| WO/2008/144290 | CONTINUOUSLY OPERATING FILTERING APPARATUS |
| WO/1994/023818 | FILTER ELEMENT WITH EXPANDED METAL JACKET |
| WO/1995/007744 | SYSTEM AND METHOD OF PROCESSING MIXTURE OF SOLIDS AND LIQUIDS |
GIRONDI, Giorgio (14 Vicolo Carbone, Mantova, Mantova, I-46100, IT)
| Claims 1 ) . A filter cartridge (30) for a filter device (10), comprising a tubular filter wall (31 ) destined to delimit an internal cavity (40), at least a support element (34) fixed to an end of the filter wall (31 ) and provided with an opening (344) communicating with the internal cavity (40) of the filter wall (31 ), and an annular seal (36) associated to the opening (344) of the support element (34), which comprises a first annular portion (360) destined to be coaxially in contact with a conduit (25) inserted in the opening (344), characterised in that the seal (36) further comprises a second annular portion (361 ), axially projecting with respect to the support element (34) on an opposite side to the filter wall (31 ), which second annular portion (361 ) is conformed such that it can achieve a sucker effect on a surface (240) that is perpendicular to the conduit (25). 2) . The filter cartridge (30) of claim 1 , characterised in that the second annular portion (361 ) comprises a flexible annular lip (362), a diameter of which diminishes in an axial direction from a free edge towards the support element (34). 3) . The filter cartridge (30) of claim 2, characterised in that a thickness of the annular lip (362) diminishes in an axial direction towards the free edge. 4) . The filter cartridge (30) of claim 2 or 3, characterised in that the annular lip (362) is convex, with a concavity thereof facing externally. 5) . The filter cartridge (30) of any one of the preceding claims, characterised in that the annular seal (36) is made in a single body with the support element (34). 6) . The filter cartridge (30) of claim 5, characterised in that the annular seal (36) is made of a different material to the support element (34). 7) . The filter cartridge (30) of any one of the preceding claims, characterised in that it comprises a further annular seal (35), which is associated to an external perimeter edge of the support element (34), and which is destined to be interposed between two separable portions (21 , 24) of a casing (20) containing the filter cartridge (30). 8) . The filter cartridge (30) of any one of the preceding claims, characterised in that the further annular seal (35) is made in a single piece with the support element (34). 9) . The filter cartridge (30) of claim 8, characterised in that the further annular seal (35) is made of a different material to the support element (34). 10) . A filter device (10) comprising a casing (20) and a filter cartridge (30), according to any one of the preceding claims, housed in the casing (20). |
Technical Field
The present invention relates to a filter cartridge for a filter device.
In more detail, the present invention relates to a filter cartridge for a filter device destined to be associated to an internal combustion engine of a motor vehicle, for example for fuel filtering.
Background Art
As is known, a filter device comprises an external casing, generally formed by a beaker-shaped body and a relative closing cover, which is provided with an inlet conduit for a fluid to be filtered and an outlet conduit for the filtered fluid, and a filter cartridge for sub-dividing the internal volume of the casing into at least two distinct operating chambers, of which a first operating chamber communicates with the inlet conduit and a second operating chamber communicates with the outlet conduit.
A typical filter cartridge comprises a tubular filter wall, generally cylindrical, for example a pleated filter wall having a star-shaped geometry, or a depth filter wall, and two support plates that are fixed to opposite ends of the filter wall.
One of the support plates is destined to close the internal cavity of the filter wall, while the opposite plate generally exhibits an opening which is designed to place the internal cavity in communication with the outside.
When the filter cartridge is mounted internally of the device casing, the opening receives a projecting tract of the inlet conduit, or alternatively the outlet conduit, such that one of the operating chambers is defined by the internal cavity of the filter wall while the other is defined externally of the filter wall.
To guarantee hydraulic separation between the operating chambers, the filter cartridge generally comprises an annular seal gasket, which is coaxially interposed between the edge of the opening and the conduit inserted therein. Because of a natural ageing process, especially in the case of filtration of especially aggressive fluids, among which fuels such as petrol or diesel, the annular seal might progressively lose efficiency, which would give rise to undesired leakage of non-filtered fluid directly from one operating chamber to another.
The same undesired leakages can also arise in the case of small positioning errors of the filter cartridge in the casing of the device, due for example to inevitable constructional tolerances of the associated parts.
