WO2016196868A1

WO2016196868A1 - Multi-section porous liquid filter with non-mechanical gas vent

Info

Publication number: WO2016196868A1
Application number: PCT/US2016/035622
Authority: WO
Inventors: Kevin John SPORRER; Timothy Allen Martin; Thomas Oliver KNIGHT III; Hyde Parker NORTON
Original assignee: Porex Corporation
Priority date: 2015-06-05
Filing date: 2016-06-03
Publication date: 2016-12-08

Abstract

Embodiments of the present invention provide filters and method for their use that introduce two sections, one filtration section and one venting section, in a single filter. The filtration section allows water to penetrate, and the venting section does not allow water to penetrate, but does allow air to penetrate. Because the venting section does not allow water to penetrate, the air will not need to overcome the bubble point pressure to move through the venting section. The venting section also provides a low pressure air pathway for the air but not water.

Description

MULTI-SECTION POROUS LIQUID

FILTER WITH NON-MECHANICAL GAS VENT

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application Serial No. 62/171,509, filed June 5, 2015, titled "Multi-Component Porous Liquid Filter with Non- Mechanical Gas Vent," the entire contents of which are hereby incorporated by reference.

FIELD OF THE DISCLOSURE

[0002] Embodiments of the present disclosure relate generally to filters designed for use in filtering a liquid in a closed system, into which it is desirable to introduce air or gas back into the system. In one example, a filter may include a filtration section and a venting section. The venting section is designed to introduce air or gas into the closed section without use of a mechanical valve or vent. BACKGROUND

[0003] There are a number of drinking bottles on the market that use a filtering system. For example, some drinking bottles are sold with a filter enclosed within a housing that cooperates with a bottle. See, for example, U.S. Patent No. 5,609,759 and U.S. Publication No. 2002/0036176. Improvements to the filters used in these systems are desirable. [0004] Filtration devices, such as water bottles with a filter and water tanks with a filter, generally have one opening. This type of device needs to allow air to move from the outside environment into the container through the filter. This compensates for pressure loss during the filtration process. Otherwise, the liquid flow will be significantly restricted or may even stop. For squeeze bottles, the filter needs to allow air move through the filter quickly in order to allow the container to restore its original shape. It is desirable for this to occur quickly after the squeezing action stops, so that the bottle is ready for another squeezing action.

[0005] Current filters are used without a vent (for example, U.S. Patent No. 5,609,569). However, this type of filter does not provide enough liquid flow because of inadequate venting. To overcome this issue, some have used a mechanical valve (U.S. Publication No. 2002/0036176) for allowing the air to move back to the container. However, the mechanical valve approach significantly increases the complexity and the cost of the filter. There is thus a need for a simple and effective solution for providing a filtration device that can filter and vent.

[0006] Some filters do not meet water flow requirements because they block air movement through the filter section. For example, when the filter is quickly enveloped with water or other liquid, the water or other liquid will penetrate into the porous matrix of the filter and fill the pores inside the matrix. Once the porous matrix of the filter is filled with liquid, the air needs to overcome the bubble point pressure in order to move through the filter. The requirement of overcoming the bubble point pressure for air to move through the filter causes the restriction of liquid flow. This can create a problem when the filter is used for a drinking bottle. This can create a problem when the filter is used to feed liquid to downstream equipment.

[0007] There are other instances when filters are used to assist with filtering a fluid. For example, antimicrobial filters may be used for humidifiers. Filters may be used for drinking water systems. Filters may be used for other fluid filtering systems, such as gasoline, saltwater, wastewater, and many other instances. Improvements to the filters used in these systems are desirable. The filters described herein are possible for use in any of these filtering systems, along with others.

BRIEF SUMMARY

[0008] Embodiments of the present invention overcome the current challenge by introducing two sections, one filtration section and one venting section, in a single filter. The filtration section allows water to penetrate, and the venting section does not allow water to penetrate. Since the venting section does not allow water to penetrate, the air will not need to overcome the bubble point pressure to move through the venting section. The venting section also provides a low pressure air pathway for the air but not water. [0009] Certain examples disclosed herein provide a fluid filter, comprising: a filtration section and a venting section, wherein both the filtration section and the venting section are porous, wherein the filtration section has a higher pore size than the venting section. In another example, the filter body can have first and second sections, with the first section comprising an average pore size of over about 40 microns, and the second section comprising an average pore size of less than about 30 microns. The first section generally functions as a filtration section and the second section generally functions as a venting section. [0010] The filtration section is generally a hydrophilic section and the venting section is generally a hydrophobic section. The sections may be made of hydrophilic polymers and hydrophobic polymers. Non-limiting examples include polyethylene, polytetrafluoroethylene, or combinations thereof. The filtration section may also include active carbon particles, ion exchange particles, zeolite particles, nutritional additives or components, such as vitamins or minerals, flavorings, or combinations thereof.

