Filter cartridge

Abstract

The invention relates to a gravity-based filter cartridge (2) having a cup-shaped upper portion (6) and a cup-shaped lower portion (4), the upper portion (6) having a main axis (X), a first rim (10) at a first axial end (8), a non-porous section (20) at a second axial end (16), and at least one water inlet (46) between the non-porous section (20) and the first rim (10), the lower portion (4) having a second rim (40) and at least one water outlet (28), wherein filter media is arranged in the lower portion (4), the filter cartridge (2) further comprising a screen (50) fixed to the upper portion (6) along a closed path, wherein the screen (50) is further fixed to the non-porous section (20) radially inside the closed path.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a gravity-based filter element, a gravity-based filter element, and a gravity-based filtration device. Background Technology

[0002] The above-mentioned types of filtration devices are used as everyday water filters in homes, which is why they are also called countertop water filters. They are primarily used to remove unwanted substances from tap water. These substances include chlorides and hardening agents such as calcium and magnesium, as well as lead, which enters the tap water through lead pipes, especially in older homes.

[0003] Countertop water filters operate on gravity. No work is required to filter the water other than pouring it into the filter. Due to gravity, the water simply flows downwards through the filter cartridge and into the container for filtered water.

[0004] The filtration apparatus known from EP 1 230 166 B1 includes an inlet funnel with a bottom wall having an opening for a filter element. The filter element is inserted into the opening, forming a seal between the opening and the sealing edge of the filter element. In use, water is introduced from above into the inlet funnel and then flows into the filter element through the inlet. A particulate treatment medium for the water is located inside the filter element. The treatment medium typically contains ion exchange resin and / or activated coal, but other components may also be used as the treatment medium. The water is treated within the filter element and then exits downwards through an outlet at the bottom of the filter element. The filter element also has an air outlet at its top to allow air from inside the filter element to exit upwards at the start of the filtration process.

[0005] Inside the filter element is a screen that prevents the treated medium from leaving the openings (inlet and air outlet) located in the head section of the filter element. The screen is attached to the head section along its lower edge. This is typically achieved through ultrasonic welding during the manufacturing process described below. The head section is arranged inverted, and a strip of screen material (e.g., from a coil) is placed on the lower edge. An ultrasonic welding die (ultrasonic generator) is then placed over the contact area between the screen material and the edge, cutting the screen from the material and simultaneously welding it to the edge. The welding die also includes a dome-shaped portion for deforming the flattened screen material prior to the cutting and welding process. As the welding die is placed on the screen, the dome-shaped portion pushes the screen downwards, forcing the screen material into a similar dome shape.

[0006] Screen materials are typically made of polyethylene terephthalate (PET), polyamide (PA), polypropylene (PP), or polyethylene (PE). Choosing the appropriate mesh size is not an easy task. On the one hand, the mesh size should be as small as possible to reduce the amount of particulate treatment media leaving the filter element. On the other hand, as the mesh size decreases, the flow resistance increases. If the mesh size is too small, the flow rate through the screen may become too low, affecting consumer acceptance of how long it takes for the water to be treated. In rare cases, even very small mesh sizes can cause the water flow to be completely blocked by the screen because the surface tension of water prevents air from escaping through the water present on the screen.

[0007] This problem has been solved in DE 19631 687 A1, which discloses a gravity-operated filter element. The filter element has a body portion with an outlet and a head portion with an inlet and an air outlet, the body portion and head portion together forming a housing with an internal volume. The air outlet is located at the very top of the filter element. The filter element includes a screen insert located within the internal volume, which is welded to the head portion. The screen insert includes a dome-shaped screen reinforced by ribs. The protrusions of the dome-shaped screen are oriented downwards in the direction of the treated medium. In use, the dome-shaped screen contacts the treated medium, thereby disrupting the surface tension of the water, which reduces the occurrence of screen clogging. Although this solution has been successfully applied in the past, the manufacturing workload of the filter element is high due to the complexity of the screen insert. Summary of the Invention

[0008] The problem of this invention is to improve the flow characteristics of the filter element.

