CN111686494A

CN111686494A - Filter assembly

Info

Publication number: CN111686494A
Application number: CN201910389501.6A
Authority: CN
Inventors: W.黑金
Original assignee: Hans Sasserath GmbH and Co KG
Current assignee: Hans Sasserath GmbH and Co KG
Priority date: 2019-03-12
Filing date: 2019-05-10
Publication date: 2020-09-22
Also published as: DE202019104963U1

Abstract

A potable water filter, comprising: a connection fitting with an inlet and an outlet for mounting directly in front of a water receiving point; the filter cup is arranged on the connecting accessory; and at least two successively connected filter stages of filter material, which are arranged in a filter cup on the flow path between the inlet and the outlet, wherein one of the filter stages is formed by an activated carbon filter, characterized in that a drain is provided at the lower end of the filter cup; and at least one of the filter stages is designed as a backflushing filter stage which can be switched from an operating position, in which water is conducted from the inlet through all the filter stages to the outlet, into a backflushing position, in which water can be conducted from the inlet in the opposite direction through the backflushing filter stage to the open outlet.

Description

Filter assembly

Technical Field

The invention relates to a drinking water filter, comprising:

(a) a connection fitting with an inlet and an outlet, the connection fitting being adapted to be mounted directly before a water receiving point (Zapfstelle);

(b) the filter cup is arranged on the connecting accessory;

(c) at least two successively connected filter stages of filter material, which are arranged in a filter cup in the flow path between the inlet and the outlet, wherein one of the filter stages is formed by an activated carbon filter.

Such filters are also known as "Point-of-Use" (POU) filters. In some countries where the water quality is not monitored or where the requirements on water quality are not sufficient to make water suitable as drinking water, the use of POU-filters is advantageous, in particular in these countries. In addition to the usual soiling caused by particles such as small stones, rust particles, micro-plastics or other suspended particles, water is contaminated by organic matter such as fertilizer, herbicide and pesticide residues from agriculture or undesirable ions. Such residues are, for example, aromatic hydrocarbons, alcohols, phenols, ethers, organophosphorus compounds, nitrogen compounds, aldehydes, ketones, acids and esters. There are also viruses, bacteria and parasites in the water. Such biological contaminants are, for example, viruses in the size range from 0.04 μm to 0.3 μm, such as norovirus, rotavirus, calicivirus and enterovirus, bacteria in the size range from 1 μm, such as E.coli, Vibrio cholerae or Salmonella typhi, and parasites in the size range from 4 μm to 11 μm, such as Cryptosporidium parvum, Giardia lamblia or Amara intestinalis.

Many undesirable substances can be removed by simple filtration. Depending on the size of these substances, different filters are suitable here: a fine filter in the form of a simple mesh can retain particles having a particle size greater than, for example, 30-50 microns. For smaller particles, macromolecules and biological contaminants, membrane filters are suitable. The membrane filter may have pores of different sizes. Particles and material above about 0.1 micron in size can be retained during microfiltration and particles and material above 0.01 micron can be retained during ultrafiltration. Nanofiltration and reverse osmosis are also possible. But the latter require particularly high pressures. Finally, there is an activated carbon filter. Activated carbon filters adsorb organic and inorganic substances.

Filters are commonly used to filter drinking and non-drinking water. In the fine filter, the dirt particles adhere to the screen. Over time, the filter material clogs. Thus, little or no more water passes through the filter. Thus requiring periodic filter updates. For membrane filters, biological material can also adhere to the membrane. This material grows over time. It forms an undesirable biofilm. For the POU-filter, the entire filter material is completely replaced after typically 6 months.

Background

Filters used directly before the water connection are disclosed in CN 101524602 a and DE 202006016132U 1.

The applicant is at his websitewww.syr.dePOU-filters with multiple filtration stages are sold under the name "POU max". The filter can be mounted under the rinsing table and accordingly has a small size. Is provided with a dirt filter, an active carbon filter and a bacteria and germ filter. The germ filter is arranged in the interior of the annular activated carbon filter cartridge. The germ filter is placed after the activated carbon filter and forms the final filtration stage. Filter cartridges composed of activated carbon are known under the name "carbon" or filter element "EPS". The filter cartridge filters pesticides, solvents, pesticides, organic pests, flavorings, and odorous substances. A sediment filter is arranged on the inlet side. The dirt filter is configured to be backwashed.

