Patent Description:
It is a process where a weaker saline solution will tend to migrate to a strong saline solution; that is, a solution that is less concentrated will have a natural tendency to migrate to a solution with a higher concentration. Reverse osmosis occurs when the solution is moved across a filter membrane against the concentration gradient, from lower concentration to higher concentration. For example, under normal osmosis, a semipermeable filter membrane with fresh water on one side and a concentrated aqueous solution on the other side would have the freshwater cross the filter membrane to dilute the concentrated solution. In reverse osmosis, pressure is exerted on the side with the concentrated solution to force the water molecules across the filter membrane to the lower concentration side.

A typical reverse osmosis water filtering system uses a semi-permeable filter membrane that has the ability to remove and reject a wide spectrum of impurities and contaminants from water. These contaminants are automatically rinsed down the drain. The purified water may then be stored in a tank.

The predetermined pressure is applied to the incoming water to force the incoming water through the filter membrane. The filter membrane filters impurities from the incoming water leaving purified water on the other side of the filter membrane, which is referred to as "permeate" stream. The impurities left on the membrane are washed away by a portion of the incoming water that does not pass through the membrane. The water carrying the impurities washed away from the membrane is called "concentrate stream.

Some of the benefits of employing a RO system include: pure, clean drinking water, removal of unwanted odors or tastes.

It is common to have RO systems comprising several filter units connected in series. Some of the unfiltered water may be flowing passed the filter membrane in a first filter unit without it passing through the filter membrane, hance this water is still uncleaned. Subsequently, this unfiltered water may be recirculated into the same, first filter unit, or into a second filter unit in connection, preferably in series, with said first filter unit.

Having a RO system comprising several units and a pump for recirulating the water may be space consuming. The circulation pumps may also malfunction due to mechanical and/or electrical failure, and hence replacement or repair of the pump may be imminent. After some time, the RO filter may also need to be replaced, a common problem on the market is that the consumer may use spare parts not approved by the manufacturer instead of the approved replacement parts.

An example of a RO system is disclosed in <CIT> Al, which relates to a filter element for treating a liquid, by means of a wound module inserted in an outer housing to form an annular gap closed at least zonally and/or at least one side, for reverse osmosis filtration or ultra-filtration, the filter element carrying a flow of the liquid to be purified.

Hence, it is of interest to overcome at least some of the deficiencies of present water filter arrangements, in order to improve its functionality.

This and other objects are achieved by providing a water filter unit having the features in the independent claim.

According to a first aspect of the present invention, there is provided a water filter unit for purifying pressurized water fed to the water filter unit, said water filter unit comprising;.

Thus, the present invention is based on the idea of providing a water filter unit for purifying water having a pump arranged with the filter unit for enhancing filter functionality. The injector pump comprises no moving parts under operation in order to create the increased flow velocity. Hence, this may provide a filter unit without any moving parts. There will be a drop in pressure over the injector pump that may create a suction effect primarily affecting the unfiltered water within the filter. More specifically this may provide a pump without any moving parts for increasing the flow velocity of said pressurized water through the injector pump and recirculating the unfiltered water within the filter by creating a suction effect affecting the unfiltered water to have it recirculated. This may provide an increased flow through the filter membrane.

This may provide a water filter requiring no maintenance or a very low amount of maintenance since there may be no moving parts within the filter nor the injector pump. This may also provide a compact water filter.

According to an embodiment the water filter unit may further comprise an elongated pipe with a perforated wall connected to the first water outlet, wherein the filter membrane may be a reverse osmosis filter membrane arranged around said elongated pipe and the filtered water enters the elongated pipe via the perforations in the elongated pipe when using the water filter unit.

This may provide for a compact solution of a water filter. This may also provide for a high performing water filter unit able to clean water from high amount of dirt or impurities.

According to an embodiment the water filter unit may further comprise a channel arranged for transporting the pressurized water and the recirculated water from said injector pump to said filter membrane, wherein said channel may be arranged within the elongated pipe such that a passage between said elongated pipe and said channel may be formed.

This may provide for a facilitated transportation and/or recirculation of uncleaned water within the filter unit.

According to an embodiment the channel may be in connection with said injector pump, and wherein said channel may be arranged off-centered within said elongated pipe at least at one end of said elongated pipe.

This may provide for facilitated assembly of the water filter unit since there will be an increased amount of space for the outlet to be attached. In turn, this may provide for improved functionality of the water filter unit since an outlet with a larger cross-section may be possible.

According to an embodiment the injector pump may comprise the water inlet and a narrowing passage, wherein the narrowing passage has a diameter, D2, and the water inlet has a diameter, D1, wherein D2 may be smaller than D1.

