Title of Invention

A FILTER INSERT FOR A LIQUID FILTER FOR FUELS

Abstract

The invention proposes a filter insert (10) for a liquid filter (21) for fuels, in which an outwardly projecting, tubular connection piece (17) is designed in such a way that, in addition to the holding function, it is also responsible for the sealing function. On the outer circumference of the connection piece (17), the filter insert (10) has a fir-tree profile (18) which, after the connection piece (17) has been inserted in the axial direction into a mating connection opening (24) in a connection module (22), is responsible for internal sealing between dirty side and clean side. The exchangeable filter insert (10) can easily and quickly be fitted to a cup-like housing (26) on a connection module (22) and allows a simple, inexpensive design.

Full Text

Prior art The invention is based on a filter insert for a liquid filter for fuels. DE-B 14 61 451 has disclosed a filter insert of this type for a liquid filter, in which a filter element which is of hollow-cylindrical design and through which medium can flow in the radial direction is arranged between sealing end plates. While one end plate is closed and produced from plastic, the other, open end plate has a central passage, the edges of the filter element being secured in a sealed manner in the plastic end plate This open end plate is integrated in a metallic base plate which, as central passage, has a tubular connection piece which projects outward. To secure the filter insert to a connection module, the tubular connection piece has an external screw thread, and the connection module has a mating internal screw thread. Furthermore, an additional sealing ring is arranged on the connection piece for forming an inner seal between dirty side and clean side. Therefore, for the securing and sealing functions, the filter insert requires a complex screw-thread arrangement and, as additional component, a seal, so that structural outlay is increased. A further drawback is that the open plastic end plate is also part of the base plate, which has external inlet openings and furthermore bears an additional sealing ring for external sealing, with the result that the base plate itself forms part of the filter housing. This design is relatively unsuitable for a simple and inexpensive filter insert. Furthermore, DE 196 04 371 Al has disclosed a filter insert in which the open end cap has a central passage with an outwardly projecting, tubular connection piece. In one embodiment of the filter insert, the outer side of the connection piece has an annular groove for receiving an 0-ring, while a second embodiment has an intemal screw thread in the connection piece. While in the former case an additional 0-ring is required for intemal sealing, in the latter case the end cap has a metallic threaded ring which is injection-molded into its connection piece; the intemal sealing is not dealt with in more detail. Furthermore, however, the document fails to give any more detailed information about the installation of the filter insert in housing. Advantages of the invention Accordingly the present invention provides a filter insert for a liquid filter for fuels, having a substantially hollow-cylindrical filter element, in particular made from filter material which has been folded into a star shape, which filter element is arranged in a sealed manner between end-side end plates and through which filter element the liquid which is to be filtered can flow in the radial direction with respect to the longitudinal axis of the filter insert, the first end plate being of closed design, while the other, second end plate has a central passage which runs through an outwardly projecting, tubular connection piece, to which connection means for securing the filter insert to a connection module and sealing means for providing an inner seal between a dirty side and a clean side are arranged, characterized in that the connection piece, on its outer circumference, has a fir-tree profile with ribs, which is responsible for the functions of the connection means and the sealing means, with the result that the centrally arranged connection piece of the filter insert can be plugged longitudinally into a connection opening in a connection module. The filter insert for a liquid filter, on the other hand, has the advantage of allowing a particularly simple and inexpensive design. The fir-tree profile on the tubular connection piece can easily be produced at the same time and can fulfill the functions of securing the filter insert and internal sealing together, so that in this case there is no need for an additional sealing ring. This profile on the tubular connection piece also makes it easy to fit the filter insert by rapidly inserting it in the axial direction, and likewise allows easy removal by pulling it out. The fir-tree profile ensures good internal sealing, the tightness of which withstands both pulsating pressure tests and shock tests. This internal sealing is also extremely stable in the event of temperature changes and, moreover, allows good storage of the filter insert. Forming the end plates from combustible plastic and the filter element from paper results in a filter insert which, once it is dirty, can readily be burnt and can therefore be utilized further for thermal purposes. The measures as described herein allow advantageous refinements and improvements to the filter insert. The embodiments as described herein further promote the simple and inexpensive design. An embodiment, allowing the filter insert to be fitted into a liquid filter in a simple manner and therefore allowing advantageous installation in a housing at a connection module, is particularly advantageous. Further advantageous configurations of a liquid filter of this type with a filter insert according to the invention are described herein. Furthermore, embodiments as described herein are expedient if the filter insert is installed in a line filter. Drawing Exemplary embodiments of the invention are illustrated in the drawing and explained in more detail in the description