The invention relates to a device for filtering a liquid, wherein the device has a container, which can be placed on the surface, with an inlet chamber for receiving the liquid to be filtered and an outlet chamber for receiving the filtered liquid, wherein the outlet chamber is arranged below the inlet chamber, wherein the inlet chamber has a filling opening and is connected to the outlet chamber via a connection section which is narrowed in cross-section relative to the inlet chamber, and wherein in the connection section a filter module can be placed in a flow opening connecting the inlet chamber to the outlet chamber, so that the liquid filled into the inlet chamber can flow through the filter module, which blocks the flow opening, into the outlet chamber.

In the course of increased attention and simultaneous concern of the population with regard to health issues, an ever greater value is placed on uncontaminated and clean drinking water. This resulted in the development of a wide variety of devices for filtering water, particularly in households. Commercial off-the-shelf water filter systems are available in the form of, for instance, a jug or a carafe. Here, first of all unfiltered water is poured through a filling opening into an inlet chamber of the jug or carafe, and then flows, driven by gravity, through a filter module into an outlet chamber arranged below the inlet chamber. The filter module is arranged in a connection section between the inlet chamber and the outlet chamber in a flow opening, sealing the latter. Subsequently, the filtered drinking water can be poured through a liquid outlet from the outlet chamber into a container or drinking glass.

Different variants of activated and often granulated solid filters, such as activated carbon filters, are used as filter media but also membrane filters in a wide variety of designs. This type of filtration is used to remove potentially harmful impurities as well as other unspecific sediments or residues from the drinking water. Membrane filters can also be used to remove bacteria and other undesirable microorganisms from the drinking water.

In addition to health concerns related to potentially impure drinking water, such gravity-operated devices are used to filter a liquid when softening drinking water, for example in the household when used in a coffee maker or kettle. The here used filters in the form of ion exchangers can soften hard water containing calcium ions. In this process, the calcium ions are in most cases replaced by sodium ions in order to allow for prevention or at least reduction of deposits caused by the formation of insoluble calcium salts. In this way, the lifetime of household appliances can be considerably increased. The filter variants already mentioned are mostly of a modular design and can, once the filter is exhausted, easily be exchanged and replaced, with no need for dismantling or replacing the casing.

Filter modules based on chemical or physical interaction of the impurity with the filter medium require, in order to achieve full filter performance, longer contact times than filters based on separating according to particle size. For this reason such systems require a minimum contact time with respect to throughput time, which must not be reduced in order to still obtain the intended filter performance. With filter modules on the basis of membrane filters the filter performance is independent of the contact time of the liquid with the filter membrane.

All variants introduced so far have in common that the filtration of drinking water by a gravity-based system requires long filtration times, with the water that is to be filtered flowing through the filter module only driven by gravity .

Therefore the problem of the present invention is to provide a device for filtering a liquid, in particular drinking water, which allows for rapid filtration in terms of time.

This problem is solved for a device mentioned at the beginning in that a manually shiftable pressure element is arranged in the inlet chamber, with which a filter pressure can be applied to the liquid located in the inlet chamber and to be filtered, which can be pressed through the filter module into the outlet chamber.

The inventive device for filtering a liquid has a casing which can be placed with a bottom side on a surface, with an outlet chamber, an inlet chamber arranged above it, and a connection section connecting the two chambers. Therein, the connection section is designed as a taper with a smaller cross-sectional area relative to the cross-sectional area of the inlet chamber. In the flow opening formed by the connection section connecting the inlet chamber and the outlet chamber a filter module can be inserted and fixed. Unfiltered water can be filled into the filling opening of the inlet chamber positioned opposite to the filter module, which can then, driven by gravity, flow through the filter module into the outlet chamber. After filling in the water that is to be filtered, a pressure element can be arranged in the inlet chamber in such a way that the filling opening can be closed off completely and watertightly. The pressure element can be shifted within the inlet chamber via manual actuation. Through this actuation a filter pressure can be applied to the liquid to be filtered, and the liquid pressed under pressure through the filter module into the outlet chamber. Due to the filter pressure acting on the liquid in addition to gravity, the filter duration can be reduced as opposed to purely gravity-operated devices for the filtration of liquids. The casing of the device is preferably made of a dimensionally stable and transparent or semi-transparent material, so that the user can verify the liquid level at any time.

