DE102014015942A1 - Coalescing element and filter element with a coalescing element - Google Patents

Abstract

The invention relates to a coalescing element (30) of a disperse phase separation device comprising a continuous phase of a fluid, in particular water from fuel in a fuel filter, comprising at least one coalescing medium (32) provided for coalescing the disperse phase contained in the fluid in that a fluid path (40) for the fluid is arranged between an inlet side (53) and an outlet side (51) through the coalescence medium (32). Furthermore, the coalescing element (30) comprises at least one hydrodynamic focusing element (34), which is provided for the flow optimization of the fluid flow and is arranged in the flow direction (41) in front of the coalescing medium (32). In this case, the fluid flow focusing element (34) has first regions (36) and second regions (38) which have different fluid flow permeabilities, the permeability of the second regions (38) being at most half that of the first Areas (36). The invention further relates to a filter element (10) with such a coalescing element (30), a filter system (100) with such a filter element (10) and the use of the filter element for filtering fuel, in particular diesel fuel.

Description

Technical area

The invention relates to a coalescence element and to a filter element having a coalescing element for separating a disperse phase from a continuous phase of a fluid and to a filter system having a filter element, in particular for separating water from fuel in a fuel filter of a motor vehicle.

State of the art

From the DE 10 2011 120 638 A1 is a filter element for filtering a fluid, for. As fuel, known, which is suitable for removing contaminants such as water from fuel. The filter element is realized in a kind of sandwich construction. In this case, a multi-layer coalescing medium is embedded between the filter medium and a support tube, wherein the coalescing medium consists of one or more formlabile materials, which is embedded in a dimensionally stable manner between the filter medium and the support tube and connected at one end face tightly with the end body. With formlabile materials coalescing media can be realized, which are optimized in terms of their Koaleszenzeffizienz and / or their flow through. Formlabile materials can be easily adapted to different installation spaces even during final assembly. In this case, form-labile means that the own dimensional stability and / or inherent rigidity of the coalescing medium is insufficient to ensure that the coalescing medium bonds to the end body when it is solely connected, ie without the aid of the sandwich construction described, in particular by pressing into a corresponding soft, later hardening Connection medium, such as adhesive or melted surface material of the end body, bends or kinked, whereby the stability and / or the tightness of the connection can be impaired. The support tube and the filter medium ensure the dimensional stability of the entire composite. The layers of the coalescing medium may consist of a single or of different materials. The coalescing medium and the filter medium may be made of different materials.

Disclosure of the invention

An object of the invention is to form a coalescing element for depositing a disperse phase from a continuous phase of a fluid such that the coalescing element is compact and simple, thereby further improving the separation of the disperse phase from the continuous phase of the fluid.

Other objects of the invention are to provide a filter element with a coalescing element for separating a disperse phase from a fluid and a filter system for receiving such a replaceable filter element with a coalescing element, which is compact and simple and wherein the deposition of the disperse phase of the continuous phase of the fluid is further improved.

The above object is achieved according to one aspect of the invention in a coalescing element of a separating device of a disperse phase from a continuous phase of a fluid, in particular water from fuel in a fuel filter, characterized in that the coalescing at least one coalescing, which coalescence in the fluid contained disperse phase is provided, and at least one hydrodynamic focusing element comprises, which is provided for the flow optimization of the fluid flow and is arranged in the flow direction in front of the coalescer.

Favorable embodiments and advantages of the invention will become apparent from the other claims, the description and the drawings.

A coalescing element of a disperse phase separation device comprising a continuous phase of a fluid, in particular of water from fuel in a fuel filter, is proposed which comprises at least one coalescing medium which is provided for coalescing the disperse phase contained in the fluid, wherein a fluid path for the fluid is arranged between an inlet side and an outlet side through the coalescing medium. Furthermore, the coalescing element comprises at least one hydrodynamic focusing element, which is provided for the flow optimization of the fluid flow and is arranged in the flow direction in front of the coalescence medium. In this case, the focussing element for the fluid flow has first regions and second regions which have different permeabilities to the fluid flow, the permeability of the second regions being at most half as great as that of the first regions. In particular, the permeability of the second regions may be zero when the second regions comprise the material, such as metal, plastic, of which the focusing element is constructed. For this purpose, the first regions may in particular comprise apertures in the material, such as holes, slots or similar structures. Also, the focusing element may be constructed of a fabric, in which case the first regions are the open apertures in the fabric, and the second regions are the impermeable structure of the fabric.

