at equal angles.

[0022] Preferably, the number of filtrate guide channels is the same as the total number of bulging and intermediate sections of the inner structure. However, this is not mandatory.

[0023] An advantage is that the fluid can flow to the other side of the filter support after passing through the filter on one side of the filter support. This allows the filtrate to be directed to the discharge port on the other side of the filter support, if necessary. For this purpose, at least one, preferably all, of the filtrate guide channels of the upper structure are positioned opposite the filtrate guide channels of the lower structure. These opposing filtrate guide channels are interconnected by a number of through-holes that allow the filtrate to pass from one filtrate guide channel to the other opposing filtrate guide channel.

[0024] If the filtrate can pass through to the opposing filtrate guide channel on the other side of the filter support, then it is sufficient that only the filtrate guide channels leading to the intermediate section on both the upper and lower sides of the filter support are fluidically connected to the discharge port. In other words, fluid in a filtrate guide channel leading to the bulge that is not fluidically connected to the discharge port can "switch sides" through the filtrate guide channel leading to the intermediate section on the opposite side and flow to the discharge port. Such a fluid connection between the filtrate guide channel and the discharge port is established by the filtrate guide channel entering the material of the filter support in the intermediate section on one side, before reaching the inner seal region, and then opening to an open space adjacent to the discharge port in the corresponding bulge on the opposite side of the filter support.

[0025] To ensure proper and stable (immovable) placement on the filter support, the upper and lower filters are sealed to outer seal regions formed on the upper and lower sides of the filter support, respectively, which surround the filtrate guide channel.

[0026] According to the first housing configuration, at least a part of the housing of the filtration device is formed by the outer part of the filter support. In particular, this housing includes outer welding regions continuously formed above and below each filter support. The outer welding region surrounds the outer seal region. The outer welding region is welded liquid-tightly to an adjacent filter support, or to the corresponding outer welding region of the upper cover, or to the corresponding outer welding region of the lower cover. According to this configuration, additional housing parts are not required, and the overall size of the filtration device is minimized depending only on the number of filter supports.

[0027] According to the second housing configuration, the housing includes an annular wall surrounding at least the filter support. That is, additional housing parts are provided, which can greatly enhance the stability of the entire filtration device.

[0028] The filtration performance of the filtration device according to the present invention can be further enhanced by an additional filter held by the lower cover. In particular, the lower cover is provided with a flat bottom filter having a filtrate side and an unfiltered liquid side. The bottom filter is sealed above the lower cover such that its filtrate side faces the lower cover and its unfiltered liquid side faces away from the lower cover. The filtrate flow path extends from the filtrate side of the bottom filter to the filtrate outlet of the lower cover, preferably via at least one filtrate guiding flow path formed above the lower cover.

[0029] When the filtration area of the bottom filter is sufficient for the purpose of the filtration device, the filter support can be omitted. In this case, the filtration device does not include a filter support, and the upper cover is directly welded to the lower cover.

[0030] Unlike known devices, and regardless of the number of filter supports, the amount of retained liquid at the bottom of the filtration device is minimized by the filtrate flow path extending from the filtrate side of the bottom filter to the filtrate outlet of the lower cover. This is extremely important especially when handling expensive chemicals.

[0031] The present invention also provides a filter support for use in a filtration device. This filter support is configured to accommodate two flat upper and lower filters of the same shape. The filtrate flow path runs from the filtrate side of the upper and lower filters to the filtrate outlet of the lower cover, via at least one filtrate guide channel formed on the upper and lower sides of the filter support. Preferably, other features of the filter support are exactly the same as those related to the filtration device described above.

[0032] In general, the present invention achieves a significant reduction in the amount of stagnant liquid (dead volume) and more efficient utilization of the filter area. Furthermore, the lower filter provided on the filter support is positioned so that the chemical (or other medium to be filtered) can completely pass through the filter when air pressure is applied, resulting in the maximum recovery rate.

[0033] Further features and advantages of the present invention will become apparent from the following description and the accompanying drawings referenced herein. [Brief explanation of the drawing]