Furthermore, it is known to filter water in hollow fiber membranes. The hollow fiber membrane has an absolute filter fineness of approximately 0.1 μm. They are suitable as pathogen barriers and prevent pathogen nests (Keimnester) and biofilm formation.

Other manufacturers, such as BRITA, also sell POU-filters under the name HS1 with multiple filtration stages in the form of pre-filters, activated carbon filters and hollow fiber-membranes. As the useful life of a filter stage ends, the entire filter material is wasted.

EP 2952239 a1 discloses a filter attachment with an impeller, in which the filter insert is divided into two parts by means of a horizontal wall section. The filter element has the same diameter along the entire height. The impeller projects through the horizontal wall from the lower filter chamber into the upper filter chamber. A valve is arranged between the upper and lower filter chambers, by means of which valve water can flow from the lower filter chamber into the upper filter chamber in the operating position. This known arrangement is complicated to construct. A high degree of pressure drop is created across the valve and the horizontal wall. This is not desirable. The filter is bulky and has only one filter screen. This filter is not suitable as a point-of-use filter arranged directly before the water connection.

Disclosure of Invention

It is an object of the invention to provide a filter of the type mentioned in the opening paragraph which saves resources and has a long service life.

According to the invention, this object is achieved by a filter of the type mentioned in the opening paragraph in that:

(d) the lower end of the filter cup is provided with a discharge part; and is

(e) At least one of the filter stages is designed as a backflushing filter stage which can be switched from an operating position, in which water is conducted from the inlet via all filter stages to the outlet, into a backflushing position, in which water can be conducted from the inlet in the opposite direction through the backflushing filter stage to the open outlet.

Through back flushing, the service life of a single filtration stage is prolonged. This is particularly advantageous when these filter stages are clogged earlier than the service life of the activated carbon filter. The service life is typically half a year. Thus, a filtration stage can be flushed after it has been previously used. It is no longer necessary to replace the entire filter material jointly.

The service life of the filter stage can be extended in particular by measures: that is, an activated carbon filter is used as the final filtration stage. All the preceding filter stages can then be backwashed. The carbon filter is passed through by water which has been filtered beforehand and clogging does not occur as quickly. Thereby also extending the useful life of the activated carbon filter.

The filter stage on the inlet side can in particular be formed by a screen which can be backwashed. Such a screen can be backwashed particularly easily. The particles trapped therein are carried away in the opposite direction through the screen by the backwash flow and are disposed of by the discharge.

The intermediate filtration stage may preferably consist of a hollow fiber membrane filter, a micro-membrane filter or another membrane filter. The hollow fiber membranes consist of a bundle of soft-bag-shaped membranes and cannot be easily backwashed. However, the following possibilities exist: i.e. to generate a flushing flow for circulating the hollow fiber-membranes within the bundle. In this case, the biofilm growing outside the hollow fiber-membrane is carried away and disposed of via the discharge with backwash water. Thereby extending the useful life of the hollow fiber membrane.

A particularly compact arrangement of the drinking water filter is achieved by the following measures:

(a) a substantially cylindrical filter element guided axially displaceably between an upper stop and a lower stop, with a screen-shaped main filter and a screen-shaped auxiliary filter and an annular space arranged around the filter element and connectable to the inlet; and is

(b) The means for separating the annular space are arranged such that the main filter can be connected to the inlet in the operating position and the auxiliary filter can be connected to the inlet in the backflushing position and can be flowed through from the outside to the inside.

The backwashing water is advantageously filtered in the auxiliary filter, so that no particles can reach the inside of the main filter or enter other filter stages.

In this case, it can be provided that the auxiliary filter is arranged in a cylindrical sleeve which interacts with an annular projection which is formed on the outside on the filter element between the main filter and the auxiliary filter, and which in the operating position blocks the transition between the annular space and the region between the auxiliary filter and the sleeve and opens when the filter element is moved into the lower position.

