FILTER STRUCTURE FOR FUEL, A CARTRIDGE AND A FILTER GROUP

Abstract

A filter structure for fuel fluids, comprising a first filter wall, a coalescing second filter wall located downstream of and in contact with the first filter wall, and a hydro phobic wall, in which the first filter wall comprises a first porous layer, realised in a material having a receding contact angle Θ rec comprised between 30° and 80°; the coalescing second filter wall comprises a second porous layer made of a material having a greater porosity than the first filter wall; the hydrophobic third wall comprises a layer located at a distance from the second layer.

Claims

1. A filter structure (100) for fuel fluids, comprising a first filter wall (1), a coalescing second filter wall (2) located downstream and in contact with the first filter wall (1), and a hydrophobic wall (3), wherein: the first filter wall (1) comprises a first porous layer, realized in a material having a receding contact angle Θrec comprised between 30° and 80°, the hydrophobic wall (3) comprises a layer located at a distance from the second coalescing filter wall (2).

2. The filter structure of claim 1, wherein the material of the first filter layer (1) is polyester.

3. The filter structure of claim 1, wherein the material of the first filter layer (1) is polybutylene terephthalate.

4. The filter structure of claim 1, wherein the coalescing second filter wall (2) has a greater thickness than the first filter wall (1).

5. The filter structure of claim 1, wherein the coalescing second filter wall (2) comprises a second porous layer realized in a material having a greater porosity than the first filter wall.

6. The filter structure of claim 1, wherein the material of the coalescing second filter layer (2) is selected from among following: viscose, polyester, fibreglass.

7. A filter cartridge (40) for fuel, comprising an upper plate (41) and a lower plate (42) between which a filter structure (100) for fuel fluids comprising a first filter wall (1) is located; a coalescing second filter wall (2) located downstream and in contact with the first filter wall, and a hydrophobic wall (3), wherein: the first filter wall (1) comprises a first porous layer, realized in a material having a receding contact angle Θrec comprised between 30° and 80°, the hydrophobic wall (3) comprises a layer located at a distance from the second layer.

8. The filter cartridge of claim 7, wherein the material of the first filter layer (1) is polyester.

9. A filter group (10) comprising an external casing (20), provided with an inlet conduit (23) for the fuel to be filtered and an outlet conduit (24) for the filtered fuel, internally of which a filter cartridge (40) is housed, according to claim 7.

10. The filter cartridge of claim 7, wherein the material of the first filter layer (1) is polybutylene terephthalate.

11. The filter cartridge of claim 7, wherein the coalescing second filter wall (2) has a greater thickness than the first filter wall (1).

12. The filter cartridge of claim 7, wherein the coalescing second filter wall (2) comprises a second porous layer realized in a material having a greater porosity than the first filter wall.

13. The filter cartridge of claim 7, wherein the material of the coalescing second filter layer (2) is selected from among following: viscose, polyester, fibreglass.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0061] The advantages and constructional and functional characteristics of the invention will emerge from the detailed description that follows, which with the aid of the accompanying tables of drawings illustrates some preferred embodiments of the invention by way of non-limiting example.

[0062] FIG. 1 is a section view of the structure of the invention;

[0063] FIG. 2 is a section view of a filter group and a filter cartridge according to the invention.

[0064] FIG. 3 is a plan section of a filter group according to an alternative embodiment of the invention;

[0065] FIG. 4 illustrates section IV-IV of FIG. 1.

BEST WAY OF CARRYING OUT THE INVENTION

[0066] FIG. 1 shows an embodiment of the filter structure 100 and the water separator according to the invention.

[0067] The structure 100 comprises a first filter wall 1 for separating impurities from the fuel. According to the invention the first filter wall comprises a porous layer of a material with a low degree of wettability, i.e. with a receding contact angle Θ.sub.rec comprised between 30° and 80°.

[0068] In the illustrated embodiment the first filter wall, is made from polybutylene terephthalate, and has a porosity of 5 μm, a thickness of 0.5 mm, and a weight of 200 g/m.sup.2.

[0069] In other embodiments of the invention the first filter wall can also be made of polyester or any other material suitable for the purpose and exhibiting a receding contact angle Θ.sub.rec comprised between 30° and 80°.