[0009] This problem is solved by the method for manufacturing gravity-based filter cartridges according to claim 1.

[0010] A method for manufacturing a gravity-based filter element includes the following steps:

[0011] - Forming a cup-shaped upper portion having a main axis, a first edge at a first axial end, a non-porous section at a second axial end, and at least one inlet between the non-porous section and the first edge;

[0012] - Pull the screen material over the first edge;

[0013] - Push the screen material toward the non-porous section into the upper part of the cup shape to form a dome-shaped screen;

[0014] - Secure the screen material to the first edge along the closed path;

[0015] - Fix the screen material to the non-porous section on the radially inner side of the closed path;

[0016] - Cut the screen from the screen material along a path that is radially outward from the closed path;

[0017] - Forming a cup-shaped lower portion having a second edge and at least one outlet;

[0018] - Insert the filter media into the lower section;

[0019] - The upper part is installed onto the lower part, wherein the second edge contacts the first edge.

[0020] These steps are preferably performed in the listed order.

[0021] In the past, the problem of screen clogging was solved by attempting to remove all air from inside the filter element. For this reason, in the prior art, the air outlet is located at the very top of the filter element. The inventors have now discovered that the clogging problem can be effectively avoided by providing a non-porous section at the upper end of the filter element, where air can accumulate to form an air cushion, and by fixing the screen material to the non-porous section such that the screen cut from the screen material is at least partially arranged in the area where the air accumulates, thus clearly providing a screen section that does not get wet during the use of the filter element. Air from below the screen will be able to easily pass upward through the unwetted portion of the screen into the non-porous section, instead of blocking water attempting to pass through the screen in the opposite direction. This improves the flow characteristics of the filter element.

[0022] The term "main axis" does not necessarily mean that the filter element or any part thereof is rotationally symmetrical. The main axis preferably extends parallel to the direction of gravity.

[0023] The upper portion preferably includes a circumferential outer wall that is closed at a second axial end by an end wall, wherein the end wall, together with adjacent sections of the outer wall, forms a non-porous section. The outer wall may include several sections along the main axis X, and at least some of these sections may extend perpendicular to or at an angle to the main axis X. The end wall is preferably flat, but not necessarily flat. The lower end of the non-porous section is particularly defined by the topmost edge of the inlet.

[0024] The non-porous section preferably includes a support to which the screen material is fixed along the main axis X at a distance from the end wall. Alternatively, the screen material can also be directly fixed to the end wall. The support ensures that the screen is spaced apart from the end wall, thereby providing a defined top volume for air accumulation and simultaneously reducing the amount of screen material required, thus limiting the manufacturing cost of the filter element.

[0025] In any case, the screen material is fixed to the non-porous section at a location axially closer to the end wall than at least one inlet. In other words, the screen material is fixed to the non-porous section above at least one inlet, particularly axially above the topmost edge of at least one inlet.

[0026] In a preferred embodiment, the support has a flat region perpendicular to the main axis X, and the screen material is fixed to this region. The flat region allows the screen material to be reliably attached to the easily manufactured support.

[0027] The screen material is preferably integrally fixed to the first edge and / or non-porous section. "Integrally" means that the connection between the screen material on one side and the edge and / or non-porous section on the other side can only be separated by breaking either of the connected elements. The integral connection, requiring no additional parts, makes manufacturing easy and cost-effective. This connection is also highly reliable, ensuring the filter element's functionality is available throughout its lifespan. The screen material is most preferably fixed to the edge and / or non-porous section by ultrasonic welding. Ultrasonic welding is particularly preferred when combined with a flat contact area as described above, as this provides a good location for the ultrasonic generator to be placed thereon. Performing both connections in the same manner ensures both connections are equally durable and reliable, and also reduces overall production costs, as the same device (e.g., the ultrasonic generator) used to create the connection can be used.

[0028] Typically, the screen material can be secured to both the first edge and the non-porous section simultaneously. This limits production time. However, it is preferable to secure the screen material continuously to both the edge and the non-porous section to ensure that the screen is not stretched too much between the two connections. Excessive tension can cause the connection to break, which is obviously undesirable.

