Water purification filter, water purification cartridge including said water purification filter, and method for assembling said water purification cartridge

Abstract

A water purification filter according to one aspect of the present invention is obtained by winding a sheet including fibrous activated carbon, and is cylindrical and has a hardness of 33-59.

Description

Water purification filter, water purification cartridge including said water purification filter, and method for assembling said water purification cartridge

[0001] The present invention relates to a water purification filter, a water purification cartridge including the water purification filter, and a method for assembling the water purification cartridge.

[0002] In recent years, various types of water purifiers have been proposed. For example, in Patent Document 1, a cylindrical water purification filter 10 is provided inside the main body of a portable water supply device, and purified water that has passed through the water purification filter 10 can be drunk from the drinking spout of the main body of the portable water supply device.

[0003] Japanese Patent Application Laid-Open No. 2016-2529

[0004] The present inventor(s) have found the following problem with conventional water purification filters such as those disclosed in Patent Document 1. Namely, the present inventor(s) have found that conventional water purification filters lack the perspective of reducing the burden on the environment. For example, Patent Document 1 lacks the perspective of further reducing the burden on the environment by making the water purification filter replaceable in a water purification cartridge equipped with a water purification filter, while making the case for storing the water purification filter reusable.

[0005] Furthermore, in order to purify raw water using a water purification filter, the raw water must naturally pass through the water filter reliably; for example, the raw water must be prevented from passing through gaps between the water purification filter and the case that houses the water purification filter.

[0006] In one aspect, the present invention has been made in consideration of the above circumstances, and its object is to provide a water purification filter that can be easily attached and detached to a case that stores the water purification filter while ensuring that raw water passes through the water purification filter.

[0007] In order to solve the above-mentioned problems, the present invention employs the following configuration.

[0008] The water purification filter according to the first aspect is cylindrical and made by winding a sheet containing fibrous activated carbon, and has a hardness of 33 to 59 as measured by the following measurement method: <Measurement method> Using a TECLOCK hardness tester GS701G as a measuring instrument, measurements are carried out according to the method specified in JIS S 6050 "Plastic erasers," and the average value for N=5 is taken as the hardness.

[0009] In this configuration, the water purification filter is a cylindrical water purification filter formed by winding a sheet containing fibrous activated carbon, and has a hardness of 33 to 59. The present inventors conducted an experiment comparing a cylindrical water purification filter formed by winding a sheet containing fibrous activated carbon as an example with the following water purification filter (comparative example). That is, the present inventors conducted an experiment comparing the comparative example with the above-mentioned example, using a water purification filter prepared by a wet molding method using granular activated carbon as a comparative example. The hardness of the example measured by the above-mentioned measurement method was "33 to 59." In contrast, the hardness of the comparative example measured by the above-mentioned measurement method was "83," which was higher than the upper limit of the hardness of the example (59). Therefore, the present inventor(s) confirmed that by winding a sheet containing fibrous activated carbon, it is possible to create a cylindrical water purification filter having a lower hardness than the water purification filter according to the comparative example described above, specifically a hardness of 33 to 59.

[0010] Furthermore, the water purification filter has a hardness of 33 to 59 and can be compressed (deformed). The water purification filter with a hardness of 33 to 59 can be compressed, for example, by human force. Therefore, the water purification filter can be easily stored, for example, in a cylindrical storage case having an inner diameter smaller than the outer diameter (diameter) of the water purification filter. The inventor(s) confirmed that the water purification filter with a hardness of 33 to 59 can be compressed and can be stored in a cylindrical storage case having an inner diameter smaller than the outer diameter of the water purification filter. Specifically, the inventor(s) confirmed that the water purification filter can be stored in a cylindrical storage case having an inner diameter 1 mm smaller than the outer diameter of the water purification filter. In particular, the inventor(s) confirmed that the water purification filter can be loaded into the storage case while being compressed (compressed radially), and that such loading does not cause the activated carbon layer of the water purification filter to collapse. In other words, the inventor(s) confirmed that by pressing the water purification filter in the axial direction, the water purification filter can be compressed radially without destroying the activated carbon layer of the water purification filter, and can be loaded into the above-mentioned storage case.

[0011] In contrast, the water purification filter according to the comparative example could not be stored in a cylindrical storage case having an inner diameter smaller than the outer diameter of the water purification filter (for example, an inner diameter 1 mm smaller than the outer diameter of the water purification filter). Specifically, when the water purification filter according to the comparative example was stored in the storage case, it could not be compressed, and the activated carbon layer collapsed when the filter was stored in the storage case.

[0012] The water purification filter, for example, can be housed in a cylindrical storage case having an inner diameter smaller than the outer diameter of the water purification filter, thereby achieving the following effects. That is, the water purification filter is housed in the storage case in a compressed (deformed) state, and the outer surface of the water purification filter and the inner surface of the storage case are in contact with each other without any gaps. Therefore, the water purification filter can prevent raw water from passing through a gap between the outer surface of the water purification filter and the inner surface of the storage case, thereby ensuring that the raw water passes through the water purification filter. The water purification filter can prevent raw water from passing through a gap between the outer surface of the water purification filter and the inner surface of the storage case without requiring any other components, thereby ensuring that the raw water passes through the water purification filter.

[0013] Furthermore, because the water purification filter has a hardness of 33 to 59, it can be detachably stored in a cylindrical storage case having an inner diameter smaller than the outer diameter of the water purification filter. In other words, the water purification filter can be easily stored in and removed from the storage case by being compressed. Therefore, only the water purification filter needs to be replaced, and the storage case can be reused. Therefore, the water purification filter can reduce environmental impact compared to conventional water purification filters that are replaced only together with the storage case.

[0014] In particular, the inventor(s) experimentally confirmed that the above-described effects can be significantly achieved by setting the hardness of the cylindrical water purification filter to 33 to 59. That is, a water purification filter with a hardness greater than the upper limit (59) (e.g., the water purification filter according to the comparative example) could not be housed in a cylindrical storage case with an inner diameter smaller than the outer diameter of the water purification filter. In contrast, the water purification filter was housed in a cylindrical storage case with an inner diameter smaller than the outer diameter of the water purification filter, preventing raw water from passing through the gap between the outer surface of the water purification filter and the inner surface of the storage case. In other words, unlike water purification filters with a hardness greater than the upper limit (59), the water purification filter's hardness of 33 to 59 ensures that raw water passes through the water purification filter. Furthermore, by setting the hardness to 33 to 59, the water purification filter can be easily compressed and loaded into a cylindrical storage case having an inner diameter smaller than the outer diameter of the water purification filter, and can also be easily removed from the storage case.

[0015] Therefore, the water purification filter has the effect of being easily attached and detached to a cylindrical storage case having an inner diameter smaller than the outer diameter of the water purification filter, while ensuring that raw water passes through the water purification filter.

[0016] A water purification filter according to a second aspect may be the water purification filter according to the first aspect, but with elasticity. In this configuration, the water purification filter is formed by winding a sheet containing fibrous activated carbon, is cylindrical, has a hardness of 33 to 59, and is elastic. The present inventor(s) temporarily placed a cylindrical water purification filter formed by winding a sheet containing fibrous activated carbon inside a cylindrical storage case having an inner diameter smaller than the outer diameter of the water purification filter, removed it, and measured the outer diameter of the water purification filter. As a result, the present inventor(s) confirmed that the outer diameter of the water purification filter after removal had almost recovered to the outer diameter of the water purification filter before it was stored inside the storage case, i.e., the water purification filter is elastic. Therefore, the water purification filter formed by winding a sheet containing fibrous activated carbon, is cylindrical, and has a hardness of 33 to 59 is elastic.

[0017] The water purification filter has elasticity, and due to this elasticity, it can be stored, for example, in a cylindrical storage case having an inner diameter smaller than the outer diameter of the water purification filter by elastic deformation. When stored in such a storage case, the water purification filter can prevent raw water from passing through a gap between the outer surface of the water purification filter and the inner surface of the storage case, thereby ensuring that the raw water passes through the water purification filter. In other words, due to the above-mentioned elasticity, the water purification filter can prevent raw water from passing through a gap between the outer surface of the water purification filter and the inner surface of the storage case without requiring any other components, thereby ensuring that the raw water passes through the water purification filter.

[0018] Furthermore, due to the above-mentioned elasticity, the water purification filter can be detachably stored in a cylindrical storage case having an inner diameter smaller than the outer diameter of the water purification filter. In other words, the water purification filter's elasticity allows it to be easily stored in the storage case and easily removed from the storage case. Therefore, only the water purification filter needs to be replaced, and the storage case can be reused. Therefore, the water purification filter can reduce environmental impact compared to conventional water purification filters that are replaced only together with the storage case.

[0019] Therefore, the water purification filter has the effect of being easily attached and detached to a cylindrical storage case having an inner diameter smaller than the outer diameter of the water purification filter, while ensuring that raw water passes through the water purification filter.

[0020] A water purification filter according to a third aspect is the water purification filter according to the first or second aspect, which is stored in a cylindrical storage case, and may have an outer diameter that is larger than the inner diameter of the storage case at least at one point in the axial direction by 1 mm or less.

[0021] In this configuration, the water purification filter is housed in a cylindrical housing case, and the outer diameter (diameter) of the water purification filter is larger than the inner diameter of the housing case at least at one point in the axial direction by 1 mm or less. For example, the outer diameter of the water purification filter is larger than the inner diameter of the cylindrical housing case, which has a constant inner diameter throughout the axial direction, by 1 mm or less.

[0022] The inventor(s) confirmed that the water purification filter can be stored in a cylindrical storage case having an inner diameter at least 1 mm smaller than the outer diameter of the water purification filter at one point in the axial direction without destroying the activated carbon layer of the water purification filter. Furthermore, the water purification filter stored in the storage case can be easily removed from the storage case by being compressed.

[0023] Therefore, the water purification filter has the effect of being easily attached to and detached from the storage case while ensuring that raw water passes through the water purification filter.

[0024] A water purification cartridge according to a fourth aspect is a storage case that includes the water purification filter according to any one of the first to third aspects and that stores the water purification filter in a removable manner, and has a cylindrical first peripheral wall portion, one axial end of the first peripheral wall portion is open, and the other axial end of the first peripheral wall portion is closed by a first surface portion, and the inner diameter of at least the other end closed by the first surface portion of the first peripheral wall portion is smaller than the outer diameter of the water purification filter by a range of 1 mm or less, and purified water flows out of the first surface portion. Alternatively, the water purification filter may include a storage case provided with a first water flow section into which raw water flows, and a lid body removably attached to the storage case, the lid body having a cylindrical second peripheral wall section, one axial end of the second peripheral wall section being open and the other axial end of the second peripheral wall section being closed by a second surface section, the second surface section being provided with a second water flow section into which raw water flows or through which purified water flows, and the second surface section being a lid body that closes the open end of the storage case in which the water purification filter is stored so as to be removable.

[0025] In this configuration, the water purification cartridge includes the water purification filter, the storage case, and the lid. The water purification filter is made by winding a sheet containing fibrous activated carbon, is cylindrical, has a hardness of 33 to 59, and is compressible. The storage case is cylindrical and has an inner diameter smaller than the outer diameter of the water purification filter. The lid is removably attached to the storage case so as to close the open end of the storage case, which removably houses the water purification filter.

[0026] Therefore, the water purification cartridge can compress the water purification filter to store it in the storage case. By storing the water purification filter in the storage case, the water purification cartridge can prevent raw water from passing through a gap between the outer circumferential surface of the water purification filter and the inner circumferential surface of the storage case, ensuring that raw water passes through the water purification filter. The water purification cartridge ensures that the outer circumferential surface of the water purification filter and the inner circumferential surface of the storage case are in contact with each other without any gaps, at least at the other end of the storage case that is closed by the first surface portion. Furthermore, the water purification cartridge can easily store the water purification filter in the storage case by compressing it, and the lid can be removably attached to the storage case storing the water purification filter. Furthermore, the lid of the water purification cartridge can be easily removed from the storage case, and the water purification filter can be easily removed from the storage case.

[0027] Therefore, the water purification cartridge has the effect of ensuring that raw water passes through the water purification filter by using the water purification filter, the storage case, and the lid, while allowing the water purification filter to be easily attached and detached from the storage case.

[0028] A water purification cartridge according to a fifth aspect may be the water purification cartridge according to the fourth aspect, wherein one axial end face of the water purification filter contacts the first surface portion of the storage case, and the other axial end face contacts the second surface portion of the lid body.

[0029] In this configuration, one axial end face of the water purification filter in the water purification cartridge contacts the first surface of the storage case, and the other axial end face in the water purification cartridge contacts the second surface of the lid. Therefore, the water purification cartridge can prevent raw water from passing through the gap between the water purification filter and the storage case and the gap between the water purification filter and the lid, and can ensure that raw water passes through the water purification filter.