According to an advantageous implementation of the idea of the invention it is provided that the inlet chamber has a pressure section with a constant cross-sectional area, and that the pressure element is arranged within the pressure section in a shiftable way, so that, when the pressure element is actuated, the filter pressure can be applied to the liquid located in the inlet chamber. The inlet chamber can have a cylindrical shape with two parallel sectional planes and a lateral surface connecting the sectional planes, wherein the sectional planes can be designed to have a circular, oval or any polygonal cross-sectional area. Preferably the sectional planes are arranged vertically relative to the cylinder axis connecting the sectional planes, in order to enable a constant filter pressure vertically to the surface and directed on the liquid to be filtered when the pressure element is actuated. Due to the constant cross-sectional area of the pressure section, the pressure element, when actuated and shifted parallel to the cylinder axis, seals the pressure section liquid-tightly at each point of shifting, so that a constant and maximized filter pressure can be achieved. The liquid-tight sealing of the pressure element in the pressure section can, for instance, be realized by an elastic O-sealing ring fixed to the circumferential lateral surface of the pressure element. The pressure section is arranged at an upper end of the inlet chamber, which faces away from the connection section, at the filling opening. The filling opening is designed in such a way that the pressure element can be removed from the pressure section when cleaning or filling in water, and can be reinserted afterwards.

Advantageously, according to the invention, it is optionally provided that the pressure element has a pressure plunger, which can be shifted within the pressure section of the inlet chamber, with a plunger plate and a plunger handle fixed to the plunger plate. The plunger plate can be realized as an even plate sealing off the pressure section, with other possible embodiments also being possible where the plunger plate has an arched shape or a form adapted to the taper of the connection section. The plunger handle is preferably designed with a cylindrical shape and is fixed centrally on the side of the plunger plate facing away from the connection section, in order to enable uniform shifting of the plunger plate when the presser plunger is actuated and thus avoid canting within the pressure section.

Furthermore, another embodiment option is envisaged, where a membrane can be fixed in a liquid-tight way between the plunger plate and the liquid to be filtered in the pressure section, and where the pressure plate has a smaller cross- sectional area than the membrane. The membrane can, for instance, be connected with an even pressure element plate along its circumferential rim, and the plunger plate can be arranged in the middle between the pressure element plate and the membrane. When actuating the pressure plunger, the plunger plate presses against the membrane and first pulls the membrane with the pressure element plate in the direction of the connection section, wherein the membrane slightly deforms elastically and the filter pressure is exerted on the liquid to be filtered via the membrane. As soon as the pressure element plate can no longer be shifted into the direction of the connection section, further actuation of the pressure plunger has the effect that only the membrane will be increasingly deformed and in the process increasingly adapts to, for instance, a tapered shape of the connection section, thus exerting the filter pressure on the liquid to be filtered.

Moreover, when actuating the pressure plunger, an inflation device, which is arranged between the plunger plate and the lid, can be inflated by inflating an elastic and air- and gas-tight shell, thus pressing the plunger plate against the water surface.

According to an advantageous embodiment of the idea of the invention it is provided that the shape of the plunger plate is adapted to the shape of the cross-sectional area of the pressure section of the inlet chamber, wherein the pressure section can be sealed completely and liquid-tightly by the plunger plate at a side opposite the filter module. The shape of the plunger plate is adapted to the shape of the pressure section in such a way, that the cross-sectional areas are identical to each other. Due to manufacturing tolerances during production and in order to ensure convenient insertion of the pressure plunger after filling the inlet chamber, sealings, in particular in the form of elastic O-sealing rings, can be attached to the lateral surface of the plunger plate to allow for a liquid-tight but still shiftable plunger plate. Because the pressure plunger, when actuated, is arranged in the pressure section in a liquid-tight way, no water can escape at the sides or upwards, so that, due to a permanent and constant pressure, the throughput time of the liquid to be filtered is as short as possible due to the inventive device.

It is also possible, and optionally provided according to the invention, that the inlet chamber has a removable lid to close the filling opening of the inlet chamber. A lid closing the filling opening of the inlet chamber allows for safe handling of the inventive device. On the one hand, it can play a hygienic role in avoiding impurities of the filled water, on the other hand, it can prevent spilling of the water to be filtered from the inlet chamber in case of imprudent handling. Furthermore, using a lid enables the realization of a filling opening with the same or bigger cross-sectional area as the pressure section. In this way, due to the large filling opening, it is possible to safely and quickly fill the inlet chamber with water, for instance under a water tap.

The lid can be designed as a support lid, clamped or connected to the filling opening with locking tongues, or have notches, projections, or even hinges for secure attachment to the filling opening of the inlet chamber.

Furthermore, it is possible and optionally provided according to the invention, that the lid has a through recess, and that the plunger handle is guided in the recess and can be actuated from outside the inlet chamber. The plunger plate is arranged in the pressure section while the plunger handle, which is attached to the plunger plate, is arranged in the recess of the lid in such a way that it protrudes from the recess with its end located opposite the plunger plate. At this end, a ball or any geometric shape or other thickening of the plunger handle with a cross-sectional area larger than that of the recess can be attached, so that the pressure plunger is fixed to the lid. A ball which can be connected to the plunger handle offers the advantage that the pressure plunger can be removed, for instance to clean the lid.