[0029] The support member is preferably a pin extending from the end wall along the main axis X toward a first axial end. The pin is easy to manufacture and provides an easily accessible attachment point for the screen. The pin in different embodiments may have different cross-sections, particularly circular or X-shaped cross-sections. The pin preferably has a disc portion disposed at its lower end. The disc portion may include a contact area.

[0030] The pin preferably has a length of at least 5 mm (L≥5 mm), and particularly preferably at most 20 mm (L≤20 mm). The length L is measured along the main axis X. A pin with a length L within this range ensures that there is sufficient space for air from the filter element to accumulate therein, without unduly increasing the overall height of the filter element.

[0031] The pin preferably extends from the end wall to a minimum pin height H1, and at least one inlet extends to a maximum inlet height H2, where H1 > H2. In other words, the highest point of the top edge of at least one inlet is not higher than the lowest point of the pin to which the screen material is fixed. This arrangement ensures that the inlets are not blocked by air accumulated in the top volume.

[0032] Turbulence and bubble formation in the filter element will be caused by the water entering through the inlet. To ensure that the inlet is not blocked by air cushions at any time, the minimum pin height H1 is preferably at least 5 mm greater than the maximum inlet height H2 (H1≥H2+5mm). Again, to limit the total height of the filter element, the minimum pin height is preferably at most 10 mm greater than the maximum inlet height (H1≤H2+10mm).

[0033] In a preferred embodiment, several water inlets are evenly arranged around the main axis X. This allows water to enter the filter element uniformly, further improving the flow characteristics of the filter element.

[0034] The screen material preferably comprises polyethylene terephthalate (PET). Specifically, the screen material is composed of PET. PET is a relatively hydrophilic material, which generally facilitates the passage of water through the screen.

[0035] The upper and lower portions of the filter element are preferably integrally connected to each other, particularly by ultrasonic welding. Again, this limits manufacturing costs because the same connection device (e.g., an ultrasonic generator) can be used.

[0036] The lower portion and the screen preferably define the filter cartridge volume. The filter cartridge volume is connected to its surrounding environment through holes in the screen and an outlet in the lower portion. The filter medium, preferably in particulate form, is arranged within the filter cartridge volume. The size of the holes in the screen and the outlet opening is selected to prevent particles from exiting the filter cartridge.

[0037] The filter medium inserted into the lower part is preferably ion exchange resin and / or activated coal.

[0038] Depending on when the screen is cut from the screen material during the manufacturing process, some of the features described above with reference to the screen material can be applied alternatively to the screen, especially if they include steps performed after the screen has been cut from the screen material. Conversely, the reverse is also true.

[0039] The problem of the present invention is further addressed by a gravity-based filter element having a cup-shaped upper portion and a cup-shaped lower portion. The upper portion has a main axis, a first edge at a first axial end, a non-porous section at a second axial end, and at least one inlet between the non-porous section and the first edge. The lower portion has a second edge and at least one outlet. A filter medium is arranged in the lower portion. The filter element also includes a screen fixed to the upper portion along a closed path. The screen is further fixed to the non-porous section radially inward of the closed path.

[0040] The filter element may have any of the features described in the above-referenced manufacturing method. Therefore, features associated with screen material can be applied to a filter element where the screen is not screen material. For example, although according to this method, screen material is fixed to the first edge and the non-porous section, the product (i.e., the filter element) has a screen fixed to the first edge and the non-porous section.

[0041] The problem of the present invention is also solved by a gravity-based filtration device having an inlet funnel with a seat and a filter element as described above arranged in the seat. Attached Figure Description

[0042] The invention is described by way of example with reference to the following accompanying drawings:

[0043] Figure 1 This is a side view of the filter element according to the present invention;

[0044] Figure 2 yes Figure 1 AA section diagram;

[0045] Figure 3 yes Figure 1 A top view of the filter element;

[0046] Figure 4 yes Figure 1 A bottom view of the filter element. Detailed Implementation

[0047] Figures 1 to 4 The gravity-based filter element 2 shown includes a cup-shaped lower portion 4 and a cup-shaped upper portion 6. The upper portion 6 is arranged on top of the lower portion 4 along the main axis X.