[0034] [Figure 1] An exploded view showing the components of a small filtration device according to the first embodiment of the present invention. [Figure 2] A perspective view of the assembled filtration system, seen from above. [Figure 3] A perspective view of the assembled filtration system, seen from below. [Figure 4] Side cross-sectional view of the assembled filtration device. [Figure 5] A perspective view showing one side of the filter support of a filtration device. [Figure 6] Figure 5 is a perspective view showing the opposite side of the filter support. [Figure 7] A detailed top view showing one side of the filter support of the filtration device. [Figure 8] A detailed top view of the filter support, showing the fluid flowing along the primary filtrate guide channel. [Figure 9]A cross-sectional view along line AA in Figure 8, showing a state where filters are provided on both sides of the filter support. [Figure 10] A detailed top view of the filter support, showing the fluid flowing along the secondary filtrate guide channel. [Figure 11] A cross-sectional view along line BB in Figure 10, showing a state where filters are provided on both sides of the filter support. [Figure 12] A detailed cross-sectional view of a filtration device consisting of three stacked filter supports, illustrating the fluid flow. [Figure 13] A detailed top view of the lower cover of the filtration device, showing the fluid flowing along the filtrate guide channel. [Figure 14] Figure 13 is a cross-sectional view along the CC line, showing a state where a filter is installed on the upper side of the lower cover. [Figure 15] A partially cutaway side view of a filtration device without a filter support. [Figure 16] A partially cutaway perspective view of a filtration device, showing nine filter supports housed in separate housings, viewed from the side. [Figure 17] A perspective view from above of a small filtration device according to a second embodiment of the present invention, in an assembled state. [Figure 18] Figure 17 is an exploded view of the components of the filtration device, seen from above. [Figure 19] An exploded view of the components of the filtration system, seen from below. [Figure 20] Figure 17 is a top view of the uppermost filter support of the filtration device, showing the filter mounted on the upper side of the filter support. [Figure 21] A perspective cross-sectional view of the filtration system, seen from the side. [Figure 22A] An exploded view illustrating possible fluid flow paths within a filtration device, with the filter itself omitted from the diagram. [Figure 22B] An exploded view showing a different disassembled state than Figure 22A. [Figure 22C] An exploded view showing a different disassembled state than Figures 22A and 22B. [Modes for carrying out the invention]

[0035] Figures 1 to 4 show a first embodiment of a small filtration device 10. The filtration device 10 comprises an upper cover 12, a lower cover 14, and a plurality of filter supports 16. The plurality of filter supports 16 are identical in shape and are stacked between the upper cover 12 and the lower cover 14. The actual number of filter supports 16 depends on the desired total effective filtration area and may be only one or even zero, as described later. The arrangement of the lower cover 14, the stacking of filter supports 16 (if present), and the upper cover 14 defines the vertical direction A.

[0036] The upper cover 12 includes an unfiltered liquid inlet 18 and a vent 20. In this example, the unfiltered liquid inlet 18 takes the form of an inlet connector. The vent 20 is optional. The lower cover 14 includes a filtrate outlet 22, which in this example takes the form of an outlet connector. The unfiltered liquid inlet 18 and the filtrate outlet 22 may be formed integrally with the upper cover 12 and the lower cover 14, respectively, or they may be attached later. Similarly, the vent pipe may be formed integrally with the vent 20 of the upper cover 12, or it may be attached later.

[0037] Figures 5 and 6 show one filter support 16. The filter support 16 is generally a flat disc shape, but may have other shapes. Multiple distribution holes 24 are formed on the periphery of the filter support 16, each extending vertically through the entire filter support 16 and fluidly connected to the unfiltered liquid inlet 18 of the upper cover 12. An outlet hole 26 (preferably located in the center) also extends vertically through the entire filter support 16. The outlet hole 26 is fluidly connected to the filtrate outlet 22 of the lower cover 14.

[0038] In the assembled state, the upper side of the filter support 16 faces the upper cover 12, and the lower side of the filter support 16 faces the lower cover 14. An upper structure 28 and a lower structure 30 are formed on the upper and lower sides of the filter support 16, respectively. The upper and lower structures 28 and 30 have the same shape, and further details are shown in Figure 7.

[0039] Both the upper structure 28 and the lower structure 30 form an inner structure that surrounds the outer circumference of the discharge hole 26. The inner structure includes an inner welded region 32 that is continuous in the circumferential direction. Depending on the position of the filter support 16 within the filtration device 10, the upward-facing inner welded region 32 of the upper structure 28 corresponds to an inner welded region 32 similarly formed downward on either the upper cover 12 or an adjacent filter support 16, and is liquid-tightly welded to this corresponding inner welded region 32. Similarly, the downward-facing inner welded region 32 of the lower structure 30 corresponds to an inner welded region 32 similarly formed upward on either the lower cover 14 or an adjacent filter support 16, and is liquid-tightly welded to this corresponding inner welded region 32. Ideally, the inner welded regions 32 that are welded to each other are congruent.

[0040] The inner structure further includes an inner seal region 34 that is continuous in the circumferential direction. Preferably, the inner seal region 34 is directly adjacent to and surrounds the inner weld region 32. The inner seal region 34 is vertically offset from the inner weld region 32. In particular, with respect to the arrangement in the assembled state of the filtration device 10, the inner weld region 32 of the upper structure 28 is positioned vertically lower than the adjacent inner seal region 34, and the inner weld region 32 of the lower structure 30 is positioned vertically higher than the adjacent inner seal region 34. The difference in vertical height between the inner weld region 32 and the inner seal region 34 on both sides of the filter support 16 is adapted to the thickness of the filter to be used, as will be described later.

[0041] The upper and lower structures 28 and 30 form outer structures on the upper and lower sides, respectively, around the periphery of the filter support 16. The outer structures include an outer sealing region 36 and an outer welding region 38, the outer welding region 38 being continuous in the circumferential direction and surrounding the outer sealing region 36. Depending on the position of the filter support 16 within the filtration device 10, the upward-facing outer welding region 38 of the upper structure 28 corresponds to the downward-facing outer welding region 38 of either the upper cover 12 or one of the adjacent filter support 16 above, and is liquid-tightly welded to this corresponding outer welding region 38. The downward-facing outer welding region 38 of the lower structure 30 corresponds to the upward-facing outer welding region 38 of either the lower cover 14 or one of the adjacent filter support 16 below, and is liquid-tightly welded to this corresponding outer welding region 38. Ideally, the outer welding regions 38 that are welded to each other coincide. Therefore, the upper and lower covers 12 and 14, together with the outer welded region 38 of the filter support 16 connected to them, form the housing of the filtration device 10.