The recess is designed in such a way that it is adapted to the shape of the plunger handle so that the latter can be guided safely in the recess when the pressure element is actuated . Secure and wobble-free guidance of the plunger plate parallel to the cylinder axis and thus an associated force perpendicular to the horizontally arranged water surface can prevent canting or uneven pressure. Moreover it is possible that the inventive device can be used with a lid without recess for purely gravity-operated liquid filtration. In this case, the lid can also be realized as an embodiment with a smaller closable opening, wherein the opening can preferably be opened and closed with one hand.

According to an advantageous implementation of the idea of the invention it is provided that the plunger handle can be fixed in the recess of the lid in such a way that the plunger plate is arranged horizontally and can be shifted vertically, wherein a filter pressure can be applied by the plunger to the liquid located in the inlet chamber which can thus be pressed through the filter module into the outlet chamber. When actuating the pressure plunger, i.e. with pressure on the plunger handle from outside the lid, the plunger plate is shifted in a vertical movement into the direction of the water surface, thus exerting pressure on it. Due to a horizontal and thus parallel positioning of the plunger plate relative to the water surface, the pressure applied to the water surface can be distributed evenly. When using an inlet chamber wherein the cylinder axis is not vertically positioned to the sectional planes of the inlet chamber, a hinged connection between plunger plate and plunger handle can, for instance, enable the plunger plate to be positioned parallel to the water surface.

Advantageously, according to the invention, it is optionally provided that the cross-sectional area of the connection section has less than half of, preferably less than one third of, and most preferably less than one quarter of the size of the cross-sectional area of the pressure section of the inlet chamber . When actuating the pressure plunger, the pressure plate presses on the water surface of the water to be filtered, applying filter pressure on it. Due to the smaller cross-sectional area of the connection section and thus the filter module, the filter pressure applied to the filter module increases due to the fact that the ratio of the force acting vertically on a surface is proportional to the surface area. The pressure difference at the filter module thus affects the filtration velocity as higher applied pressure helps to achieve a faster flowrate.

According to an advantageous embodiment of the idea of the invention it is provided that the inlet chamber with the connection section is manufactured separately and attached removably in a container casing forming the outlet chamber. The inlet chamber, manufactured separately from the outlet chamber, with the connection section fixed to it, must be inserted into the inlet opening of the outlet chamber before using the filter system. Here variants can be considered where the inlet chamber can be inserted into the outlet chamber either completely or partly, and, for instance, can be fixed by clamping it. Such separate manufacturing allows for easy cleaning, in particular of the outlet chamber, wherein both, outlet chamber and inlet chamber, can be designed to be dishwasher-safe. Furthermore, an embodiment variant can also be considered where the inlet chamber, the connection section and the outlet chamber are manufactured in one piece. Such an embodiment variant made of one piece, and thus fewer individual components, requires fewer sealings or, respectively, liquid-tight connections for preventing potentially leaky connections or leaks.

It is also possible, and optionally provided according to the invention, that the outlet chamber has a liquid outlet for pouring the filtered liquid. The liquid outlet, e.g. designed as a nozzle, can be attached at different heights of the outlet chamber, and can be realized in the shape of a pipe or in the shape of a bulge of the chamber wall forming a spout. After filtration, the filtered liquid can be poured from the outlet chamber into a vessel or a drinking glass via the nozzle.

Preferably it is provided that the filter module can be inserted into and removed from the connection section through the inlet chamber. Replacing the filter module can take place, if necessary after taking off the lid, through the filling opening of the inlet chamber, without any further steps being required. The filter module can be clamped or latched in the flow-through opening, for instance, and inserted or removed vertically.

Furthermore, it is possible and optionally provided according to the invention, that the filter module has a removal ring for taking out the filter module. At the top side of the filter module, facing the lid, a ring, tab, or chain can be attached . By pulling the chain, the filter module can be taken out of the flow opening.

According to an advantageous embodiment of the idea of the invention it is provided that the filter module is a hollow fiber membrane filter. Membrane filters are understood to be filters wherein unwanted substances are separated by means of a permeable membrane. With hollow fiber membrane filters, the separation takes place via hollow fibers which are mos11y combined in one compound to create a filter module, wherein the walls of the hollow fibers act as a membrane. Depending on the nature of the hollow fibers, separation takes place either by diffusion or convection. The starting materials for the hollow fiber synthesis include polyether sulfones, polysulfones, polyaryl nitriles, but also ceramic materials or metals. Due to a modular design of the filter modules, also filter modules with other filter media such as activated carbon can be used in the inventive device.

Further advantageous embodiments of the device for filtering a liquid are explained by the examples of embodiments shown in the drawing as follows:

Figure 1 shows a schematic sectional view of the inventive device for filtering a liquid, wherein the casing is manufactured in one piece.

Figure 2 shows a schematic sectional view of an exploded drawing of the inventive device from figure 1.

