WO2013083309A1

WO2013083309A1 - Fuel filter and fuel filter arrangement for filtering fuel

Info

Publication number: WO2013083309A1
Application number: PCT/EP2012/069165
Authority: WO
Inventors: Martin Veit; Klaus SCHWEMLEIN; Martin Klein
Original assignee: Mann+Hummel Gmbh
Priority date: 2011-12-09
Filing date: 2012-09-28
Publication date: 2013-06-13
Also published as: DE112012005158A5; DE102011120643A1

Abstract

The invention relates to a fuel filter (4) for filtering fuel, comprising a filter element (28), in particular one shaped like a bellows, for precipitating particles from the fuel, and a coalescing element (29) for removing water from the fuel. For passing through the fuel filter (4) in a radial direction, the coalescing element (29) surrounds the filter element (28) and extends in an axial direction across the entire expansion of the filter element (28).

Description

description

Fuel filter and fuel filter assembly for filtering fuel Technical field

The invention relates to a fuel filter for filtering fuel, comprising a particularly bellows-shaped filter element for separating particles from the fuel and a coalescing element for separating water from the fuel.

State of the art

A generic fuel filter is known from DE 10 2007 039 679 A1. There, a fuel filter is described, which has a high degree of separation of water to be separated from the fuel and particles to be separated from the fuel in a compact design and in which a means for water separation and a means for particle separation are used, wherein the two means are arranged in that the fuel to be filtered passes through the means for separating water before the means for particle separation, wherein a further means for separating particles is disposed and spaced from the means for particle separation, wherein the means for separating water is arranged between the two means for separating the particles.

In such a fuel filter, the filter surface of the means for separating water is bounded by the design for the purpose of particle separation in the radial direction and in the axial direction by a flow channel for guiding the separated water.

The invention is based on the object to provide a fuel filter and a fuel filter assembly with improved water separation, which can withstand particularly high pressure loads in particular. Disclosure of the invention

This object is achieved by a fuel filter of the aforementioned type, which is characterized in that the coalescence element surrounds the filter element for the flow through the fuel filter in the radial direction and extends in the axial direction over the entire extent of the filter element. The inventive Fuel filter is flowed through radially from the inside to the outside, wherein the filter element serves as a first filter stage and the coalescing element as a second filter stage. The first filter stage serves to separate particles from the fuel to be filtered, while by means of the second filter stage the water droplets contained in the filtered fuel accumulate to form water drops and are subsequently deposited. By the coalescence element surrounding the filter element in the radial direction, it is possible to position a large filter surface of the coalescing element on the clean side of the filter element. Due to the larger inner diameter of the coalescing element in comparison to that of the filter element, the specific surface load and thus the flow speed of the fuel to be filtered upon entry into the coalescing element are lower compared to the flow speed at the inner diameter of the filter element. This increases the residence time of the water droplets in the coalescing element and reduces the force which presses the water droplets through the coalescing element. The formation and separation of water drops can thus be carried out efficiently.

As a filter material for the (bellows-shaped) filter element, for example, cellulose or meltblown based on polyester can be used. The coalescing element may e.g. consist of a hydrophilic material, which transforms water fractions in the fuel by adhesion to larger drops of water. Suitable materials are known from the literature. The filter element and the coalescing element can be constructed in multiple layers.

In a preferred embodiment, the filter element and the coalescing element are arranged adjacent to one another. In this way, the filter element can be supported in the radial flow from the radially outer, full-surface circumferential coalescing and possibly further support elements.

A preferred embodiment of the fuel filter is characterized in that the filter element and the coalescing element are each fastened at their axial end faces in a sealing manner to a common end disk. For example, filter element and coalescing element can be glued to the end plate. In the radial flow from the inside to the outside can thus be dispensed with a separate seal for sealing raw and clean side of the coalescing. In a further development of the embodiment just described, at least one end disk of the fuel filter has at least one feed opening for unfiltered fuel to a radially inward, raw-side region of the fuel filter. For example, the feed opening is arranged centrally in the end disk, whereby a centric inflow of the fuel to be filtered is made possible in the filter element. In particular, when the centric feed opening extends in the radial direction to the inner diameter of the filter element, an efficient flow over the entire filter surface of the fuel filter is ensured. However, it is also possible to provide a plurality of feed openings, in particular a plurality of smaller feed openings, on one of the two end disks.