The transition between the backflushing position and the operating position takes place here by an axial displacement of the filter element.

In a further embodiment of the invention, it is provided that the means for separating the annular space are formed by an annular projection which is formed on the outside on the filter element and which interacts with an inwardly projecting annular shoulder of the filter cup and separates the annular space in a backflush position in which the filter element is in the lower end position. The annular projection may be the same annular projection that cooperates with the cylindrical sleeve. The annular projection then acts like a double valve. In the upper end position (operating position) of the filter element, the annular projection separates the auxiliary filter from the annular space and guides the water through the main filter. In the lower end position of the filter element (backflush position), the annular projection separates the annular space and guides the water through the auxiliary filter. The sleeve and the annular shoulder serve here as stops for defining the respective end position.

In a further embodiment of the invention, provision is made for:

(a) the filter element has a bottom;

(b) guide ribs fixed to the housing for guiding the bottom are provided, which extend through the bottom of the filter element, so that the bottom is closed by the guide ribs in the upper operating position and in the lower backwashing position; and is

(c) The guide rib has a constriction between the upper end and the lower end, so that when the filter element is moved between the operating position and the backflushing position, a passage is formed in the region of the constriction in transition, through which backflushing water flows from the filter cup to the drain.

Not only is the main filter, i.e. the screen, backwashed, but also the region flowing through the membrane filter, in particular the flushing flow between the hollow fiber membranes, is backwashed. In which case the biofilm may be removed. The biofilm should as far as possible not reach the main filter from the inside. During the transition phase, the initially produced backwash water is therefore directed directly downwards to the discharge. For this purpose, a via is temporarily formed in the bottom. The drinking water filter has a transition region due to the constriction between the operating position and the backflushing position, in which region water and the biofilm located therein can flow out through the bottom.

A particularly effective backwashing is achieved by means of an impeller which is rotatable about the longitudinal axis of the filter element within the filter element and by means of which, in the backwashing position, water can be conducted through a reduced angular range of the main filter from the inside to the outside. Thus, the entire main filter is not backwashed, but always backwashed at an increased flow rate over only a small angular range.

The drinking water filter is particularly advantageous if the filter stage comprises activated carbon and a membrane filter arranged in a filter sleeve which is arranged cylindrically in a filter cup. Membrane filters must be replaced periodically even when they are capable of backwashing. Cartridges with different filter materials can be easily and quickly replaced in their entirety. This is particularly user friendly.

In an advantageous embodiment of the invention, it is provided that the membrane filter is arranged in a pot-shaped water guiding element, which guides the backwash flow or the transitional flushing flow at least partially through the filter region with the membrane filter and to the open outlet. A high flow speed with good rinsing effect is achieved with the pot-shaped water guide element.

In order to perform backwashing regularly:

(a) a blocking member which is operated by a motor is arranged in the inlet;

(b) a mechanism for measuring flow is arranged in the outlet; and is

(c) An evaluation and control unit is provided which is supplied with signals from the means for measuring the flow and which closes the blocking element when a selected flow volume flows through the drinking water filter.

After the selected flow volume has passed through the potable water filter, the blocking member is closed. Then no more water can be taken off. The user immediately realizes that the back flushing is required by opening the discharge. After the backwash, the blocking element can be opened again and the water can be discharged. In this way it is ensured that always clean water is used.

Drawings

The design of the invention is the subject of the dependent claims. The embodiments are described in detail below with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view of a backwash filter assembly with a filter and an auxiliary filter for filtering backwash water in an operating position;

FIG. 2 shows a detail of FIG. 1 with a blocking member;

FIG. 3 shows a detail of FIG. 1 with a filter and an auxiliary filter;

FIG. 4 shows a detail of FIG. 1 with an outlet at the lower end of the assembly;

FIG. 5 is an exploded view of a portion of the filter;

FIG. 6 is a cross-sectional view of the assembly of FIG. 1 during a transition from the run position to the backwash position;

FIG. 7 is a cross-sectional view of the assembly of FIG. 1 in a backwash position;

FIG. 8 shows a detail of FIG. 6 with the bottom of the filter cup;

FIG. 9 is a perspective view of an impeller of the assembly according to FIG. 1;

FIG. 10 illustrates the impeller of FIG. 9 in an exploded view;

fig. 11 shows an alternative embodiment with a blocking element at the inlet, which is operated by a motor.