[0070] A coalescing second filter wall 2 is positioned downstream, in the flow direction of the fuel to be treated and in contact with the first filter wall 1.

[0071] The coalescing second filter wall 2 can be made of a material exhibiting a coalescing structure and a known composition, i.e. one that is able to obtain the coalescing effect in relation to water particles present in the fluid fuel to be filtered.

[0072] For example, the second filter wall 2 can be made of viscose, polyester, glass fibre, single-component fibre, bi-component fibre and/or bi-constituents.

[0073] In the illustrated embodiment the second filter wall 2 is made of polyester and has a porosity of 5-20 μm, a thickness of 2 mm, and a weight of 450 g/m.sup.2.

[0074] In general, in accordance with the invention the coalescing second filter wall 2 must exhibit a greater porosity than the first filter wall 1. Further, in a preferred embodiment, the coalescing second filter wall 2 has a greater thickness than the first filter wall 1.

[0075] It is however possible for the filter walls 1 and 2 to be of a same thickness, for example comprised between 0.5 mm and 1 mm, preferably substantially 0.7 mm.

[0076] A hydrophobic wall 3 is located downstream of the second filter wall 2, which hydrophobic wall 3 is able to provide a barrier against the water droplets that have collected while crossing the coalescing second filter wall 2.

[0077] The hydrophobic wall 3 is located at a certain distance from the coalescing second filter wall 2. Preferably, this distance varies from 0.1 mm to 20 mm depending on applications.

[0078] According to a preferred embodiment the hydrophobic wall 3 comprises a network of fibres, known per se, having a hydrophobic surface.

[0079] The hydrophobic wall 3 is preferably made of polyester, preferably polyethylene terephthalate (PET) coated with a hydrophobic material, for example a silicone or fluorinated material.

[0080] In the present embodiment the hydrophobic wall 3 has a porosity of 20 μm, a thickness of 38 μm and a weight of 26 g/m.sup.3.

[0081] The structure 100 illustrated in FIG. 1 is applied in a filter cartridge 40 intended, for example, to be used in a filter assembly 10 (FIG. 2), for the filtration of fluids, particularly fuel for an internal combustion engine.

[0082] The filter assembly 10 comprises an external casing, denoted in its entirety by 20, provided with an inlet conduit 23 for the fuel to be filtered and an outlet conduit 24 for the filtered fuel.

[0083] In the illustrated embodiment the casing 20 comprises a cup-shaped body 21, and a cover 22 able to close the cup-shaped body 21, on which the inlet conduit 23 for the fuel filter and the outlet conduit 24, which is axial, for the filtered fuel are located.

[0084] The cup-shaped body 21 comprises, positioned at a bottom thereof, a discharge conduit 25 for the water that accumulates on the bottom of the cup-shaped body 21, provided with a closure cap 26.

[0085] The filter cartridge 40 is accommodated internally of the casing 20, which filter cartridge 40 divides the internal volume of the casing 20 into two distinct chambers 211, 212, of which a first chamber 211 for the fuel to be filtered (in the example external), in communication with the inlet conduit 23, and a second chamber 212 of the filtered fuel (in the example internal), in communication with the outlet conduit 24.

[0086] The filter cartridge 40 comprises an upper support plate 41 and a lower support plate 42 between which the previously-described filter structure 100 is located.

[0087] The upper support plate 41 is substantially disc-shaped and affords a central hole 410 centred on the longitudinal axis A of the filter cartridge 40.

[0088] The lower support plate 42 is also substantially disc-shaped and has a central hole 420 centred on the longitudinal axis A of the filter wall 43.

[0089] The central hole 410 of the upper support plate 41 inserts on a terminal internal end portion of the outlet conduit 24, with the interposing of a usual seal ring 411 fixed in a suitable seating at the central hole 410.

[0090] The lower support plate 42, instead, enters and rests on the bottom of a cylindrical annular seating 421 afforded in the vicinity of the bottom of the cup-shaped body 21 (at a distance therefrom) by interposing of a further seal ring 422.

[0091] In the present embodiment, the first filter wall 1 and the coalescing second wall 2 are realized as loop-closed pleated walls, i.e. exhibiting, in horizontal section, a known star-shape.