[0011] The venting section may comprise a water-repellant material. The venting section may comprise a hydrophobic plug positioned in one end of the filter. The venting section may comprise a ring. In some versions, the filtration section and the venting section are integrally formed and co-sintered with one another.

[0012] There is also provided methods for filtering a liquid using any of the above- described filters, comprising causing fluid to move through the filtration section in one direction and air to move through the venting section in an opposite direction.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 shows a side perspective view of one embodiment of a filter having a hydrophobic vent positioned into an open end of the filter.

[0014] FIG. 1A shows a side cut-away view of the filter of FIG. 1.

[0015] FIG. 2 is a top perspective view of a filter designed for use with a humidifier, having a plug vent. [0016] FIG. 3 shows a front plan view of one embodiment of a filter comprising a liquid filter section and a venting section that have been co-molded to one another.

[0017] FIG. 4 is a top perspective view of one embodiment of the filter of FIG. 3.

[0018] FIG. 5 is a bottom perspective view of one embodiment of the filter of FIG. 3.

[0019] FIG. 5A shows an alternate embodiment of a filter, with the venting section located at an opposite end from where it is shown in the filter of FIG. 5.

[0020] FIG. 6 shows a humidifier using the filter of FIG. 2.

[0021] FIG. 7 is a water bottle during insertion of a filter into a filter cage. [0022] FIG. 8 shows the water bottle of FIG. 7 with the filter in place in the filter cage.

[0023] FIG. 9 shows a cut away view of the filter of FIG. 7 in place in the cage, as the cage is secured to the cap.

DETAILED DESCRIPTION

[0024] Embodiments of the present invention provide a filter 10 that is designed to provide optimal liquid flow therethrough, while also allowing air to easily move through the filter. The filter 10 described may find particular use in connection with a closed system, wherein the filter 10 allows air to flow back into the closed system.

[0025] In one example, the filter 10 includes a filtration section 12 and a venting section 14. Both of these sections are generally porous, such that passage of liquids (such as water, other beverages, gasoline, oil, or any other liquid to be filtered) and/or air is allowed. In normal operation condition, water or other liquid to be filtered can move through filtration section 12, but will not penetrate venting section 14. The air entrapped inside the filter 10 may move out from the filter 10 through the venting section 14. [0026] Instead of using a non-porous mechanical valve for air venting, the venting section 14 is generally designed to be a sintered, hydrophobic, water-repellent vent. Providing a hydrophobic venting section 14 may help address the air movement issue that is experienced with other types of filters.

[0027] In one example, it has been found that providing the filtration section 12 with a higher pore size than the venting section 14 is beneficial. This can allow the liquid to quickly pass through the filtration section 12, but prevents the liquid from penetrating (or at least from fully penetrating) the venting section 14. In one example, the filtration section 12 may have an average pore size of about 30 microns to about 60 microns, In a more particular example, the filtration section may have a pore size of about 40-50 microns. In another example, the filtration section may have a pore size of greater than about 40 microns.

[0028] In one example, the venting section may have an average pore size of less than about 30 microns. In another example, the venting section 14 may have an average pore size of less than about 20 microns. In a more particular embodiment, the venting section may have a pore size of less than about 10 microns. In an even more particular embodiment, the venting section may have a pore size of about 6-10 microns. In one example, the pore size differential may be at least about 10 microns between the filtration section and the venting section. In another example, the pore size differential may be at least about 50 microns between the filtration section and the venting section.

[0029] Various features of the filtration section 12 and the venting section 14 are described herein, and it should be understood that various features of the filtration section 12 described may be combined with one or more of the various features of the venting section 14 described. As illustrated by FIGS. 3-5, the filter 10 may be a filter body 22 with a hollowed interior 16. The filter body 22 may have either one open end 20 or two opened ends. In other examples, it is possible for the filter body 22 to have two closed ends, with the fluid flowing in through the pores of the material and being vented at whichever end or any portion along the filter body that is provided as the venting section.