[0030] Furthermore, the inner diameter of the storage case, at least at the other end closed by the first surface, is smaller than the outer diameter of the water purification filter by 1 mm or less. However, as described above, the water purification filter has a hardness of 33 to 59 and is compressible. Therefore, the lid presses the water purification filter in the axial direction with the second surface, compressing the water purification filter and pushing it into the storage case, thereby storing the water purification filter inside the storage case. The lid then closes the open end of the storage case with the second surface. Therefore, the lid can stably store the water purification filter in the storage case in a compressed state.

[0031] A water purification cartridge according to a sixth aspect may be a water purification cartridge according to the fourth or fifth aspect, wherein the lid body is removably attached to the storage case by threading a male threaded portion provided on the outer peripheral surface of the first peripheral wall portion of the storage case with a female threaded portion provided on the inner peripheral surface of the second peripheral wall portion of the lid body.

[0032] In this configuration, the lid of the water purification cartridge is detachably attached to the storage case by threading a male thread on the outer peripheral surface of the storage case into a female thread on the inner peripheral surface of the lid. Therefore, the lid of the water purification cartridge can be easily attached to and removed from the storage case.

[0033] Furthermore, by screwing the male thread portion and the female thread portion together, the water purification cartridge can be attached to the storage case, for example, by using the second surface portion of the lid to push the water purification filter into the storage case. Therefore, the water purification cartridge can easily store the water purification filter in the storage case by pushing the water purification filter into the storage case with the lid as it is attached to the storage case.

[0034] A water purification cartridge according to a seventh aspect is the water purification cartridge according to any one of the fourth to sixth aspects, wherein the first peripheral wall of the storage case is formed with a tapered portion whose inner diameter increases toward the open end. In this configuration, the storage case is formed with a tapered portion whose inner diameter increases toward the open end. Therefore, the water purification cartridge makes it easy to insert the water purification filter into the storage case from the open end of the storage case.

[0035] A water purification cartridge according to an eighth aspect is the water purification cartridge according to any one of the fourth to seventh aspects, wherein a protrusion that protrudes axially outward is provided on an axially outer surface of at least one of the first surface of the storage case and the second surface of the lid. In this configuration, a protrusion that protrudes axially outward is provided on an outer surface of at least one of the first surface of the storage case and the second surface of the lid. Therefore, the water purification cartridge allows a user of the water purification cartridge to use the protrusion as a knob to easily remove the water purification cartridge from a container (pitcher) or the like to which the water purification cartridge is attached.

[0036] A method for assembling a water purification cartridge according to a ninth aspect includes the steps of: preparing a cylindrical water purification filter made by winding a sheet containing fibrous activated carbon, the water purification filter having a hardness of 33 to 59 measured by the following measurement method; and preparing a storage case for removably storing the water purification filter, the storage case having a cylindrical first circumferential wall portion, one axial end of the first circumferential wall portion being open and the other axial end of the first circumferential wall portion being closed by a first surface portion, the inner diameter of at least the other end closed by the first surface portion being smaller than the outer diameter of the water purification filter by a range of 1 mm or less, and the first surface portion being provided with a first water flow portion through which purified water flows out or raw water flows in; and the water purification filter inserted into the first peripheral wall of the storage case; preparing a lid that can be removably attached to the storage case, the lid having a cylindrical second peripheral wall, one axial end of the second peripheral wall being open and the other axial end of the second peripheral wall being closed by a second surface, the second surface being provided with a second water flow section through which raw water flows in or purified water flows out; and storing the storage case with the water purification filter inserted into the first peripheral wall from the open end side of the lid inside the lid, and removably attaching the lid to the storage case so that the open end of the storage case is closed by the second surface of the lid. <Measuring Method> A hardness tester GS701G manufactured by TECLOCK is used as a measuring instrument, and measurements are carried out in accordance with the method specified in JIS S 6050 "Plastic Erasers." The average value for N=5 is taken as the hardness.

[0037] In this configuration, the assembly method includes the steps of inserting the water purification filter into the storage case and removably attaching the lid to the storage case with the water purification filter inserted therein. The water purification filter is made by winding a sheet containing fibrous activated carbon, is cylindrical, has a hardness of 33 to 59, and is compressible (deformable). The storage case is cylindrical and has an inner diameter smaller than the outer diameter of the water purification filter. The lid is removably attached to the storage case so as to close the open end of the storage case, which removably houses the water purification filter.

[0038] As described above, the water purification filter has a hardness of 33 to 59 and is compressible. Therefore, the assembly method allows the water purification filter to be stored in the storage case by compressing the water purification filter. The assembly method compresses the water purification filter and stores it in the storage case, thereby bringing the outer peripheral surface of the water purification filter into contact with the inner peripheral surface of the storage case without any gaps. The assembly method brings the outer peripheral surface of the water purification filter into contact with the inner peripheral surface of the storage case without any gaps, at least at the other end of the storage case that is closed by the first surface portion.

[0039] Therefore, the assembly method can provide a water purification cartridge in which, by storing the water purification filter in the storage case, raw water is prevented from passing through a gap between the outer peripheral surface of the water purification filter and the inner peripheral surface of the storage case, ensuring that raw water passes through the water purification filter. The assembly method also allows the water purification filter to be compressed and easily stored in the storage case, and the lid can be detachably attached to the storage case containing the water purification filter. Furthermore, the water purification cartridge assembled using the assembly method allows the lid to be easily removed from the storage case, and the water purification filter to be easily removed from the storage case.

[0040] Therefore, the assembly method has the effect of providing a water purification cartridge in which the water purification filter and the storage case can be easily attached and detached to the storage case while ensuring that raw water passes through the water purification filter.

[0041] A method for assembling a water purification cartridge according to a tenth aspect may be the same as the method for assembling a water purification cartridge according to the ninth aspect, wherein in the step of removably attaching the lid body, the water purification filter is pushed into the interior of the storage case by the second surface portion of the lid body, thereby storing the water purification filter inside the first peripheral wall portion of the storage case.

[0042] In this configuration, in the step of detachably attaching the lid, the assembly method includes pressing the water purification filter into the storage case with the second surface of the lid, thereby storing the water purification filter inside the storage case. That is, the assembly method includes attaching the lid to the storage case while pressing the water purification filter into the storage case with the second surface of the lid. Therefore, the assembly method allows the water purification filter to be easily stored in the storage case by pressing the water purification filter into the storage case with the lid in conjunction with attaching the lid to the storage case.

[0043] A method for assembling a water purification cartridge according to an eleventh aspect is the method for assembling a water purification cartridge according to the ninth or tenth aspect above, wherein a male threaded portion is provided on the outer peripheral surface of the first peripheral wall portion of the storage case, and a female threaded portion is provided on the inner peripheral surface of the second peripheral wall portion of the lid body, and in the step of removably attaching the lid body, by screwing the male threaded portion and the female threaded portion together, the lid body can be removably attached to the storage case while the second surface portion of the lid body pushes the water purification filter into the interior of the storage case.

[0044] In this configuration, in the step of detachably attaching the lid, the male threaded portion and the female threaded portion are screwed together to attach the lid to the storage case while pushing the water purification filter into the storage case with the lid. Therefore, in the assembly method, the water purification filter can be easily and reliably stored in the storage case by gradually pushing the water purification filter into the storage case with the lid as it is attached to the storage case.

[0045] According to the present invention, it is possible to provide a water purification filter that can be easily attached to and detached from a case that houses the water purification filter, while ensuring that raw water passes through the water purification filter.

[0046] FIG. 1 is a cross-sectional schematic diagram showing an example of the main configuration of a water purifier according to the present embodiment; FIG. 2 is a perspective view showing an example of the main configuration of a water purification cartridge according to the present embodiment, and a cross-sectional schematic diagram showing an example of the main configuration of each member constituting the water purification cartridge; FIG. 3 is a cross-sectional schematic diagram showing an example of the main configuration of the water purification cartridge of FIG. 2; FIG. 4 is a diagram showing an example of the main configuration of a water purification filter according to the present embodiment; FIG. 5 is a diagram showing an example of the main configuration of a storage case according to the present embodiment; FIG. 6 is a diagram showing an example of the main configuration of a lid according to the present embodiment; and FIG. 7 is a flowchart showing an example of the execution procedure of an assembly method according to the present embodiment. It is a diagram showing the water purification filter being arranged between the storage case and the lid in an elastically deformed state in the water purification cartridge according to the present embodiment.

[0047] An embodiment according to one aspect of the present invention (hereinafter also referred to as "the present embodiment") will be described below with reference to the drawings. However, the present embodiment described below is merely an example of the present invention in all respects. It goes without saying that various improvements and modifications can be made without departing from the scope of the present invention. In other words, specific configurations according to the embodiment may be appropriately adopted when implementing the present invention.

[0048] 1. Overview of the Water Purifier An embodiment of a water purifier WP having a water purification cartridge 1 according to one aspect of the present invention and a container 2 to which the water purification cartridge 1 is attached will be described below with reference to the drawings. FIG. 1 is a cross-sectional view schematically illustrating an example of the main configuration of a water purifier WP according to this embodiment. That is, FIG. 1 schematically illustrates the cross-sectional configuration of the water purifier WP parallel to and in contact with the axis (axial line) of the water purification cartridge 1 (particularly, the water purification filter 10 described below using FIG. 2 and other figures). As shown in FIG. 1, the water purifier WP includes a container (pitcher) 2 and a water purification cartridge 1 housed therein.

[0049] As shown in FIG. 1 , the container 2 has an opening S1 at the top and an open-topped tank TK inside. The tank TK is used to store raw water, and raw water can be poured into the tank TK through the opening S2 at the top. An opening S4 is formed at the bottom of the tank TK, and the water purification cartridge 1 is attached to seal the periphery of the opening S4 together with a packing (not shown). However, it is not essential that the water purifier WP (container 2) be provided with a packing; in the water purifier WP, the water purification cartridge 1 may be attached to seal the periphery of the opening S4 without using a packing.

[0050] The water purification cartridge 1 illustrated in Fig. 1 has a first protrusion 313 that protrudes axially outward (upward in the example shown in Fig. 1) from a second surface 310 of the lid 30 (details will be described later in Fig. 6, etc.). Raw water in the tank TK flows into the water purification cartridge 1. Note that opening S2 is formed smaller than opening S1, and therefore opening S1 is divided into openings S2 and S3.

[0051] After passing through the interior of the water purification cartridge 1, the raw water flows out as purified water from the bottom of the water purification cartridge 1 and is stored in the server space SS below the tank TK. The opening S3 functions as an outlet for taking out purified water from the server space SS.

[0052] As explained above with reference to Figure 1, the water purifier WP has a structure in which a water purification cartridge 1 is interposed between a tank TK located at the upper side of a container 2 and a server space SS located at the lower side. Raw water stored in the tank TK flows into the server space SS through the water purification cartridge 1 due to its own weight, and is purified within the water purification cartridge 1.

[0053] 2. Overview of the Water Purification Cartridge Next, the water purification cartridge 1 will be described with reference to FIGS. 2 and 3. FIGS. 2 and 3 are each a schematic diagram illustrating an example of the main configuration of the water purification cartridge 1 according to this embodiment. Specifically, FIG. 2A is a perspective view of the water purification cartridge 1. FIG. 2B is a schematic cross-sectional view illustrating an example of the main configuration of each component constituting the water purification cartridge 1, that is, a schematic cross-sectional view illustrating an example of the main configuration of each of the water purification filter 10, the storage case 20, and the lid 30. In particular, FIG. 2B schematically illustrates the cross-sectional configuration of each of the water purification filter 10, the storage case 20, and the lid 30, which are parallel to and tangent to the axis (axis; dotted line extending vertically in FIG. 2B) of the water purification filter 10. In the water purification cartridge 1, the water purification filter 10 is disposed coaxially with the storage case 20 and the lid 30, for example, and the extension direction of the central axis of the water purification filter 10 coincides with the axial direction of the water purification cartridge 1. Also, Fig. 3 is a cross-sectional schematic diagram showing an example of the main configuration of the water purification cartridge 1, which is formed by attaching the lid 30 to the storage case 20 that houses the water purification filter 10.

[0054] As illustrated in Fig. 2A, the water purification cartridge 1 according to this embodiment is generally cylindrical and typically has a cylindrical appearance. As illustrated in Fig. 2B, the water purification cartridge 1 includes a storage case 20, a cylindrical water purification filter 10 housed inside the storage case 20, and a lid 30 that closes the open end of the storage case 20 housing the water purification filter 10. As illustrated in Fig. 3, in the water purification cartridge 1, raw water that flows into the water purification filter 10 from the second water flow section 311 of the lid 30 passes through the water purification filter 10 in the axial direction (from top to bottom in the illustrated example) and flows out as purified water from the first water flow section 211 of the storage case 20.