Detailed Description

Operating position of fig. 1 to 5

Figure 1 shows a filter assembly generally designated 10. The assembly 10 is used for filtering potable or non-potable water and is installed directly in front of a water receiving point. The assembly 10 has an attachment accessory with a housing 12. The housing 12 has an inlet 14 and an outlet 16 by means of which the assembly can be installed in a pipeline (not shown) before a water receiving point. In the present embodiment, a coaxial assembly is provided between the inlet 14 and the outlet 16, which assembly may be mounted directly into the pipeline. However, it is also possible to use a flange connection, with which the component is flanged to the connection fitting via a corresponding flange. The outlet is then configured as an annular channel which is arranged around the inlet in the form of a central channel, and vice versa.

In the present first embodiment, a blocking member in the form of a ball valve 18 is arranged in the inlet region 14. The ball valve 18 includes a ball 20 with a handle 22. The ball 20 has a through hole. The ball 20 is rotated about a vertical axis in order to close and open the blocking member. But of course any other form of blocking member may be used.

Fig. 11 shows an embodiment in which a motor is provided instead of the handle.

The inlet region 14 is separated from the outlet region 16 by a wall 24. The housing 12 forms a narrowed, downwardly projecting neck 26. The wall portion 24 extends downwardly through the neck portion 26. At the lower end, the neck 26 opens into a downwardly projecting nipple 28. The upper end of the filter cup 30 is inserted into the open end of the adapter tube 28 and sealed with 2O-rings (seals) and one seal 32. The filter cup 30 has a radially outer circumferential edge 34 in the upper region. This edge forms a stop so that the filter cup 30 assumes a defined position.

The lower region 36 of the filter cup 30 has a smaller diameter than the upper region 38. An inwardly projecting annular shoulder 40 is thereby formed in the transition region between the lower region 36 and the upper region 38.

A drain opening 44 is formed in the bottom 42 of the filter cup 30. A cylindrical discharge portion 46 is formed on the bottom surface of the bottom portion 42. The discharge portion 46 is provided with an external thread 48. The discharge body 52 is inserted into the discharge portion 46, and is sealed with two seals against the inside of the discharge portion 46. The union nut 50 surrounds an outer circumferential edge 54 of the discharge body 52. This is clearly seen in the enlarged view of fig. 4. The lock nut 50 is screwed to the external thread 48 with an internal thread. Thereby rotatably retaining the discharge body 52 in its axial position.

The discharge body 52 is provided with a vertical through hole 56. The through-hole 56 may be blocked by a blocking member 58. In the present embodiment, the blocking member 58 is formed by a ball valve with a ball 62 and a handle 64. The ball 62 can be rotated for opening and closing about a horizontal axis by means of a handle 64 via a pin (Zapfen) 66.

The outlet body 52 and the blocking element 58 are located in a pot-shaped cover 60 with openings for the outlet and the handle 64. The cover 60 is open at the upper end and extends around the lower region 36 of the filter cup 30 to the shoulder 40. This can be seen in fig. 1. In this way, the outer radii of the components are substantially equal and the blocking member is protected.

A water filter with three filtration stages is located in the filter cup 30. The first filtration stage is constituted by a fine filter 66. The fine filter 66 is a predominantly cylindrical sieve which forms part of a filter body 68. The subsequent second filtration stage consists of hollow fiber membranes 70, which are described in detail below. The last, third filtration stage is constituted by an activated carbon filter 72.

The filter pack consisting of hollow fiber membrane 70 and activated carbon filter 72 is held within a two-component filter cartridge. Carbon filter 72 is located in an upper sleeve portion 74 of the filter sleeve. The hollow fiber-membrane 70 is located in the lower sleeve portion 76 of the filter sleeve. This filter group can also be clearly seen in fig. 5. The lower sleeve portion 76 has a reduced diameter in a lower region 78. Thereby forming an inwardly projecting annular shoulder 80. The lower portion 76 of the filter sleeve forms an intermediate bottom 81 in the plane of the shoulder 80.