[0042] The inner and outer sealing regions 34 and 36 of the filter support 16 seal to the flat filters 40 and 42, particularly the filter membranes (see Figures 4, 9, and 11). Specifically, the upper inner sealing region 34 of the filter support 16 seals to the filtrate-side inner region of the upper filter 40, and the upper outer sealing region 36 of the filter support 16 seals to the filtrate-side outer region of the upper filter 40. Similarly, the lower inner sealing region 34 of the filter support 16 seals to the filtrate-side inner region of the lower filter 42 of the same shape, and the lower outer sealing region 36 of the filter support 16 seals to the filtrate-side outer region of the lower filter 42. In other words, each filter support 16 is fitted with two filters 40 and 42 of the same shape, one on the upper side and one on the lower side of the filter support 16, and the unfiltered side of both filters is oriented away from the filter support 16.

[0043] As described above, filters 40 and 42 may be single-layer filter media or may contain multiple layers of filter media. Accordingly, the geometric features of the filter support 16, in particular the vertical offset between the inner welding region 32 and the inner sealing region 34, are adapted to the thickness of the filter on both sides of the filter support 16.

[0044] Between the inner and outer sealing regions 34, 36, the filters 40, 42 cover a plurality of filtrate collection channels 46. The filtrate collection channels 46 lead to filtrate guide channels 48a, 48b, both of which are formed in the upper and lower structures 28, 30 of the filter support 16, respectively. The filtrate collection channels 46 extend substantially horizontally, but preferably slightly inclined toward the filtrate guide channels 48a, 48b. The filtrate collection channels 46 may be formed by substantially parallel webs. Such webs may be formed as continuous walls (in which case a rigid support for the sealed filter 40 or 42 is provided) and / or as discontinuous walls (in which case the contact area between the filter 40 or 42 and the filtrate collection channels 46 is reduced, resulting in an increased effective filtration area).

[0045] As shown in Figures 5 to 7, on both sides of the filter support 16, the inner structure, i.e., the inner welded region 32 and the inner seal region 34, has a plurality of bulges 50 and a plurality of intermediate regions 52. The plurality of bulges 50 have substantially the same shape as each other, and the intermediate regions 52 have substantially the same shape as each other. The bulges 50 and intermediate regions 52 are arranged alternately along the outer circumference of the discharge hole 26. The bulges 50 extend radially and horizontally away from the discharge hole 26. The intermediate regions 52 are formed as recesses that extend radially and horizontally toward the discharge hole 26.

[0046] In the illustrated embodiment, the number of bulges 50 and intermediate portions 52 on both sides of the filter support 16 is four, and therefore it has a shape resembling a four-leaf clover. However, the number of regularly arranged bulges 50 and intermediate portions 52 may be three or more than four, but preferably seven or less. Furthermore, the intermediate portions 52 may be formed as straight sections without recesses. The bulges 50 and (if present) recesses may have rounded contours, or they may have sharp corners, such as triangular or square shapes.

[0047] In any case, the bulging portion 50 and the intermediate portion 52 of the inner structure have a shape that is rotationally symmetric with respect to the vertical direction A. The degree of rotational symmetry corresponds to the number of bulging portions 50. In the case of a four-leaf clover shape, rotating it by 90 degrees results in a perfectly identical shape, so the degree of rotational symmetry is 4.

[0048] In the illustrated embodiment, the number of filtrate guide channels 48a and 48b corresponds to the total number of bulging sections 50 and intermediate sections 52. The filtrate guide channels 48a and 48b are spaced apart from each other in the circumferential direction. Each filtrate guide channel 48a or 48b extends substantially radially from the outer seal region 36 to either the bulging section 50 or the intermediate section 52 of the inner structure. However, not all of the bulging sections 50 or intermediate sections 52 are necessarily associated with the filtrate guide channels 48a and 48b.

[0049] Only the filtrate guide channel 48a leading to the intermediate section 52 is directly and fluidly connected to the discharge hole 26. Hereafter, this channel will be referred to as the primary filtrate guide channel 48a. The filtrate guide channel 48b leading to the bulge section 50 terminates at the inner seal region 34 located at a high position in the inner structure and is not directly and fluidly connected to the discharge hole 26. Hereafter, this channel will be referred to as the secondary filtrate guide channel 48b. Details of the paths in the inner regions of the primary and secondary filtrate guide channels 48a and 48b will be described later in relation to the operation of the filtration device 10.

[0050] As described above, the upper and lower structures 28 and 30 of the filter support 16 are substantially identical to at least the inner structure and at least a portion of the filtrate guide channels 48a and 48b. However, the upper and lower structures 28 and 30 are arranged offset from each other in the rotational direction. In particular, the inner structures of the upper and lower structures 28 and 30 are arranged such that the bulge 50 of the upper structure 28 faces the intermediate portion 52 of the lower structure 30, and the intermediate portion 52 of the upper structure 28 faces the bulge 50 of the lower structure 30.