The coalescing element is designed to coalesce the majority of the disperse phase in the fluid, that is, the droplet size of the disperse phase following that of a water-diesel fuel mixture DIN ISO 16332 (as of: 2009) is on the order of 10 microns to 150 microns, to increase, and to separate the thus coalesced water from the fuel. The water, which is heavier than fuel, can settle to the bottom and drain through suitable passages. Also, the water drops can be crushed in subsequent pumps.

The coalescing medium used may be customary media, such as nonwovens or cellulosic media, which may be in wound or pleated form.

The coalescence element according to the invention has measures for the optimization of coalescence-based liquid-liquid filters, which are based on the multistage principle of droplet coalescence (increase in droplet size due to coalescence) and the subsequent droplet deposition due to density differences. The main coalescing stage for enlarging the droplets consists of one or more coalescing media layers, which in pleated or wound form represent a coalescing bellows.

Usually, coalescing media layers are flowed through without any further upstream or downstream measures for optimization. The coalescing power is based on collision processes of drops that are delayed by the coalescing medium. In certain cases, and especially in coalescing media with a high proportion of pores, accumulations of the disperse phase in the coalescing medium occur. In combination with certain flow conditions, the so-called "Graping" effect is favored. The term "graping" generally refers to agglomeration, including the agglomeration of drops-in-drops, that is to say fluid which is enveloped by a shell of the disperse phase, which leads to a drastic deterioration of the separation efficiency.

The focusing element, which comprises the coalescing element, generates a hydrodynamic focusing. In the case of an accumulation of disperse phase in the coalescence medium, the release condition for the formation of droplets of the disperse phase from the fluid is thereby achieved earlier, and thus the "graping" effect and the formation of further droplet-in-droplet agglomerates are prevented or at least minimized , Another effect that optimizes the coalescence performance is the higher entrance velocity of the disperse phase. As a result, the coalescence probability is drastically increased in the case of drop contacts. In the second regions, which are covered by the geometry or at least have a lower permeability for the fluid to be filtered, the inflowing phase is retarded rapidly. There are high velocity gradients of the fluid, which in addition favors the impact processes of the droplets of the disperse phase. For example, a speed increase to twice the normal fluid flow rate can be achieved.

An advantage of the coalescing element according to the invention is the merging of the disperse phase by reducing the inflow surface and thereby also an improved deposition with a small proportion of the disperse phase in the fluid.

The focusing element may be in flexible or rigid form and / or porous. In the simplest case, it is a film whose porosity is ensured by holes. The number, size and shape of the holes is variable. For example, a distance between the holes of 5-7 mm with a hole diameter of about 5 mm may be favorable. The thickness of the film or sheet may be, for example, 0.3 mm. For example, the region of lesser permeability may be between 20% and 90% of the total inflow area of the focussing element. The free surface achieves hydrodynamic focusing, which increases the coalescing power as a function of the overall system. The second regions with lower permeability, a spatial separation between a particle and the coalescing medium is achieved, which also contributes to performance improvement.

According to an advantageous embodiment, the focusing element can rest force-free on the coalescing medium. In this way, a support of the coalescing medium is achieved, which may be formed, for example, as a nonwoven or sponge-like and thus has a certain shape lability. If the focusing element is made rigid, for example with a foil or a metal sheet, then the coalescence medium can be supported without it lying against a filter bellows or a housing. The coalescing medium is protected against compression by a particle filter medium. As a result, the coalescence of the disperse phase to be deposited can be favorably improved.

According to an advantageous embodiment, the coalescing medium can be arranged according to the intended direction in the flow direction after a particle filter medium. Since the fluid first flows through the particle filter medium and only then through the coalescing medium, the particle filter medium can remove any dirt particles from the fluid filter out, so that thereby the risk that the coalescing medium is added by these dirt particles, can be reduced.

According to an advantageous embodiment, a spatial distance between the coalescer and the particulate filter medium may be provided. Since pre-coalescence generally takes place on or in a first filter stage when the coalescing element is used as intended in a filter element, such as a particulate filter medium, a spatial separation between particle filter and coalescing medium is favorable for coalescence in the main coalescence media layer. As a result of the spatial separation, drops can form until reaching the separation condition caused by the flow (due to a so-called Rayleigh plateau instability). In comparison, the contact between the particle filter and the coalescing medium leads to a structural change and thus to locally high flow velocities and to deflections of the flow direction which predominantly prevent the formation of large droplets. This is prevented by the coalescing element according to the invention. By specifically influencing the flow conditions and the spatial separation in multistage coalescence concepts by special geometries, the performance of coalescence-based liquid-liquid filter is thus further improved.