[0030] For example, FIG. 1A illustrates that a plug 18 may provide the venting section function. The plug 18 may be positioned at a first end 20 in the lumen of the filter. In this example, the internal lumen 16 of the filter is hollow and a second open end 21 remains open. This second open end 21 may be useful for securing the filter to a housing or other structure. In one specific example, the second open end 21 of the filter may be used to secure the filter to a humidifier post as shown by FIG. 6.

[0031] In one example, the filtration section 12 is hydrophilic. (Hydrophilic generally means that fluid can wick through the porous media under ambient conditions.) If used for filtering water or other consumable liquid, the filtration section 12 may be made of a mixture of binding particles and a filtration additive. In one example, the filtration additive may be active carbon particles, ion exchange particles, zeolite particles, nutritional additives or components, such as vitamins or minerals, flavorings, or combinations thereof. The filtration additive is generally intended to remove chemicals from the liquid prior to consumption. For example, the filtration additive may be provide to remove chlorine. Filtration additives may be incorporated into the sintered porous matrix of the filter body by co-sintering the additives with the plastic particles that form the filter body. Filtration additives may be incorporated into the filter in any amount. Exemplary ratios of nutritional additives include but are not limited to less than about 10% or less than about 5% of the particles that make up the filter body. [0032] The binding particles that form the filtration section could be, for example, polyethylene particles, polypropylene particles, Nylon particles or combinations thereof. The polyethylene particles may include low density polyethylene particles (LDPE), linear low density polyethylene particles (LLDPE), high density polyethylene (HDPE) particles, and ultrahigh molecular weight polyethylene (UHMWPE) particles, or combinations thereof. The percentages and ratios of these materials may change, depending upon the desired and intended use of the filter. In one example, the filtration section may comprise about at least 20% active carbon. In another example, the filtration section may comprise at least about 50% active carbon or more. [0033] In one example, the venting section 14 may be made primarily of hydrophobic polymers. (Hydrophobic generally means that fluid will have a contact angle over about 90 degrees under ambient conditions.) Exemplary materials include but are not limited to polyethylene, polypropylene, polytetrafluoroethylene (PTFE), or any combination thereof.

[0034] There will generally be provided two ends provided on the filter body 22. The venting section 14 can be provided at one of the open ends of the filter body 22. In another example, the venting section 14 may be provided as a part of a closed end 24. This is illustrated by FIG. 5A.

[0035] In one example, the venting section 14 may be provided as a hydrophobic, water repellent porous plug 18. One example of this embodiment is shown in FIG. 1. The plug 18 may be positioned at an open end of 20 of the hollowed interior 16. It is possible for the plug 18 to be press fit into the open end 20 of the filtration section 12. It is possible for the plug 18 to be adhered to the filter 10 at an end of the filtration section 12 via an adhesive. It is possible for the plug 18 to be formed integrally with the filter end 20, or any other appropriate configuration or combination of the above. The plug 18 may be any appropriate length. For example, the plug 18 may be a percentage of the length of the filter body 10. It may be 5% of the length, it may be 10% of the length, or any other appropriate percentage. In one specific embodiment, the length of plug 18 is equal or less than the wall thickness of filter 10. A cut away view of this embodiment is illustrated by FIG. 1A. FIG. 1A shows a plug 18 positioned in the open end 20 of the filter body 10 and extending only partially into the hollowed interior 16. The opposite end 21 of filter body, in this example, remains open. [0036] FIG. 2 illustrates another filter embodiment, having a plug 18 positioned in an open end 20 of the filter body. This particular filter is designed for use in a humidifier, as shown in FIG. 6. However, it should be understood that this embodiment is usable in other environments as well. In FIG. 6, there is provided a lower filter ring 50. Lower filter ring 50 may be provided as a ring that cooperates around a base of the filter, where it secures to the humidifier or other structure housing.