[0055] The water purification filter 10 is a cylindrical member housed inside the storage case 20 and filters raw water. The axial end surfaces of the storage case 20 are an upper end surface 110 and a lower end surface 120. The storage case 20 is a cylindrical member with one axial end (the upper end in the illustrated example) open and the other axial end (the lower end in the illustrated example) closed by a disk-shaped first surface portion 210. The first surface portion 210 of the storage case 20 is provided with a first water flow section 211 through which purified water flows out, and a male thread portion 221 is provided on the outer circumferential surface of the storage case 20. The lid 30 is a cylindrical member with one axial end (the lower end in the illustrated example) open and the other axial end (the upper end in the illustrated example) closed by a disk-shaped second surface portion 310. The lid 30 is detachably attached to the storage case 20 so as to close the open end (the upper end in the illustrated example) of the storage case 20 with the water purification filter 10 housed inside. A second surface portion 310 of the lid body 30 is provided with a second water flow portion 311 into which raw water flows, and a male thread portion 221 is provided on the inner peripheral surface of the lid body 30.

[0056] In this embodiment, the lid body 30 is removably attached to the storage case 20 that stores the water purification filter 10 by threading the male thread portion 221 of the storage case 20 into the female thread portion 321 of the lid body 30 .

[0057] One axial end face of the water purification filter 10 (in the illustrated example, the lower end face 120) contacts the first surface 210 (particularly, its inner surface) of the storage case 20, and the other end face (in the illustrated example, the upper end face 110) contacts the second surface 310 (particularly, its inner surface) of the lid body 30.

[0058] The raw water flows into the water purification cartridge 1 from the second water flow section 311 of the lid 30, passes through the water purification filter 10 in the axial direction (from top to bottom in the illustrated example), and flows out as purified water from the first water flow section 211 of the storage case 20. Each component will be described in detail below.

[0059] 3. Water Purification Filter Fig. 4 is a diagram that schematically illustrates an example of the main configuration of the water purification filter 10. Specifically, Fig. 4A is a cross-sectional view that schematically illustrates an example of the main configuration of the water purification filter 10. That is, Fig. 4A schematically illustrates the cross-sectional configuration of the water purification filter 10 that is parallel to and in contact with the axis (axial line) of the water purification filter 10. Furthermore, Fig. 4B is a perspective view that schematically illustrates an example of the main configuration of the water purification filter 10.

[0060] As described above, the water purification filter 10 is a component that filters raw water flowing in from the second water flow section 311 of the lid body 30 by passing the raw water in the axial direction (from top to bottom in the illustrated example) to produce purified water. The purified water filtered by the water purification filter 10 flows out of the water purification cartridge 1 from the first water flow section 211 of the storage case 20.

[0061] 4, the water purification filter 10 is a cylindrical water purification filter having a side surface 130 (outer peripheral surface) and, as axial end faces, an upper end face 110 and a lower end face 120. That is, the water purification filter 10 is formed in a cylindrical shape and has an upper end face 110 and a lower end face 120 at both ends in the axial direction. A sealant may be applied to each of the upper end face 110 and the lower end face 120.

[0062] In Figure 4, height AH11 indicates the height in the axial direction of the water purification filter 10 (side surface 130), and outer diameter (diameter) OD11 indicates the length of the diameter (diameter) in the radial direction of the water purification filter 10 (each of the upper end surface 110 and the lower end surface 120).

[0063] As will be described in detail later, in this embodiment, the water purification filter 10 is stored in a compressed state in a storage case 20 having an inner diameter (inner diameter ID21) smaller than the outer diameter OD11 of the water purification filter 10. The outer diameter OD11 of the water purification filter 10 stored in the storage case 20 is equal to the inner diameter ID21 of the storage case 20. Therefore, in the following description, when the term "outer diameter OD11" is simply used, this refers to the "outer diameter OD11(B)," which is the radial diameter (diameter) of the water purification filter 10 before storing the water purification filter 10 in the storage case 20. Furthermore, after storing the water purification filter 10 in the storage case 20 and then removing it from the storage case 20, the radial diameter (diameter) of the water purification filter 10 is referred to as the "outer diameter OD11(A)," which is to be distinguished from the "outer diameter OD11(B)."

[0064] The water purification filter 10 according to this embodiment is cylindrical and made by winding a sheet containing fibrous activated carbon. Its hardness, measured by the following measurement method, is 33 to 59. For example, the water purification filter 10 has a radial hardness of 33 to 59, measured by the following measurement method. That is, in this embodiment, the hardness is measured using a TECLOCK hardness meter GS701G according to the method specified in JIS S 6050 "Plastic Eraser," and the average value for N=5 is taken as the hardness. For example, the water purification filter 10 is placed on a base with the radial direction (side surface 130) of the water purification filter 10 aligned vertically, and the hardness is measured at the center (approximately center) of the axial direction of the side surface 130 of the water purification filter 10.

[0065] As will be described in detail in <6. Various Experiments>, the present inventors conducted an experiment comparing a cylindrical water purification filter (water purification filter 10) formed by winding a sheet containing fibrous activated carbon as an example with the following water purification filter (comparative example). Specifically, the present inventors conducted an experiment comparing the comparative example (water purification filter 10) with a water purification filter produced by a wet molding method using granular activated carbon as a comparative example. The hardness of the water purification filter 10 measured using the above-mentioned measurement method was 33 to 59. In contrast, the hardness of the comparative example measured using the above-mentioned measurement method was 83, which was higher than the upper limit (59) of the hardness of the water purification filter 10. Therefore, the present inventors confirmed that by winding a sheet containing fibrous activated carbon, a cylindrical water purification filter 10 having a lower hardness than the water purification filter according to the comparative example, specifically a hardness of 33 to 59, can be produced.

[0066] Furthermore, the water purification filter 10 has a hardness of 33 to 59 and can be compressed (deformed). A water purification filter 10 with a hardness of 33 to 59 can be compressed (easily compressed) by human force, for example. Therefore, the water purification filter 10 can be easily stored in, for example, a cylindrical storage case (e.g., storage case 20) having an inner diameter smaller than the outer diameter (diameter) OD11 of the water purification filter 10. The present inventor(s) confirmed that a water purification filter 10 with a hardness of 33 to 59 can be compressed and can be stored in a cylindrical storage case having an inner diameter smaller than the outer diameter OD11 of the water purification filter 10. Specifically, the present inventor(s) confirmed that the water purification filter 10 can be stored in a cylindrical storage case having an inner diameter 1 mm smaller than the outer diameter OD11 of the water purification filter 10. In particular, the present inventor(s) confirmed that the water purification filter 10 can be loaded into the above-mentioned storage case while being compressed (compressed radially), and that such loading does not collapse the activated carbon layer of the water purification filter 10. In other words, the present inventor(s) confirmed that by pressing the water purification filter 10 in the axial direction, the water purification filter 10 can be compressed radially and loaded into the above-mentioned storage case without collapsing the activated carbon layer of the water purification filter 10.

[0067] In contrast, the water purification filter according to the comparative example could not be stored in a cylindrical storage case having an inner diameter smaller than the outer diameter of the water purification filter (for example, an inner diameter 1 mm smaller than the outer diameter of the water purification filter). Specifically, when an attempt was made to store the water purification filter according to the comparative example in the storage case, the water purification filter could not be compressed, i.e., could not be deformed, and the activated carbon layer collapsed when the filter was stored in the storage case.

[0068] The water purification filter 10 is housed in, for example, a cylindrical storage case having an inner diameter smaller than the outer diameter OD11 of the water purification filter 10, thereby achieving the following effects. Specifically, the water purification filter 10 is housed in the storage case in a compressed (deformed) state, and the outer peripheral surface (side surface 130) of the water purification filter 10 is in contact with the inner peripheral surface of the storage case without any gaps. Therefore, the water purification filter 10 can prevent raw water from passing through the gap between the side surface 130 of the water purification filter 10 and the inner peripheral surface of the storage case, ensuring that the raw water passes through the water purification filter 10. The water purification filter 10 can prevent raw water from passing through the gap between the side surface 130 of the water purification filter 10 and the inner peripheral surface of the storage case without requiring any additional components, ensuring that the raw water passes through the water purification filter 10.

[0069] Furthermore, because the water purification filter 10 has a hardness of 33 to 59, it can be detachably stored in a cylindrical storage case having an inner diameter smaller than the outer diameter OD11 of the water purification filter 10. In other words, the water purification filter 10 can be easily stored in and removed from the storage case by being compressed. Therefore, only the water purification filter 10 needs to be replaced, and the storage case can be reused. Therefore, the water purification filter 10 can reduce the burden on the environment compared to conventional water purification filters that are replaced only together with the storage case.

[0070] In particular, the present inventor(s) experimentally confirmed that the above-mentioned effects can be significantly achieved by setting the hardness of a cylindrical water purification filter (water purification filter 10) made by winding a sheet containing fibrous activated carbon to 33 to 59. That is, a water purification filter with a hardness greater than the upper limit (59) (e.g., the water purification filter according to the comparative example) could not be housed in a cylindrical storage case with an inner diameter smaller than the outer diameter of the water purification filter. In contrast, the water purification filter 10 is housed in a cylindrical storage case with an inner diameter smaller than the outer diameter (OD11) of the water purification filter 10, preventing raw water from passing through the gap between the outer surface (side surface 130) of the water purification filter 10 and the inner surface of the storage case. In other words, unlike water purification filters with a hardness greater than the upper limit (59), the water purification filter 10, by setting the hardness to 33 to 59, can ensure that raw water passes through the water purification filter 10. Furthermore, by setting the hardness to 33 to 59, the water purification filter 10 can be easily compressed and loaded into a cylindrical storage case having an inner diameter smaller than the outer diameter OD11 of the water purification filter 10, and can also be easily removed from such a storage case.

[0071] Therefore, the water purification filter 10 has the effect of being easily attached and detached to a cylindrical storage case having an inner diameter smaller than the outer diameter OD11 of the water purification filter 10, while ensuring that raw water passes through the water purification filter 10.

[0072] The water purification filter 10 may be formed by winding a plurality of "sheets containing fibrous activated carbon" having different thicknesses (bulk densities). Bulk density may also be referred to as apparent density. The water purification filter 10 may be a cylindrical water purification filter formed by winding a sheet containing fibrous activated carbon and having a hardness of 33 to 59 as measured by the above-mentioned method. The "sheet containing fibrous activated carbon" constituting the water purification filter 10 may be a single one, or the water purification filter 10 may be formed by winding a plurality of "sheets containing fibrous activated carbon" having different thicknesses.

[0073] For example, the water purification filter 10 may be formed by winding a relatively thick (low bulk density) "sheet containing fibrous activated carbon" near the axial center, and a relatively thin (high bulk density) "sheet containing fibrous activated carbon" around the outer periphery of the water purification filter 10. The water purification filter 10 may include (1) a core (core region) around the axial center formed by winding a relatively thick sheet, and (2) a peripheral region around the core formed by winding a relatively thin sheet.

[0074] By adopting this configuration, the water purification filter 10 can reduce the difference in bulk density between the axial center (core region) and its outer periphery (peripheral region), thereby preventing one-sided flow when filtering raw water. By reducing the difference in bulk density between the core region and the peripheral region, the water purification filter 10 can prevent raw water from flowing unevenly toward the core region or the peripheral region.

[0075] Furthermore, the water purification filter 10 according to this embodiment has elasticity. Details will be described later in <6. Various Experiments>, but the present inventor(s) measured the following values ​​for a cylindrical water purification filter (water purification filter 10) made by winding a sheet containing fibrous activated carbon. Specifically, the present inventor(s) temporarily housed the water purification filter in a cylindrical storage case having an inner diameter smaller than the outer diameter of the water purification filter, removed it, and measured the outer diameter of the water purification filter. As a result, the present inventor(s) confirmed that the outer diameter of the water purification filter after removal almost returned to the outer diameter of the water purification filter before it was housed in the storage case, i.e., the water purification filter has elasticity. Therefore, the water purification filter 10, which is cylindrical and made by winding a sheet containing fibrous activated carbon and has a hardness of 33 to 59, has elasticity.

[0076] The water purification filter 10 has elasticity, and due to this elasticity, it can be elastically deformed and stored in, for example, a cylindrical storage case (e.g., storage case 20) having an inner diameter smaller than the outer diameter OD11 of the water purification filter 10. When stored in such a storage case, the water purification filter 10 can prevent raw water from passing through a gap between the outer surface (side surface 130) of the water purification filter 10 and the inner surface of the storage case, ensuring that the raw water passes through the water purification filter 10. In other words, due to the above-mentioned elasticity, the water purification filter 10 can prevent raw water from passing through a gap between the side surface 130 of the water purification filter 10 and the inner surface of the storage case without requiring any other components, ensuring that the raw water passes through the water purification filter 10.