According to an embodiment the injector pump comprises a second inlet passage, the narrowing passage may be arranged at a distance, H, from the center of said second inlet passage (<NUM>), wherein said distance H may be within the range -<NUM> *D1 to <NUM>*D1 and said injector pump may be furthermore arranged to receive unfiltered water through said second inlet passage.

At least some of the above embodiments may provide for an increased flowrate and/or flow velocity through the injector pump. At least some of the above embodiments may further provide for the unfiltered water to be sucked into the channel and recirculated within the filter unit.

According to an embodiment the ratio D1/D2 may be at least <NUM>, more preferably at least <NUM> most preferably at least <NUM>.

This may provide for a desired flowrate and/or flow velocity through the injector pump compared to that of the pressurized water fed to the containment. This may provide the flow rate and/or flow velocity through the injector pump to be preferably around at least twice, more preferably around three times, most preferably around four times, the flowrate and/or flow velocity of the pressurized water fed to the containment.

According to an embodiment at least part of the wall section may be attached to at least part of the filter membrane.

This may provide for decreased amount of water within the filter unit getting stuck, not being part of the flow of water within the filter unit. This may provide a decreasing risk for the unfiltered water to leak, passing the filter membrane without passing through the filter membrane.

According to an embodiment the injector pump may be arranged within said containment and wherein; said injector pump <NUM> may be further arranged to receive the pressurized water from the water inlet <NUM>.

This may provide for a compact water filter unit.

According to an embodiment the water filter unit comprises a second outlet for at least part of the unfiltered water.

This may provide for additional recirculation of the uncleaned water. This may also provide for adjustable outflow of clean water when the feed pump has a constant flow.

According to an embodiment the water filter unit further comprises a capillary tube enabling venting of the water filter unit.

This may provide for facilitated venting of the water filter unit if needed, since air might be transported with the water entering the water filter unit. If there is a substantial amount of air accumulated within the water filter unit, the functionality may be substantially decreased. Hence, capillary tubes for venting the water filter unit may also provide for improved functionality of the water filter unit.

According to an embodiment the wall section may be permanently sealed to at least one of the first end section and the second end section.

This may provide for a leak proof containment of the filter unit. The fact that the containment may be permanently sealed provide for improved reliability of that the filter unit since the filter unit only will contain components assembled and approved by the manufacturer.

According to an embodiment there may be provided a water purification system comprising at least one water filter unit according to any preceding embodiment of present invention and a feed pump for feeding pressurized water to said at least one water filter unit.

According to an embodiment the feed pump feeds the pressurized water to the at least one water filter unit using a pulsating pressure.

This may provide for improved functionality of the filter unit because of turbulence being induced by the pulsating pressure from the feed pump. The turbulence helps keeping particles from not getting stuck in the filter membrane and hence this may provide for a reduced requirement for maintenance and hence a longer lifespan for a possibly sealed water filter unit may be provided.

According to a second aspect of present invention there may be provided a method of manufacturing a water filter unit according to previous embodiments, wherein the filter membrane may be arranged around an elongated pipe; wherein said method comprises.

This provides for a method of manufacturing a water filter unit according to the present inventive concept. This may provide a water filter requiring no maintenance or a very low amount of maintenance since there may be no moving parts within the filter nor the injector pump. This may also provide a compact water filter since the injector pump may be arranged within said containment, i.e. within said water filter unit.

According to an embodiment the method may also comprise;.

This may provide for a decreasing risk of unused water or "dead" water within the filter unit. Without the curable plastic there may be an increasing risk of pockets to be built up that may trap part of the water within the filter, i.e. disturbing the circulation of the water within the filter. This may provide for a properly sealed container.

<FIG> schematically illustrates a water filter unit <NUM> according to at least one possible embodiment of present invention. <FIG> shows a water filter unit <NUM> for purifying pressurized water fed to the water filter unit. The water filter unit <NUM> comprising a containment <NUM> defined by a wall section <NUM>, a first end section <NUM> and a second end section <NUM>, wherein the wall section <NUM> is attached to the first end section <NUM> and the second end section <NUM>. The water filter unit <NUM> in <FIG> further comprises a water inlet <NUM> arranged in said first end section <NUM>. It should be understood that the water inlet <NUM> may also be arranged in said second end section <NUM>. The water filter unit <NUM> further comprises a filter membrane <NUM> arranged in said containment <NUM> such that at least part of the water is fed through the filter membrane <NUM>. The water filter unit <NUM> comprises a first water outlet <NUM> for filtered water from the membrane. The water filter unit <NUM> further comprises an injector pump <NUM> arranged to create an increased flow velocity trough the injector pump of said pressurized water fed to the filter membrane <NUM>. The injector pump <NUM> is furthermore arranged to receive unfiltered water not fed through the membrane and recirculate said unfiltered water within the containment <NUM>.