[0037] In another example, the venting section 14 may be provided as a hydrophobic, water repellent porous area 26. It is also possible for the venting section 14 to be formed as an integral part of the body of the filter 10. An example of this is shown in FIGS. 3-5 and 5A. In these embodiments, the venting section 14 and the filtration section 12 are two component parts or sections that are formed into a single filter body 22. In this embodiment, the filtration section 12 may be slightly shortened, since the venting section 14 is a part of the filter body 22. In one example, the filtration section 12 and the venting section 14 are co- sintered together. [0038] This embodiment may be manufactured by co-sintering. For example, a venting section powder mixture and a filtration section powder mixture may be filled into different locations of a mold cavity. The powders may be sintered into a single piece filter with distinguishable venting and filtration sections/functions. The venting section 14 may be provided at an open end, as illustrated by FIG. 4. Additionally or alternatively, the venting section 14 may be provided at a closed end, as illustrated by FIG. 5 A. The location of the venting section 14 depends upon the orientation of the filter body in use and will depend upon the ultimate filtering needs for which the filter body is designed.

[0039] In another embodiment, the filter may be made by membrane coating. A section of sintered filtration section may be coated with a hydrophobic porous membrane, wherein the membrane has a lower pore size than the sintered filtration section. In one specific embodiment, the sintered porous filtration section close to the open end of filter may be coated with a submicron pore size hydrophobic membrane. The membrane may be applied by phase inversion process. The membranes that may be used in this embodiment include but are not limited to PVDF and Polysulfone based membrane, or combinations thereof. [0040] In one example, the water intrusion pressure (or liquid intrusion pressure) for the venting section 14 may be above about 1 psi, above about 2 psi, above about 3 psi, or above about 5 psi. The water intrusion pressure (or liquid intrusion pressure) for the filtration section may be less than about 0.5 psi, less than about 0.4 psi, less than about 0.3 psi, less than about 0.1 psi, or zero. The actual intrusion pressure of the venting section 14 may be a function of the size of the pores of the venting section material, the particular material of the venting section, the fluid being filtered, the surface tension of the venting section, or combinations thereof. These variables may be optimized in order to allow the venting section 14 to be hydrophobic to the fluid being filtered, while the filtering section allows passage of the fluid being filtered.

[0041] The surface tension of the filtration section 12 is generally higher than the surface tension of the venting section 14. In a specific example, the surface tension of the filtration section 12 may be about 20 dynes/cm or higher than the surface tension of the venting section 14. In another specific example, the surface tension of the filtration section 12 may be about 10 dynes/cm or higher than the surface tension of the venting section 14.

[0042] The filters described may be used as a water filter for a squeeze water bottle. The filters described may be used as a water tank filter for gravity filtration. The filters described may be used as a filter for any other liquid filtration use. The general intent is that the filters are usable for filtering any appropriate body of liquid that also needs to have trapped air released.

[0043] If used in connection with a squeeze water bottle, the venting section 14 may be designed to surround the filter's open end 20. This is because, in use, the water bottle (and the filter) is turned upside down, and it is desirable for the vent to be immersed in fluid. (Otherwise, if the filter is exposed to air when no water is present, it may vent air into the user who is attempting to drink water, resulting in a big gulp of air.) One example of this vent location is illustrated by FIGS. 4 and 7. As illustrated by FIG. 4 and as shown in more detail by FIG. 9, the filter's open end 20 section may have a ledge portion 26 extending around an edge circumference at or near the end. The ledge portion 26 can help the filter cooperate with a cap 28 or other structure. As shown by FIG. 7, the cap 28 may have a series of internal ridges/grooves 30. These ridges/grooves 30 may help the cap secure and connect with a bottle, as well as help cooperate and secure the filter/filter cage into place. The filter may have an opening face 32 between the filter end and the hollowed lumen portion 16. The opening face 32 may be defined by the ledge portion 26 that forms an upper ridge that can be received or otherwise fit tightly within one of the cap grooves for securement. Extending down from ledge portion 26 may be an external lip 34. Securement may also be assisted by a filter cage 36.

[0044] As illustrated by FIG. 7, the filter's open end 20 section may be mounted to the cap 28 of a squeeze water bottle B. This is the vent section 14, which allows air to flow therethrough so that pressures are compensated for when fluid is consumed from the bottle B. The filter body may be positioned in a filter cage 36, as shown by FIGS. 7 and 8. The filter cage 36 is illustrated as having a plurality of slits or openings 38 therethrough, which allow passage of fluid into and out of the filter cage 36. When the bottle B is squeezed, the fluid may move through the filtration section 12 but not through the venting section 14. When the squeeze pressure is released, the air may move through the venting section 14 from the external environment into the squeeze bottle B. This allows the filter 10 to provide a quicker recovery for squeeze bottle and can provide more water delivery.