[0092] The first filter wall 1 and the coalescing second filter wall 2 are inserted externally of a cylindrical core 43 that connects the first and the second plate.

[0093] The core 43 exhibits a cage-like structure of substantially tubular shape and a diameter substantially equal to (or slightly smaller than) the internal diameter of the coalescing second filter wall 2.

[0094] In particular, the cage structure of the core 43 is constituted by a plurality of vertical uprights 430 (e.g. equidistant) which join a plurality of horizontal rings 431 (for example, equidistant) defining the openings 432 for the passage of the fluid.

[0095] The opposite ends of the longitudinal core 43 are both open and respectively fastened, for example by gluing or welding, to the facing internal faces of the upper support plate 41 and the lower support plate 42.

[0096] A second core 45 is housed internally of the core 43, coaxial to the first core 43 and having a cage-like structure exhibiting a substantially tubular shape and a diameter that is smaller than the diameter of the first core 43.

[0097] In particular, the cage structure of the core 45 is constituted by a plurality of vertical uprights 450 (e.g. equidistant) which join a plurality of horizontal rings 451 (for example, equidistant) defining the openings 452 for the passage of the fluid.

[0098] The hydrophobic wall 3 of the filter structure 100 is inserted on the external surface of the second core 45.

[0099] In other embodiments of the invention the hydrophobic wall 3 can be associated to the external or internal surface of the second core 45 by means of a method of any known type, for example by welding or gluing.

[0100] The upper end of the second core 45 is inserted into an internal extension 240 of the discharge conduit 24 and exhibits at an edge thereof a flange 453, a lower surface of which rests against an annular shelf 433 that branches internally from the first core 43. With this configuration, the flange 453 of the core is clamped between the annular shelf 433 and the upper plate 41.

[0101] The lower end of the second core 45 is, instead, closed by a disc-shaped body 454 located at the central hole of the lower plate 42.

[0102] In the light of the foregoing, the operation of the filter assembly 10 is evident.

[0103] The flow of fuel to be treated moves from the periphery towards the centre of the filter assembly 10.

[0104] The fuel passes through the first filter wall 1, which, thanks to its low porosity, separates the impurities from the fluid. When passing through the first filter wall 1, the fuel and the water particles in it reduce speed thanks both to the low degree of wettability of the material of which the wall is made and to the low porosity of the first filter wall 1.

[0105] Subsequently, the fluid (fuel and water particles) passes through the coalescing second filter wall 2, which by virtue of the coalescing effect collects the water particles to form larger-size drops. The drops of collected water are blocked by the hydrophobic wall 3, which instead allow the filtered fuel to pass through, which filtered fuel is then directed towards the outlet conduit 24.

[0106] The drops of water blocked by the hydrophobic fall by effect of gravity into a lower collecting chamber superiorly delimited by the lower plate 42, and from there are discharged through the discharge hole 25.

[0107] The structure 100 illustrated in FIG. 1 is also applied in a filter assembly 61 of the type illustrated in FIG. 3, also for the filtration of fluids, particularly fuel for an internal combustion engine.

[0108] The filter group 61 comprises an external container 62 conformed for example as a tray a mouth of which is closed by a cover 63.

[0109] The bottom 620 of the container 62 has a narrow and elongate shape and exhibits two sides 621, parallel to one another, ends of which are joined by two curved portions 622.

[0110] A profiled element 64 is housed internally of the container, comprising a horizontal plate 640, from which a first vertical part 641 rises, which has a complementary shape to the internal surface of the container 62, against which it rests, and a second part 642, also a wall, which branches from an end of the first portion 641 and is arranged perpendicularly thereto so as to define a vertical wall. The wall divides the internal volume of the container 62 into a first and a second chamber 65 and 66, fluidly connected; these chambers can communicate, for example, thanks to a vertical slot 67 fashioned in the part 642 defining the wall. As can be observed from the figures, the two chambers 65 and 66 can be flanked to one another and develop in the direction of the height of the container.

[0111] An inlet conduit 68 of the fuel heads the chamber 65, which can open above the cover 63; while an outlet conduit 69 of the fuel heads the chamber 66, which can open below the bottom 620 of the container 62.