Thus, the present invention is based on the idea of providing a water filter unit <NUM> for purifying water having a pump arranged with the filter unit for enhancing filter functionality. The injector pump <NUM> comprises no moving parts under operation in order to create the increased flow velocity. Hence, this may provide a filter unit without any moving parts. There will be a drop in pressure over the injector pump <NUM> that may create a suction effect primarily affecting the unfiltered water within the filter unit <NUM>. More specifically this may provide a pump without any moving parts for increasing the flow velocity of said pressurized water through the injector pump <NUM> and recirculating the unfiltered water within the filter by creating a suction effect affecting primarily the unfiltered water to have it recirculated.

This may provide a water filter requiring no maintenance or a very low amount of maintenance since there may be no moving parts within the filter nor the injector pump <NUM>. This may also provide a compact water filter.

The injector pump may be at least partly arranged in one of the first end section and the second end section. the injector pump may be at least partly arranged in one of the first end section and the second end section to receive the pressurized water and create an increased flow velocity trough the injector pump of said pressurized water fed to the filter membrane.

The pressurized water fed to the filter water may also be referred to as feed water. The cleaned water exiting the filter unit after passing through the filter membrane <NUM> may also be known as the permeate.

The wall section <NUM> may be permanently sealed to the first end section <NUM> and/or the second end section <NUM> to ensure a leak proof containment of the filter unit. The fact that the containment may be permanently sealed provide for increased reliability of that the filter unit since the filter unit only will only contain components assembled and approved by the manufacturer.

By the word injector pump <NUM> may here be meant a pump without any moving parts. In other words, the injector pump <NUM> may comprise no moving parts. Hence, the injector pump <NUM> may be free of moving parts in order to create an increase flow velocity trough the injector pump <NUM>. In other words, the injector pump <NUM> may comprise only fixed parts. In other words, the pump <NUM> may comprise only stationary parts. In other words, the injector pump <NUM> may comprise stationary or fixed parts in order to create the inceased flow velocity through the pump. Known names for such injector pump <NUM> according to present invention are injector pump, aspirator, water injector, educator-jet pump, venturi pump and water educator. The significant part of the injector pump <NUM> according to present invention may thus be a pump without any moving parts.

<FIG> also shows an elongated pipe <NUM> with a perforated wall connected to the first water outlet <NUM> that may be present according to some embodiments of the present invention. The filter membrane <NUM> in <FIG> may according to at least some embodiments according to the present invention be a reverse osmosis filter membrane <NUM> arranged around said elongated pipe <NUM>, as illustrated in <FIG>. The filtered water enters the elongated pipe <NUM> via the perforations in the elongated pipe <NUM> when using the water filter unit.

In other words, the water gets filtered and cleaned when penetrating the filter membrane <NUM>. The filter membrane <NUM> may be arranged such that the cleaned water subsequently enters the perforations in the elongated pipe <NUM> when using the water filter unit.

This may provide for a compact solution of a water filter. This may also provide for a high performing water filter unit <NUM> able to clean water from high amount of dirt or impurities.

Also shown in <FIG> is that the water filter unit <NUM> may further comprise a channel <NUM> arranged for transporting the pressurized water and the recirculated water from said injector pump <NUM> to said filter membrane <NUM>. The channel <NUM> may be arranged within the elongated pipe <NUM> such that a passage between said elongated pipe <NUM> and said channel <NUM> may be formed.

This may provide for a facilitated transportation and/or recirculation of uncleaned water within the filter unit. In other words, the pressurized water fed to the water filter unit <NUM> enters the injector pump <NUM> and may be transported by said channel <NUM> to the water filter membrane <NUM>. The injector pump <NUM> may be arranged at least partly within the filter unit. The pressurized water may be transported by the channel <NUM> within the perforated pipe arranged within the filter membrane <NUM> to the side of the filter membrane <NUM> comprising unclean water when the filter unit is in use. Subsequently the pressurized water will either penetrate the filter membrane <NUM> or pass the filter membrane <NUM> as uncleaned water and be recirculated within the filter unit to once again approach the filter membrane <NUM>. The part of the pressurized water that penetrates the filter membrane <NUM> is cleaned by the filter membrane <NUM> and may further be transported through the perforations in the elongated pipe <NUM>. The channel <NUM> may be arranged centered within the elongated pipe <NUM>.