In a development of the embodiment described above, at least one end disk has a peripheral edge extending in the axial direction and lying radially on the outside. In this case, the edge is preferably arranged so far outward in the radial direction that it is located outside the radial region in which the filter element (and the coalescence element) are fastened to the end disk. For example, the edge may be provided with a seal to seal the clean or the raw side of the fuel filter against a filter housing. In particular, with the help of the peripheral edge in a particularly simple manner, a pressure compensation space between the fuel filter and the housing can be formed.

A particularly preferred embodiment is characterized by radially outwardly mounted support elements for supporting the coalescing element. For example, the support elements may have a grid-shaped structure. The support elements can in this case be attached to the end disks which are located on the axial end faces of the filter and coalescing element, for example by latching or snap-fastening, gluing or by IR welding. Through the support elements, a breakthrough or destruction of the coalescing element and the filter element can be prevented, which otherwise can occur especially at high pressure differences between raw and clean side. Thus, the operability of the fuel filter is ensured especially at high pressures or pressure differences. The support elements may in particular be designed in the form of a support basket which extends in the axial direction along the fuel filter. In a further development of the embodiment just described, the supporting elements abut against the coalescing element. For example, the support elements are designed as a lattice-shaped or otherwise structured casing of the coalescing element. Thus, a particularly effective support of the coalescer is given.

An embodiment in which a hydrophobic element extends in the axial direction in the radial direction from the coalescing element is particularly preferred. The hydrophobic element preferably surrounds the coalescing element at least in a partial region of its axial extent. The hydrophobic element serves as a separator, since it is permeable to the filtered fuel while it does not pass through the water located on the clean side of the coalescing element, so that an annular space for water guidance is formed between the coalescing element and the hydrophobic element, by means of which the separated water can be brought under gravity into a below arranged water collection room. The hydrophobic element can be made of polyamide or polyester, for example. Particularly preferred is a development of the embodiment just described, wherein the hydrophobic element has a holding device for attachment to at least one end plate of the fuel filter. For example, the hydrophobic element can be encapsulated by plastic, whereby on the one hand the hydrophobic element is supported and on the other hand an attachment of the hydrophobic element to an end disc is made possible. It is understood that the hydrophobic element may be attached to the end plate in other ways, e.g. by latching.

The scope of the invention also covers a fuel filter arrangement for filtering fuel with a fuel filter as described above and with a filter housing in which the fuel filter is arranged. The filter housing protects the fuel filter against external influences. In addition, it provides interfaces for the supply and discharge of the fuel and thus for the integration of the fuel filter in an existing fuel system. A refinement of the fuel filter arrangement is characterized in that, in the installed state of the fuel filter in the filter housing, at least one end disk in the axial direction is followed by a pressure equalization chamber. Preferably, its extent in the radial direction at least largely corresponds to the radial extent of the filter element. Through the pressure equalization chamber, a pressure equalization between opposite sides of the end plate over the entire radial extent of the filter element take place, so that a tearing of the end plates of the filter and Coalescermedien is prevented. In a further development of the embodiment just described, the filter housing has a collar which rests against the radially outer edge of the end disk for sealing between the raw and clean side in the installed state of the fuel filter. The collar of the filter housing and the edge of the fuel filter form sealing surfaces. In addition, in the region of the edge of the end plate, a seal may be provided, for example in the form of an O-ring. For example, the rim of the end plate can be slid over the collar of the filter housing during installation of the fuel filter in the filter housing, whereby a centering of the fuel filter is made possible along the edge of the annular collar in the filter housing. Thus, a correct fit of the fuel filter is ensured on the collar of the filter housing side facing the fuel filter.