[0051] Due to the rotational offset between the upper and lower structures 28, 30, particularly the offset with respect to the inner seal region 34, the filter supports 16 are stacked on top of each other with the same amount of rotational offset. This is because the inner seal regions 34 of the opposing upper and lower structures 28, 30 need to be aligned with each other, and ideally they should coincide when welded together.

[0052] The primary filtrate guide channel 48a on one side of the filter support 16 is positioned directly opposite the secondary filtrate guide channel 48b on the other side of the filter support 16. Multiple through-holes 54 are formed in the filtrate guide channels 48a and 48b, thereby allowing fluid to be transferred from the secondary filtrate guide channel 48b on one side to the primary filtrate guide channel 48a on the other side (the reverse direction is also possible, but this is not the intended flow, as will be evident from the operation description of the filtration device 10 described later).

[0053] The upper side of the lower cover 14 has an upper structure 28 similar to the upper structure 28 of the filter support 16. The upper structure 28 of the lower cover 14 includes an inner structure having an inner welded region 32 and an inner seal region 34, and an outer structure having an outer welded region 38 and an outer seal region 36. The upper structure 28 of the lower cover 14 also includes a filtrate collection channel 46 and a primary filtrate guide channel 48a, but does not necessarily have a secondary filtrate guide channel 48b. A flat bottom filter 44 is sealed to the inner and outer seal regions 34 and 36 of the lower cover 14. The bottom filter 44 is preferably the same shape as the upper and lower filters 40 and 42 provided on the filter support 16. The unfiltered liquid side of the bottom filter 44 is positioned upward, i.e., opposite to the lower cover 14.

[0054] Furthermore, because the upper and lower structures 28, 30 of the filter support 16 and the upper structure 28 of the lower cover 14 are similarly but alternately offset in the rotational direction, filters 40, 42, and 44 of the same shape can be used. In particular, all filters 40, 42, and 44 have the same two-dimensional shape, including an inner contour that fits the contour of the inner seal region 34. With respect to this inner contour, the alternating rotational arrangement of filters 40, 42, and 44 is automatically determined by the rotational direction of the corresponding inner seal region 34 to which each filter 40, 42, and 44 is sealed. Therefore, there is no need to distinguish between the upper, lower, and bottom filters 40, 42, and 44 during the assembly of the filtration device 10.

[0055] Furthermore, the filter support 16 is a non-porous and non-perforated material. The filter support 16 has only dedicated holes, such as distribution holes 24, discharge holes 26, and through holes 54, that allow fluid to pass through the filter support 16 in a controlled flow from one side to the other. Therefore, the unnecessary dead volume of the filtration device 10 is minimized.

[0056] The following explanation will describe the fluid flow through the filtration device 10, which is generated by gravity and system pressure, with reference to Figures 8 to 14.

[0057] The filtration device 10 is held such that the upper cover 12 is positioned above the lower cover 14 and direction A is substantially oriented vertically. The liquid to be filtered (unfiltered liquid) is supplied to the unfiltered liquid inlet 18 of the upper cover 12. Along the unfiltered liquid flow path, the unfiltered liquid flows to the unfiltered liquid side of filters 40, 42, and 44. As shown in Figure 4, a blocking means 56, for example having a roof-like structure, is provided to prevent the unfiltered liquid from flowing directly from the unfiltered liquid inlet 18 through the discharge hole 26 of the filter support 16 to the filtrate outlet 22 of the lower cover 14. The distribution holes 24 of the filter support 16 ensure that the unfiltered liquid is distributed to the unfiltered liquid side of all filters 40, 42, and 44. All filters here include the bottom filter 44 sealed on the upper side of the lower cover 14. Alternatively, a means other than the distribution hole 24 may be provided to guide all the unfiltered liquid between the filter supports 16, thereby allowing the unfiltered liquid to flow to the unfiltered liquid side of the filters 40 and 42 placed on the filter supports 16.

[0058] The vertical offset between the inner sealing region 34 and the inner welding region 32 is, on the one hand, large enough to allow unfiltered liquid to flow into the space between the lower filter 42, which is located below the filter support 16, and the upper filter 40, which is located above the adjacent filter support 16 below it. On the other hand, this space is small enough to enable an ultra-compact design.

[0059] As the fluid passes through the filters 40 and 42 sealed to the filter support 16, the fluid is filtered and becomes a filtrate. The fluid can pass downward through the upper filter 40, and can also pass upward through the lower filter 42 with the assistance of system pressure. The filtrate is collected by the filtrate collection channel 46 of the filter support 16 and flows into the filtrate guide channels 48a and 48b.