According to an advantageous embodiment, the focusing element can be integrated in a support tube. Preferably, the geometry of the focusing element, for example in the form of a perforated plate, can be integrated in a so-called center tube as a support tube of a filter element. This is particularly conceivable if the support tube is made as usual as a plastic injection-molded part and the focusing element is injected with. A support tube usually has large recesses between stable support areas. Advantageously, the focusing element can cover usual recesses of the central tube.

According to an advantageous embodiment, the coalescing medium for the purpose of separating droplets of the disperse phase can be intended to interact with a final separator arranged on its outlet side, which is formed from a hydrophobic material. A hydrophobic material has the advantage that the disperse phase is particularly easy to drain on the surface and is thus retained. Advantageously, the end separator can be screen-like as a separation medium. A sieve-like, in particular woven separation medium has the advantage that the droplets of the disperse phase are held on the screen fibers and in particular drip down, or, depending on the density difference of disperse and continuous phase, can rise to the top. On a sieve-like separation medium, the disperse phase can be optimally retained. The mesh openings of a sieve-like fabric can be defined in a simple and defined manner. It can be optimally permeable to the fuel. With a sieve-like structure, it is easy to minimize the pressure loss on the separation medium.

According to an advantageous embodiment, a sedimentation gap can be provided between the coalescing medium and the final separator. Advantageously, the end separator can limit the sedimentation gap on the side opposite the coalescing medium. The droplets of the disperse phase combined with the coalescing medium can be precipitated in the flow path of the fluid behind the coalescence medium in the sedimentation gap. They can fall down or rise up depending on the specific weight of the fluid.

In the coalescing medium, the droplets of the disperse phase are enlarged during the passage through the coalescing element. In the sedimentation gap between the coalescing element and the final separator, droplets are collected under gravity in a collecting space of a filter system, from where the coalesced, formerly disperse phase can be drained off, for example via a screw during service.

Smaller drops, which were not initially separated due to gravity, are prevented from passing through the hydrophobic surface of the end separator on the clean side and are then also deposited in the collecting space.

According to an advantageous embodiment, the focusing element may be formed from a sheet metal, in particular from a perforated plate. The sheet may for example be galvanized to be protected from corrosion. The number, size and shape of the holes is variable. The design as a metal sheet is particularly favorable, since such a filter bellows and / or the coalescing medium, which are possibly designed to be dimensionally stable, can be supported against the flow pressure. Other geometries for the design of the hydrodynamic focusing element are conceivable, such as grid, fabric, slots, which can lead to a partial covering or blocking the Gesamtanströmfläche.

According to an advantageous embodiment, the focusing element may be formed from a plastic film, in particular from a polyamide (PA) film or a polyethylene (PE) film. The polyamide film may, for example be laser sintered. Also, a design as a laminated and / or stamped film may be favorable, since the focusing element can be manufactured as cost-effective and flexible in various forms and with a varying distribution of first and second regions with different permeability. This also makes it possible to save weight of the coalescing element.

According to an advantageous embodiment, the focusing element may be formed of cellulose. The cellulose medium may additionally be advantageously impregnated with a binder in order to achieve an impregnating effect. Even so, a cost-effective and very flexible design of the focusing element is possible.

According to an advantageous embodiment, the first regions of the focusing element may comprise between 20% and 90%, preferably between 30% and 80%, of a total inflow surface through the fluid. By such a distribution of first and second regions with different permeability to the fluid and the phase dispersed therein, particularly favorable values of velocity gradients can be achieved in the hydrodynamic focusing, so that the coalescence performance can be further improved. Particularly advantageously, the first regions can be distributed over the total inflow surface. In particular, the first regions can be distributed homogeneously over the total inflow surface.

According to an advantageous embodiment, the coalescing medium can be designed as a hollow body, in particular as a hollow cylinder. In this way, the use in the interior of a filter element, which is often carried out in a hollow cylindrical shape, can be represented very cheaply. Especially in the liquid filter area round filter shapes are very common, since they can be used in terms of flow and space moderately low.

According to a further aspect, the invention relates to a filter element for filtering a fluid, having a fluid path between a raw side and a clean side, with at least one coalescence element according to the invention as described above.