[0077] Furthermore, due to the above-described elasticity, the water purification filter 10 can be detachably stored in a cylindrical storage case having an inner diameter smaller than the outer diameter OD11 of the water purification filter 10. In other words, the water purification filter 10's elasticity allows it to be easily stored in and removed from the storage case. Therefore, only the water purification filter 10 needs to be replaced, and the storage case can be reused. Therefore, the water purification filter 10 reduces the burden on the environment compared to conventional water purification filters that are replaced only together with the storage case.

[0078] Therefore, the water purification filter 10 has the effect of being easily attached and detached to a cylindrical storage case having an inner diameter smaller than the outer diameter OD11 of the water purification filter 10, while ensuring that raw water passes through the water purification filter 10.

[0079] The water purification filter 10 according to this embodiment is housed in a cylindrical storage case 20, and has an outer diameter OD11 that is larger by 1 mm or less than the "inner diameter ID21 (inner diameter ID21(1)) of the storage case 20 at least at one point in the axial direction," which will be described later with reference to Fig. 5. In other words, the outer diameter OD11 of the water purification filter 10 (side surface 130) is larger by 1 mm or less than the "inner diameter ID21 (inner diameter ID21(1)) of the storage case 20 at least at one point in the axial direction."

[0080] As described below, the storage case 20 that stores the water purification filter 10 may have a tapered portion 222 in which the inner diameter ID21 increases toward the open end. In this case, the outer diameter OD11 of the water purification filter 10 is larger than the inner diameter ID21(1) at the closed end of the storage case 20 by 1 mm or less. If the inner diameter ID21 of the storage case 20 varies along the axial direction, the outer diameter OD11 of the water purification filter 10 only needs to be larger than the minimum inner diameter ID21(min) of the storage case 20 by 1 mm or less.

[0081] However, it is not essential that the storage case 20 include the tapered portion 222, and the storage case 20 may not include the tapered portion 222. If the storage case 20 does not include the tapered portion 222, that is, if the inner diameter ID21 of the storage case 20 is constant throughout the axial direction, the outer diameter OD11 of the water purification filter 10 may be larger than the constant inner diameter ID21 by 1 mm or less. For example, the outer diameter OD11 of the water purification filter 10 may be larger than the constant inner diameter ID21 of a storage case 20 whose inner diameter ID21 is constant throughout the axial direction by 1 mm or less.

[0082] Although details will be described later in <6. Various Experiments>, the present inventor(s) confirmed that the water purification filter 10 can be stored in the following storage case 20 without destroying the activated carbon layer of the water purification filter 10. That is, they confirmed that the water purification filter 10 can be stored in a cylindrical storage case 20 having an inner diameter ID21 at at least one point in the axial direction that is 1 mm smaller than the outer diameter of the water purification filter 10 without destroying the activated carbon layer of the water purification filter 10. Furthermore, the water purification filter 10 stored in the storage case 20 by being compressed can be easily removed from the storage case 20.

[0083] Therefore, the water purification filter 10 has the effect of being easily attached to and detached from the storage case 20 while ensuring that raw water passes through the water purification filter 10 .

[0084] The hardness of the water purification filter 10 is lower than that of the storage case 20 and lower than that of the lid 30. As will be described in detail below, the water purification filter 10 is pressed axially by the storage case 20 and the lid 30, and in particular is pushed into the storage case 20 by the lid 30. The water purification filter 10 is stored in the storage case 20 in a compressed (e.g., elastically deformed) state, in particular in a radially compressed state. The water purification filter 10, which is disposed between the storage case 20 and the lid 30 inside the storage case 20, is loaded (stored) in the storage case 20 in a state where it is pressed axially by the storage case 20 and the lid 30 and compressed (deformed) in the radial direction.

[0085] <3-1. Manufacturing Method of Water Purification Filter> As described above, the water purification filter 10 is formed by winding a sheet containing fibrous activated carbon, but in other respects, there are no particular limitations on the manufacturing method of the water purification filter 10. An example of a manufacturing method of a water purification filter in which a sheet containing fibrous activated carbon is molded in a wound state will be described below.

[0086] A method for producing a water purification filter in which a sheet containing fibrous activated carbon is formed in a wound state includes a step of preparing a sheet containing fibrous activated carbon and a step of winding the sheet to obtain a water purification filter. The above-mentioned production method may also include a step of winding the sheet containing fibrous activated carbon and molding it to obtain an intermediate molded body, and a step of applying a sealant to the axial end faces (corresponding to the upper end face 110 and the lower end face 120 of the water purification filter 10) of the obtained intermediate molded body.

[0087] In the above-described method for producing a water purification filter, for example, a sheet containing fibrous activated carbon (activated carbon fiber sheet, dry nonwoven fabric) is first wound (wound) around a thin resin or metal core. Next, the core is removed, and the hollow space formed by removing the core is crushed to produce a new core made of the sheet. The sheet is then wound around the resulting core under tension to obtain a cylindrical activated carbon molded body of a predetermined thickness. The cylindrical activated carbon molded body of a predetermined thickness may then be placed in a furnace and heat-treated. This heat treatment integrates the stacked sheet layers together.

[0088] As described above, the water purification filter 10 may be formed by winding a plurality of "sheets containing fibrous activated carbon" having different thicknesses (bulk densities). Therefore, the above-described "cylindrical activated carbon molded body of a predetermined thickness" may be obtained by winding a plurality of "sheets containing fibrous activated carbon" having different thicknesses. For example, a plurality of "sheets containing fibrous activated carbon" having different thicknesses may be prepared, and a relatively thick "sheet containing fibrous activated carbon" having a low bulk density may be first wound to a certain diameter to form a core. In this case, the relatively thick sheet may be wound around a thin resin or metal core, and then the core may be removed, and the resulting hollow portion may be collapsed to produce a core made of the above-described "relatively thick sheet." The above-mentioned "cylindrical activated carbon molded body of a predetermined thickness" may be obtained by winding a relatively thin (high bulk density) "sheet containing fibrous activated carbon" around the outer periphery of a core (winding core) formed by winding a relatively thick "sheet containing fibrous activated carbon." This method can reduce the difference in bulk density between the vicinity of the axial center (core region) and the outer periphery (peripheral region) of the "cylindrical activated carbon molded body of a predetermined thickness" (water purification filter 10), thereby preventing one-sided flow during filtration of raw water.

[0089] The cylindrical activated carbon molded body having the predetermined thickness is then cut so that the axial height of the activated carbon molded body from the side is a predetermined value (corresponding to the height AH11(B) of the water purification filter 10 (side surface 130) before being stored in the storage case 20), thereby obtaining a cylindrical activated carbon molded body having a desired axial height. The front or back surface of the wound sheet of the cylindrical activated carbon molded body forms the side surface (side surface 130) of the activated carbon molded body (water purification filter 10). Furthermore, the longitudinal ends of the sheet are arranged in a spiral shape to form the upper surface (upper end surface 110) and lower surface (lower end surface 120) of the activated carbon molded body (water purification filter 10). The water purification filter 10 may be obtained by this manufacturing method.

[0090] As described above, a sealant (e.g., a hot melt adhesive) may be applied to the axial end faces (corresponding to the upper end face 110 and lower end face 120 of the water purification filter 10) of a cut cylindrical activated carbon molded body having a predetermined axial height, to form the upper end face 110 and lower end face 120 of the water purification filter 10.

[0091] In addition, the sheet containing fibrous activated carbon can contain, in addition to fibrous activated carbon (activated carbon fiber), granular activated carbon, zeolite, ion exchange fiber, ion exchange resin, chelating fiber, ceramic, calcium sulfite, hollow fiber, etc. Among these, from the viewpoint of further improving the antibacterial properties of the sheet containing fibrous activated carbon during storage of the water purifier of the present invention, it is preferable to include activated carbon fiber that does not support an antibacterial agent and one or more antibacterial agent-supporting materials selected from the group consisting of activated carbon fiber, granular activated carbon, and zeolite. From the viewpoint of further maintaining the antibacterial properties even after long-term use, it is more preferable to include activated carbon fiber that does not support an antibacterial agent and activated carbon fiber or granular activated carbon kneaded with an antibacterial agent. The antibacterial agent kneaded into the activated carbon is preferably, for example, one or more metals or metal compounds selected from the group consisting of silver, zinc, and copper, and the metal compound is preferably a metal salt. Examples of silver salts include silver nitrate, silver acetate, silver sulfate, and silver acetylacetonate, examples of zinc salts include zinc nitrate, zinc acetate, and zinc sulfate, and examples of copper salts include copper nitrate, copper acetate, and copper sulfate. Furthermore, the sheet containing fibrous activated carbon preferably contains a binder component, and examples of the binder component include pulp and heat-fusible fibers.

[0092] (Axial Height of the Water Purification Filter) The axial height AH11 of the water purification filter 10 (side surface 130) according to this embodiment is equal to the axial height AH22 of the "internal space (first internal space 230) of the storage case 20 that stores the water purification filter 10," which will be described later with reference to Fig. 5. In particular, the axial height AH11(B) of the water purification filter 10 before it is stored in the storage case 20 is equal to the axial height AH22 of the first internal space 230 of the storage case 20.

[0093] However, the axial height AH11(B) of the water purification filter 10 (side surface 130) before being stored in the storage case 20 may be greater than the axial height AH22 of the first internal space 230 of the storage case 20. For example, the axial height AH11(B) of the water purification filter 10 before being stored in the storage case 20 may be greater than the axial height AH22 of the first internal space 230 of the storage case 20 by 1 mm or less. In other words, before being stored in the storage case 20, the axial distance between the upper end surface 110 and the lower end surface 120 of the water purification filter 10 may be greater than the height AH22 of the first internal space 230 of the storage case 20 by 1 mm or less.

[0094] As described above, the hardness of the water purification filter 10 is 33 to 59, and the water purification filter 10 can be compressed (deformed). In particular, the water purification filter 10 is elastic, i.e., it can be elastically deformed. Therefore, the water purification filter 10 can be stored in the first internal space 230 (the first internal space 230 of the storage case 20) having an axial height AH22 smaller than the "axial height AH11(B) of the water purification filter 10" by, for example, compressing (elastically deforming) the water purification filter 10 in the axial direction. In other words, by compressing (elastically deforming) the water purification filter 10, which has a height AH11(B) larger than the height AH22 of the first internal space 230 of the storage case 20, the water purification filter 10 can be stored in the first internal space 230 of the storage case 20.

[0095] Because the water purification filter 10 is elastic, when the open end of the storage case 20 storing the water purification filter 10 in the first internal space 230 is closed with the lid 30 and then the lid 30 is removed from the storage case 20, the following occurs: Because the water purification filter 10 is elastic, the axial height AH11(A) of the water purification filter 10 after the lid 30 is removed substantially returns to the axial height AH11(B) of the water purification filter 10 before it was stored in the storage case 20. As described above, the axial height AH22 of the first internal space 230 is smaller than the axial height AH11(B) of the water purification filter 10 before it was stored in the storage case 20. Therefore, after the open end of the storage case 20 storing the water purification filter 10 in the first internal space 230 is closed with the lid body 30, by removing the lid body 30 from the storage case 20, a portion of the water purification filter 10 will protrude outside the open end of the storage case 20.

[0096] Therefore, a user of the water purification cartridge 1 can easily remove the water purification filter 10 stored in the storage case 20 from the storage case 20 by using the part of the water purification filter 10 that protrudes outside the open end of the storage case 20. For example, a user of the water purification cartridge 1 can easily remove the water purification filter 10 stored in the storage case 20 from the storage case 20 by hooking a fingernail on the part of the water purification filter 10 that protrudes outside the open end of the storage case 20.

[0097] However, it is not essential that the height AH11(B) of the water purification filter 10 before it is stored in the storage case 20 be greater than the height AH22 of the first internal space 230 of the storage case 20. The height AH11(B) of the water purification filter 10 before it is stored in the storage case 20 may be the same as the height AH22 of the first internal space 230 of the storage case 20. That is, the axial height AH22 of the first internal space 230 of the storage case 20 may be equal to the axial height AH11(B) of the water purification filter 10 (side surface 130) before it is stored in the storage case 20. Furthermore, the height AH11(B) of the water purification filter 10 before it is stored in the storage case 20 may be smaller than the height AH22 of the first internal space 230 of the storage case 20.

[0098] 4. Storage Case Fig. 5 is a diagram that schematically illustrates an example of the main configuration of the storage case 20 according to this embodiment. Specifically, Fig. 5A is a cross-sectional schematic diagram that schematically illustrates an example of the main configuration of the storage case 20. That is, Fig. 5A schematically illustrates the cross-sectional configuration of the storage case 20 that is parallel to and in contact with the axis (axial line) of the storage case 20. Moreover, Fig. 5B is a bottom view that schematically illustrates an example of the main configuration of the storage case 20.

[0099] The storage case 20 is a cylindrical member that removably stores the water purification filter 10. The storage case 20 is made of, for example, a plastic material, and its hardness is greater than that of the water purification filter 10. In other words, the storage case 20 is harder than the water purification filter 10.

