Patent Application
20130048552
The invention relates to a filter device that is intended in particular for fluids, such as diesel oil, contaminated with water impurities, and that comprises a filter housing which has a fluid inlet and a fluid outlet and in which at least one filter element can be accommodated, through whose filter medium, which surrounds an inner filter cavity in the filtration process, the respective fluid flows from the unfiltered side to the filtered side, on at least one side of the filter medium there being a water separation device with a separating region for separated water which is connected to a water collecting space via at least one water passage which is open to the separating region, and the filter element having a passage which forms a fluid connection to the inner filter cavity and being securable on an element retainer of the filter housing.
Furthermore the invention relates to a filter element that is intended for use in such a filter device.
Filter devices of the aforementioned type are known from the prior art. Such filter devices are typically used in fuel systems for internal combustion engines in order to protect sensitive components, in particular the injection systems, against degradation due to the water content entrained in the fuel. In this case, separation of the water content entrained in the fuel can be effected by a coagulation process during which water droplets are formed on the filter medium, and these water droplets can flow out of the separation space, formed in the filter element, to the water collecting space.
In order to ensure the operational reliability of the systems located downstream of the filter, it is critical that in the processes of changing the filter element which are necessary over the service life, wherein the fluid connection between the filtered side of the filter element and the fluid outlet of the housing is interrupted when the end cap of the used filter element is decoupled from the element retainer, no contamination of the system takes place by dirt, which has accumulated on the used filter element, falling off. Furthermore, a separate reliable conveyance of the respective fluid by the water which forms is desirable; this increases operational reliability.
Based on the above-described problem, the object of the invention is to provide a filter device of the type under consideration, whose construction ensures a maximum of operational reliability, and during changing processes reduces the risk of contamination in particular at the fluid outlet of the housing.
This object is achieved according to the invention by a filter device having the features specified in claim 1 in its entirety.
According to the characterizing part of claim 1, an important feature of the invention lies in the fact that there is a fluid-conducting device in which fluid paths, which are separated from one another, are formed, of which the first fluid path leads from the fluid inlet of the housing to the unfiltered side of the filter element and the second fluid path connects the respective water passage to the water collecting space. In this way, a reliable separation of the fluid paths under consideration via the fluid-conducting device is created so that even when a used filter element is removed and replaced by a new element, no contamination of the system by dirt, which has accumulated on the used filter element, falling off takes place in the direction of the filtered side, but rather this dirt remains on the unfiltered side. An inadvertent introduction of water either to the filtered side or to the unfiltered side is not possible either.
Compared to known filter devices of this type, in which in the filtration process flow takes place through the filter medium of the filter element from its outer unfiltered side to the inner filter cavity which forms the filtered side, in one advantageous embodiment of the invention, the fluid-conducting device induces a kind of flow reversal so that flow takes place through the filter element preferably from the inner filter cavity to the outside. This substantially improves the situation during the process of changing the filter. When flow takes place through the filter element from the inside to the outside, the unfiltered side is located in the inner filter cavity so that dirt particles, which have accumulated on the unfiltered side and which might fall off when the filter element is removed, remain in the separated region of the unfiltered-side fluid path, while the fluid outlet which discharges on the outside of the filter medium which forms the filtered side is located outside the “endangered” region. The risk of fouling of the system downstream of the fluid outlet is thus effectively prevented.
In an especially advantageous manner, the arrangement is designed such that the unfiltered side is formed by the inner filter cavity of the filter element and that the water separation device with its water passage which is open toward the separating region are components of the filter element.
The water collecting space is preferably arranged such that at the lowest point of the filter housing, it adjoins the latter, with the element retainer of the filter housing being located above the water collecting space.
In exemplary embodiments, in which the filter element on the lower end has an end cap which has the passage which leads into the filter cavity and at least one water passage, the fluid-conducting device can be brought into a sealed fluid connection to the end cap; mechanically this results in a simple structure.
Especially advantageously, the arrangement can be designed such that the fluid-conducting device for forming the separate fluid paths has an adapter part which is designed as a connecting element via which the end cap of the filter element can be secured on the element retainer. The end cap thus can be designed as a disposable component to be changed together with the filter element in a simple, economically producible construction, while the fluid-conducting device, comprising the means which form the separate fluid paths, can form its own component separate therefrom in the form of the adapter part.
In advantageous exemplary embodiments, the preferably circular end cap on its peripheral edge has an annular body which forms inner annular jacket surfaces which are separated from one another and extend in the axial direction, and one of which adjoins a hydrophobic screen which surrounds the outside of the filter medium at a radial distance which forms the separating region and another of which forms a sealing surface for the fluid-tight contact of a peripheral edge part of the adapter part.
With respect to the configuration of the end cap, the arrangement is preferably made such that the end cap for formation of the passage has a pipe section which extends from the end cap bottom which forms the support for the filter medium and which defines the main plane of the end cap axially upward into the filter cavity and axially downward for a sealed engagement with an inner pipe which is located in the adapter part and which as part of the fluid path is fluid-connected to the fluid inlet of the housing.