In an attempt to obviate the above drawbacks, patent FR1186926 describes an annular seal which can be used in filter groups, which comprises a central body with two flexible ring-shaped lips emerging from opposite sides thereof. When the seal is compressed between two rigid surfaces of the filter group, the lips flex such as to extend over and rest on the surfaces, thus improving the seal.
Patent DE19935297 describes a filter cartridge having a filter wall fixed between two support plates, in which the support plates comprise a projecting collar suitable for coupling with an inlet or outlet conduit of the fluid to be filtered. The collar comprises an intermediate portion suitable for defining a radial seal, and a ring-shaped end portion. This conformation of the collar is such that it is compressible in an axial direction, with the main aim of compensating for small mounting errors and generating an elastic force in contrast that enables the filter cartridge to be centred with respect to the casing thereof.
Patent DE202005013478 discloses a filter for fluids comprising a cylindrical filter element to which a terminal plate is applied that exhibits a concentric seal. The seal comprises a ring-shaped portion which exhibits two free ends.
When the seal is pressed against the cover of the filter group, the end flexes such as to realise the seal, and at the same time causes the other end to tighten slightly against the outlet mouth of the cover.
Though each of these patents discloses a seal having at least a flexible annular portion, generally tapered, the seal is still able to seal only following an external force which keeps it constantly pressed against a relative abutting surface.
If this thrust force diminishes or is completely removed, for example due to the above-mentioned ageing process, these seal behave exactly as traditional seals, i.e. they progressively lose adherence to the abutting surfaces, rapidly reducing their efficiency up to causing undesired fluid leakage.
Disclosure of Invention
In the light of the above-mentioned drawbacks, an aim of an embodiment of the present invention is to improve the hydraulic seal between the operating chambers of the filter device.
A further aim is to attain the above-cited objective with a simple, rational and relatively inexpensive solution.
These and other aims besides are attained by the embodiments of the invention, the characteristics of which are reported in the independent claims. The dependent claims delineate preferred and/or especially advantageous aspects of the various embodiments of the invention.
In particular, an embodiment of the invention makes available a filter cartridge for a filter device, which in general terms comprises a tubular filter wall destined to delimit an internal cavity, at least a support element fixed to an end of the filter wall and provided with an opening communicating with the internal cavity of the filter wall of the support element.
The seal comprises a first annular portion destined to be coaxially in contact with a conduit inserted in the opening, and a second annular portion, axially projecting with respect to the support element on the opposite side with respect to the filter wall, which is conformed such as to be able to realise a sucker effect on a surface which is perpendicular to the conduit.
Thanks to this solution, the internal cavity of the filter wall is sealedly closed at both the annular portions of the seal, of which the first portion acts radially contactingly with the conduit inserted in the opening, while the second acts axially in contact with the perpendicular surface, thus reducing the risk of leakage. Further, the sucker effect realised by the second annular portion of the seal naturally tends to maintain the surface of the seal in adherence to the corresponding surfaces of the conduit and the perpendicular surface, thus guaranteeing seal even following small positioning errors of the filter cartridge or when the seal begins deteriorating due to the ageing process.
Generating the sucker effect usually relates to when the second annular portion of the seal is sucker-conformed, i.e. it is designed to define a cavity which is closed by the perpendicular surface, and is destined to be compressed against the perpendicular surface during mounting of the filter cartridge, such as to reduce the volume of the cavity, causing a part of the air imprisoned therein to exit and thus generating a depression internally of the cavity which tends to maintain the sucker portion in adhesion to the surface. Naturally not all annular shapes are suitable for obtaining the sucker effect when compressed against a surface; further, in order to obtain this effect the surfaces of the sucker portion have to be sufficiently smooth to realise, with the perpendicular surface, a hermetic seal which allow no air to re-enter the cavity when the compression force between the parts ceases.
In an aspect of the invention, the second annular portion comprises a flexible annular lip, the diameter of which diminishes in an axial direction from a free edge towards the support element.
This solution gives the second annular portion a cup-shape of a simplest type from among the shapes able to realise the sucker effect.
In particular, the annular lip can have a thickness that reduces in an axial direction towards the free edge, and can also be at least slightly convex, with the concavity of the convexity facing externally.
These details enable the sucker effect to be improved.
In an embodiment of the invention, the annular seal is realised in a single body with the support element, thus simplifying the realisation of the filter cartridge and further reducing the mounting operations.