With continued reference to <FIG>, the injector pump <NUM> may be arranged within the containment <NUM>. The inlet of the injector pump <NUM> may be arranged downstream from the inlet of the water filter unit. In other words, when the pressurized water enters the filter unit <NUM> through the water inlet <NUM> the pressurized water subsequently enters the injector pump <NUM>. The pressurized water may be transported via the injector pump <NUM> to the upstream side of the filter membrane <NUM> after entering the inlet of the water filter unit. By having the injector pump <NUM> arranged within said containment <NUM> a compact solution may be provided.

As earlier mentioned the wall section <NUM> may be permanently sealed to the first end section <NUM> and the second end section <NUM>. Because of the novel construction of the present invention of having the provided compact solution with an injector pump <NUM> arranged within the filter unit and that the injector pump <NUM> comprises no moving parts. It is made possible to permanently seal the filter unit which may be beneficial in some applications. Because of no moving parts in the injector pump <NUM> the need of maintenance and repair of the filter unit may be at least reduced or may even be eliminated.

<FIG> schematically illustrates a water filter unit <NUM> according to at least one possible embodiment of present invention. <FIG> show the channel <NUM> in connection with said injector pump <NUM>. The channel <NUM> in <FIG> is arranged off-centered within said elongated pipe <NUM>. The channel <NUM> in <FIG> is arranged off-centered within said elongated pipe <NUM> at one end of said elongated pipe <NUM>. In other words, the channel <NUM> may be arranged off-centered within parts of the elongated pipe <NUM>. The channel <NUM> may be diagonally arranged within the elongated pipe <NUM>. The channel <NUM> may also be arranged off-centered within and along the whole elongated pipe <NUM>. This may provide for facilitated assembly of the water filter unit <NUM> since there will be an increased amount of space for the outlet to be attached. In turn, this may provide for improved functionality of the water filter unit <NUM> since an outlet with a larger cross-section is possible. When the channel <NUM> is arranged off-centered when in connection to the injector pump <NUM> a facilitated connection with the first water outlet <NUM> may be achieved.

As seen in <FIG> and <FIG> and described above the channel <NUM> may be arranged in connection to the injector pump <NUM> at one end of the channel <NUM>. The opposing end of the channel may be in connection to the upstream side of the filter membrane. The channel <NUM> may be arranged in connection to the injector pump <NUM> in one of said end sections <NUM>,<NUM> and be in connection to the upstream side of the filter membrane in the other end of said channel. In <FIG> and <FIG> the injector pump is arranged in said first end section <NUM>. In the opposite end of the channel <NUM>, the channel <NUM> is in connection to the upstream side of the filter membrane in said second end section <NUM>. One end of the channel <NUM> may thus be arranged in connection to the injector pump <NUM> at said first end section and arranged in connection to the second end section <NUM> in the opposing end of the channel <NUM>.

In other words, the channel <NUM> may have two ends, a first and second end. Said first end may be arranged in connection to said injector pump <NUM> in said first end section <NUM> and said second end may be arranged in connection to said second end section <NUM>.

In order to prevent uncleaned water to leak from the upstream side, or the feed water side, to the clean water side, or the permeate side, the channel may be sealed to the elongated pipe in at least one end of said channel, preferable in both ends. In <FIG> and <FIG> the channel is sealed to the elongated pipe in both ends.

In said first end of said channel <NUM> the seal may be constituted by a first filter end part <NUM>. In <FIG> and <FIG> the channel is sealed to the elongated pipe <NUM> by first being sealed the first filter end part <NUM> which in turn may be sealed to the elongated pipe by a rubber seal and/or by welding.

In said second end of the channel the channel may be sealed to the elongated pipe <NUM> by a second filter end part <NUM> enclosing the channel <NUM>, the second filter end part <NUM> may be sealed to the elongated pipe <NUM> by a rubber seal or by welding.

In said first end of said channel <NUM> the seal may be constituted by a connecting piece <NUM> for the injector pump <NUM> according to some embodiments of present invention, which can be seen in <FIG>. In <FIG> the channel <NUM> is enclosed by the connecting piece <NUM>, the connecting piece <NUM> may then be sealed to the elongated pipe <NUM> by a rubber seal <NUM>. The connecting piece <NUM> may be sealed to the elongated pipe <NUM> by welding and/or by a rubber seal.

This may prevent uncleaned water to leak from the upstream side, or the feed water side, to the clean water side, or the permeate side.