Also preferred is a development of the embodiment just described, which is characterized in that the pressure equalization space between the at least one supply port for unfiltered fuel having end plate and a housing pot of the filter housing is formed and is preferably enclosed in the radial direction of the collar. By way of example, the end disk facing the pressure equalization chamber has a centric feed opening for unfiltered fuel. Thus, a pressure equalization between the fuel in the pressure compensation chamber and the fuel in the filter element via the feed opening take place. As a result, the pressure of the fuel on the side of the end disk facing the pressure equalization chamber substantially corresponds to the pressure of the fuel on the side of the end disk facing the filter element. Thus, an additional supporting the pressure compensation chamber facing end plate by further structural measures is not necessary. A deformation of the pressure compensation chamber facing end plate due to high pressures on the raw side of the fuel filter is prevented by the pressure equalization. Thus, especially at high pressures on the raw side of the fuel filter or between the raw side and the clean side, there is no increased load on the connection between the filter or coalescing element and the end plate facing the pressure equalization chamber.

Also preferred is a development of the embodiment just described, in which the filter housing has a Wasserammeiraum, are provided on the support elements for supporting the fuel filter, in particular also for locking with the fuel filter. The on the side facing away from the pressure compensation chamber side of the fuel filter end plate of the fuel filter can be supported on its side facing the filter housing by supporting elements against a voltage applied to the end plate internal pressure. In addition, these support elements or other support elements may be provided to z. B. with the water collecting space facing end plate to lock. Thus, a fixation of the fuel filter on the water collection chamber facing side of the fuel filter is ensured (in the manner of a key-lock system).

A development of the embodiment just described is characterized in that the water collection chamber is formed in a housing cover of the filter housing. For example, housing cover and housing pot are connected to one another via a thread. If the housing cover is separated from the housing pot and support elements are provided which are latched to the water collecting chamber facing end plate, so when lifting the housing cover from the housing pot also the fuel filter with the housing cover removed from the housing pot. This allows easy disassembly and thus a simple replacement of the fuel filter.

Further features and advantages of the invention will become apparent from the following description of embodiments of the invention, with reference to the figures of the drawing, which show details essential to the invention, and from the claims. The individual features can be realized individually for themselves or for several in any combination in a variant of the invention. Brief description of the drawings

Embodiments are illustrated in the schematic drawing and will be explained in the following description. 1 shows a fuel filter arrangement according to the invention in the sectional view,

2 is a perspective view of a fuel filter according to the invention and FIG. 3 is a sectional view of the fuel filter of FIG. 2 according to the invention.

Embodiment of the invention

1 shows a fuel filter assembly 1 with a filter housing 2 having an inlet opening 3, an outlet opening at the back of the filter housing 2 (hidden by the filter housing 2) and a fuel filter 4. The filter housing 2 comprises a top-mounted housing pot 5 and a bottom-mounted housing cover 6. Both are connected to one another via a thread 60, wherein a seal 7 seals the interior formed between housing pot 5 and housing cover 6 from the environment 8. At the inlet opening 3 facing side of the housing pot 5, the housing pot 5 has a circumferential, extending in the axial direction collar 9. This collar 9 is surrounded by an edge 10 on a first end plate 1 1 of the fuel filter 4 in the radial direction. At the peripheral edge 10 of the first end plate 1 1, a seal 12 is provided which separates the clean side 13 of the raw side 14 of the fuel filter 4 sealing. In the region of the inlet opening 3, a pressure equalization chamber 15 extending in the axial direction is formed between the housing pot 5 and the first end disk 11, which is bounded in the radial direction by the collar 9. The inlet opening 3 is connected to the pressure equalization chamber 15. The first end plate 1 1 has a feed opening 16, which is also connected to the pressure compensation chamber 15.