[0060] As an example, Figures 8 to 11 show the fluid pathways through which the fluid passes through filters 40 or 42 and is received in the filtrate collection channel 46 of the filter support 16. The open arrows indicate the flow direction of the unfiltered liquid before passing through filters 40 or 42, and the filled arrows indicate the flow direction of the filtrate after passing through filters 40 or 42. For simplification, in Figures 8 and 10, the position where the fluid has finished passing through the upper filter 40 is indicated by three small open circles. Due to gravity, the incline of the filtrate collection channel 46, and system pressure, the filtrate received in the filtrate collection channel 46 flows into the filtrate guide channels 48a and 48b.

[0061] Figures 8 and 9 show the flow of filtrate within the primary filtrate guide channel 48a leading to the intermediate portion 52 of the inner structure. As shown in Figure 9, the primary filtrate guide channel 48a flows into a passage 58 formed in the material of the filter support 16 before reaching the inner seal region 34. This passage 58 opens into an open space 60 adjacent to the discharge hole 26 at the corresponding bulge 50 on the opposite side of the filter support 16. Thus, the filtrate can flow directly to the filtrate outlet 22 through the discharge hole 26 of the filter support 16 (and further through the discharge hole 26 of another filter support 16 if another filter support 16 is located below it).

[0062] Figures 10 and 11 show the flow of filtrate in the secondary filtrate guide channel 48b leading to the bulge 50 of the internal structure. As shown in Figure 11, the secondary filtrate guide channel 48b is terminated by a vertical wall defining the inner seal region 34 and is therefore not directly fluidically connected to the discharge hole 26. However, the filtrate can pass through the through-hole 54 and flow into the primary filtrate guide channel 48a on the opposite side. From there, the filtrate flows into the discharge hole 26 as described above.

[0063] In a modified version, although not shown in the illustration, the filtrate may flow to the other side of the filter support 16 through one or more interruptions provided in the web-shaped inner welded region 32. That is, the filtrate may be configured to pass through the inner welded region 32 and flow to the opposite side of the filter support 16. Of course, if such a flow path is provided, it is necessary that the inner seal region 32 can maintain a liquid-tight state with respect to its surrounding members.

[0064] To illustrate the general flow concept of the filter support 16, Figure 12 illustrates the flow paths provided in three stacked filter support 16.

[0065] Figures 13 and 14 show the fluid flow path through the bottom filter 44 provided in the lower cover 14. As described above, the upper structure 28 of the lower cover 14 does not have a secondary filtrate guide channel 48b because it is not intended for the filtrate to be switched to the lower structure 30. Therefore, its flow path is substantially the same as that shown in Figures 8 and 9. Since the primary filtrate guide channel 48a of the upper structure 28 of the lower cover 14 is directly and fluidly connected to the filtrate outlet 22, there is almost no stagnant liquid below the bottom filter 44. In fact, this design allows the filtration device 10 to be automatically and almost completely discharged after use.

[0066] In principle, sealing in the outer sealing region 36 is not essential. The corresponding seal may be formed only on the web constituting the filtrate collection channel 46 formed in the filter support 16. Alternatively, the upper filter 40 and lower filter 42 may be sealed by contact in their outer regions. That is, the pressure applied for filtration may be applied to the flat filters 40 and 42 so that each filter membrane is in liquid-tight contact with the opposing support structure. However, if a seal in the outer sealing region 36 is provided, it is preferable.

[0067] Figure 15 shows a simplified modification of the first embodiment, in which the filter support 16 is omitted. The upper cover 12 and the lower cover 14 are directly connected by their respective inner and outer welded regions 32, 38. In this modification, the bottom filter 44 is the only filter, and the bottom filter 44 is sealed to the inner and outer sealing regions 34, 36 of the upper structure 28 of the lower cover 14. The unfiltered liquid supplied to the unfiltered liquid inlet 18 flows directly to the unfiltered liquid side of the bottom filter 44 through the unfiltered liquid flow path. That is, in this modification, a blocking means 56 is provided to prevent the unfiltered liquid from flowing directly from the unfiltered liquid inlet 18 of the upper cover 12 to the filtrate outlet 22 of the lower cover 14, while the distribution hole 24 is unnecessary. The flow path from the bottom filter 44 to the filtrate outlet 22 is the same as described above with reference to Figures 13 and 14.

[0068] Both the embodiments shown in Figures 1 to 14 and the modified example shown in Figure 15 are particularly advantageous compared to known filtration devices in that they can minimize the amount of retained liquid. This is especially important when only a small amount of media is available or when the media itself has a high monetary value.

[0069] Figure 16 shows another modification of the first embodiment. The filtration device 10 comprises a separate housing 62, which has an annular wall 64 surrounding at least the filter support 16. The outer welded regions 38 of the upper and lower covers 12,14 are liquid-tightly welded to the axial end faces of the annular wall 64. Preferably, but not essential, the outer welded regions 38 of the upper and lower covers 12,14 coincide with the outer welded region 38 of the filter support 16.

[0070] In the embodiment shown in Figure 16, the filter support 16 preferably does not have an outer welded region 38 at all. In this embodiment, the outer welded region 38 is not necessary for the formation of the housing, and the annular wall 64 performs that function.