According to an advantageous embodiment, for filtering a fluid having a fluid path between a raw side and a clean side, the filter element may comprise at least one filter bellows, which is preferably formed from a particulate filter medium, and a support tube arranged inside the filter bellows. Furthermore, the filter element may comprise at least one end separator arranged in the flow direction downstream of the filter bellows, which has passages for flowing through the fluid, and at least one coalescing element which comprises at least one coalescing medium and at least one focusing element in the flow direction in front of the coalescing medium. In this case, the coalescence element is arranged in the flow direction between the filter bellows and the final separator and provided for coalescence of the disperse phase contained in the fluid. Furthermore, a spatial distance can be provided between the filter bellows and the coalescing element, and a sedimentation gap can be provided between the coalescing element and the final separator.

According to an advantageous embodiment, the focusing element may rest against the filter bellows, in particular bear force-free. In this way, the focusing element can support the filter bellows against the flow pressure of the fluid to be filtered and prevent the filter bellows from contacting the coalescing medium. The free space between the filter bellows and the coalescence medium further improves the coalescence performance.

According to an advantageous embodiment, the focusing element may be integrated in the support tube; Preferably, the geometry of the focusing element, for example in the form of a perforated plate, be integrated into a so-called center tube as a support tube. This is particularly conceivable when the support tube is made as usual as a plastic injection molded part.

Further advantageous is a possible separation of particle separation and coalescence. Touching the particulate filter and coalescing media often has a negative impact on coalescing performance, for example, by simple contact. It is also advantageous that a pressure, especially after loading, of the particle filter medium on the coalescing medium is prevented. In addition, the coalescence medium can develop because it is not suppressed in its extent.

According to an advantageous embodiment, the filter bellows and / or the coalescing element can be hollow-cylindrical, with the fluid path leading radially through the filter bellows and the coalescing element, in particular leading from an outside area into an interior area of the hollow cylindrical shape. Such a hollow cylindrical shape is favorable to use the filter element in a round filter system, as they are often used in the automotive sector, especially in commercial vehicles. Advantageously, the first fluid path can lead radially from an outer region into an inner region into the filter element. This arrangement allows an inflow, for example, of fuel from the outside over the circumference of the filter element by the example star-folded filter medium of the filter body. The fuel can then the filter element after flow through the inside and be discharged via the inner region of the filter element in the fuel supply of an internal combustion engine.

According to an advantageous embodiment of the filter bellows, the coalescer, and the Endabscheider can be arranged coaxially within the filter element, and the Koaleszenzmedium and the focusing element within the Koaleszenzelements be arranged coaxially. This coaxial arrangement is favorable in terms of space in an embodiment of the filter element as a hollow cylinder.

According to a further aspect, the invention relates to a filter system having a filter element which is exchangeably arranged in a filter housing for filtering a fluid, wherein the filter element has at least one hollow-cylindrical filter bellows. At least one end separator is arranged inside the filter bellows. Further, a coalescing element is arranged in the flow direction between the filter bellows and the end separator. In this case, the coalescing element comprises at least one coalescing medium, as well as at least one focusing element in the flow direction in front of the coalescence medium, the coalescing element being arranged in the flow direction between the filter bellows and the final separator.

According to an advantageous embodiment, the filter system for filtering a fluid can be equipped with a filter element arranged exchangeably in a filter housing, the filter element providing on its clean side a coalescing element for coalescing a disperse phase contained in the fluid.

According to an advantageous embodiment, the filter system may be equipped with a filter element, wherein the filter element has a hollow cylindrical filter bellows with an arranged inside the filter bellows end. In this case, a coalescing element can be arranged in the flow direction between the filter bellows and the end separator, and the coalescing element can comprise at least one coalescing medium and at least one focusing element in the flow direction in front of the coalescing medium, wherein the coalescing element can be arranged in the flow direction between the filter bellows and the final separator.

It is advantageous to use the filter system for filtering fuel, in particular diesel fuel, in particular an internal combustion engine, and in particular a motor vehicle. Alternatively, the use of such a configuration for other liquid fluids that need to be filtered and contain a dispersed phase is conceivable. Of course, such filter systems for other liquid fluids usually coalescing provide, so that the use of the proposed coalescing element is also conceivable when filtering other fluids.

Brief description of the drawings

Further advantages emerge from the following description of the drawing. In the drawings, embodiments of the invention are shown. The drawings, the description and the claims contain numerous features in combination. The person skilled in the art will expediently also consider the features individually and combine them into meaningful further combinations.