In especially advantageous exemplary embodiments, the inner pipe of the adapter part is surrounded by a sleeve body which is open toward the water collecting space on the lower end facing away from the end cap and surrounds the inner pipe at a distance by which a water channel is formed as part of the second fluid path.
Furthermore, the adapter part can advantageously be made such that the sleeve body of the adapter part on its end facing the end cap has a flat ring washer which is continuous without interruption up to its peripheral edge part, which can be moved into sealed contact with the assigned annular jacket surface of the end cap, and in the operating position extends along the end cap bottom at a distance by which the water channel of the sleeve body is continued up to the respective water passage which is formed in the end cap bottom. The adapter part which is used as a fluid-conducting device, together with the underside of the end cap bottom, thus forms the part of the second fluid path via which the water which has collected in the separation space drains out, which part leads to the respective water passage.
The element retainer can advantageously have a pipe connector which forms the connection between a water collecting space and the main part of the housing which accommodates the filter element, in which connector the sleeve body of the adapter part can be accommodated in order to secure the pertinent filter element via its end cap, which is in sealing connection to the adapter part in the housing.
For its function as a fluid-conducting device, the adapter part can advantageously be designed such that the sleeve body on its outside for contact with the inside of the pipe connector of the element retainer has two radially projecting annular parts which are arranged at an axial distance from one another, and by which an annulus is formed between the outside of the sleeve body and the inside of the pipe connector of the element retainer, with a feed channel which leads to the fluid inlet of the housing as part of the first fluid path discharging into the annulus.
For this fluid path to run from the inner pipe to the fluid inlet, the arrangement can be made such that from the inner pipe of the adapter part a connecting channel branches off and discharges into the annulus on the outside of the sleeve body and continues the first fluid path to the fluid inlet of the housing.
With respect to the sealing between the end cap of the filter element, adapter part, and element retainer, the sealing of the annular parts of the sleeve body on the pipe connector of the element retainer, of the pipe body of the end cap on the inner pipe of the adapter part, and of the edge part of the ring washer of the adapter part on the annular jacket surface of the end cap, can be formed by O-rings.
The sealing of the outside of the sleeve body of the adapter part relative to the inside wall of the element retainer affords the additional advantage that the otherwise conventional sealing of the outer periphery of the end cap relative to the inside of the housing is dispensed with and instead the sealing between the filtered side and the unfiltered side is effected with much smaller seal diameter, as a result of which reduced installation forces and thus a simplification result during the installation and removal of filter elements.
The subject matter of the invention is also a filter element which is intended for use in the filter device according to the invention and which has the features indicated in claim 15. Advantageous configurations of this filter element are the subject matter of the following dependent claims.
The invention is detailed below using one exemplary embodiment, which is shown in the drawings.
The device has a filter housing 1 with a hollow cylindrical main part 3 and a bottom part 5 which adjoins its bottom side. On the upper end, a housing cover 7 which can be removed for installing and removing a filter element 9 is screwed to the main part 3. Between the outside of the filter element 9 held in the housing 1 and the inside wall of the housing 1, there is an intermediate space which in the filtration process forms the filtered side 13. A fluid outlet which leads from the filtered side 13 out of the housing 1 for the drainage of the cleaned fluid is designated as 44 in
The ends of the filter element have in the conventional manner end caps 19 and 21 which form enclosures for the filter medium 11 and the support pipe 15. The end caps 19, 21 moreover form an enclosure for a hydrophobic screen 23 which in the form of an hollow cylinder surrounds the outside of the filter medium 11 at a distance by which a separating region 25 in the form of a separating space is formed between the hydrophobic screen 23 and the filter medium 11. In order to effect water separation, as is conventional in these fuel filters, a filter medium 11 is used which acts to coagulate the water entrained by the fuel so that water in droplet form precipitates out of the fluid and sinks down in the separation space 25 since the screen 23 is impermeable to coagulated water droplets.
The lower end cap 21, by means of which the filter element 9 in the operating position in the housing 1 can be secured in the housing I is designed such that it interacts with a fluid-conducting device for filtration operation. For this purpose, the end cap 21 has a pipe section 27 which forms a passage 29 for the inflow of fluid to the inner filter cavity 17. The pipe section 27 extends from the end cap bottom 31 which forms a flat support surface for the lower edge of the filter medium 11, both axially upward into the filter cavity 17 and also downward axially from the end cap bottom 31. As an outer peripheral edge, the end cap bottom 31 has an annular body 33, and gaps in the end cap bottom 39 which are aligned to the separating region 25 form water passages 35 for the exit of water from the separation space 25. The annular body 33 of the end cap 21 is shaped such that above and below the end cap bottom 31, annular jacket surfaces 37 are formed whose upper surface adjoins the hydrophobic screen 23 and whose lower annular jacket surface 37 forms a sealing surface for the interaction with a peripheral edge part 39 of an adapter part 41 which is used as the fluid-conducting device.