[0071] Furthermore, even if it were theoretically possible, the lower cover 14 does not need to have a filtrate collection channel 46 or an upper filtrate guide channel 48. As shown in Figure 16, the filter support 16 is inserted into an existing housing 62 equipped with a lower cover 14. The lower cover 14 has no special configuration; instead, the upper part of the lowest filter support 16 performs this function. In this embodiment, the filter 40 is sealed only to the upper part of the lowest filter support 16. The lower part of this filter support 16 is welded to the lower cover 14, forming a liquid-tight barrier. As a result, unfiltered liquid does not reach the filtrate collection channel 46 or the lower filtrate guide channel 48. Alternatively, at least the lowest filter support 16 may be welded to the annular wall 64 instead of the lower cover 14.

[0072] Figures 17 to 22 show a second embodiment of the small filtration device 10. Components and parts of the filtration device 10 that have the same function as those in the first embodiment are given the same reference numerals, and detailed explanations are omitted to avoid repetition.

[0073] In the second embodiment, the upper and lower covers 12, 14 and the filter support 16 are not circular as in the first embodiment. Instead, their outer contours have a substantially honeycomb shape.

[0074] Unlike the first embodiment, the discharge holes 26 of each filter support 16 are not central holes, although they are fluidically connected to the filtrate outlet 22. Instead, the discharge holes 26 are located at one of the vertices of the filter support 16. Opposite this vertex is a single distribution hole 24 that is fluidically connected to the unfiltered liquid inlet 18. However, in other modifications, multiple distribution holes 24 may be provided.

[0075] As shown in Figures 18 and 19, the generally flat filter support 16 has substantially identical upper and lower structures 28, 30. In particular, the lower structure 30 of one filter support 16 is similar to the upper structure 28 of the same filter support 16 rotated 180 degrees around the axis passing through the discharge hole 26 and the distribution hole 24.

[0076] The filtrate collection channel 46, formed by the upper and lower structures 28 and 30 of the filter support 16, is inclined and leads to a through-hole 54. The through-hole 54 is located along the side of the filter support 16, between the discharge hole 26 and the distribution hole 24. The through-hole 54 allows the fluid to pass through to filtrate guide channels 48a provided on opposite sides of the filter support 16. These filtrate guide channels 48a are fluidically separated from the filtrate collection channel 46 by a high-positioned outer seal region 36. The fluid guide channels 48a provided on both sides of the filter support 16 are fluidically connected to the discharge hole 26 of the filter support 16. Thus, the filtrate guide channels 48a functionally correspond to the primary filtrate guide channels 48a in the first embodiment.

[0077] As shown in Figure 18, the upper structure 28 of the lower cover 14 is basically identical in shape and orientation to the upper structure 28 of the filter support 16 (in this case, the upper filter support 16), which is located one unit apart, except for the filtrate collection channel 46 and the through-hole 54. In particular, the filtrate collection channel 46 of the lower cover 14 extends in a different direction (particularly a 90-degree rotation) than the filtrate collection channel 46 of the filter support 16. The filtrate collection channel 46 of the lower cover 14 is inclined and leads to a passage 58. This passage 58 further leads to the filtrate outlet 22 (see Figure 21).

[0078] Figure 20 shows the filter support 16 with a flat upper filter 40 (membrane) sealed to the outer sealing region 36 of the upper structure 28 that surrounds the filtrate collection channel 46 and its associated through-hole 54. Therefore, the filter 40 does not cover the filtrate guide channel 48a. A flat lower filter 32 of the same shape is similarly sealed to the outer sealing region 36 of the lower structure 30.

[0079] Similar to the first embodiment, outer welded regions 38 are formed on both sides of the periphery of the filter support 16. Similarly, outer welded regions 38 are also formed on the lower surface of the upper cover 12 and the upper surface of the lower cover 14.

[0080] Note that in the second embodiment, the inner sealing region 34 is not provided.

[0081] In the second embodiment, it should be noted that the two consecutive filter supports 16 are not actually identical, but are mirror images of each other. If they were not mirror images, the positions of the distribution holes 24 and discharge holes 26 would be reversed left and right. However, the filters 40 and 42 are always the same size and shape (i.e., identical), because they are rotationally symmetric. Due to the mirror image arrangement of the consecutive filter supports 16, the embodiments shown in Figures 17 to 22 are basically only operable when an even number of filter supports 16 are provided. However, if two different (mirror image) lower parts are provided, the number of filter supports 16 can be flexibly changed.

[0082] Figure 21 shows a cross-sectional view of the assembled state of the filtration device 10 according to the second embodiment, in which two filter supports 16 are stacked on top of each other.

[0083] Figures 22A, 22B, and 22C exemplify the fluid flow through the filtration device 10 shown in Figure 21, which is generated by gravity and system pressure. The only difference between Figures 22A to 22C is the way the stacked filter supports 16 are illustrated. Specifically, Figure 22A shows the upper sides of both filter supports 16. Figure 22B shows the lower side of the upper filter support 16 and the upper side of the lower filter support 16. Figure 22C shows the lower sides of both filter supports 16.