In a preferred aspect of this embodiment, the annular seal is made of a different material with respect to the support element. For example, the support element can be made of rigid plastic, such as to provide a stable support for the filter wall, while the annular seal can be made of a more elastic and flexible plastic material than the support element, such as to effectively realise the hydraulic seal and the sucker effect.
From the constructional point of view, this solution can be obtained by means of a co-moulding or over-moulding process with an injection of plastic materials, in which a plurality of injections of different plastic materials are performed in a same mould.
In a further embodiment of the invention, the filter cartridge comprises a further annular seal, which is associated to a perimeter edge of the support element, and is destined to be interposed between two separable portions of a casing containing the filter cartridge, typically between the beaker body and a relative closing cover.
In this solution, the filter cartridge enables a contemporaneous realisation of the sealed closure of the casing of the filter device.
Further, with a single replacement operation of the filter cartridge, all the main seals of the filter device are replaced, thus restoring complete efficiency.
In a preferred aspect of this embodiment, the further annular seal can also be made in a single piece with the support element, and preferably be made of a different material, thus obtaining advantages similar to those previously described for the internal seal.
In a further embodiment of the present invention, a filter device is provided which comprises an external casing and the filter cartridge previously described housed internally of the casing.
Brief Description of Drawings
Further characteristics and advantages of the invention will emerge from a reading of the following description, provided by way of non-limiting example with the aid of the figures of the accompanying drawings, in which:
figure 1 is an axial section of a filter device of an embodiment of the present invention;
figure 2 is a detail of figure 1 illustrated during mounting of the filter device; figure 3 is the detail of figure 2 shown when the filter device is mounted.
Best Mode for Carrying Out the Invention
Figure 1 illustrates a filter device 10 for diesel fuel, which is designed to be associated to a diesel engine of a motor vehicle.
The filter device 10 comprises an external casing, denoted in its entirety by 20, and a filter cartridge 30 housed internally of the casing 20.
In more detail, the casing 20 comprises a body 21 in the shape of a cylindrical beaker, a mouth of which is defined by two flat and concentric annular edges, being a first edge 22 and a second raised edge 23 externally surrounding the first edge 22.
The mouth of the beaker-shaped body 21 is superiorly closed by an openable cover 24 having a generally disc, flat and slim shape, to which are associated an inlet conduit 25 for the fuel to be filtered and an outlet conduit 26 for the filtered fuel.
The inlet conduit 25 is in a central position, coaxial with the beaker-shaped body 21 and perpendicular to the cover 24, while the outlet conduit 26 is in a peripheral position.
The cover 24 rests on the raised edge 23 of the beaker body 21 , where it is blocked by a plurality of locking screws 27.
In this way, a slim gully or perimeter seating 28 is defined between the cover 24 and the annular edge 22 of the beaker body 21 , a cavity of which faces internally of the casing 20 and the function of which will be clarified herein below.
The filter cartridge 30 comprises a substantially-cylindrical tubular filter wall 31 , for example a depth filter or a pleated wall having a star-shaped geometry, which defines an internal cavity 40 having an axial development. A perforated support cylinder 32 is coaxially inserted in the cavity 40, usually made of a rigid plastic and known as a core, which is destined to be in contact with the filter wall 31 in order to support it radially.
The filter cartridge 30 further comprises two support elements, respectively a lower 33 and an upper 34 support element, which are fixed to the opposite axial ends of the filter wall 31 and are reciprocally connected by the support cylinder 32.
The lower support element 33 comprises a continuous disc-shaped plate 330, usually made of a stiff plastic material, which is coaxial to the filter wall 31 and is destined to close on the bottom of the internal cavity 40.
The upper support element 34 comprises a disc-shaped plate 340, which is directly fixed coaxially of the filter wall 31 , and a flat annular flange 341 , which externally surrounds the plate 340, is positioned coaxially thereto and is connected thereto by means of a plurality of ribs 342, separate from one another, which bring it into a slightly raised position with respect to the plate 340, i.e. axially distanced therefrom on the opposite side with respect to the filter wall 31.
The external perimeter edge of the annular flange 341 bears a coaxial annular seal 35, which also partly covers the upper and lower surfaces of the annular flange 341 , and is destined to be placed internally of the volume between the cover 24 and the beaker body 21.
In particular, at least a portion of the annular seal 35 is housed in the perimeter seating 28, where it is compressed between the facing surfaces of the edge 22 of the beaker body 21 and the cover 24, such as to guarantee sealed closure of the casing 20, as well as complete axial blocking of the filter cartridge 30.