They show by way of example:

1 a longitudinal section through a filter element according to an embodiment of the invention with a single-layer coalescer and a Endabscheider for fuel filtration in a motor vehicle;

2 a longitudinal section through a filter element according to another embodiment of the invention with a single-layer coalescing and a Endabscheider for fuel filtration in a motor vehicle;

3 a partial section through the filter element after 2 ;

4 a longitudinal section through a filter system according to an embodiment of the invention with a filter element with a single-layer coalescer and a Endabscheider;

5 a schematic diagram of a focusing element according to an embodiment of the invention to illustrate the operation of the hydrodynamic focusing; and

6 a schematic diagram of a focusing element according to an embodiment of the invention for illustrating the operation of the detachment of a drop of a disperse phase due to a plateau Rayleigh instability, driven by the capillary force of the droplet of the disperse phase.

Embodiments of the invention

In the figures, the same or similar components are numbered with the same reference numerals. The figures are merely examples and are not intended to be limiting.

The invention is illustrated with reference to a fuel filter for filtering fuel, in particular diesel fuel, but may also be provided for other filter systems with appropriate adaptation of the construction.

1 shows a longitudinal section through a filter element 10 according to an embodiment of the invention for fuel filtration in a motor vehicle with a single-layer coalescing element 30 as well as an end separator 106 , The filter element 10 for filtering a fluid, having a fluid path 40 between a raw page 52 and a clean side 50 , includes a filter bellows 12 which preferably consists of a particulate filter medium 14 is formed, one in the flow direction 41 after the filter bellows 12 arranged Endabscheider 106 which passages 20 for flowing through the fluid, as well as a coalescing element 30 as a separating device of a disperse phase of a continuous phase of the fluid, for example water from a fuel, for. B. diesel fuel. The coalescing element 30 which is provided for coalescing the disperse phase contained in the fluid comprises a coalescing medium 32 , as well as a focusing element 34 in the flow direction 41 in front of the coalescence medium 32 where the coalescing element 30 in the flow direction 41 between the filter bellows 12 and the final separator 106 is arranged and is provided for coalescence of the disperse phase contained in the fluid. Between the filter bellows 12 and the coalescing element 30 is a spatial distance 16 intended. Between the coalescing element 30 and the final separator 106 is still a sedimentation gap 18 intended. The focusing element 34 , which is provided for the flow optimization of the fluid flow and in the flow direction 41 in front of the coalescence medium 32 is arranged, has first areas for the fluid flow 36 and second areas 38 which have different fluid flow permeabilities from each other, the permeability of the second regions 38 at most half the size of the first areas 36 , In particular, the permeability of the second regions 38 be zero when the second areas 38 the material such as metal, plastic include, from which the focusing element 34 is constructed. This can be the first areas 36 In particular, breakthroughs in the material such as holes, slots or similar structures include. Also, the focusing element 34 be constructed of a fabric, in which case the first areas 36 the open breakthroughs are in the tissue, and the second areas 38 the impermeable structure of the fabric.

The focusing element 34 lies as a thin sheet or thin film on Koaleszenzmedium 32 force-free. Alternatively, the focusing element could 34 also on the filter bellows 12 abutment, in particular force-free. Another possibility is that the focusing element 34 of coalescing medium 32 and filter bellows 12 spaced apart.

In the filter element 10 to 1 is between the filter bellows 12 and the coalescing medium 32 a support tube 22 arranged. It is between the support tube 22 and the focusing element 34 located on the outside of the coalescing medium 32 attached, a gap 16 formed, the flow dynamics favorable to the effect of the focusing element 34 contributes.

Alternatively to the in 1 illustrated embodiment is also conceivable that the focusing element 34 in the support tube 22 is integrated. Especially in the design as a thin perforated plate or thin plastic film is an integration into the support tube 22 , which is usually manufactured as an injection molded part, advantageous. Also, the geometry of the focusing element could be 34 in the form of a perforated plate or as a slotted sheet directly in the plastic material of the support tube 22 be educated.

The coalescing medium 32 is in the flow direction 41 after the particulate filter medium 14 arranged. The coalescing medium 32 for the deposition of droplets of the disperse phase acts with the on its exit side 51 arranged Endabscheider 106 together, which is formed of a hydrophobic material.