[0084] The white arrows indicate the unfiltered liquid supplied from the unfiltered liquid inlet 18. The diagonal arrows in Figure 22A indicate the flow of unfiltered liquid that passes over the upper filter 40 located above the upper filter support 16, and then passes through the filter 40 to become the filtrate. The filtrate is collected by the upper filtrate collection channel 46 and flows into the lower filtrate guide channel 48a through the corresponding through-hole 54. The filtrate flows through the filtrate guide channel 48a and the discharge hole 26 to the filtrate outlet 22, as indicated by the black arrows in Figures 22B and 22C.

[0085] The dotted arrows in Figures 22B and 22C indicate the flow of unfiltered liquid that passes over the lower filter 42 located below the upper filter support 16, and then passes through the filter 42 to become filtrate. The filtrate is collected by the lower filtrate collection channel 46 and flows into the upper filtrate guide channel 48a through the corresponding through-hole 54. The filtrate flows through the filtrate guide channel 48a and the discharge hole 26 to the filtrate outlet 22, as indicated by the black arrows in Figure 22A.

[0086] The arrows in the lateral hatches shown in Figures 22A and 22B indicate the flow of unfiltered liquid that passes over the upper filter 40 located above the lower filter support 16, and then passes through the filter 40 to become filtrate. The filtrate is collected by the upper filtrate collection channel 46 and flows into the lower filtrate guide channel 48a through the corresponding through-hole 54. The filtrate flows through the filtrate guide channel 48a and the discharge hole 26 to the filtrate outlet 22, as shown by the black arrows in Figure 22C.

[0087] The arrows in the vertical hatches shown in Figures 22A, 22B, or 22C indicate the flow of unfiltered liquid that passes over the bottom filter 44 located above the lower cover 14, and then passes through the filter 44 to become filtrate. The filtrate is collected by the upper filtrate collection channel 46 and flows into a passage 58 (see Figure 21) leading to the filtrate outlet 22.

[0088] The filtration device 10 is designed for single-use applications. Therefore, all components of the filtration device 10 are made of plastic materials suitable for common sterilization methods, particularly gamma ray sterilization (irradiation) and chemical sterilization, such as sterilization by ethylene oxide (ETO). Here, "suitable" means that relevant material properties such as stability and brittleness are not substantially affected by the sterilization process.

[0089] The principle of the present invention is not limited to the embodiment of the filtration device 10 described above, but can be applied to other suitable designs. However, it should be understood that the general structure of the filtration device 10 is applicable only to dead-end filtration and cannot be used for other filtration methods such as tangential flow filtration (TFF). [Explanation of Symbols]

[0090] 10. Filtration device 12. Top cover 14. Bottom cover 16. Filter support 18 unfiltrate inlet 20 Ventilation opening 22 filtrate outlet 24 distribution hole 26 drain hole 28. Upper side structure 30 Lower side structure 32 inner welding area 34. Inner sealing area 36. Outer sealing area 38 Outer welding area 40 Upper filter 42 Lower filter 44 Bottom filter 46 Filtrate collecting channel 48a Primary filtrate guiding channel 48b Secondary filtrate guiding channel 50 Bulge 52 Intermediate section 54 Through opening 56 Blocking means 58 Passage 60 Open space 62 Housing 64 Annular wall

Claims

1. A filtration device (10), a small filtration device in particular for the manufacture of biopharmaceuticals, A housing including an upper cover (12) having an unfiltered liquid inlet (18) and a lower cover (14) having a filtrate outlet (22), One or more filter supports (16) are stacked vertically (A) between the upper cover (12) and the lower cover (14), Equipped with, The upper side of each filter support (16) is directed toward the upper cover (12), and the lower side of each filter support (16) is directed toward the lower cover (14). Each filter support (16) is fitted with a flat upper filter (40) and a flat lower filter (42), and the upper and lower filters (40, 42) each have a filtrate side and an unfiltered liquid side on the opposite side. The upper and lower filters (40, 42) are sealed to the upper and lower sides of the filter support (16) respectively, such that the filtrate side faces the filter support (16) and the unfiltered liquid side faces away from the filter support (16). The unfiltered liquid flow path extends from the unfiltered liquid inlet of the upper cover (12) to the unfiltered liquid side of the upper filter (40) and the unfiltered liquid side of the lower filter (42), The blocking means prevents the unfiltered liquid from flowing directly from the unfiltered liquid inlet of the upper cover (12) to the filtrate outlet (22) of the lower cover (14). The filtrate flow path extends from the filtrate side of the upper and lower filters (40, 42) through at least one filtrate guide flow path (48a, 48b) formed on the upper side of the filter support (16) and at least one filtrate guide flow path (48a, 48b) formed on the lower side of the filter support (16) to the filtrate outlet (22) of the lower cover (14). The upper filter (40) and the lower filter (42) have the same shape. Filtration device (10).

2. The filtrate guide channels (48a, 48b) extend substantially horizontally and are fluidly connected to the discharge holes (26) of the filter support (16), the discharge holes (26) extend vertically so as to penetrate the entire filter support (16) and are fluidly connected to the filtrate outlet (22) of the lower cover (14). The filtration apparatus (10) according to claim 1.