[0100] As illustrated in FIG. 5 , the storage case 20 includes a cylindrical first peripheral wall portion 220 and a disk-shaped first surface portion 210. One axial end (the upper end in the illustrated example) of the first peripheral wall portion 220 is open, and the other axial end (the lower end in the illustrated example) is closed by the first surface portion 210. That is, the storage case 20 includes the first peripheral wall portion 220 and the first surface portion 210. For example, the first surface portion 210 of the storage case 20 contacts the lower end surface 120 of the water purification filter 10, and the water purification filter 10 is pressed axially by the first surface portion 210 while being compressed (elastically deformed) in the radial direction. Furthermore, the first peripheral wall portion 220 of the storage case 20 (particularly, its inner peripheral surface) contacts the side surface 130 (outer peripheral surface) of the water purification filter 10.

[0101] As shown in Fig. 5B, the first surface portion 210 has one or more openings as a first flow portion 211 through which purified water flows out. Also, as shown in Fig. 5A, a male thread portion 221 is provided on the outer circumferential surface of the first circumferential wall portion 220.

[0102] In the storage case 20, the first peripheral wall 220 and the first surface 210 form a cylindrical first internal space 230 that is open at one end (the upper end in the illustrated example), and the water purification filter 10 is removably stored in the first internal space 230. That is, the water purification filter 10 is inserted into the interior of the first peripheral wall 220 (i.e., the first internal space 230) from the open end (the upper end in the illustrated example) of the storage case 20, and is removably stored in the first internal space 230.

[0103] In the first peripheral wall portion 220, the inner diameter ID21(1) at least at the end portion (the lower end in the illustrated example) closed by the first surface portion 210 is smaller than the outer diameter OD11 of the water purification filter 10 by 1 mm or less.

[0104] In the storage case 20 illustrated in FIG. 5 , the first peripheral wall 220 has a tapered portion 222 in which the inner diameter ID21 increases toward the open end (the upper end in the illustrated example). The inner diameter ID21(1) of the first peripheral wall 220, at least at the lower end closed by the first surface 210, is smaller than the outer diameter OD11 of the water purification filter 10 by 1 mm or less. However, the tapered portion 222 is not essential for the storage case 20, and the storage case 20 does not necessarily have to have the tapered portion 222. If the storage case 20 does not have the tapered portion 222, i.e., if the inner diameter ID21 of the storage case 20 is constant throughout the axial direction, the outer diameter OD11 of the water purification filter 10 will be larger than the constant inner diameter ID21 by 1 mm or less.

[0105] As described above, the first peripheral wall portion 220 of the storage case 20 may be formed with a tapered portion 222 in which the inner diameter ID21 increases toward the open end (the upper end in the illustrated example). That is, in the example shown in Fig. 5A, the inner diameter ID21(2) at the open upper end of the storage case 20 is larger than the inner diameter ID21(1) at the lower end closed by the first surface portion 210.

[0106] The inner diameter ID21(2) at the open upper end of the storage case 20 may be larger than the outer diameter OD11 of the water purification filter 10. By making the inner diameter ID21(2) at the upper end of the storage case 20 larger than the outer diameter OD11 of the water purification filter 10, it becomes easier to insert the water purification filter 10 into the first internal space 230 from the open upper end of the storage case 20.

[0107] However, the inner diameter ID21(2) at the upper end of the storage case 20 may be the same as the outer diameter OD11 of the water purification filter 10, or may be smaller than the outer diameter OD11 of the water purification filter 10. The inner diameter ID21(2) at the upper end must be larger than the inner diameter ID21(1) at the lower end. The inner diameter ID21(1) at the end of the storage case 20 that is closed by the first surface portion 210 must be smaller than the outer diameter OD11 of the water purification filter 10 by 1 mm or less.

[0108] The storage case 20 (water purification cartridge 1) has a tapered portion 222 in the first peripheral wall portion 220, in which the inner diameter ID21 increases toward the open end, thereby achieving the following effect: The water purification cartridge 1 makes it easy to insert the water purification filter 10 into the interior of the storage case 20 (first internal space 230) from the open end of the storage case 20 (the upper end in the illustrated example).

[0109] However, it is not essential for the storage case 20 to have the tapered portion 222 formed on the first peripheral wall portion 220. The inner diameter ID21 of the storage case 20 may be constant, and for example, the inner diameter ID21 of the storage case 20 (first internal space 230) may be equal between the upper end and the lower end in the axial direction.

[0110] 5 , the axial height AH22 of the first internal space 230 is equal to the axial height AH11(B) of the water purification filter 10 before it is stored in the storage case 20. Therefore, the second surface 310 of the lid 30, which will be described later with reference to FIG. 6 , contacts one axial end surface (upper end surface 110) of the water purification filter 10 that is removably stored in the storage case 20. The second surface 310 of the lid 30 closes the open end (the upper end in the illustrated example) of the storage case 20 that stores the water purification filter 10, and presses the water purification filter 10 in the axial direction, forcing the water purification filter 10 into the first internal space 230 of the storage case 20. That is, the lid body 30 uses the second surface portion 310 to push the water purification filter 10 axially (from top to bottom in the illustrated example) into the first internal space 230 of the storage case 20, while using the second surface portion 310 to close the open end of the storage case 20.

[0111] However, as described above, the axial height AH22 of the first internal space 230 may be lower than the axial height AH11(B) of the water purification filter 10 before it is stored in the storage case 20. By adopting such a configuration, when the open end of the storage case 20 storing the water purification filter 10 in the first internal space 230 is closed with the lid 30 and then the lid 30 is removed from the storage case 20, a portion of the water purification filter 10 protrudes outside the open end of the storage case 20. That is, as described above, because the water purification filter 10 is elastic, the axial height AH11(A) of the water purification filter 10 after the lid 30 is removed nearly returns to the axial height AH11(B) of the water purification filter 10 before it is stored in the storage case 20. As described above, the axial height AH22 of the first internal space 230 is smaller than the axial height AH11(B) of the water purification filter 10 before it is stored in the storage case 20. Therefore, when the lid 30 is removed from the storage case 20, a portion of the water purification filter 10 protrudes outside the open end of the storage case 20. Therefore, a user of the water purification cartridge 1 can easily remove the water purification filter 10 stored in the storage case 20 from the storage case 20 by using the portion of the water purification filter 10 protruding outside the open end of the storage case 20.

[0112] However, it is not essential that the axial height AH22 of the first internal space 230 in the storage case 20 be smaller than the axial height AH11(B) of the water purification filter 10 before it is stored in the storage case 20. The axial height AH22 of the first internal space 230 may be the same as the axial height AH11(B) of the water purification filter 10 before it is stored in the storage case 20. Furthermore, the axial height AH22 of the first internal space 230 may be greater than the axial height AH11(B) of the water purification filter 10 before it is stored in the storage case 20.

[0113] The axial height AH21 of the storage case 20 (first peripheral wall portion 220) is the sum of the height AH22 of the first internal space 230 of the storage case 20 and the thickness (axial thickness) of the first surface portion 210. The axial height AH21 of the storage case 20 is equal to the axial height AH32 of the second internal space 330 of the lid body 30, which will be described later with reference to FIG. 6 . Therefore, the storage case 20 is accommodated in the second internal space 330 of the lid body 30 so that the axially outer surface (the lower side in the illustrated example) of the first surface portion 210 of the storage case 20 and the axially outer surface of the second peripheral wall portion 320 of the lid body 30 are smoothly continuous with no gaps. Furthermore, the storage case 20 is accommodated in the second internal space 330 of the lid body 30 with the open end of the storage case 20 (first internal space 230) closed by the second surface portion 310 of the lid body 30.

[0114] 5 is the outer diameter (radial length) of the storage case 20 (first peripheral wall portion 220), and is the inner diameter ID21 of the storage case 20 (first peripheral wall portion 220) plus the thickness of the first peripheral wall portion 220. The outer diameter OD21 of the storage case 20 is equal to the inner diameter ID31 of the second internal space 330 of the lid body 30, which will be described later. Therefore, in the water purification cartridge 1, the outer peripheral surface of the storage case 20 (first peripheral wall portion 220) is in contact with the inner peripheral surface of the lid body 30 (second peripheral wall portion 320) without any gaps.

[0115] 5. Lid> Figure 6 is a diagram that schematically illustrates an example of the main configuration of the lid 30 according to this embodiment. Specifically, (A) of Figure 6 is a cross-sectional schematic diagram that schematically illustrates an example of the main configuration of the lid 30. That is, (A) of Figure 6 is a schematic diagram that illustrates the cross-sectional configuration of the lid 30 that is parallel to and in contact with the axis (axial line) of the lid 30. Also, (B) of Figure 6 is a top view that schematically illustrates an example of the main configuration of the lid 30.

[0116] The lid 30 is a cylindrical member that is detachably attached to the storage case 20 and closes the open end (the upper end in the illustrated example) of the storage case 20, which houses the water purification filter 10 inside (the first internal space 230). The lid 30 is made of, for example, a plastic material, and its hardness is greater than that of the water purification filter 10, i.e., the lid 30 is harder than the water purification filter 10.

[0117] As illustrated in FIG. 6 , the lid 30 includes a cylindrical second peripheral wall portion 320 and a disk-shaped second surface portion 310. One axial end (the lower end in the illustrated example) of the second peripheral wall portion 320 is open, and the other axial end (the upper end in the illustrated example) is closed by the second surface portion 310. That is, the lid 30 includes the second peripheral wall portion 320 and the second surface portion 310. For example, the second surface portion 310 of the lid 30 contacts the upper end surface 110 of the water purification filter 10, and the water purification filter 10 is pressed axially by the second surface portion 310 while being compressed (elastically deformed) in the radial direction. Furthermore, the second peripheral wall portion 320 of the lid 30 (particularly, its inner circumferential surface) contacts the outer circumferential surface of the storage case 20 (the first peripheral wall portion 220).

[0118] As shown in Fig. 6B, the second surface portion 310 has one or more openings as second flow portions 311 through which raw water flows in. Furthermore, as shown in Fig. 6A, the inner peripheral surface of the second peripheral wall portion 320 has a female thread portion 321.

[0119] In the lid body 30, the second peripheral wall portion 320 and the second surface portion 310 form a cylindrical second internal space 330 with one end (the lower end in the illustrated example) open, and the entire storage case 20 containing the water purification filter 10 is stored in this second internal space 330 in a removable manner.

[0120] Specifically, the storage case 20 with the water purification filter 10 inserted into the interior of the first peripheral wall portion 220 (first internal space 230) is stored in the second internal space 330 of the lid body 30 from the side of the open end (the lower end in the illustrated example) of the lid body 30. The lid body 30 is detachably attached to the storage case 20 so that the second surface portion 310 closes the open end of the storage case 20 with the water purification filter 10 stored in the first internal space 230.

[0121] 6, a first protrusion 313 that protrudes axially outward may be provided on the axially outer surface (the upper side in the illustrated example) of the second surface 310 of the lid 30. The water purification cartridge 1 allows a user of the water purification cartridge 1 to use the first protrusion 313 of the lid 30 as a knob to easily remove the water purification cartridge 1 from the container 2 to which the water purification cartridge 1 is attached.

[0122] As illustrated in Fig. 6 , the inner surface of the second surface 310 of the lid 30 may be provided with a second protrusion 312 that protrudes inwardly of the lid 30. That is, the second protrusion 312 that protrudes inwardly in the axial direction may be provided on the axially inner surface (the lower side in the illustrated example) of the second surface 310. In the example illustrated in Fig. 6 , a plurality of second protrusions 312 are formed on the inner surface of the second surface 310 at predetermined angles to each other in the circumferential direction (every 90 degrees in the illustrated example).

[0123] The lid body 30 has the second protrusion 312 on the inner surface of the second surface 310, which provides the following effect compared to a case where the second protrusion 312 is not provided on the inner surface of the second surface 310. That is, the second protrusion 312 provided on the inner surface of the second surface 310 allows the lid body 30 to press the water purification filter 10 stored inside the storage case 20 (first internal space 230) more strongly in the axial direction than a case where the second protrusion 312 is not provided.

[0124] However, it is not essential for the lid body 30 to have the second protrusion 312 on the inner surface of the second surface 310. The inner surface of the second surface 310 does not necessarily have to have the second protrusion 312 that protrudes toward the inside of the lid body 30.

[0125] The axial height AH32 of the second internal space 330 of the lid body 30 is equal to the axial height AH21 of the storage case 20 (first peripheral wall portion 220). Therefore, the storage case 20 is housed in the second internal space 330 of the lid body 30 so that the axially outer surface (the lower side in the illustrated example) of the first face portion 210 of the storage case 20 and the axially outer surface of the second peripheral wall portion 320 of the lid body 30 are smoothly continuous without any gaps. For example, by screwing the male thread portion 221 of the storage case 20 into the female thread portion 321 of the lid body 30, the entire storage case 20 that houses the water purification filter 10 is housed in the second internal space 330 of the lid body 30.