[0112] A filter cartridge 610 is housed internally of the chamber 65, for filtering the fuel which is sent internally of the filter group through the inlet conduit 68.

[0113] In the illustrated embodiment, the filter cartridge 610 is toroidal and can be crossed radially from inside towards outside, but this does not exclude the possibility in other embodiments of the invention for it to be crossed from outside to inside, or for it also to have a different shape, for example flat.

[0114] The filter cartridge 610 comprises the first filter wall 1 and the second coalescing filter wall 2 of the filter structure 100, which are arranged in such a way as to be crossed in series by the fuel: first the filter wall 1 and then the coalescing filter wall 2.

[0115] In the present embodiment, the first filter wall 1 and the coalescing second wall 2 are generally tubular in shape and are coaxially inserted one inside the other.

[0116] For example, they can be realized as loop-closed pleated walls, i.e. exhibiting, in horizontal section, a known star-shape.

[0117] The profiled body 64 further comprises a horizontal upper plate 643 which is located below the cover 63 and has the function of preventing axial translations of the filter wall 610.

[0118] The fuel that crosses the filter wall 610 pours into the second chamber 66, in which the hydrophobic wall 3 of the filter structure 100 is housed, which has the function of preventing passage of the water droplets collected by the coalescing filter 2, so as to separate the water from the diesel fuel.

[0119] In greater detail, during normal functioning, the fuel enters the chamber 65 from the inlet conduit 68, passes through the first filter wall 1, which, thanks to its low porosity, separates the impurities from the fluid. When passing through the first filter wall 1, the fuel and the water particles in it reduce speed thanks both to the low degree of wettability of the material of which the wall is made and to the low porosity of the first filter wall 1. Subsequently, the fluid (fuel and water particles) passes through the coalescing second filter wall 2, which by virtue of the coalescing effect collects the water particles to form larger-size drops. The filtered fuel collects in the second chamber 66, passing for example through the opening 67 in which the drops of collected water are blocked by the hydrophobic wall 3, which instead allows the filtered fuel to pass through, which filtered fuel is then directed towards the outlet conduit 69.

[0120] In fact the water has a specific weight that is greater than that of the diesel fuel, so that the droplets of water tend to collect on the bottom of the chamber 66.

[0121] In the illustrated example the hydrophobic wall 3 is applied to a panel 612, which is supported by the profiled element 64 and is provided with a plurality of openings 6120 which are closed by the hydrophobic wall 3.

[0122] In particular, a side of the hydrophobic wall 3 rests in a step 6410 fashioned at the end of the part 641 of the element 64, while the opposite side rests on a step 6420 of the wall 642.

[0123] The water that collects on the bottom of the second chamber 66 is expelled through a usual drainage means 613, for example a usual tap located on the bottom of the chamber. The diesel fuel separated from the water, differently, exits from the second chamber through the outlet conduit 69.

[0124] From what is described above it can be deduced that the filter group advantageously makes available a filter structure 100 which is distributed in two distinct chambers 65 and 66, in which the first chamber 65 contains the filter wall 1 and the coalescing filter wall 2, while the second chamber 66 only contains the hydrophobic wall 3.

[0125] In other words, a filter group is disclosed which according to the invention comprises an external casing with a first and a second chamber 65 and 66, in fluid communication, in which the first filter wall 1 and the second coalescing filter wall 2 are placed in contact with one another and are crossed in series by the flow of fuel in the first chamber 65, while the hydrophobic wall is located at a distance from the second coalescing filter wall and is crossed by the flow of fuel in the second chamber 66.

[0126] In this way, the collection chamber of the water exhibits large dimensions and is able to collect a quantity of water that is considerably greater than that collected in other filter groups. Therefore maintenance of the group, i.e. the need to intervene to remove the water collected in the chamber, can be less frequent.

[0127] The invention as it is conceived is susceptible to numerous modifications and variants, all falling within the scope of the inventive concept.

[0128] Further, all the details can be replaced with other technically-equivalent elements.

[0129] In practice the materials used, as well as the contingent shapes and dimensions, can be any according to requirements, without forsaking the scope of protection of the following claims.