3. The upper structure (28) and the lower structure (30) are formed on the upper and lower sides, respectively, of each filter support (16). Both the upper structure (28) and the lower structure (30) form an inner structure that surrounds the discharge hole (26). Each inner structure includes an inner welded region (32), which is liquid-tightly welded to a corresponding inner welded region (32) of an adjacent filter support (16), or to a corresponding inner welded region (32) of the upper cover (12), or to a corresponding inner welded region (32) of the lower cover (14). The filtration apparatus (10) according to claim 2.

4. The inner structure includes an inner sealing region (34) that is sealed to the inner region of the upper filter (40) or the lower filter (42), The inner sealing region (34) surrounds the inner welding region (32), is adjacent to the inner welding region (32), and is offset vertically from the inner welding region (32). The filtration apparatus (10) according to claim 3.

5. The inner welding region (32) and the inner sealing region (34) each have a plurality of substantially identical bulges (50) and substantially identical intermediate portions (52), the bulges (50) and intermediate portions (52) are alternately arranged around the outer circumference of the discharge hole (26), and the bulges (50) extend horizontally from the discharge hole (26). The filtration apparatus (10) according to claim 4.

6. The number of the bulging portion (50) and the intermediate portion (52) is the same for the upper structure (28) and the lower structure (30). The filtration apparatus (10) according to claim 5.

7. The inner structure of the upper structure (28) is positioned to be offset from the inner structure of the lower structure (30) in a rotational direction about the vertical direction, so that the bulging portion (50) of the upper structure (28) faces the intermediate portion (52) of the lower structure (30), and vice versa. The filtration apparatus (10) according to claim 6.

8. The upper and lower filtrate guide channels (48a, 48b) of the filter support (16) are spaced apart from each other in the circumferential direction. The filtrate guide channels (48a, 48b) reach the bulging portion (50) and the intermediate portion (52) of the upper and lower structures (28, 30), and are preferably alternately connected to the bulging portion (50) and the intermediate portion (52). The filtration apparatus (10) according to claim 7.

9. The number of filtrate guide channels (48a, 48b) is equal to the total number of the bulging portions (50) and intermediate portions (52) of the inner structure. The filtration apparatus (10) according to claim 8.

10. Preferably, at least one of the filtrate guide channels (48a, 48b) of the upper structure (28) is positioned opposite to the filtrate guide channels (48a, 48b) of the lower structure (30). Opposing filtrate guide channels (48a, 48b) are interconnected by a plurality of through-holes (54), and the filtrate can pass from one filtrate guide channel (48a, 48b) to the opposing filtrate guide channel (48a, 48b) through the through-holes (54). The filtration apparatus (10) according to claim 8 or 9.

11. In the upper and lower parts of the filter support (16), only the filtrate guide channel (48a) leading to the intermediate section (52) is fluidly connected to the discharge hole (26). The filtrate guide channels (48a) are, Before reaching the inner sealing region (34), it enters the material of the filter support (16). On the opposite side of the filter support (16), the corresponding bulge (50) opens into an open space adjacent to the discharge hole (26), A filtration apparatus (10) according to any one of claims 5 to 10.

12. The outer sealing region (36) is formed on the upper and lower sides of the filter support (16), The outer sealing region (36) surrounds the filtrate guide channels (48a, 48b) and seals to the upper and lower filters (40, 42), respectively. A filtration apparatus (10) according to any one of claims 1 to 11.

13. The housing includes outer welded regions (38) that are continuously formed on the upper and lower sides of each of the filter supports (16), The aforementioned outer welding region (38) is Surrounding the outer sealing region (36), The filter support (16) is liquid-tightly welded to the corresponding outer welded region (38) of the adjacent filter support (16), or to the corresponding outer welded region (38) of the upper cover (12), or to the corresponding outer welded region (38) of the lower cover (14), The filtration apparatus (10) according to claim 12.

14. The housing (62) includes at least an annular wall (64) surrounding the filter support (16), A filtration apparatus (10) according to any one of claims 1 to 12.

15. A flat bottom filter (44) is attached to the lower cover (14), and the bottom filter (44) has a filtrate side and an unfiltered liquid side on the opposite side. The bottom filter (44) is sealed to the upper side of the lower cover (14) such that the filtrate side faces the lower cover (14) and the unfiltered liquid side faces away from the lower cover (14). The filtration device (10) includes a filtrate channel from the filtrate side of the bottom filter (44) to the filtrate outlet (22) of the lower cover (14), preferably via at least one filtrate guide channel (48a, 48b) formed on the upper side of the lower cover (14). A filtration apparatus (10) according to any one of claims 1 to 14.

16. The filtration device (10) does not include any filter support (16), The upper cover (12) is directly welded to the lower cover (14). The filtration apparatus (10) according to claim 15.

17. A filter support (16) used in a filtration device (10) according to any one of claims 1 to 15, The filter support (16) is fitted with a flat upper filter (40) and a flat lower filter (42), and the upper and lower filters (40, 42) are identical in shape. The filtrate flow path extends from the filtrate side of the upper and lower filters (40, 42) to the filtrate outlet of the lower cover (14) via at least one filtrate guide flow path (48a, 48b) formed on the upper side of the filter support (16) and at least one filtrate guide flow path (48a, 48b) formed on the lower side of the filter support (16). Filter support (16).

Images