[0126] The inner diameter ID31 of the second internal space 330 of the lid body 30 is equal to the outer diameter OD21 of the storage case 20 (first peripheral wall portion 220). Therefore, in the water purification cartridge 1, the outer peripheral surface of the storage case 20 (first peripheral wall portion 220) and the inner peripheral surface of the lid body 30 (second peripheral wall portion 320) are in contact with each other without any gaps.

[0127] The axial height AH31 of the lid body 30 is the sum of the axial height AH32 of the second internal space 330 of the lid body 30 and the thickness (axial thickness) of the second surface 310. The axial height AH31 of the lid body 30 is equal to, for example, the axial depth of the opening S4 formed in the bottom of the tank TK in FIG. 1. Therefore, the water purification cartridge 1 is attached to the tank TK (container 2) so that the axially outer surface (upper side in the illustrated example) of the lid body 30 (second surface 310) and the axially inner surface (upper side in the illustrated example) of the bottom of the tank TK are smoothly continuous with no gaps.

[0128] 6. Various Experiments The inventor(s) conducted the following first and second experiments to confirm the physical properties of the water purification filter 10.

[0129] 6-1. First Experiment (Hardness) As described above, the water purification filter 10 is formed by, for example, winding a sheet containing fibrous activated carbon. Therefore, the present inventor(s) wound a sheet containing fibrous activated carbon to create multiple cylindrical water purification filters 10 (multiple water purification filters 10 according to each of Examples 1 to 5 below). The outer diameter OD11 (particularly, the outer diameter OD11(B) before being stored in a storage case) of the multiple water purification filters 10 (wound filters) according to each Example was 52.8 mm. The axial height AH11 (particularly, the axial height AH11(B) before being stored in a storage case) of the multiple water purification filters 10 according to each Example was 21.5 mm. Because the multiple water purification filters 10 according to each Example were all cylindrical, the inner diameter was 0 mm.

[0130] The present inventors also created the following water purification filters as comparative examples for comparison with the above-described examples (water purification filters 10). Specifically, the present inventors created several cylindrical water purification filters as comparative examples using granular activated carbon via a wet molding method. The outer diameters of the water purification filters according to the comparative examples (particularly, the outer diameters before being housed in a storage case) were all 56.9 mm. The axial heights of the water purification filters according to the comparative examples (particularly, the axial heights before being housed in a storage case) were all 80.0 mm. Furthermore, the inner diameters of the cylindrical water purification filters according to the comparative examples were all 41.0 mm.

[0131] The outline of each of the above-mentioned Examples and Comparative Examples is summarized in Table 1 below. (Table 1)

[0132] The inventor(s) measured the hardness of each of the above-mentioned Examples and Comparative Examples using the following method. Specifically, using a TECLOCK hardness tester GS701G, hardness measurements were performed using the method specified in JIS S 6050 "Plastic Eraser," and the average value for N=5 was used as the hardness of each Example and Comparative Example. As a result, the hardness of the water purification filter 10 according to each Example was between 33 and 59. Specifically, the hardness of the water purification filter 10 according to Example 4 was 59, and the hardness of the water purification filter 10 according to Example 5 was 33. Similarly, the hardness of the cylindrical water purification filter according to the Comparative Example (produced by a wet molding method using granular activated carbon) was 83. The hardness of each Example and Comparative Example is summarized in Table 2 below. The water purification filters 10 of Examples 1 to 5 were each constructed to have the following hardness and outer diameter by adjusting the tension and winding length of the sheet containing fibrous activated carbon. (Table 2)

[0133] Through the first experiment described above, the present inventor(s) confirmed that a cylindrical water purification filter 10 including an activated carbon layer and having a hardness measured by the above-mentioned measurement method of 33 to 59 can be produced by winding a sheet including fibrous activated carbon. The present inventor(s) also confirmed that the water purification filter 10 formed by winding a sheet including fibrous activated carbon can have a lower hardness than a cylindrical water purification filter (comparative example) produced by a wet molding method using granular activated carbon.

[0134] <6-2. Second Experiment (Regarding Elasticity)> The present inventor(s) further conducted a second experiment to confirm whether each of the Examples and Comparative Examples created in the first experiment had elasticity and whether they could be stored in a storage case having an inner diameter smaller than the outer diameter of each of the Examples and Comparative Examples.

[0135] Specifically, first, the water purification filters according to each of the Examples and Comparative Examples created in Experiment 1 were prepared. In addition, a cylindrical storage case was prepared, the inner diameter of which was 1 mm smaller than the outer diameter of each water purification filter, and the axial height of the internal space was the same as the axial height of each water purification filter.

[0136] As described above, the outer diameter OD11 (particularly, the outer diameter OD11(B) before being stored in the storage case) of the water purification filter 10 according to each embodiment is 52.8 mm. The axial height AH11 (particularly, the axial height AH11(B) before being stored in the storage case) of the water purification filter 10 according to each embodiment is 21.5 mm. Therefore, the inner diameter ID21 of the storage case (storage case 20) that stores the water purification filter 10 inside (the first internal space 230) is set to be 1 mm smaller than the outer diameter OD11 of the water purification filter 10. In other words, the inner diameter ID21 of the storage case 20 is set to be 51.8 mm. The axial height AH22 of the first internal space 230 of the storage case 20 is set to be the same as the axial height AH11 of the water purification filter 10. In other words, the height AH22 of the storage case 20 is set to be 21.5 mm.

[0137] As described above, the outer diameter (particularly, the outer diameter (B) before being stored in a storage case) of the comparative cylindrical water purification filter produced by a wet molding method using granular activated carbon is 56.9 mm. The axial height (particularly, the axial height (B) before being stored in a storage case) of the comparative water purification filter is 80.0 mm. Therefore, the inner diameter ID of the storage case (hereinafter referred to as the "comparative storage case") that houses the comparative water purification filter is set to be 1 mm smaller than the outer diameter of the comparative water purification filter, i.e., the inner diameter ID of the comparative storage case is set to be 55.9 mm. The axial height of the internal space of the comparative storage case is set to be the same as the axial height of the comparative water purification filter, i.e., the axial height of the internal space of the comparative storage case is set to be 80.0 mm.

[0138] The inventor(s) confirmed whether each of the Examples and Comparative Examples could be housed in the storage case described above. Specifically, they confirmed whether the water purification filter 10 according to each Example, which has an outer diameter OD11 (B) of 52.8 mm, could be housed in the first internal space 230 of the storage case 20, which has an inner diameter ID21 of 51.8 mm. They also confirmed whether the water purification filter according to the Comparative Example, which has an outer diameter (B) of 56.9 mm, could be housed in the internal space of the comparative storage case, which has an inner diameter ID of 55.9 mm. As described above, in each of the Examples and Comparative Examples, the difference between the outer diameter of the water purification filter before and after it is housed in the storage case (the amount of compression of the outer diameter when installed) is 1.0 mm.

[0139] As a result, the inventor(s) confirmed that the water purification filters 10 according to each embodiment can be loaded (stored) while being compressed into the first internal space 230 of the storage case 20. Furthermore, when the water purification filters 10 according to each embodiment were temporarily stored in the first internal space 230 of the storage case 20 and then removed, the value of the outer diameter OD11(A) after removal (52.4 to 52.7 mm) was approximately equal to the value of the outer diameter OD11(B) before storage (52.8 mm). The inventor(s) confirmed that the value of the outer diameter OD11(A) after removal of the water purification filters 10 according to each embodiment recovered to the value of the outer diameter OD11(B) before storage in the range of "0 mm" to "1.0 mm." That is, the inventor(s) confirmed that, for the water purification filter 10 according to each example, the difference between the outer diameter OD11(A) after removal and the outer diameter OD11(B) before storage was in the range of 0 mm to 1.0 mm (0 mm or more and less than 1.0 mm). The inventor(s) confirmed that when the water purification filter 10 according to each example was removed from the first internal space 230 of the storage case 20, the outer diameter OD11(A) after removal nearly returned to the outer diameter OD11(B) before storage, and that the water purification filter 10 according to each example had elasticity.

[0140] In contrast, the comparative example's cylindrical water purification filter, which was made using granular activated carbon by a wet molding method, could not be compressed and could not be compressed and loaded (stored in the internal space of the comparative storage case). Specifically, the inventors confirmed that the comparative example's water purification filter could not be compressed (deformed), and that the activated carbon layer collapsed when attempting to force it into the internal space of the comparative storage case. Furthermore, when the comparative example's water purification filter was removed from the internal space of the comparative storage case, the outer diameter (A) after removal did not recover to the outer diameter (B) value (56.9 mm) before storage, and was equal to the inner diameter ID (55.9 mm) of the comparative storage case. The inventors confirmed that the comparative example's water purification filter did not recover to the outer diameter (B) value before storage when removed from the internal space of the comparative storage case, confirming that the comparative example's water purification filter lacks elasticity. The outline and results of the second experiment described above are summarized in Table 3 below. (Table 3)

[0141] In a second experiment shown in Table 3, the inventor(s) confirmed that a cylindrical water purification filter 10 made by winding a sheet containing fibrous activated carbon and having a hardness of 33 to 59 has elasticity. The inventor(s) also confirmed that the water purification filter 10 can be stored in the first internal space 230 of the storage case 20, whose inner diameter ID 21 is 1 mm smaller than the outer diameter OD 11 (B) of the water purification filter 10 before storage in the storage case 20. For example, the water purification filter 10 according to Example 4, which has a hardness of "59," and the water purification filter 10 according to Example 5, which has a hardness of "33," both have elasticity and can be stored in the storage case 20 by compressing (deforming). In contrast, the water purification filter according to the comparative example, which has a hardness of "83," does not have elasticity and could not be compressed and stored in the comparative storage case. In other words, the inventor(s) confirmed that there is a significant difference between the water purification filters 10 according to Examples 4 and 5, which have elasticity, and the water purification filter according to the Comparative Example, which does not have elasticity. The inventor(s) also confirmed that there is a significant difference between the water purification filters 10 according to Examples 4 and 5 and the water purification filter according to the Comparative Example, in that the water purification filter according to the Comparative Example could not be compressed for storage, whereas the water purification filter 10 according to Examples 4 and 5 could be compressed for storage.

[0142] As described above, the water purification filter 10 can be stored in the first internal space 230 of the storage case 20 whose inner diameter ID21 is 1 mm smaller than the outer diameter OD11(B) of the water purification filter 10 before it is stored in the storage case 20. Therefore, the water purification filter 10 can naturally be stored in the first internal space 230 of the storage case 20 whose inner diameter ID21 is smaller by 1 mm or less than the outer diameter OD11(B) of the water purification filter 10 before it is stored in the storage case 20. In other words, the inner diameter ID21 of the storage case 20 that stores the water purification filter 10 in the first internal space 230 may be larger than the inner diameter ID21 of the storage case 20 used in the second experiment described above. The inner diameter ID21 of the storage case 20 capable of storing the water purification filter 10 in the first internal space 230 may be smaller than the outer diameter OD11(B) of the water purification filter 10 by no more than 1 mm, and may be smaller by, for example, 0.1 mm or 0.5 mm. As with the storage case used in the second experiment described above, the inner diameter ID21 of the storage case 20 may be smaller by 1 mm than the outer diameter OD11(B) of the water purification filter 10.

[0143] 7. Method for Assembling a Water Purification Cartridge> Figure 7 is a flowchart showing an example of the execution procedure of the assembly method according to this embodiment. The execution procedure described below is an example of the "method for assembling a water purification cartridge" of the present invention. The water purification cartridge 1 is assembled, for example, through the following steps (procedures) illustrated in Figure 7.

[0144] (Step S110, Step of Preparing a Water Purification Filter) In step S110, the water purification filter 10 is prepared. As described above, the water purification filter 10 is made by winding a sheet containing fibrous activated carbon, has a cylindrical shape, and has a hardness of 33 to 59. The water purification filter 10 can be compressed (deformed), and can be easily compressed by human force, for example.

[0145] (Step S120, Step of Preparing a Storage Case) In step S120, a storage case 20 is prepared. The storage case 20 is a cylindrical case that removably stores the water purification filter 10. Specifically, the storage case 20 has a cylindrical first peripheral wall portion 220, one axial end of which is open and the other axial end of which is closed by the first surface portion 210. The inner diameter ID21(1) of at least the end of the first peripheral wall portion 220 that is closed by the first surface portion 210 is smaller than the outer diameter OD11 of the water purification filter 10 by 1 mm or less. In other words, the inner diameter ID21(1) of at least the end of the first peripheral wall portion 220 that is closed by the first surface portion 210 is smaller than the outer diameter OD11(B) of the water purification filter 10 before it is stored in the storage case by 1 mm or less. The first surface portion 210 is also provided with a first water flow portion 211 through which purified water flows out or raw water flows in.