[0048] At the first axial end portion 8, the upper portion 6 includes a first edge 10 having an annular shape extending around the main axis X. The first edge 10 includes a first contact region 12 that is generally flat, perpendicular to the main axis X, and defines the first axial end portion 8.

[0049] An upper portion 6, having a cup-shaped form, is arranged inverted on the lower portion 4. The upper portion 6 includes a circumferential outer wall 14, which is closed by an end wall 18 at a second axial end 16 opposite to the first contact area 12. The end wall 18, together with the adjacent section of the outer wall 14, forms a non-perforated section 20 of the upper portion 6.

[0050] The lower portion 4 includes an elongated body 22 that transitions into four legs 24 at its bottom end 26. At the bottom end 26, the lower portion 4 is closed except for outlets 28 disposed in the bottom walls 30 of the legs 24 (see [reference]). Figure 4 The support leg 24 is separated by grooves 32, one of which is differently shaped from the other, so that it serves as a positioning groove 34 for properly aligning the filter element 2 in the inlet funnel (not shown) of the filter device (not shown).

[0051] The lower portion 4 has a second edge 40 at the upper end 42. The second edge 40 includes a generally flat second contact area 44, on which the first contact area 12 of the upper portion 6 is disposed.

[0052] Several inlets 46 are located in the outer wall 14 of the upper portion 6, and are situated axially between the first edge 10 and the non-porous section 20 (see...). Figure 1 Water can enter the upper portion 6 through these inlets 46. In the illustrated embodiment, all inlets 46 have similar shapes and are arranged at the same height along the main axis X. The highest point of the inlets 46 is at the maximum inlet height H2 (vertical distance from the bottom wall 30).

[0053] The upper part 6 also includes a dome-shaped screen 50 (see Figure 2 The screen 50 is fixed to the first edge 10 along a closed path that extends around the main axis X.

[0054] The non-perforated section 20 of the upper portion 6 also includes a pin 52 extending from the end wall 18 along the main axis X toward the first axial end 8. The screen 50 is attached to the pin 52 in a region 54 radially inward of the closed path, where the screen 50 is attached to the first edge 10. Thus, the screen 50 is maintained in a dome-shaped form.

[0055] Pin 52 is at the minimum pin height H1 (vertical distance of 30 from the bottom wall, see...). Figure 2 The minimum pin height H1 is greater than the maximum inlet height H2. This ensures that the screen 50 extends into the area above the maximum inlet height H2. Therefore, air will be able to easily pass through the screen 50 and accumulate in the non-porous section 20, thus not clogging the inlet 46.

[0056] The lower part 4 and the screen 50 define the filter element volume 56, and the filter medium (not shown) is arranged in the filter element volume 56.

[0057] Water entering the filter element 2 via inlet 46 first enters the top volume 58 defined by the outer wall 14 and end wall 18 of the upper portion 6 and the screen 50. The water then wets the screen 50 and further passes through it into the filter element volume 56 defined by the lower portion 4 and the screen 50. Air present in the filter element volume 56 can escape upwards through the screen 50 to the top volume 58. This air will then not obstruct the water from passing through the screen 50. The water can then be processed by the filter media and subsequently exit the filter element 2 through outlet 28 into the space below 60.

[0058] The filter element 2 shown in the attached figure is manufactured as follows: First, a cup-shaped upper portion 6 is formed by injection molding. The cup-shaped upper portion 6 has a main axis X, a first edge 10 at a first axial end 8, a non-porous section 20 at a second axial end 16, and an inlet 46 between the non-porous section 20 and the first edge 10. Next, PET screen material is pulled over the first edge 10. Then, the screen material is pushed into the upper portion 6 towards the non-porous section 20, thereby forming a dome-shaped screen 50. The screen 50 is then fixed to the first edge 10 along a closed path. Furthermore, the screen 50 is fixed to the region 54 of the pin 52 of the non-porous section 20 on the radially inner side of the closed path. The screen 50 is then cut from the screen material along a path on the radially outer side of the closed path. The lower portion 4, having a second edge 40 and an outlet 28, is also formed by injection molding. Subsequently, ion exchange resin and activated coal (both in granular form) are inserted into the lower portion 4 as filter media. Then, the upper portion 6 is installed upside down onto the lower portion, with the second edge 40 contacting the first edge 10.