At least part of the wall section <NUM> may be attached to at least part of the filter membrane <NUM>. In other words, at least a part of the wall section <NUM> may be attached to at least part of an outer part of the filter membrane <NUM>. By the word "attached" may here be meant sealed or permanently attached. The outer part of the filter membrane <NUM> may be any part of the surface area enclosing the filter membrane <NUM>. The filter membrane <NUM> may be attached to the wall section <NUM> such that the majority of the surface area enclosing the filter membrane <NUM> is attached to the wall section <NUM>. The filter membrane <NUM> may be attached to the wall section <NUM> such that the whole surface area enclosing the filter membrane <NUM> is attached to the wall section <NUM>. The filter membrane <NUM> may be attached to the wall section <NUM> along a region enclosing the filter membrane <NUM>. The filter membrane <NUM> may be of cylindrical shape. The filter membrane <NUM> may have a top and a bottom portion. The filter membrane <NUM> may be attached to the wall section <NUM> in the transition <NUM> between the surface area and the top and/or bottom portion of the filter membrane <NUM>.

This may provide for decreased amount of water within the filter unit getting stuck, not being part of the flow of water within the filter unit. This may provide a decreasing risk for the unfiltered water to leak, passing the filter membrane <NUM> without passing through the filter membrane <NUM>.

The connection between the injector pump <NUM> and the filter membrane <NUM> may be welded or connected by screwing part of the injector pump <NUM> into the elongated pipe <NUM> of the filter membrane <NUM>. The connection between the injector pump <NUM> and the filter membrane <NUM> may be connected by inserting part of the injector pump <NUM> into the elongated pipe <NUM> of the filter membrane <NUM> clamping the injector pump <NUM> by the first or second section pressing down being attached to the wall section <NUM>.

The wall section <NUM> may be permanently sealed to at least one of the first end section <NUM> and the second end section <NUM>. The wall section <NUM> may be welded to the first end section <NUM> and/or the second end section <NUM>.

<FIG> schematically illustrates a close-up on the injector pump <NUM> and parts of the filter unit. <FIG> show the water inlet <NUM> and a narrowing passage <NUM> in the injector pump <NUM>. The narrowing passage <NUM> may have a diameter, D2, and the water inlet may have a diameter, D1, wherein D2 is smaller than D1. The injector pump may be partly located outside the filter unit <NUM> or the whole injector pump may be located inside the filter unit <NUM>. By the whole injector pump being located inside the filter unit it may be meant that the injector pump is arranged within the containment <NUM> and/or in at least one of the parts defining the containment <NUM>, i.e. the wall section <NUM>, the first and second end sections <NUM>, <NUM>. The injector pump <NUM> may be arranged at least partly in at least one the first end section <NUM> and the second end section <NUM>. Also, the injector pump <NUM> may be partly arranged in the first or second end section <NUM>, <NUM> and partly arranged in the containment <NUM>. Further, the injector pump <NUM> may be partly arranged outside the filter unit <NUM>, partly arranged in at least one of the first and second end section <NUM>, <NUM>, and partly within the containment <NUM>.

Further, the injector pump <NUM> may comprise a first inlet passage. The first inlet passage may be in fluid connection to the water inlet <NUM> of the filter unit <NUM>. The first inlet passage of the injector pump may be arranged within the water inlet <NUM> of the filter unit <NUM>.

The first inlet passage of the injector pump <NUM> may be the same as the water inlet <NUM> of the filter unit <NUM>. In other words, the injector pump <NUM> may comprise the water inlet <NUM>. Hence, the injector pump <NUM> may be at least partly arranged in at least one of the first and second end section <NUM>, <NUM> and comprise the water inlet <NUM>.

<FIG> also shows a second inlet passage <NUM> of the injector pump <NUM>. Said second inlet passage <NUM> may be arranged downstream from the narrowing passage <NUM>. The second inlet passage <NUM> may be arranged upstream from the narrowing passage <NUM> or parallel to the narrowing passage <NUM>. The injector pump <NUM> may furthermore be arranged to receive unfiltered water through said second inlet passage <NUM>. In other words, unfiltered water that has passed the filter membrane <NUM> without penetrating it will enter the second inlet passage <NUM> and get transported by means of the injector pump <NUM> and the channel <NUM> to the upstream side of the filter membrane <NUM>. In other words, unfiltered water that has passed the filter membrane <NUM> without penetrating it will be recirculated to the upstream side of the filter membrane <NUM> by means of the injector pump <NUM> and the channel <NUM>.