The adapter part 41, in its operation as a fluid-conducting device, forms fluid paths which are separated from one another, of which a first fluid path leads from the fluid inlet 43 of the housing 1 via the passage 29 to the filter cavity 17 which forms the unfiltered side 14, and the second fluid path leads via the water passages 35 out of the separating region 25 as far as the water collecting space 45 in the bottom part 5 of the housing. Instead of an independent adapter part 41, its connection geometry can also be an integral component of the lower end cap 21 of the filter element 9.
In this example, the element retainer 47, on which the filter element 9 can be secured via the adapter part 41 which is used as a connecting or intermediate element, has a pipe connector 49 which forms the single connection between the main housing part 3 which holds the filter element 9 and the water collecting space 45. The adapter part 41 has a sleeve body 51 which can be accommodated in the pipe connector 49 and which on the lower end 53 is open to the water collecting space 45 and on the top end undergoes transition into a ring washer 55 which extends in a radial plane and which on its peripheral edge forms the edge part 39 which projects axially upward and which is sealed to the inner annular jacket surface 37 of the annular body 33 of the end cap 21. In this way, proceeding from the water passages 35 a water channel 57 is formed between the end cap bottom 31 and the washer 55 of the adapter part 41 which continues along the inside of the sleeve body 51 as far as the water collecting space 45 and forms the second fluid path.
For the formation of the first fluid path from the fluid inlet 43 of the housing 1 via the adapter part 41 and the passage 29 of the end cap 31 into the inner filter cavity 17, the adapter part 41 has an inner pipe 59 which extends concentrically within the sleeve body 51 at a distance from its inside wall so that a space remains open for the water channel 55 on the outside of the inner pipe 59. The pipe section 27 with the passage 29 sealingly engages the inner pipe 59.
The sleeve body 51, in the vicinity of its lower end and in the vicinity of the upper ring washer 55, has a radially projecting annular part 61 and 63 respectively on which sealing takes place relative to the inside wall of the pipe connector 49 of the element retainer 47. The radially projecting annular parts 61, 63 between the pipe connector 49 and the sleeve body 51 form an annulus 65, from which a feed channel, which is not visible in the drawings, leads to the fluid inlet 43 which forms the inlet part of the first fluid path. For the continuation of this fluid path via the inner pipe 49 of the adapter part 41 as far as the filter cavity 17 which forms the unfiltered side 14, there is a connecting channel 69 which branches off from the closed end 67 of the inner pipe 59 and which leads into the annulus 65 so that the first fluid path continues from the fluid inlet 43, the annulus 65, and the connecting channel 69 of the inner pipe 49 as far as to the passage 29 of the end cap 21. The inner pipe 59 is connected preferably integrally to the sleeve body 51 via the connecting channel 69 and/or via connecting bridges which are not detailed.
As is apparent from the figures, the sealings of the annular parts 61, 63 of the sleeve body 51 take place on the pipe connector 49 of the element retainer 47 as well as of the pipe section 27 of the end cap 21 on the inner pipe 59 of the adapter part 41 and likewise of the edge part 49 of the ring washer 55 of the adapter part 41 on the annular jacket surface 37 of the end cap 21 by O-rings 71. In the sealing formed in this way, it is not necessary to seal the outer periphery of the end cap 21 of the filter element 9 relative to the inside of the housing 1.
The filter element 9 has the filter medium 11 which surrounds the inner filter cavity 17 and through which flow by the respective fluid which is to be filtered takes place for the filtration process, on the outer peripheral side of the filter medium 11 there being the water separation device 23 and the separating region 25 for separated water. The separating region 25 has at least one water passage 35, there being a passage 29 which forms the fluid connection to the inner filter cavity 17 of the filter element 9. Furthermore, the water passage 35 is separated from the passage 29 within the filter element 9 by means of the adapter-shaped fluid-conducting device 41.
On the lower end of the filter element 9, it has the end cap 21 which is provided to accommodate the filter medium 11 and which has the passage 29 which leads into the inner filter cavity 17 and the respective water passage 35, with the end cap 21 being fluid-connected in a sealed manner to the fluid-conducting device 41. When the filter element 9 which has been completed in this way is removed from the filter housing 1 after unscrewing the upper housing cover 7, for example, to replace a used filter element with a new element, the particulate dirt which has settled on the inside of the filter medium 11 as well as possible residues of unfiltered fluid remain on the unfiltered side 14 of the filtration assembly, and it is furthermore ensured that separated water that is still present in the separating region 25 travels via the respective passage site 35 further in the direction of the water collecting space 45 and in this respect does not inadvertently reach the unfiltered side 14 nor the filtered side 13 either.
The water collecting space 45 which is located on the bottom side of the filter housing 1 is surrounded by a collection housing which can be screwed onto the filter housing 1 from underneath. The collection housing consists preferably of a transparent, cup-shaped plastic, and, as is especially apparent from
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2010 010 304.7 | Mar 2010 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP11/01014 | 3/2/2011 | WO | 00 | 10/17/2012 |