Claims

1. A method for manufacturing a gravity-based filter element (2), comprising the steps described above, wherein the steps are performed in the order listed: - A cup-shaped upper portion (6) having a main axis (X), a first edge (10) at a first axial end (8), a non-porous section (20) at a second axial end (16), and at least one inlet (46) between the non-porous section (20) and the first edge (10), wherein the upper portion (6) includes a circumferential outer wall (14) which is closed at the second axial end (16) by an end wall (18), wherein the end wall (18) together with an adjacent section of the outer wall (14) forms the non-porous section (20). - Pull the screen material over the first edge (10); - Push the screen material toward the non-porous section (20) into the upper part (6) of the cup shape to form a dome-shaped screen (50). - Secure the screen material to the first edge (10) along the closed path; - The screen material is fixed to the non-porous section (20) at a position radially inside the closed path and axially above at least one inlet (46), wherein the screen material is continuously fixed to the first edge (10) and the non-porous section (20). - Cut the screen (50) from the screen material along the radially outer path of the closed path; - Form a cup-shaped lower portion (4) having a second edge (40) and at least one outlet (28); - Insert the filter media into the lower part (4); - The upper part (6) is mounted onto the lower part (4), wherein the second edge (40) contacts the first edge (10). in, The non-porous section (20) includes a support member, and the screen material is fixed to the support member at a distance from the end wall along the main axis X. The support member is a pin (52) extending from the end wall (18) along the main axis X toward the first axial end (8). The pin (52) has a length L of at least 5 mm and a minimum pin height H1 that is at least 5 mm greater than the maximum inlet height H2 of the inlet (46).

2. The method according to claim 1, characterized in that, The support has a flat area (54) perpendicular to the main axis X, and the screen material is fixed to the area (54).

3. The method according to claim 1, characterized in that, The pin (52) has a circular or X-shaped cross-section.

4. The method according to claim 1, characterized in that, The pin (52) has a length L of up to 20 mm.

5. The method according to claim 1, characterized in that, The screen material is fixed to the first edge (10) and / or the non-porous section (20) by ultrasonic welding.

6. The method according to any one of the preceding claims, characterized in that, The screen material includes polyethylene terephthalate.

7. A gravity-based filter element (2) manufactured according to the method of any one of the preceding claims, having a cup-shaped upper portion (6) and a cup-shaped lower portion (4), the upper portion (6) having a main axis (X), a first edge (10) at a first axial end (8), a non-porous section (20) at a second axial end (16), and at least one inlet (46) between the non-porous section (20) and the first edge (10), wherein the upper portion (6) includes a circumferential outer wall (14), the circumferential outer wall (14) being at the second axial end (16). The axial end (16) is closed by an end wall (18), wherein the end wall (18) together with the adjacent section of the outer wall (14) forms a non-porous section (20), the lower portion (4) has a second edge (40) and at least one outlet (28), wherein the filter medium is arranged in the lower portion (4), and the upper portion (6) is mounted on the lower portion (4), wherein the second edge (40) contacts the first edge (10), and the filter element (2) further includes a dome-shaped screen (50) fixed to the first edge (10) of the upper portion (6) along a closed path; Its features are, The screen (50) is also fixed to the non-porous section (20) at a position radially inside the closed path and axially above at least one inlet (46), wherein the screen (50) is continuously fixed to the first edge (10) and the non-porous section (20). The non-porous section (20) includes a support member, and the screen material is fixed to the support member at a distance from the end wall along the main axis X. The support member is a pin (52) extending from the end wall (18) along the main axis X toward the first axial end (8). The pin (52) has a length L of at least 5 mm, and the minimum pin height H1 is at least 5 mm greater than the maximum inlet height H2 of the inlet (46).

8. A gravity-based filtration device having an inlet funnel with a seat and a filter element (2) according to claim 7 arranged in the seat.

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