The focusing element 34 For example, it can be formed from a metal sheet, in particular from a perforated metal sheet, from a plastic film, for example a PA or PE film, or from cellulose. The focusing element 34 can advantageously be a first area 36 between 20% and 90% of a total inflow area through the fluid. Alternatively, embodiments of the focusing element 34 in the form of a grid, a fabric, or slits conceivable.

The filter element 10 is executed in hollow cylindrical form. The filter bellows 12 and the coalescing element 30 are designed as a hollow cylinder, wherein the fluid path 40 radially through the filter bellows 12 and the coalescing element 30 leads, especially from an outdoor area 42 in an interior area 44 the hollow cylindrical shape leads. The filter bellows 12 , the coalescing element 30 , and the final separator 106 are coaxially disposed within the filter element, and the coalescing medium 32 and the focusing element 34 are inside the coalescing element 30 arranged coaxially.

In 2 is a longitudinal section through a filter element 10 according to a further embodiment of the invention with a single layer coalescing 30 as well as an end separator 106 shown for the fuel filter in a motor vehicle. The arrangement of the individual components is similar to that in 1 shown filter element 10 , However, lies in 2 the coalescing medium 32 with the focusing element attached to the outside 34 , which is formed in this embodiment as a thin perforated plate, on the inside of the filter bellows 12 also in this embodiment from the outside with the fluid along the flow path 40 in the flow direction 41 is flowed through. Because in this case no support tube 22 , as in 1 , between filter bellows 12 and coalescing medium 32 is arranged, is also no gap 16 between filter bellows 12 and coalescing medium 32 educated. The sedimentation gap 18 between coalescing medium 32 and final separator 106 is like in 1 educated.

3 shows a partial section through the filter element 10 to 2 , In this case, the hollow cylindrical configuration of the filter element 10 clearly visible. As outer hollow cylinder is the filter bellows 12 shown from the outside with the fluid along the flow path 40 in the flow direction 41 is flowed through. On its inside lies the focusing element 34 designed as a thin perforated plate. In the flow direction 41 then becomes the coalescing medium 32 flows through, directly to the focusing element 34 follows. In the deeper sedimentation gap 18 is the disperse phase, in the embodiment of fuel separated water, as a drop due to gravity and favored by the hydrophobic effect of the further inside the Endabscheiders 106 sink down and collected. focusing element 34 , Coalescence medium 32 , Final separator 106 are hollow cylindrical.

In 4 is a longitudinal section through a filter system 100 according to an embodiment of the invention with a filter element 10 with a single-layer coalescing element 30 as well as an end separator 106 shown.

The filter system 100 has a in a filter housing 108 arranged filter element 10 for filtering a fluid, wherein the filter element 10 on his clean side 50 a coalescing element 30 for coalescing a disperse phase contained in the fluid. The filter element 10 is a round filter element in a round filter housing 108 , which consists of an upper housing part 112 and a housing lower part 114 exists, used. The filter element 10 sits centrally in the housing 108 and comes with two end discs 15 . 17 in the filter housing 108 braced. Inside the filter element 10 is on a clean side 50 an end separator 106 arranged, which the entire fluid path 40 covering, since the Endabscheider 106 on both ends over the filter element 10 protrudes and with the upper housing part 112 and the lower housing part 114 is connected fluid-tight. In the filter housing 108 is fed from the outside via an inlet, not shown fluid, which from a radial outer side of the filter element 10 penetrates and over the filter bellows 12 , the coalescing element 30 as well as the final separator 106 in an inner area of the filter housing 108 can get. Through this interior, the filtered fluid is via an outlet 104 discharged again. The filter system 100 can with this outlet 104 via a screw thread 110 be screwed onto a connecting piece.

The filter system comprises a filter element 10 , which is a hollow cylindrical filter bellows 12 with one inside the filter bellows 12 arranged Endabscheider 106 wherein the coalescing element 30 in the flow direction between the filter bellows 12 and the final separator 106 is arranged. In this case, the coalescing element comprises 30 a coalescing medium 32 and a focusing element 34 in the flow direction in front of the coalescing medium 32 where the coalescing element 30 in the flow direction between the filter bellows 12 and final separator 106 is arranged.

The disperse phase in the fluid is largely through the filter bellows 12 directed. In the coalescing medium 32 become the droplets of the disperse phase during the passage through the coalescer 30 increased. In the gap 18 between the coalescing element 30 and the final separator 106 The drops are gravity assisted in a collection room 60 collected from the filter system, from where the coalesced, formerly disperse phase can be drained, for example via a screw during service to the outside.