In an inner region of the fuel filter 4, a water level sensor 17 is arranged over the entire axial length of the fuel filter 4, which detects the water level in a water collection chamber 18 of the housing cover 6. In the region of the first end disk 1 1, the water level sensor 17 is arranged in the feed opening 16, wherein the outer diameter of the water level sensor 17 is smaller than the diameter of the feed opening 16, so that fuel from the pressure equalization chamber 15 can get into the interior of the fuel filter 4. On the water melraum 18 facing side of the fuel filter 4, the water level sensor 17 extends through a second end plate 19. This has a central opening 20, in which the free end of the water level sensor 17 protrudes. The water level sensor 17 has, in the region of the second end disk 19, a seal 21 which seals the water collecting chamber 18 with respect to the raw side 14 of the fuel filter 4.

It is possible to dispense with the water level sensor 17 in the fuel filter assembly 1. In this case, eliminates the central opening 20 and the second end plate 19 is closed. Of course, the feed opening 16 in the first end disk 11 remains in the case of an unintended water level sensor 17 in order to allow the inflow of fuel into the fuel filter 4. However, it may vary in size or e.g. be replaced by several small feed openings. On the fuel filter 4 side facing the housing cover 6 inner support elements 22 are arranged on an inner radius, which are in the installed state of the fuel filter 4 in contact with the second end plate 19. On an outer radius which is greater than the inner radius, 6 outer support members 23 are arranged on the housing cover. These latch with a Verrastaufnahme 24, which is formed on the second end plate 19. Depending on requirements but can be dispensed with support elements 23.

On the side facing away from the inlet opening 3 of the housing cover 6, a discharge opening 25 is provided. This is closed by a drain plug 26, wherein sealing elements 27 are provided between the housing cover 6 and the drain plug 26, which seal the water collecting chamber 18 from the environment 8. The drain plug 26 is threaded out of the drain port 25 by means of a thread 260 for draining the water collection chamber 18, e.g. during the inspection of a motor vehicle, in which the filter assembly 1 is installed.

Fig. 2 and Fig. 3 show the fuel filter 4 of Fig. 1, which has a plurality of filter stages. A filter element designed as a filter bellows 28 for separating particles from the fuel to be filtered forms the first filter stage. The filter bellows 28 is preferably designed as a zigzag folded filter bellows. The filter bellows 28 is in radial Seen on its outer side by a coalescing element 29 for separating water from the filtered through the filter bellows 28 fuel surrounded. The coalescing element 29 extends in the axial direction over the entire length of the filter bellows 28 and forms the second filter stage of the fuel filter 4. The coalescing element 29 and the filter bellows 28 are fastened at their axial end faces to respective common end disks 11, 19. At the radially outer side of the coalescing element 29, support elements designed as a lattice-shaped sheath 30 are provided for supporting the coalescing element 29, which rest against the coalescing element 29. The latticed sheath 30 is attached to the end plates 1 1, 19 in the present example. For this purpose, lugs 31 are provided, with which the latticed sheath 30 engages the end plates 1 1, 19, for example by the lugs 31 are embedded in the manufacture of the fuel filter 4 in the plastic material of the end plates 1 1, 19. The grid-shaped sheath 30 may also be glued or otherwise attached to the end plates 1 1, 19 or attached to this, for example by the sheath 30 is subsequently snapped onto the end plates 1 1, 19.