The channel <NUM> may be arranged downstream from the narrowing passage <NUM>. The channel <NUM> may have a second inlet passage <NUM> substantially perpendicular to the channel <NUM>. The second inlet passage <NUM> may be arranged at a distance H, from the center of the second inlet passage <NUM> to the narrowing section <NUM>. The distance, H, between the narrowing passage <NUM> and the center of the second inlet passage <NUM> may preferably be in the range -<NUM>*D1 to <NUM>*D1 more preferably in the range -<NUM>*D1 to <NUM>*D1, most preferably in the range -<NUM>*D1 to <NUM>*D1, where D1 is the diameter of the first inlet passage of the injector pump <NUM>. A negative distance, H, from the center of the inlet passage <NUM> to the narrowing passage <NUM> means that the narrowing section will be positioned further downstream compared to a positive distance, H. Further, the distance, H, may be in the range -<NUM>*D1 to <NUM>*D1 or -<NUM>*D1 to -<NUM> *D1. Diameter, D3, of the second inlet passage <NUM> may preferably be equal to or less than the diameter of the first inlet passage. The distance, H, may also be in the range -<NUM>*D3 to -<NUM>/<NUM>*D3, alternatively in the range -<NUM>*D3 to -<NUM> *D3. Hence, the narrowing passage <NUM> may be arranged downstream from the second inlet passage <NUM>. There may be a plurality of water inlet passages arranged to receive pressurized water converging to at least one narrowing passage <NUM>. There may be a plurality of water inlet passages arranged to receive unclean water for recirculation. The sum of collected cross sectional area of the connecting inlets for pressurized water may preferably be larger than the sum of collected cross sectional area of the connecting inlets arranged to receive unclean water for recirculation. The sum of collected cross sectional area of the connecting inlets for pressurized water may preferably at least twice as big as the sum of collected cross sectional area of the connecting inlets arranged to receive unclean water for recirculation.

The injector pump <NUM> being arranged as described above and illustrated in <FIG> may provide for an increased flowrate and/or flow velocity through the injector pump <NUM> and may further provide for the unfiltered water to be sucked into the channel and recirculated within the filter unit.

The ratio D1/D2 may be at least <NUM>, more preferably may it be at least <NUM> most preferably may it be at least <NUM>.

Preferably, D1 may be within the range of <NUM> - <NUM> and D2 may be within the range of <NUM> - <NUM>.

As seen in <FIG>, the water inlet <NUM> and said first water outlet <NUM> may be in connection with the elongated pipe. The water inlet <NUM> and said first water outlet <NUM> may be sealed to the elongated pipe by a seal <NUM>. The seal may be achieved by welding the water inlet <NUM> and said first water outlet <NUM> to the elongated pipe <NUM>. The water inlet <NUM> and said first water outlet <NUM> may be held in place by the first or second section. The seal may be a rubber seal, such as a o-ring seal, in between the elongated pipe and the water inlet <NUM> and said first water outlet <NUM> in order to prevent water from entering the elongated pipe without passing the filter membrane.

When welding the water inlet <NUM> and said first water outlet <NUM> to the elongated pipe <NUM> larger connections are possible since this embodiment will need lesser space, since the demand for insertion of the water inlet <NUM> and said first water outlet <NUM> into the elongated pipe may not be as high as when sealing with a o-ring seal.

The water inlet <NUM> and said first water outlet <NUM> may be arranged in a connecting arrangement holding the connections in place. The connecting arrangement may be connected to the elongated pipe by welding or by applying a rubber seal, such as an o-ring seal, in between the elongated pipe and the connecting arrangement in order to prevent water from entering the elongated pipe without passing the filter membrane. Part of the elongated pipe and/or the connecting arrangement may be threaded, i.e. part of the elongated pipe and/or the connecting arrangement may comprise a threaded section, and the connecting arrangement may be screwed into the elongated pipe <NUM>.

When welding the connecting arrangement to the elongated pipe <NUM> larger connections for the water inlet <NUM> and said first water outlet <NUM> are possible since this embodiment will need lesser space, since the demand for insertion of the connection arrangement into the elongated pipe may not be as high as when sealing with a o-ring seal.

<FIG> schematically illustrates a water filter unit <NUM> according to one embodiment of the present invention. <FIG> shows a second outlet <NUM> of the water filter unit <NUM> for at least part of the unfiltered water. In other words, a second outlet <NUM> may be provided to transport at least part of the unfiltered water away from said filter unit. By transporting at least part of the unfiltered water away from the filter unit another possibility of recirculating the uncleaned water may be provided. This may also provide for adjustable outflow of clean water, depending on for example the size of the second outlet <NUM>, when the feed pump has a constant flow when the filter unit is in use. In connection with the second outlet <NUM> an adjustable valve may be connected in order to control flow of unclean water from the filter unit. When a constant flow from the feed pump is used lesser amount of clean water may exit the filter when higher amount of unclean water exits the filter unit.