Smaller drops, which were not separated by gravity, become attached to the hydrophobic surface of the end separator 106 on the passage to the clean side 50 prevented and are then also deposited in the collection room.

The filter system 100 is preferably used for filtering fuel, in particular diesel fuel, in particular an internal combustion engine, and in particular a motor vehicle.

5 shows a schematic diagram of a focusing element 34 according to an embodiment of the invention to illustrate the operation of the hydrodynamic focusing. The inflowing fluid in the flow direction 41 meets the focusing element 34 which is a first area 36 , which is permeable to the fluid, and a second area 38 that is responsible for the fluid not permeable. In simple form, the focusing element 34 be represented by a perforated plate. The first area 36 is then formed by holes in the sheet, the second area 38 is then the area between the holes, so the non-perforated plate itself. The fluid flows to the perforated plate at a flow velocity v ₀ and can only flow through the holes. In this case, a velocity distribution of the fluid flow is formed as in the enlarged view of the perforated plate in 4 indicated schematically. The velocity v _{1 of} the part of the fluid flow which passes centrally through a hole is substantially greater than the velocity v _{n of} the fluid flow in the edge region of the hole. It forms an increased velocity gradient 84 the fluid flow, which can lead to a doubling of the velocity v _{1 of} the fluid flow in the central region with respect to the velocity v _{0 of} the inflowing fluid.

6 shows a further schematic diagram of a focusing element 34 according to an embodiment of the invention to illustrate the operation of the detachment of a drop 82 the disperse phase due to the so-called plateau Rayleigh instability, driven by the capillary force of the drop 82 , Due to the increased velocity gradient of the fluid flow in the central region of the hole in the sheet, more favorable separation conditions for the droplet form 82 the disperse phase, the more easily from the fluid drop 80 solve and thus in a coalescing medium 32 can be conveniently deposited.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102011120638 A1 [0002]

Cited non-patent literature

• DIN ISO 16332 (as of 2009) [0008]

Claims (23)