[0146] (Step S130: Inserting the Water Purification Filter into the Storage Case) In step S130, the water purification filter 10 is inserted into the first peripheral wall 220 (first internal space 230) of the storage case 20 from the open end of the storage case 20. In step S130, at least a portion of the water purification filter 10 in the axial direction may be inserted into the storage case 20. In step S130, for example, a portion of the lower end of the water purification filter 10 (at least a portion of the lower end surface 120 side in the axial direction) may be inserted into the storage case 20. In step S130, it is not necessary to store the entire water purification filter 10 inside the storage case 20 (first internal space 230). In the assembly method according to this embodiment, in step S150 (attaching the lid to the storage case), the lid 30 may be detachably attached to the storage case 20, and the water purification filter 10 may be pushed into the storage case 20 using the lid 30. The water purification filter 10 may be stored inside the storage case 20 by pushing the water purification filter 10 into the storage case 20 using the lid 30. Step S150 will be described in detail later.

[0147] (Step S140, Step of Preparing the Lid) In step S140, the lid 30 is prepared. The lid 30 is a cylindrical member that is detachably attached to the storage case 20 and closes the open end (upper end in the illustrated example) of the storage case 20, with the water purification filter 10 housed inside (first internal space 230). Specifically, the lid 30 has a cylindrical second peripheral wall portion 320, one axial end (lower end in the illustrated example) of the second peripheral wall portion 320 being open, and the other axial end (upper end in the illustrated example) being closed by a second surface portion 310. The second surface portion 310 is provided with a second water flow portion 311 into which raw water flows and from which purified water flows out.

[0148] (Step S150, Step of Attaching the Lid to the Storage Case) In step S150, the storage case 20, with the water purification filter 10 inserted from the open end side of the lid 30 into the interior of the first peripheral wall portion 220 (first internal space 230), is stored inside the lid 30 (second internal space 330). Additionally, in step S150, the lid 30 is detachably attached to the storage case 20 so that the open end of the storage case 20 is closed by the second surface portion 310 of the lid 30. That is, in step S150, the lid 30 is detachably attached to the storage case 20 while the storage case 20 with the water purification filter 10 inserted therein is stored inside the lid 30. For example, the lid body 30 is used to push the water purification filter 10 into the storage case 20 to store the water purification filter 10 inside the storage case 20, and the open end of the storage case 20 inside which the water purification filter 10 is stored is closed by the lid body 30.

[0149] As described above, the water purification filter 10 is made by winding a sheet containing fibrous activated carbon, is cylindrical, has a hardness of 33 to 59, and is compressible (deformable). A water purification filter 10 with a hardness of 33 to 59 can be compressed (easily compressed) by human force, for example. The storage case 20 is cylindrical and has an inner diameter ID21 (particularly, inner diameter ID21(1)) that is smaller than the outer diameter OD11 (OD11(B)) of the water purification filter 10. Furthermore, the lid 30 is removably attached to the storage case 20 so as to close the open end (open end) of the storage case 20, which stores the water purification filter 10 in a removable manner.

[0150] The assembly method compresses the water purification filter 10, thereby enabling the water purification filter 10 to be easily stored in a storage case 20 having an inner diameter ID21 smaller than the outer diameter OD11 of the water purification filter 10. The assembly method compresses the water purification filter 10 and stores it in the storage case 20, thereby bringing the side surface 130 of the water purification filter 10 into contact with the inner circumferential surface of the storage case 20 (first peripheral wall portion 220) without any gaps. The assembly method brings the side surface 130 of the water purification filter 10 into contact with the inner circumferential surface of the storage case 20 (first peripheral wall portion 220) without any gaps at least at the end of the storage case 20 that is closed by the first surface portion 210.

[0151] Therefore, the assembly method can provide a water purification cartridge 1 that prevents raw water from passing through a gap between the side surface 130 of the water purification filter 10 and the inner surface of the storage case 20 by storing the water purification filter 10 in the storage case 20, thereby ensuring that raw water passes through the water purification filter 10. Furthermore, the assembly method can compress the water purification filter 10 and easily store it in the storage case 20, and can detachably attach the lid 30 to the storage case 20 storing the water purification filter 10. Furthermore, the water purification cartridge 1 assembled by the assembly method can easily remove the lid 30 from the storage case 20, and the water purification filter 10 can also be easily removed from the storage case 20.

[0152] Therefore, the assembly method has the effect of providing a water purification cartridge 1 in which the water purification filter 10 can be easily attached and detached to the storage case 20 while ensuring that raw water passes through the water purification filter 10 by using the water purification filter 10 and the storage case 20.

[0153] In step S150, the water purification filter 10 is pushed into the interior (first internal space 230) of the storage case 20 by the second surface portion 310 of the lid body 30, and the water purification filter 10 is stored inside the first peripheral wall portion 220 of the storage case 20 (first internal space 230).

[0154] In step S150, the assembly method stores the water purification filter 10 inside the storage case 20 by pushing the water purification filter 10 into the storage case 20 using the second surface 310 of the lid 30. That is, the assembly method attaches the lid 30 to the storage case 20 while pushing the water purification filter 10 into the storage case 20 using the second surface 310 of the lid 30. Therefore, the assembly method allows the water purification filter 10 to be easily stored in the storage case 20 by pushing the water purification filter 10 into the storage case 20 using the lid 30 at the same time as attaching the lid 30 to the storage case 20.

[0155] As described above, the external thread 221 is provided on the outer peripheral surface of the first peripheral wall 220 of the storage case 20, and the internal thread 321 is provided on the inner peripheral surface of the second peripheral wall 320 of the lid 30. In step S150, the external thread 221 and the internal thread 321 are screwed together, whereby the lid 30 is detachably attached to the storage case 20 while the second surface 310 of the lid 30 presses the water purification filter 10 into the interior of the storage case 20.

[0156] In step S150, the assembly method involves attaching the lid 30 to the storage case 20 while pushing the water purification filter 10 into the interior of the storage case 20 by threading the male thread portion 221 and the female thread portion 321 together. Therefore, in the assembly method, the water purification filter 10 is gradually pushed into the interior of the storage case 20 by the lid 30 as the lid 30 is attached to the storage case 20, making it possible to easily and reliably store the water purification filter 10 in the storage case 20.

[0157] In the water purification cartridge 1 assembled through the above steps illustrated in Fig. 7, the water purification filter 10 is placed in a compressed (deformed) state between the storage case 20 and the lid 30, as illustrated in Fig. 8. The relationship between the water purification filter 10, storage case 20, and lid 30 in the water purification cartridge 1 will be described below with reference to Fig. 8.

[0158] FIG. 8 is a diagram showing the water purification cartridge 1 according to this embodiment, in which the water purification filter 10 is arranged between the storage case 20 and the lid 30 in a compressed (elastically deformed) state.

[0159] In the water purification cartridge 1 illustrated in FIG. 8 , the upper end surface 110 of the water purification filter 10 contacts the second surface 310 (particularly, its inner surface) of the lid 30 and is pressed axially (from top to bottom in the illustrated example) by the second surface 310. In particular, in the water purification cartridge 1 illustrated in FIG. 8 , the inner surface of the second surface 310 is provided with a second protrusion 312 that protrudes toward the inside of the lid 30 (from bottom in the illustrated example). As described above, in the storage case 20, the axial height AH22 of the first internal space 230 is equal to the axial height AH11(B) of the water purification filter 10 before it is stored in the storage case 20. Therefore, the upper end surface 110 of the water purification filter 10 is strongly pressed axially (from top to bottom in the illustrated example) by the second protrusion 312 provided on the inner surface of the second surface 310.

[0160] Furthermore, one axial end (the lower end in the illustrated example) of the storage case 20 (first peripheral wall portion 220) is closed by the first surface portion 210. As described above, the height AH22 of the first internal space 230 of the storage case 20 is equal to the axial height AH11(B) of the water purification filter 10 before it is stored in the storage case 20. Therefore, the water purification filter 10 is pressed in the axial direction (from top to bottom in the illustrated example) by the second surface portion 310 (and the second protrusion 312) of the lid 30, and is simultaneously pressed in the axial direction (from bottom to top in the illustrated example) by the first surface portion 210 of the storage case 20.

[0161] The water purification filter 10 has a hardness of 33 to 59 and can be compressed (elastically deformed). In particular, when pressed axially by the second surface 310 (and second protrusion 312) of the lid 30 and the first surface 210 of the storage case 20, the water purification filter 10 deforms (elastically deforms) and attempts to expand radially. The inner diameter ID21 (particularly, inner diameter ID21(1)) of the storage case 20 (first peripheral wall 220) is smaller than the outer diameter OD11 (outer diameter OD11(B)) of the water purification filter 10 by 1 mm or less. Therefore, the side surface 130 (outer peripheral surface) of the water purification filter 10 and the inner peripheral surface of the storage case 20 (first peripheral wall 220) are in contact with each other without any gaps. In particular, at the end of the storage case 20 closed by the first surface 210, the side surface 130 of the water purification filter 10 and the inner peripheral surface of the storage case 20 are in contact with each other without any gaps.

[0162] As explained above, in the water purification cartridge 1, one axial end face (lower end face 120 in the illustrated example) of the water purification filter 10 contacts the first surface 210 (particularly, its inner surface) of the storage case 20. The other axial end face (upper end face 110 in the illustrated example) of the water purification filter 10 contacts the second surface 310 (particularly, its inner surface) of the lid 30.

[0163] As described above, in the water purification cartridge 1, the water purification filter 10 is pushed into the storage case 20 by the second surface 310 of the lid 30 and is stored inside the storage case 20 in a radially compressed (e.g., elastically deformed) state. In particular, the water purification filter 10 is stored inside the storage case 20 in a state in which the side surface 130 is pressed against the inner peripheral surface of the storage case 20 by being pressed axially by the storage case 20 and the lid 30. The water purification filter 10 is deformed (expanded) in the radial direction by being pressed axially by the storage case 20 and the lid 30, and the side surface 130 of the water purification filter 10 is in close contact with the inner peripheral surface of the storage case 20, i.e., without any gaps.

[0164] As described above, the bottom surface 120 of the water purification filter 10 contacts the first surface 210 of the storage case 20, and the top surface 110 of the water purification filter 10 contacts the second surface 310 of the lid 30. Therefore, the water purification cartridge 1 can prevent raw water from passing through the gap between the water purification filter 10 and the storage case 20 and the gap between the water purification filter 10 and the lid 30, and can ensure that raw water passes through the water purification filter 10.

[0165] Furthermore, the inner diameter ID21(1) of at least the end of the storage case 20 closed by the first surface 210 is smaller than the outer diameter OD11 (OD11(B)) of the water purification filter 10 by 1 mm or less. However, as described above, the water purification filter 10 has a hardness of 33 to 59 and can be compressed. Therefore, the lid 30 presses the water purification filter 10 in the axial direction with the second surface 310, compressing the water purification filter 10 and forcing it into the storage case 20, thereby storing the water purification filter 10 inside the storage case 20. The lid 30 then closes the open end (open end) of the storage case 20 with the water purification filter 10 housed inside with the second surface 310. Therefore, the lid 30 can stably store the water purification filter 10 in a compressed state in the storage case 20.

[0166] In particular, in this embodiment, the lid body 30 is removably attached to the storage case 20 by threading a male screw portion 221 provided on the outer peripheral surface of the first peripheral wall portion 220 of the storage case 20 with a female screw portion 321 provided on the inner peripheral surface of the second peripheral wall portion 320 of the lid body 30.

[0167] Therefore, the water purification cartridge 1 allows the lid body 30 to be easily attached to the storage case 20 and the lid body 30 to be easily removed from the storage case 20.

[0168] Furthermore, by threading the male thread portion 221 and the female thread portion 321 of the water purification cartridge 1, for example, the second surface portion 310 of the lid 30 can be used to attach the lid 30 to the storage case 20 while pushing the water purification filter 10 into the storage case 20. Therefore, the water purification cartridge 1 can easily store the water purification filter 10 in the storage case 20 by pushing the water purification filter 10 into the storage case 20 with the lid 30 at the same time as attaching the lid 30 to the storage case 20.

[0169] 8. Features As described above, the water purification filter 10 according to one aspect of the present invention is a cylindrical water purification filter formed by winding a sheet containing fibrous activated carbon, and having a hardness of 33 to 59.

[0170] As described above, the present inventor(s) confirmed that by setting the hardness of a cylindrical water purification filter (water purification filter 10) made by winding a sheet containing fibrous activated carbon to 33 to 59, the water purification filter can remarkably achieve the following effects. That is, a water purification filter 10 with a hardness of 33 to 59 can be compressed (deformed) by human force (e.g., can be easily compressed). Therefore, the water purification filter 10 can be easily stored, for example, in a cylindrical storage case (e.g., storage case 20) with an inner diameter smaller than the outer diameter OD11 of the water purification filter 10. Furthermore, storing the water purification filter 10 in such a storage case prevents raw water from passing through the gap between the side surface 130 of the water purification filter 10 and the inner surface of the storage case, ensuring that raw water passes through the water purification filter 10.