[0045] The filter body 22 may have an open end 20 and a closed end 24, as illustrated by FIG. 5. This allows fluids to be completely filtered when passing anywhere along the filtration section 12 (illustrated by dotted shading in FIGS. 3-5). In another example, the closed end 24 may be the venting section and may be hydrophobic with a smaller pore size than the rest of the filter. If used in connection with a water tank filter for gravity filtration, the filter may have a hollowed structure with one open end and one closed end. One example of this is illustrated by FIG. 6. Water may move through the filtration section 12 from the water tank to the outlet, and air may move through the venting section 14 from environment into the water tank. The vented filter 10 can provide more consistent and higher water flow by allowing air to move from the environment into the water tank through venting section.

[0046] To optimize the air venting performance, the wall thickness of venting section 14 of the filter 10 may be different from the wall thickness of filtration section 12. In a preferred embodiment, the wall thickness of venting section 14 of filter 10 is less than the wall thickness of filtration section 12. In another embodiment, at least a portion of the wall thickness of venting section 14 of filter 10 is less than the wall thickness of filtration section 12. The wall thickness of venting section 14 of filter 10 may be 10%, 20% 30 %, 40, 50% or even more less than the wall thickness of filtration section 12. [0047] Changes and modifications, additions and deletions may be made to the structures and methods recited above and shown in the drawings without departing from the scope or spirit of this disclosure.

Claims

Claims:

1. A fluid filter, comprising:

a filtration section and a venting section, wherein both the filtration section and the venting section are porous, wherein the filtration section has a higher pore size than the venting section.

2. The fluid filter of claim 1 , wherein the filtration section comprises a hydrophilic section and the venting section comprises a hydrophobic section.

3. The fluid filter of claim 2, wherein the hydrophilic section comprises hydrophilic polymers and wherein the hydrophobic section comprises hydrophobic polymers.

4. The fluid filter of any of the preceding claims, wherein the venting section comprises polyethylene, polytetrafluoroethylene, or combinations thereof.

5. The fluid filter of any of the preceding claims, wherein the filtration section comprises active carbon particles, ion exchange particles, zeolite particles, nutritional additives or components, such as vitamins or minerals, flavorings, or combinations thereof.

6. The fluid filter of any of the preceding claims, wherein the venting section comprises a water-repellant material.

7. The fluid filter of any of the preceding claims, wherein the venting section comprises a hydrophobic plug positioned in one end of the filter.

8. The fluid filter of any of the preceding claims, wherein the venting section comprises a ring.

9. The fluid filter of any of the preceding claims, wherein the filtration section and the venting section are integrally formed and co-sintered with one another.

10. The fluid filter of any of the preceding claims, wherein the venting section comprises a liquid intrusion pressure of above about 1 psi.

11. The fluid filter of any of the preceding claims, wherein the filtration section comprises a liquid intrusion pressure of below about 0.5 psi.

12. The fluid filter of any of the preceding claims, wherein the filtration section comprises at least about 20% active carbon.

13. The fluid filter of any of the preceding claims, wherein a wall thickness of the venting section is smaller than a wall thickness of the filtration section.

14. A fluid filter, comprising:

a filter body comprising first and second sections, the first section comprising an average pore size of over about 40 microns, the second section comprising an average pore size of less than about 30 microns.

15. The fluid filter of claim 14, wherein the first section is hydrophilic and the second section is hydrophobic.

16. The fluid filter of any of claims 14-15, wherein the first section comprises at least about 20% active carbon.

17. The fluid filter of any of claims 14-16, wherein the second section is positioned at an open end or at a closed end of the filter body.

18. The fluid filter of any claims 14-17, wherein a wall thickness of the second section is smaller than a wall thickness of the first section.

19. The fluid filter of any of claims 14-18, wherein the second section comprises polyethylene, polytetrafluoroethylene, or combinations thereof.

20. The fluid filter of any of claims 14-19, wherein the first section and the second section are integrally formed and co-sintered with one another.

21. The fluid filter of any of claims 14-20, wherein the first section comprises active carbon particles, ion exchange particles, zeolite particles, nutritional additives or components, such as vitamins or minerals, flavorings, or combinations thereof.

22. A method of filtering a liquid using the filter of any of claims 1-13, comprising causing fluid to move through the filtration section in one direction and air to move through the venting section in an opposite direction.

23. A method of filtering a liquid using the filter of any of claims 14-21 , comprising causing fluid to move through the first section in one direction and air to move through the second section in an opposite direction.