The upper sleeve part 74 has an intermediate opening 82 at the upper end which opens into a tubular outlet 84. This can be seen clearly in figure 5. The tubular outlet 84 is provided externally in the upper region with an annular groove in which a seal is arranged. The upper sleeve part 74 is inserted from below into the neck 26 of the housing 12 with a tubular outlet 84. In this manner, the outlet 84 opens into an outlet passage 86 defined by the wall 24 and the housing 12 that connects with the outlet 16. This can be seen clearly in figures 1 and 2.

On the left side of the wall portion 24 in fig. 1, an inlet passage 88 is formed. The inlet passage 88 extends from the inlet 14 through the blocking member and curves downwardly in front of the wall portion 24. The inlet passage 88 extends further through the neck into the region outside the filter sleeve. The filter sleeve with upper sleeve portion 74 and lower sleeve portion 76 has an outer diameter that is smaller than the inner diameter of filter cup 30. In this way, an outer annular space 90 is formed. The inlet passage 88 is connected to an outer annular space 90. Through the annular space 90, water flows from the inlet 14 through the inlet passage 88 down each filter stage. This can be seen clearly in figure 2.

The filter body 68 with the fine filter 66 is shown in detail in fig. 3. The filter body 68 has a circumferential annular projection 92 on the outside. The filter body 68 is inserted from below into the lower sleeve part 76. Here, the annular projection 92 serves as a stop. The lower free edge of the region 78 with the smaller diameter rests in the operating state on the annular projection 92. The lower portion of the filter body 68 extends downwardly into the region 36 of the filter cup 30 having the smaller diameter. At the lower edge, the filter body 68 has internal threads 94. The bottom member 96 is externally threaded into threads 94 of the filter body 68. The bottom part 96 and thus the filter body 68 are applied with the spring force of the spring 98. The lower end of the spring 98 rests on a spring support 104 located on the bottom 42 of the filter cup 30. The spring 98 urges the filter body 68 upward toward the filter cartridge.

The bottom member 96 has an opening. The guide ribs 100 extend through these openings. These guide ribs are molded onto the spring support 104. In the region above it, each guide rib 100 has a recess 106 on the outside. This recess is clearly visible in fig. 6. The recess 106 forms a passage during the transition period if the bottom member 96 is moved downward by the filter body 68 against the spring pressure of the spring 98 as described below. Water and, if necessary, particles can pass down through the passage. The transition period ends when the bottom part 96 is at a lower level than the recess 106 in the region of the opening.

The bottom part 96 is lowered in the region of the shaft and thus forms a circular receptacle 108. Around the receptacle 108, an annular projection 110 is formed on the top surface of the bottom member 96. A guide rod 112 is rotatably disposed in the accommodating portion 108. The guide rod 112 is rotatable but not movable in the axial direction. For this purpose, retaining

rings

118 and 120 are provided. The fixing rings 118 and 120 are fitted into annular grooves in the guide rod 112. The securing ring 120 is arranged above the bottom of the filter sleeve, which is set at the level of the shoulder 80, while the securing ring 118 is arranged below it. This can be seen clearly in figure 1. The guide rod 112 is thus unable to move in the axial direction.

The rotatable impeller 122 is strung onto (auff ä deln) the guide bar 112. This impeller is again shown separately in fig. 9 and 10. The impeller 122 is fixed to the guide rod 112 in the axial direction by the fixing rings 114 and 116. Impellers for backwashing fine screens are known from the prior art and therefore need not be described in detail here. For backwashing, water flows from above into the interior 121 of the impeller 122 and flows at an increased speed outwards through the

lateral nozzles

123 and 125.

Nozzles

123 and 125 are at different heights. This results in the entire height of the filter screen being reached with a smaller nozzle size. Here, it reaches the filter screen concentrically. The water flows through the filter screen in the opposite direction and carries away dirt particles. With the

nozzles

123 and 125 arranged laterally, a torque is applied to the impeller 122 by the back-flushing flow, so that the impeller rotates upon back-flushing. The

nozzles

123 and 125 then sweep through the entire angular extent of the filter screen. For manufacturing reasons, the ring 124 snaps into the impeller 122 on top. The ring 124 closes the nozzle upwardly.