Coalescing element ( 30 ) a separation device of a disperse phase from a continuous phase of a fluid, in particular water from fuel in a fuel filter, comprising - at least one coalescence medium ( 32 ) provided for coalescing the disperse phase contained in the fluid, wherein a fluid path ( 40 ) for the fluid between an entrance side ( 53 ) and an exit side ( 51 ) through the coalescence medium ( 32 ), - at least one hydrodynamic focusing element ( 34 ), which is provided for the flow optimization of the fluid flow and in the flow direction ( 41 ) in front of the coalescing medium ( 32 ) is arranged, wherein the focusing element ( 34 ) for the fluid flow first areas ( 36 ) and second areas ( 38 ), which have mutually different fluid flow permeabilities, the permeability of the second regions ( 38 ) is at most half the size of the first areas ( 36 ). Coalescing element according to claim 1, wherein the focusing element ( 34 ) on the coalescing medium ( 32 ) rests force-free. Coalescing element according to claim 1 or 2, wherein the coalescing medium ( 32 ) as intended in the flow direction ( 41 ) after a particulate filter medium ( 14 ) is arranged. Coalescence element according to claim 3, wherein a spatial distance ( 16 ) between the coalescing medium ( 32 ) and the particulate filter medium ( 14 ) is provided. Coalescing element according to one of the preceding claims, wherein the focusing element ( 34 ) in a support tube ( 22 ) is integrated. Coalescing element according to one of the preceding claims, wherein the coalescing medium ( 32 ) for the deposition of droplets of the disperse phase as intended with one on its exit side ( 51 ) arranged end separator ( 106 ), which is formed of a hydrophobic material. Coalescing element according to claim 6, wherein between the coalescing medium ( 32 ) and the final separator ( 106 ) a sedimentation gap ( 18 ) is provided. Coalescing element according to one of the preceding claims, wherein the focusing element ( 34 ) is formed from a metal sheet, in particular from a perforated plate. Coalescing element according to one of claims 1 to 7, wherein the focusing element ( 34 ) is formed from a plastic film, in particular from a polyamide film or a polyethylene film. Coalescing element according to one of claims 1 to 7, wherein the focusing element ( 34 ) is formed from cellulose. Coalescing element according to one of the preceding claims, wherein the first regions ( 36 ) of the focusing element ( 34 ) comprise between 20% and 90% of a total inflow area through the fluid. Coalescing element according to claim 11, wherein the first regions ( 36 ) distributed over the Gesamtanströmfläche, in particular homogeneously distributed, are arranged. Coalescing element according to one of the preceding claims, wherein the coalescing medium ( 32 ) is designed as a hollow body, in particular as a hollow cylinder. Filter element ( 10 ) for filtering a fluid, having a fluid path ( 40 ) between a raw page ( 52 ) and a clean page ( 50 ), with at least one coalescing element ( 30 ) according to one of the preceding claims. Filter element according to claim 14, further comprising - at least one filter bellows ( 12 ), which preferably consists of a particulate filter medium ( 14 ), - one within the filter bellows ( 12 ) arranged support tube ( 22 ), - at least one in the flow direction ( 41 ) after the filter bellows ( 12 ) arranged end separator ( 106 ), which passages ( 20 ) for flowing through the fluid, the at least one coalescing element ( 30 ) containing at least one coalescing medium ( 32 ), as well as at least one hydrodynamic focusing element ( 34 ) in the flow direction ( 41 ) in front of the coalescing medium ( 32 ), wherein the coalescing element ( 30 ) in the flow direction ( 41 ) between the filter bellows ( 12 ) and the final separator ( 106 ) is arranged and is provided for coalescence of a disperse phase contained in the fluid, wherein between the filter bellows ( 12 ) and the coalescing element ( 30 ) a spatial distance ( 16 ) and between the coalescing element ( 30 ) and the final separator ( 106 ) a sedimentation gap ( 18 ) is provided. Filter element according to claim 14 or 15, wherein the focusing element ( 34 ) on the filter bellows ( 12 ) is applied, in particular force-free. Filter element according to one of claims 14 to 16, wherein the focusing element ( 34 ) in the support tube ( 22 ) is integrated. Filter element according to one of claims 14 to 17, wherein the filter bellows ( 12 ) and / or the coalescing element ( 30 ) are hollow cylindrical and wherein the fluid path ( 40 ) radially through the filter bellows ( 12 ) and the coalescing element ( 30 ), in particular from an outdoor area ( 42 ) into an interior area ( 44 ) leads the hollow cylindrical shape. Filter element according to one of claims 14 to 18, wherein the filter bellows ( 12 ), the coalescing element ( 30 ), and the final separator ( 106 ) are arranged coaxially within the filter element, and wherein the coalescence medium ( 32 ) and the focusing element ( 34 ) within the coalescing element ( 30 ) are arranged coaxially. Filter system ( 100 ) with a in a filter housing ( 108 ) interchangeable filter element ( 10 ) for filtering a fluid, wherein the filter element ( 10 ) at least one hollow cylindrical filter bellows ( 12 ), wherein within the filter bellows ( 12 ) at least one final separator ( 106 ), and wherein a coalescing element ( 30 ) in the flow direction ( 41 ) between the filter bellows ( 12 ) and the final separator ( 106 ), and wherein the coalescing element ( 30 ) at least one coalescence medium ( 32 ), as well as at least one hydrodynamic focusing element ( 34 ) in the flow direction ( 41 ) in front of the coalescing medium ( 32 ), wherein the coalescing element ( 30 ) in the flow direction ( 41 ) between the filter bellows ( 12 ) and the final separator ( 106 ) is arranged. Filter system with one in a filter housing ( 108 ) interchangeable filter element ( 10 ) according to one of claims 14 to 19 for filtering a fluid, wherein the filter element ( 10 ) on its clean side ( 50 ) a coalescing element ( 30 ) for coalescing a disperse phase contained in the fluid. Filter system according to claim 20, wherein the filter element ( 10 ) a hollow cylindrical filter bellows ( 12 ) with one inside the filter bellows ( 12 ) arranged end separator ( 106 ), wherein a coalescing element ( 30 ) in the flow direction ( 41 ) between the filter bellows ( 12 ) and the final separator ( 106 ), and wherein the coalescing element ( 30 ) at least one coalescence medium ( 32 ), as well as at least one hydrodynamic focusing element ( 34 ) in the flow direction ( 41 ) in front of the coalescing medium ( 32 ), wherein the coalescing element ( 30 ) in the flow direction ( 41 ) between the filter bellows ( 12 ) and the final separator ( 106 ) is arranged. Use of a filter system ( 100 ) according to one of claims 20 to 22 for filtering fuel, in particular diesel fuel, in particular an internal combustion engine, in particular of a motor vehicle.

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