Figure 3 shows a schematic sectional view of the inventive device with a plunger plate adapted to the connection section.

Figure 4 shows a schematic sectional view of the inventive device with the liquid outlet being arranged above the filter module.

Figure 5 shows a schematic sectional view of the inventive device, wherein the inlet chamber and the connection section are manufactured separately and can be inserted into the outlet chamber. Figure 6 shows an exploded drawing of the inventive device from figure 5.

Figure 1 shows a schematic sectional view of the inventive device for filtering a liquid. The device has a free-standing casing 1 of an almost cylindrical shape with an inlet chamber 2 for receiving the liquid to be filtered, a connection section 3 and an outlet chamber 4 for receiving the filtered liquid. The outlet chamber 4 can be placed on the surface with a bottom side, and the inlet chamber 2 is arranged above the outlet chamber 4 and connected to it via a flow opening 5 in the connection section 3 which is arranged between the two chambers 2 and 4. The connection section 3 has a smaller cross-sectional area than the inlet chamber 2, while the inlet chamber 2 and the outlet chamber 4 are realized with an identical cross-sectional area. In the flow opening 5 a filter module 6 is fixed which, in this exemplary embodiment, is realized as a hollow fiber membrane filter with filter membranes 7. At the filter module 6, a removal ring 8 for taking out the filter module 6 is arranged. At a side opposite the connection section 3, the inlet chamber 2 has a filling opening 9 for filling in the liquid to be filtered, which can be closed with a lid 10. Any liquid filled into the inlet chamber 2 passes, following gravity, through the filter module 6 into the outlet chamber 4. At the outlet chamber 4, a liquid outlet 11 is fixed, through which the filtered water can be poured. In this exemplary embodiment, the casing 1 with the inlet chamber 2, the connection section 3 and the outlet chamber 4 is manufactured in one piece. Here, the liquid outlet 11 of the outlet chamber 4 is arranged below the filter module 6.

The inlet chamber 2 has a pressure section 12 with a constant cross-sectional area. In this pressure section 12 the pressure element is arranged in a shiftable way. The pressure element is designed as a pressure plunger, consisting of an even plunger plate 13 and a cy1indrically shaped plunger handle 14, which is centrally fixed at an upper side of the plunger plate 13. The plunger plate 13 is adapted to the cylindrical geometry of the pressure section 12 and can close it off liquid-tightly by means of a sealing ring which is fixed to the peripheral surface of the plunger plate 13. In the lid 10 closing the filling opening 9, a recess is centrally arranged, in which the plunger handle can be arranged and guided. This recess is adapted to the shape of the plunger handle 14. The plunger plate 13 has a circumferential sealing 15 along its peripheral rim which can be designed, for instance, as a ring sealing fixed in a peripheral groove. At the end of the plunger handle 14 protruding through the recess of the lid and located opposite the plunger plate 13, a thickening 16 with a larger cross- sectional area than the recess is attached. In this exemplary embodiment, the thickening is designed as a ball. The thickening 16 facilitates comfortable gripping and actuating of the pressure plunger and prevents, for instance, that the pressure plunger can be accidentally detached from the lid 10 in the course of cleaning. The thickening 16 can be removably attached onto the plunger handle 14, for instance screwed in place, and thus also enables, as needed, a deliberate removal of the pressure element from the lid 10.

By actuating the pressure plunger 13, 14 from outside the inlet chamber 2, the plunger plate 13 can be pressed against the surface of the liquid, wherein the liquid can be applied with a filter pressure and pressed through the filter module 6 into the outlet chamber 4.

Figure 2 shows a schematic sectional view of an exploded drawing of the inventive device from figure 1, which has, including but not limited to, the casing 1, the filter module 6, the pressure plunger 13, 14, and the lid 10.

Figure 3 shows a schematic sectional view of the inventive device from figure 1 with a plunger plate 13 adapted to the connection section 3.

Figure 4 shows a schematic sectional view of the inventive device from figure 3, wherein the liquid outlet 11 is arranged above the filter module 6.

Figure 5 shows a schematic sectional view of the inventive device, wherein the inlet chamber 2 and the connection section 3 are manufactured separately and inserted into the outlet chamber 4 in a clamping manner. Here the liquid outlet 11 is designed as a spout. Figure 6 shows an exploded drawing of the inventive device from figure 5, consisting of the casing 1, the filter module 6, the pressure plunger 13, 14, and the lid 10.

LIST OF REFERENCE SIGNS

1 Casing

2 Inlet chamber

3 Connection section

4 Outlet chamber

5 Flow opening

6 Filter module

7 Filter membrane

8 Removal ring

9 Filling opening

10 Lid

11 Liquid outlet

12 Pressure section

13 Plunger plate

14 Plunger handle

15 Sealing ring

16 Ball at the plunger handle