The filter body 68 has an upper, essentially cylindrically configured part 126 above the annular projection 92 and a lower, likewise essentially cylindrically configured part 128 aligned therewith below the annular projection 92. The upper portion 126 includes an auxiliary filter 130. The auxiliary filter 130 filters backwash water in a backwash state. The lower portion 128 includes the actual fine filter 66. The fine filter 66 filters water in an operating state.

The upper portion 126 is provided with a thickened rim 134 above the secondary filter 130. The thickened rim 134 is provided with an externally encircling annular groove, in which a seal 136 is arranged. By means of the thickened edge 134, the filter body 68 is guided displaceably in the axial direction in the lower region 78 of the lower part 76 of the filter sleeve. An opening 138 is provided in the intermediate bottom 81, which opening is delimited by a tubular channel 140 molded onto the intermediate bottom 81.

A part of the channel 140 projects above the intermediate floor 81 into the interior space of the lower part 76 of the filter sleeve. A water guide element 142 is plugged onto the annular projection of the channel 140 formed in this way. The water guide member 142 is substantially pot-shaped. In the bottom region, the water guide element 142 has an opening. The opening is defined by a downwardly projecting annular projection 144. The water guide element rests with an annular projection 144 on the annular projection of the channel 140. Thereby guiding the water flowing upward through the passage 140 near the axis into the inner space of the water guide member 142.

In the lower part 76 of the filter sleeve, the hollow fiber membranes 70 are arranged. These hollow fiber membranes 70 are generally known. The ends of the hollow fibers are secured to plates 146, respectively. The hollow fiber membranes 70 thereby project somewhat U-shaped down into the water guide elements 142. The water-conducting element 142 surrounds with its side walls only the lower region of the hollow fiber membrane 70.

Carbon filter 72 is located on base plate 146. Activated carbon filter 72 is comprised of sintered activated carbon and is known in the art as a filter element known by the name "EPS".

The filter assembly 10 is shown in an operational state in fig. 1. The inlet side ball valve 18 is opened. The discharge-side ball valve 58 is closed. Water flows from the inlet 14 through the ball valve in the direction of arrow 150 to the inlet passage 88. Water flows from inlet passage 88 externally through filter sleeve 74 into an outer annular space 90. There, the water flows downward in the direction of arrow 152 and into a region 154 above shoulder 40.

In the operating state, the filter body 68 is pressed by the spring 98 into an upper position in which the annular projection 92 rests against the lower edge of the lower part 76 of the filter sleeve. Thus, water may flow downwardly through annular projection 92 and shoulder 40. This is shown by arrow 158. The outer annular space 90 is defined downwardly by a ring 160 with a seal. The ring 160 bears on the inside against the filter body 68 and against the base 96, which is likewise provided with a seal in this region.

The water thus cannot continue to flow downwardly and flows inwardly through the fine filter 66 in the direction of arrow 158. There, coarse dirt particles are trapped in the first filter stage. In the inner space of the fine filter 66, the water flows externally past the impeller upwards via the channel 140 into the inner space of the water guide element 142. This is illustrated by

arrows

160 and 162. The hollow fiber membranes project into the water guide elements 142.

The water now flows from the outside into the hollow fiber membrane. The ultrasonic filtration is carried out here according to the second filtration stage. Germs and fine dirt particles in the range of a few micrometers which have passed through the fine filter screen adhere externally to the hollow fiber-membrane. At the upper end, the water flows out of the hollow fiber membrane. The water then flows through the activated carbon filter, which is embodied in the present exemplary embodiment as a block. This is illustrated in fig. 1 by arrow 164. It goes without saying that, depending on the filtering task and application, instead of lumps, pellets or other filter materials can also be used in the third filter stage. At the upper end, the water flows through the outlet passage 82 to the outlet 16 where it is subjected to three stages of filtration for subsequent use.