The portions of the annular seal 35 in contact with the edge 22 and with the cover 24 comprise respective projecting lips which, being compressed, improve the seal.
The plate 340 exhibits a raised portion 343 having at a centre thereof a through-hole 344 which is coaxial with the filter wall 31 , which is destined to place the internal cavity 40 of the filter wall 31 in communication with the outside environment.
The through-hole 344 is destined to coaxially receive a tract of the inlet conduit 25 which projects from the cover 24 towards the inside of the casing 20. In this way, the internal volume of the casing 20 is subdivided by the filter cartridge 30 into two separate chambers, of which a first chamber is defined by the internal cavity 40 and is in communication with the inlet conduit 25, and a second chamber 50 is defined externally of the filter wall 31 and is in communication with the outlet conduit 26.
The filter wall 31 is thus destined to be radially crossed by the flow of diesel passing from the first chamber 40 to the second chamber 50, such as to separate and retain the impurities which might be contained therein.
In order to guarantee the sealed separation between the first chamber 40 and the second chamber 50, the filter cartridge 30 comprises an annular seal 36 associated to the edge of the through-hole 344 of the plate 340.
As illustrated in detail in figures 2 and 3, the annular seal 36 comprises a first annular portion 360 destined to be contactingly coaxial with an inlet conduit 25.
The internal diameter of the first annular portion 360 is smaller than the external diameter of the inlet conduit 25, such that the reciprocal insertion causes the compression of the first annular portion 360, between the edge of the through-hole 344 and the inlet conduit 25, such that the first annular portion 360 radially grips the inlet conduit 25 and thus realises the seal.
The annular seal 36 further comprises a second annular portion 361 , coaxial to the preceding first annular portion 360, which projects axially with respect to the raised portion 343 of the plate 340, on the opposite side with respect to the filter wall 31.
The second annular portion 361 comprises a slim annular lip 362 which is flexible and tapered, the diameter of which diminishes in an axial direction from a free end towards the plate 340, such as to give the second annular portion 361 the shape of a cup with the concavity thereof facing axially upwards.
In particular, the annular lip 362 has a thickness that diminishes in an axial direction towards the free edge, and is also slightly convex, with the concavity of the convexity facing radially externalwise. As can be seen in a comparison between figures 2 and 3, the axial development of the second annular portion 361 is overall greater than the distance which separates the raised portion 343 of the plate 340 from the cover 24, when the filter device 10 is completely mounted.
Thus, when the filter cartridge 30 is mounted, the lower surface 240 of the cover 24 rests first on the free edge of the second annular portion 361 of the seal 36, closing the mouth of the cavity defined thereby, and thus causes a flexion of the annular lip 362 radially externalwise, such as to reduce the volume of the cavity, causing a part of the air imprisoned therein to exit.
In this way, a depression is generated internally of the cavity which generates a sucker effect, which tends to keep the annular lip 362 in adhesive contact with the lower surface 240 of the cover 24.
Naturally, in order to realise the sucker effect, the surface 240 of the cover 24 and the internal surfaces of the annular lip 362 must be sufficiently smooth to realise a hermetic seal which allows no air to enter the cavity when the filter cartridge 30 is definitively mounted.
Thanks to this solution, the first chamber 40 defined internally of the filter wall 31 is also sealedly closed from the second annular portion 361 of the seal 36, which acts axially contactingly against the surface 240 of the cover 24; this reduces the risk of leakage of diesel fuel towards the second chamber 50. Further, the sucker effect realised by the second annular portion 361 tends to maintain the annular lip 362 in adhesion to the surface 240 of the cover 24, thus guaranteeing the seal even following small errors in positioning between the filter cartridge 30 and the casing 20 or when the seal 36 begins to deteriorate due to wear and tear.
In the illustrated example, both the annular seals 35 and 36 are made in a single piece with the support element 34, i.e. with the plate 340, the annular flange 341 and the ribs 342, for example by means of a co-moulding or over- moulding injection process, in which the support element 34 is made of a rigid plastic material destined to guarantee a stable support for the filter wall 31 , while the seals 35 and 36 are made of a more elastic and flexible material than the support element 34, such as to be able effectively to realise the seal and sucker effect.
This solution prevents problems at the mounting stage and guarantees correct positioning of the seals 35 and 36 in all the functioning conditions of the filter device 10.
Obviously a technical expert in the sector might make numerous changes of a practical-applicational nature to the filter device 10 as described herein above, without forsaking the ambit of the invention as it is claimed herein below.