[0171] In contrast, a water purification filter having a hardness greater than the upper limit value (59) (for example, the water purification filter according to the comparative example) could not be stored in a cylindrical storage case having an inner diameter smaller than the outer diameter of the water purification filter.

[0172] In other words, unlike water purification filters with a hardness greater than the above-mentioned upper limit (59), the water purification filter 10 has a hardness of 33 to 59, which allows raw water to reliably pass through the water purification filter 10. Furthermore, by setting the hardness to 33 to 59, the water purification filter 10 can be easily compressed and loaded into a cylindrical storage case having an inner diameter smaller than the outer diameter OD11 of the water purification filter 10, and can also be easily removed from the storage case.

[0173] Therefore, the water purification filter 10 has the effect of being easily attached and detached to a cylindrical storage case having an inner diameter smaller than the outer diameter OD11 of the water purification filter 10, while ensuring that raw water passes through the water purification filter 10.

[0174] A water purification cartridge 1 according to one aspect of the present invention includes a water purification filter 10, a storage case 20, and a lid 30. The storage case 20 removably stores the water purification filter 10 and has a cylindrical first peripheral wall 220. One axial end of the first peripheral wall 220 is open, and the other end is closed by a first surface 210. The inner diameter ID21(1) of at least the end of the first peripheral wall 220 closed by the first surface 210 is smaller than the outer diameter OD11 of the water purification filter 10 by 1 mm or less. The first surface 210 is provided with a first water flow section 211 through which purified water flows out or raw water flows in. The lid 30 is detachably attached to the storage case 20 and has a cylindrical second peripheral wall 320. One axial end of the second peripheral wall 320 is open, and the other axial end is closed by the second surface 310. The second surface 310 is provided with a second water flow section 311 through which raw water flows in and purified water flows out. The second surface 310 closes the open end (open end) of the storage case 20 that stores the water purification filter 10 so that it can be removed.

[0175] As described above, the water purification filter 10 has a hardness of 33 to 59 and can be compressed. The storage case 20 is cylindrical and has an inner diameter ID21 (particularly, inner diameter ID21(1)) that is smaller than the outer diameter OD11 (OD11(B)) of the water purification filter 10. The lid 30 is removably attached to the storage case 20 so as to close the open end (open end) of the storage case 20, which stores the water purification filter 10 in a removable manner.

[0176] Therefore, the water purification cartridge 1 can compress the water purification filter 10 to store it in the storage case 20 (allowing for easy storage). By storing the water purification filter 10 in the storage case 20, the water purification cartridge 1 achieves the following effects. That is, the water purification cartridge 1 can prevent raw water from passing through a gap between the side surface 130 of the water purification filter 10 and the inner circumferential surface of the storage case 20 (first circumferential wall portion 220), thereby ensuring that raw water passes through the water purification filter 10. The water purification cartridge 1 ensures that the outer circumferential surface of the water purification filter 10 and the inner circumferential surface of the storage case 20 are in contact with each other without any gaps, at least at the end of the storage case 20 that is closed by the first surface portion 210. Furthermore, the water purification cartridge 1 can compress the water purification filter 10 to store it easily in the storage case 20, and the lid 30 can be detachably attached to the storage case 20 storing the water purification filter 10. Furthermore, the cover 30 of the water purification cartridge 1 can be easily removed from the storage case 20, and the water purification filter 10 can also be easily taken out from the storage case 20.

[0177] Therefore, the water purification cartridge 1 has the effect of ensuring that raw water passes through the water purification filter 10 by using the water purification filter 10, the storage case 20, and the lid 30, while allowing the water purification filter 10 to be easily attached and detached to the storage case 20.

[0178] A method for assembling a water purification cartridge according to one aspect of the present invention includes the above-described steps S110 to S150. Specifically, in step S110, the water purification filter 10 is prepared. In step S120, the storage case 20 is prepared. In step S130, the water purification filter 10 is inserted into the first peripheral wall portion 220 of the storage case 20 (first internal space 230). In step S140, the lid 30 is prepared. In step S150, the storage case 20 with the water purification filter 10 inserted therein is stored inside the lid 30, and the lid 30 is removably attached to the storage case 20. Specifically, in step S150, the storage case 20 with the water purification filter 10 inserted into the first peripheral wall portion 220 (first internal space 230) is stored inside the lid 30 (second internal space 330) from the open end side of the lid 30. Additionally, in step S150, the lid 30 is removably attached to the storage case 20 so that the open end (opening end) of the storage case 20 is closed by the second surface portion 310 of the lid 30.

[0179] As described above, the water purification filter 10 has a hardness of 33 to 59 and can be compressed. The assembly method compresses the water purification filter 10, allowing the water purification filter 10 to be housed in a storage case 20 having an inner diameter ID21 smaller than the outer diameter OD11 of the water purification filter 10. The assembly method compresses the water purification filter 10 and houses it in the storage case 20, thereby bringing the side surface 130 of the water purification filter 10 into contact with the inner circumferential surface of the storage case 20 without any gaps. The assembly method brings the side surface 130 of the water purification filter 10 into contact with the inner circumferential surface of the storage case 20 without any gaps, at least at the end of the storage case 20 that is closed by the first surface 210.

[0180] The assembly method achieves the following effects by storing the water purification filter 10 in the storage case 20. That is, the assembly method can provide a water purification cartridge 1 that prevents raw water from passing through the gap between the side surface 130 of the water purification filter 10 and the inner surface of the storage case 20, ensuring that raw water passes through the water purification filter 10. Furthermore, the assembly method can compress the water purification filter 10 and easily store it in the storage case 20, and can detachably attach the lid 30 to the storage case 20 that stores the water purification filter 10. Furthermore, the water purification cartridge 1 assembled using the assembly method can easily remove the lid 30 from the storage case 20, and the water purification filter 10 can be easily removed from the storage case 20.

[0181] Therefore, the assembly method has the effect of providing a water purification cartridge 1 in which the water purification filter 10 can be easily attached and detached to the storage case 20 while ensuring that raw water passes through the water purification filter 10 by using the water purification filter 10 and the storage case 20.

[0182] 9. Modifications Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present invention. Note that the following modifications can be combined as appropriate.

[0183] 1 to 3 illustrate an example of a water purification cartridge 1 in which the lid 30 is disposed vertically on the upper side and the storage case 20 is disposed vertically on the lower side. However, it is not essential that the lid 30 is disposed vertically on the upper side and the storage case 20 is disposed vertically on the lower side in the water purification cartridge 1. In the water purification cartridge 1, the lid 30 may be disposed vertically on the lower side and the storage case 20 may be disposed vertically on the upper side.

[0184] When the lid 30 is positioned vertically downward and the storage case 20 is positioned vertically upward, raw water flows into the first water flow section 211 provided on the first surface 210 of the storage case 20. Purified water flows out of the second water flow section 311 provided on the second surface 310 of the lid 30.

[0185] Furthermore, when the lid 30 is positioned vertically downward and the storage case 20 is positioned vertically upward, a knob that allows a user of the water purification cartridge 1 to easily remove the water purification cartridge 1 from the container 2 may be provided on the first surface 210 of the storage case 20. That is, when the lid 30 is positioned vertically downward and the storage case 20 is positioned vertically upward, a protrusion that protrudes axially outward may be provided on the axially outer (upper) surface of the first surface 210 of the storage case 20. The water purification cartridge 1 may allow a user of the water purification cartridge 1 to easily remove the water purification cartridge 1 from the container 2 by using the protrusion provided on the upper surface of the first surface 210 of the storage case 20 as a knob.

[0186] 1...water purification cartridge, 10...water purification filter, 20...storage case, 30...lid, 110...upper end surface (other axial end surface of water purification filter), 120...lower end surface (one axial end surface of water purification filter), 210...first surface portion, 211...first water flow portion, 220...first circumferential wall portion, 221...male thread portion, 222...tapered portion, 310...second surface portion, 311...second water flow portion, 313...first protrusion (protrusion portion), 320...second circumferential wall portion, 321...female thread portion, ID21...inner diameter of storage case, OD11...outer diameter of water purification filter, S110...step of preparing water purification filter, S120...step of preparing storage case, S130...step of inserting water purification filter into storage case, S140...step of preparing lid portion, S150: Attaching the lid to the storage case

Claims

1. A water purification filter, which is formed by winding a sheet containing fibrous activated carbon, has a cylindrical shape, and has a hardness of 33 to 59 as measured by the following measurement method. <Measurement method> Using a TECLOCK hardness meter GS701G as a measuring instrument, measurements are performed according to the method specified in JIS S 6050 "Plastic eraser", and the average value for N=5 is regarded as the hardness.

2. The water purification filter according to claim 1, which has elasticity.

3. The water purification filter according to claim 1 or 2, which is housed in a cylindrical storage case, and the outer diameter is larger than the inner diameter of the storage case at least at one point in the axial direction by 1 mm or less.

4. A water purification filter according to claim 1 or 2; a storage case for removably storing the water purification filter, the storage case having a cylindrical first peripheral wall portion, one axial end of the first peripheral wall portion being open and the other axial end of the first peripheral wall portion being closed by a first surface portion, the inner diameter of at least the other end of the first peripheral wall portion closed by the first surface portion being smaller than the outer diameter of the water purification filter by a range of 1 mm or less, the first surface portion being provided with a first water flow portion through which purified water flows out or through which raw water flows in; and a lid body removably attached to the storage case, the storage case having a cylindrical second peripheral wall portion, one axial end of the second peripheral wall portion being open and the other axial end of the second peripheral wall portion being closed by a second surface portion, the second surface portion being provided with a second water flow portion through which raw water flows in or purified water flows out, the second surface portion closes the open end of the storage case that removably stores the water purification filter; and a lid body.

5. The water purification cartridge according to claim 4, wherein one axial end face of the water purification filter contacts the first surface of the storage case, and the other axial end face contacts the second surface of the lid.

6. The water purification cartridge described in claim 4, wherein the lid body is removably attached to the storage case by screwing together a male threaded portion provided on the outer peripheral surface of the first peripheral wall portion of the storage case and a female threaded portion provided on the inner peripheral surface of the second peripheral wall portion of the lid body.

7. The water purification cartridge according to claim 4, wherein the first peripheral wall of the storage case is formed with a tapered portion whose inner diameter increases toward the open one end.

8. The water purification cartridge according to claim 4, wherein at least one of the first surface of the storage case and the second surface of the lid body has a protrusion on the axially outer surface thereof that protrudes outward in the axial direction.

9. A step of preparing a water purification filter, which is made by winding a sheet containing fibrous activated carbon, has a cylindrical shape, and has a hardness of 33 to 59 measured by the following measurement method; a step of preparing a storage case for removably storing the water purification filter, the storage case having a cylindrical first peripheral wall portion, one axial end of the first peripheral wall portion being open and the other axial end of the first peripheral wall portion being closed by a first surface portion, the inner diameter of at least the other end closed by the first surface portion being smaller than the outer diameter of the water purification filter by a range of 1 mm or less, and the first surface portion being provided with a first water flow portion through which purified water flows out or through which raw water flows in; a step of inserting the water purification filter into the inside of the first peripheral wall portion of the storage case from the open end of the storage case; A method for assembling a water purification cartridge, comprising the steps of: preparing a lid body that is removably attached to the storage case, the lid body having a cylindrical second peripheral wall portion, one axial end of the second peripheral wall portion being open, the other axial end of the second peripheral wall portion being closed by a second surface portion, and the second surface portion being provided with a second water flow portion through which raw water flows in or purified water flows out; and storing the storage case, in which the water purification filter is inserted into the first peripheral wall portion from the open end side of the lid body, inside the lid body, while removably attaching the lid body to the storage case so that the open end of the storage case is closed by the second surface portion of the lid body. <Measuring method> Measurement is performed using a TECLOCK hardness tester GS701G as a measuring instrument according to the method specified in JIS S 6050 "Plastic Eraser", and the average value for N=5 is taken as the hardness.

10. A method for assembling a water purification cartridge as described in claim 9, wherein in the step of removably attaching the lid body, the water purification filter is pushed into the interior of the storage case by the second surface portion of the lid body, thereby storing the water purification filter inside the first peripheral wall portion of the storage case.

11. A method for assembling a water purification cartridge as described in claim 9 or 10, wherein an outer peripheral surface of the first peripheral wall portion of the storage case is provided with a male threaded portion, and an inner peripheral surface of the second peripheral wall portion of the lid body is provided with a female threaded portion, and in a step of removably attaching the lid body, the male threaded portion and the female threaded portion are screwed together, so that the lid body is removably attached to the storage case while the second surface portion of the lid body pushes the water purification filter into the interior of the storage case.

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