Over time, the fine filter 66 becomes clogged. On the hollow fiber membrane, trapped pathogens also grow undesirably. This deteriorates the filtering effect with time. The service life is limited. The fine filter 66 primarily traps relatively large particles of a size above, for example, 30 to 50 microns, and it can be cleaned by backwashing. With the present assembly, the hollow fiber-membranes can also be flushed to extend their service life. In this case, the water flow is guided through the region around the hollow fiber membranes 70 in the following manner. This water flow carries away the slime and microbial residues on the outer side of the hollow fiber membrane 70. The hollow fiber membranes 70 thus washed to some extent have a long service life without having to be replaced so frequently.

Transition positions of fig. 6 and 8

For backwashing, the ball valve 58 is opened. Thereby creating a pressure differential. The water flows downward through the drain 56. Here, the filter body 68 and the bottom 96 are moved downward against the spring force of the spring 98. Before reaching the backflushing position, the filter body 68 occupies the transition position shown in fig. 6 and 8 for a short transition period.

As the filter body 68 moves downward, the annular projection 92 also moves downward. The lower free edge of the region 78 with the smaller diameter no longer bears against the annular projection 92 in the transitional position. Water may flow inwardly from the outer annular space 90 in the direction of arrow 166 (fig. 6). Where it passes through an auxiliary filter 130. Where the water is cleaned of larger particles.

In the region of the auxiliary filter 130, the filter body 68 forms a cylindrical inner wall section 168. The inner wall portion 168 abuts against the wall of the channel 140. The water thus cannot continue to flow inwardly but rather flows upwardly outside of the inner wall portion 168. This is shown by arrow 166. The water enters the lower sleeve 76 via openings in the bottom 81 and flows upwards on the outside past the water guiding element 142. This is shown by arrow 170.

In the central region of the assembly, the water flows downwardly toward the drain 46. In this case, the water flows around the hollow body membrane 70 and entrains the biofilm, the microbial growth and, if necessary, the particles. The water flows downwardly through the channel 140 in the direction of arrow 72. The water then flows through the impeller 122 in the direction of arrow 174. Below the impeller 122, the water enters a bottom region 180 of the filter element 68 in the direction of arrow 178. In the transition position, the bottom region 180 of the filter element 68 is connected to the bottom region 182 of the filter cup 30 via the recess 106 in the guide rib 100 for a short transition period. The water may thus flush the hollow fiber-membranes 70 for this brief period of time and flow along the recesses 106 to the drain 46. This is again shown in detail in fig. 8.

It can be seen that the bottom 96 rests against the guide rib 100 below the recess 106 when moved further downward. The connection between these areas is then interrupted again.

Backwash position of figure 7

Figure 7 shows the backwash position of the assembly. This is the lower end position of the filter body 68. In this position, the annular projection 92 rests on the shoulder 40 and blocks the connection between the annular space 90 and the region around the fine filter 66. The connection between the annular space 90 and the area around the auxiliary filter 130 is now open.

The filter element 68 with the seal 184 thereon, the lower edge of which is now below the ring 160. A gap 186 is formed between the outer wall of the filter element 68 and the ring 160 in the backwash position, as shown in fig. 7.

Water flowing into the outer annular space 90 from the inlet now flows in the direction of arrow 188 in fig. 7 to the auxiliary filter 130. The water is then coarsely filtered in the auxiliary filter and flows upwards in the direction of arrow 190 just as at the transition point. The water further flows in the direction of arrow 192 through water directing element 142 to hollow fiber-membrane 70. From the hollow fiber membranes 70, the water flows downward through the channels 140 in the direction of arrows 194. In the back flush position, the connection to the area outside of the impeller 122 is closed. All of the water now flows into the impeller 122. This is shown by arrow 196.

The water is forced through the nozzle of the impeller 122. In this case high flow velocities are generated. The jets so generated are directed in opposite directions through a fine screen 66. In which case the particles are entrained. The fine screen 66 is backwashed. The nozzles are at an angle to the fine screen 66. The impeller 122 is thereby pulsed and rotated. In this way the entire angular area of the fine screen is backwashed.

Behind the fine screen 66, the water flows through the gap 186 past the ring 160 down to the drain 46. This is shown by arrow 198.