<FIG> also illustrates that the water filter unit <NUM> further comprises a capillary tube <NUM> enabling venting of the water filter unit.

A facilitated venting of the water filter unit <NUM> may be desirable since air might be transported with the water entering the water filter unit. The capillary tube <NUM> may be connected on any of the sides suitable for venting, preferably on a side of the filter unit facing upwards, in a direction opposite to the direction of gravity, when the filter unit is in use. The capillary tube <NUM> may be arranged the filter unit <NUM> so that venting of the filter unit may be enabled. If there is a substantial amount of air accumulated within the water filter unit <NUM> when in use, the functionality may be substantially decreased. Hence, the capillary tube <NUM> for venting the water filter unit <NUM> may provide for increased functionality of the water filter unit <NUM> when in use.

The second outlet <NUM> may be positioned in said first end section <NUM> and/or said second end section <NUM>. The water inlet <NUM> and/or the first water outlet <NUM> may be connected to the connecting piece <NUM>. The second outlet <NUM> may be connected to the connecting piece <NUM>. Said connecting piece <NUM> may be positioned within the containment <NUM> or partly outside the containment <NUM>. The connecting piece <NUM> may be forced and held in place by the first or second end section <NUM>, when said first or second end section <NUM> is attached to the wall section <NUM>. The connecting piece <NUM> may be welded to the first or second end section <NUM>,<NUM>. There may be o-ring seals, sealing the connection between the connecting piece <NUM> and the first or second end section <NUM>,<NUM>.

The injector pump <NUM> has a feed pressure of preferably at least <NUM> bar, more preferably at least <NUM> bar, most preferably at least <NUM> bar. This may provide the injector pump <NUM> to function without electrical components since the pressure from the feed pump drives the injector pump <NUM>.

<FIG> schematically illustrates a water filter unit <NUM> according to at least one example embodiment of present invention. In <FIG> the second end section <NUM> comprises a connection <NUM> for filling curable plastic material <NUM>.

This may provide for a facilitated sealing of the filter unit. The curable plastic material may be thermosetting plastic or any plastic material suitable to be cured with time such as different type of epoxy or equivalent.

<FIG> schematically illustrates a close-up on the injector pump <NUM> according to a least one possible embodiment of the present invention. The passage <NUM> immediately after the narrowing passage <NUM> in the flow direction may be a passage with straight walls as seen in <FIG>. As seen in <FIG> the passage <NUM> immediately after the narrowing passage <NUM> in the flow direction may have second narrowing section <NUM>, that may further increase the flow velocity trough said injector pump <NUM>. The second narrowing section <NUM> may preferably be arranged after the second inlet passage <NUM> in the flow direction. The passage <NUM> may be flared and the passage may expand so that the diameter of the channel <NUM> may be larger than the diameter of the inlet passage <NUM>. This may also provide a larger flow rate and/or flow velocity through the injector pump <NUM>. The passage <NUM> may have any form or shape that is known in the art to achieve an increased flow velocity and/or flow rate through said pump.

<FIG> schematically illustrates a water purification system <NUM> comprising one water filter unit <NUM> according to any preceding embodiment of present invention. The system also comprises a feed pump <NUM> for feeding pressurized water to said at least one water filter unit <NUM>.

The feed pump <NUM> in <FIG> may feed the pressurized water to the at least one water filter unit <NUM> using a pulsating pressure.

This may provide for increased functionality of the filter unit <NUM> because of turbulence being induced by the pulsating pressure from the feed pump <NUM>. The turbulence may help keeping particles from not getting stuck in the filter membrane <NUM> and hence this may provide for a reduced requirement for maintenance and hence a longer lifespan for a possibly sealed water filter unit <NUM> may be provided. The feed pump may feed the pressurized water to the at least one water filter unit <NUM> using a constant pressure. The feed pump may feed the pressurized water to the at least one water filter unit <NUM> using an alternating pressure. By alternating pressure may be meant a pressure that changes over time. By constant pressure may be meant a pressure that is kept the same over time. By pulsating pressure may be meant a pressure that changes over time with a cyclic characteristic. In other words, by a pulsating pressure may be meant a pressure alternating over time, alternating between a target value and a lower value. Said target value may be dependent on the desired pressure at the filter input and said lower value may be close to no pump pressure.