Radially spaced from the outside of the coalescing element 29 is a hydrophobic element designed as a hydrophobic layer 32. The inner lateral surface of the hydrophobic layer 32 is shown in detail in FIGS. 1 and 3. Provided on the hydrophobic layer 32 is a holding device designed as a lattice-shaped structure 33, which surrounds the hydrophobic layer 32 and has a latching element 34 on its side facing the first end plate 11. This latching element 34 latches with a receptacle 35, which is arranged outside on the peripheral edge 10 of the first end plate 1 1. On the side of the hydrophobic layer 32 facing the second end disk 19, an opening 36 is provided between the second end disk 19 and the latticed support structure 33 of the hydrophobic layer 32. In the following, the operation of the fuel filter assembly 1 will be briefly explained with reference to FIG. 1. The fuel to be filtered is introduced into the fuel filter arrangement 1 via the inlet opening 3 (directional arrow 37). From the inlet opening 3, the fuel to be filtered flows into the pressure equalization chamber 15 and from there through the feed opening 16 into the fuel filter 4 (directional arrow 38). The fuel to be filtered flows through the fuel filter 4 from the inside to the outside, ie from the raw side 14 radially through the filter bellows 28 and the coalescing element 29 (direction arrows 39) to the clean side 13. At the radially outer side of the coalescing element 29 of the filtered fuel strikes the hydrophobic layer 32, wherein the filtered fuel passes through the hydrophobic layer 32 and flows upward in the direction of the outlet (hidden by the pressure compensation chamber 15) (direction arrows 40). The separated water is retained by the hydrophobic layer 32 and guided under gravity in the direction of the opening 36 between the second end plate 19 and the hydrophobic layer 32 in the direction of the Wasserammeiraums 18 (directional arrows 41).

Claims

claims

1 . Fuel filter (4) for filtering fuel, comprising a particularly bellows-shaped filter element (28) for separating particles from the fuel and a coalescence element (29) for separating water from the fuel, characterized in that for the flow through the fuel filter (4 ) in the radial direction, the coalescing element (29) surrounds the filter element (28) and extends in the axial direction over the entire extent of the filter element (28).

2. Fuel filter according to claim 1, characterized in that the filter element (28) and the coalescing element (29) are arranged adjacent to each other.

3. Fuel filter according to one of the preceding claims, characterized in that the filter element (28) and the coalescing element (29) at their axial end faces are each sealingly attached to a common end plate (1 1, 19).

4. Fuel filter according to claim 3, characterized in that at least one end disk (1 1, 19) of the fuel filter (4) at least one feed opening (16) for unfiltered fuel to a radially inner, raw-side region (14) of the fuel filter (4). having.

5. Fuel filter according to claim 3 or 4, wherein at least one end plate (1 1, 19) has an axially extending, radially outer edge (10).

6. Fuel filter according to one of the preceding claims, characterized by radially outwardly mounted support elements (30) for supporting the Koaleszenzelements (29).

7. Fuel filter according to claim 6, characterized in that the support elements (30) rest on the coalescing element (29).

8. Fuel filter according to one of the preceding claims, characterized by a in the radial direction of the coalescing element (29) spaced, in the axial Direction extending hydrophobic element (32).

9. Fuel filter according to claim 8, characterized in that the hydrophobic element (32) has a holding device (33) for attachment to at least one end plate (1 1, 19) of the fuel filter (4).

10. A fuel filter arrangement for filtering fuel with a fuel filter (4) according to any one of the preceding claims and with a filter housing (2) in which the fuel filter (4) is arranged.

1 1. Fuel filter assembly according to claim 10, characterized in that in the installed state of the fuel filter (4) in the filter housing (2) at least one end plate (1 1, 19) in the axial direction of a pressure compensation chamber (15) connects, the expansion in the radial direction preferably at least largely corresponds to the radial extent of the filter element (28).

12. Fuel filter assembly according to claim 1 1, characterized in that the filter housing (2) has a collar (9) for sealing between raw (14) and clean side (13) in the installed state of the fuel filter (4) on the radially outer edge (10) of the end plate (1 1) is applied.

13. Fuel filter assembly according to claim 1 1 or 12, characterized in that the pressure compensation chamber (15) between which the at least one feed opening (16) for unfiltered fuel having end plate (1 1) and a housing pot (5) of the filter housing (2) is formed and preferably in the radial direction of the collar (9) is enclosed.

14. Fuel filter arrangement according to one of claims 10 to 13, characterized in that the filter housing (2) has a Wasserammeiraum (18), on the support elements (22, 23) for supporting the fuel filter (4), in particular also for locking with the fuel filter (4) are provided.

15. Fuel filter arrangement according to claim 14, characterized in that the water collection chamber (18) is formed in a housing cover (6) of the filter housing (2).