With the assembly shown, not only is the fine screen 66 back flushed, but also unwanted material is flushed from the surface of the hollow fiber-membrane 70. In this way, the service life of the filter material can be significantly increased.

The filter material together with the

filter sleeves

74, 76 can be easily removed from the filter cup for replacement, maintenance or cleaning.

FIG. 11 shows an automated version of the assembly. Here, the blocking element on the inlet side is not actuated manually, but rather by means of a control element by means of the motor 200. In the outlet 16 a turbine is arranged. Magnets are fixed to the turbine 202. The reed contact 204 gets pulsed each time the magnet passes the rotating turbine. From these pulses, the control and evaluation unit on the motor 200 determines the volume that has flowed through the assembly. When a predetermined amount of water has flowed through the assembly, the ball valve 18 is closed by the control member using the motor 200. The filter may then be backwashed as described above.

Claims

1. A potable water filter, comprising:

(a) a connection fitting with an inlet and an outlet for mounting directly in front of a water receiving point;

(b) a filter cup disposed on the attachment;

(c) at least two successively connected filter stages of filter material, which are arranged in the filter cup in the flow path between the inlet and the outlet, wherein one of the filter stages is formed by an activated carbon filter,

it is characterized in that the preparation method is characterized in that,

(d) the lower end of the filter cup is provided with a discharge part; and is

(e) At least one of the filter stages is designed as a backflushing filter stage which can be switched from an operating position, in which water is conducted from the inlet through all the filter stages to the outlet, into a backflushing position, in which water can be conducted from the inlet in the opposite direction through the backflushing filter stage to the open outlet.

2. The drinking water filter according to claim 1, wherein the inlet-side filter stage is formed by a screen which can be backwashed.

3. The drinking water filter according to claim 1, wherein the filter stage with the activated carbon filter is placed after the other filter stages.

4. The drinking water filter according to claim 1, wherein the intermediate filtration stage is formed by a hollow fiber membrane filter, a micro-membrane filter or another membrane filter.

5. Drinking water filter according to claim 1,

6. The drinking water filter according to claim 5, wherein the auxiliary filter is arranged in a cylindrical sleeve which cooperates with an annular projection which is formed externally on the filter element between the main filter and the auxiliary filter, and which sleeve, in the operating position, blocks the transition between the annular space and the region between the auxiliary filter and the sleeve and, when the filter element is moved into the lower position, opens.

7. The drinking water filter according to claim 5, wherein the means for separating the annular space are formed by an annular projection which is formed externally on the filter element and which interacts with an inwardly projecting annular shoulder of the filter cup and separates the annular space in a backflush position in which the filter element is in the lower end position.

8. Drinking water filter according to claim 5,

(a) the filter element has a bottom;

(b) a guide rib fixed to the housing for guiding the bottom is provided, which extends through the bottom of the filter element, so that the bottom is closed by the guide rib in an upper operating position and a lower backwashing position; and is

(c) The guide rib has a constriction between an upper end and a lower end, so that when the filter element is moved between the operating position and the backflushing position, a passage is formed in the region of the constriction in transition, through which backflushing water flows from the filter cup to the drain.

9. The drinking water filter according to claim 5, characterized by an impeller inside the filter element, which is rotatable about the longitudinal axis of the filter element, by means of which impeller in the backflush position water can be conducted through a reduced angular range of the main filter from the inside outwards.

10. The drinking water filter according to claim 1, wherein the filter stage comprises activated carbon and a membrane filter arranged in a filter sleeve, which is arranged cylindrically in the filter cup.

11. The drinking water filter according to claim 10, wherein the membrane filter is arranged in a pot-shaped water guide element which guides the backwash flow or the transitional flushing flow at least partially through the filter region with the membrane filter and to the open drain.

12. Drinking water filter according to claim 1,

(a) a blocking member which is operated by a motor is arranged in the inlet;

(b) a mechanism for measuring flow is arranged in the outlet; and is

(c) An evaluation and control unit is provided which is supplied with the signal of the flow measuring means and which closes the blocking element when a selected flow volume flows through the drinking water filter.