The feed pump <NUM> may deliver a feed pressure of preferably at least <NUM> bar, more preferably within the range of <NUM>-<NUM> bar. With other words, the pressure of the water fed to the filter unit may be delivered at, at least <NUM> bar, more preferably within the range of <NUM>-<NUM> bar. This may provide the injector pump <NUM> to function without electrical components since the pressure from the feed pump drives the injector pump <NUM>. The pressure within the filter unit may preferably be at least <NUM> bar, more preferably within the range of <NUM>-<NUM> bar.

The purified water may be fed from the filter unit <NUM> to a storage tank <NUM> for storing clean water.

<FIG> schematically illustrates a method for manufacturing a filter unit according to present invention. <FIG> shows a method <NUM> of manufacturing a water filter unit <NUM> comprising a filter membrane <NUM> wherein the filter membrane <NUM> may be arranged around an elongated pipe <NUM>. The method <NUM> comprises connecting <NUM> the injector pump to a channel <NUM>. The method also comprises assembling <NUM> the injector pump <NUM>, with the channel <NUM> connected, to the filter membrane <NUM> so that said channel <NUM> may be arranged within said elongated pipe <NUM> creating a passage between said elongated pipe <NUM> and said channel <NUM>. The method further comprises assembling <NUM> the wall section <NUM> to the filter membrane <NUM>. The method also comprises assembling <NUM> a first end section <NUM> and a second end section <NUM> to said wall section <NUM> creating a filter housing. The method comprises sealing <NUM> said first end section <NUM> to said wall section <NUM> and said wall section <NUM> to said second end section <NUM>.

This provides for a method of manufacturing a water filter unit according to the present inventive concept. This may provide a water filter requiring no maintenance or a very low amount of maintenance since there may be no moving parts within the filter nor the injector pump. This may also provide a compact water filter since the injector pump may be arranged at least partly within said containment, i.e. at least partly within said water filter unit.

The method <NUM> may further comprise applying <NUM> a connection <NUM> to the second end section <NUM>. The method may comprise connecting <NUM> a vacuum pump <NUM> to the water inlet <NUM> and connecting <NUM> a container for uncured curable plastic to said connection <NUM>. The method may further comprise evacuating <NUM> said filter housing with said vacuum pump so that said curable plastic may be sucked into said second section of said filter housing;.

Other openings on the filter unit <NUM> may be temporarily sealed during evacuation of the filter unit <NUM>. Preferably, the first water outlet <NUM> may be sealed during evacuation of the filter unit. The vacuum pump <NUM> may then be switched off in order for the curable plastic <NUM> to settle properly. Switching of the vacuum pump may provide for improved sealing by the curable plastic <NUM> since air channels within the plastic may otherwise be present in the cured plastic <NUM>. The curable plastic <NUM> may be thermosetting plastic or any plastic material suitable to be cured with time. The curable plastic <NUM> may be epoxy or any material suitable to be cured according to the described process. After the curable plastic is cured the air may be let inside the filter unit <NUM>.

Claim 1:
A water filter unit (<NUM>) for purifying pressurized water fed to the water filter unit (<NUM>), said water filter unit (<NUM>) comprising;
a containment (<NUM>) defined by a wall section (<NUM>), a first end section (<NUM>) and a second end section (<NUM>), wherein the wall section (<NUM>) is attached to the first end section (<NUM>) and the second end section (<NUM>);
a water inlet (<NUM>) arranged in said first or second end section (<NUM>,<NUM>) through which the pressurized water is fed into the containment (<NUM>);
a filter membrane (<NUM>) arranged in said containment such that at least part of the water is fed through the filter membrane (<NUM>);
a first water outlet (<NUM>) for filtered water from the membrane;
wherein the water filter unit (<NUM>) further comprises an injector pump (<NUM>) arranged to create an increased flow velocity through the injector pump (<NUM>) of said pressurized water fed to the filter membrane (<NUM>), and said injector pump (<NUM>) is furthermore arranged to receive unfiltered water not fed through the membrane and recirculate said unfiltered water within the containment (<NUM>);
wherein the water filter unit (<NUM>) further comprises an elongated pipe (<NUM>) with a perforated wall connected to the first water outlet (<NUM>), wherein the filter membrane (<NUM>) is a reverse osmosis filter membrane (<NUM>) arranged around said elongated pipe (<NUM>) and the filtered water enters the elongated pipe (<NUM>) via the perforations in the elongated pipe (<NUM>) when using the water filter unit (<NUM>);
characterized in that
the water filter unit (<NUM>) further comprises a channel (<NUM>) arranged for transporting the pressurized water and the recirculated water from said injector pump (<NUM>) to said filter membrane (<NUM>);
wherein said channel (<NUM>) is arranged within the elongated pipe (<NUM>) such that a passage between said elongated pipe (<NUM>) and said channel is formed (<NUM>).