which follows. Figure 1 shows a longitudinal section through a filter insert for a liquid filter in simplified form, figure 2 shows the filter insert shown in figure 1, installed in a liquid filter on a reduced scale, in simplified form and as a longitudinal section on II-II in figure 3, and figure 3 shows a view of the liquid filter shown in figure 2 from below; figure 4 shows, as a partial longitudinal secfion, the filter insert in a line filter. Description of the exemplary embodiments Figure 1 shows a longitudinal section through a filter insert 10 for a liquid filter in simplified form, as used in fuel filters. The filter insert 10 has a filter element 11 which is of hollow-cylindrical design, consists of a filter paper folded in a star shape and the zigzag edges of which are secured in a sealed manner in end-side end plates 12, 13 made from plasfic. The lower end plate 12 is closed and designed as a _ planar, circular plate, while the upper end plate 13 is designed to be open by virtue of having a central passage 14. The star-shaped filter element 11 is therefore provided for medium to flow through it in the radial direction, generally from the inside outward. The edges which run in a star shape at the end sides of the filter element 11 are cast into the end plates 12 and 13, which consist of plastic, so that a sealed and secure connection is formed. As shown in more detail in figure 1, the open end plate 13 is of two-part structure and comprises an outer ring 15, which is connected to the filter element 11, and an inner part 16, which is of rotationally symmetrical design and has the central passage 14 . The inner part 16 has a tubular connection piece 17 which projects outward from the filter insert 10 and on its outer circumference has a fir-tree profile 18. This profile is in this case formed from two annular ribs 19 which run at a distance from one another and are arranged close to the end of the connection piece 17. This profile 18 has two functions, namely on the one hand as a connection means for securing the filter insert 10 in a connection module (not shown in more detail) and secondly as a sealing means for internal sealing in the liquid filter between a dirty side and a clean side. The inner part 16 is of simple, stable and inexpensive structure and can be produced from the same plastic as the outer ring 15. A plastic which is not affected by fuel, such as for example polyamide, can advantageously be used for this purpose. If the inner part 16 is produced from plastic, the fir-tree profile 18 can be molded on relatively easily. Figure 2 shows a simplified illustration of a longitudinal section through a liquid filter 21 in which the filter insert 10 shown in figure 1 is fitted, the filter insert 10 being illustrated on a reduced y scale. The liquid filter 21 has a connection module 22 in which a first connection opening 23 for the inlet and a second connection opening 24 for the outlet are formed. Both connection openings 23, 24 lie close together in a planar connection surface 25 of the connection module 22. The diameter and depth of the second connection opening 24 for the outlet are such that this opening can receive the connection piece 17 with its fir-tree profile 18 in a tightly fitting manner. The filter insert 10 can easily and quickly be fitted into the second connection opening 24 by simply inserting its connection piece 17 in the axial direction. After the filter insert 10 has been mounted on the connection module 22, the connection piece 17, with its ribs 19, is responsible both for a holding function and a sealing function. The filter insert 10 is then covered by a cup-shaped housing 26, the housing 26 bearing against the connection surface 25 by means of an annular flange 27 which is formed at its open end. Four eyelets 28, at which the housing 26 is secured to the connection module 22 with the aid of screw connections 29, are distributed uniformly over the circumference of the annular flange 27. An annular groove 31, which receives an 0-ring 32 which is used for external sealing, is formed in the annular flange 27. Of course, the connection openings 23 and 24 lie within the area which is covered by the housing 26. Furthermore, the axial length of the housing 26 is such that the lower end plate 12 can be supported on the housing, so that the filter insert 10 is axially fixed in the housing 26. As shown in more detail in figure 3, which illustrates a view of the liquid filter 21 shown in figure 2 from below, to remove the dirty filter insert 10, the four screw connections 29 are released and the housing 26 is removed. Then, the dirty filter insert 10 can quickly and easily be pulled out by means of an axial movement and can be replaced with a new filter insert. The liquid filter 21 with the exchangeable filter insert 10 therefore leads to low levels of waste, since the filter insert 10 consists only of combustible material, such as polyamide and filter paper, and can therefore be utilized for heating purposes. As shown in more detail by figure 2 in conjunction with figure 3, the structure of the liquid filter 21 allows a simple and inexpensive design of the housing 26. If necessary, the housing 26 may expediently be produced from metal, in which case the screw connections 29 allow perfect, secure and sealed attachment to the connection module 22. In this case, the screw connections 29 are also responsible for a centering function for the housing 26, so that the holding function and sealing function of the tubular connection piece 17 are not impaired. In this case, the filter insert 10 may be supported at the bottom of the cup-shaped housing 26, so that it is also fixed in the axial direction. Furthermore, if necessary it is also readily possible for the housing 26 to be produced from plastic, in which case a polyamide reinforced with up to 25% of glass fibers is advantageously suitable. In the case of a housing 26 which is produced from plastic, the securing may take place in the same way using the screw connections 29; on the other hand, it is possible, in the case of a plastic housing 26, to provide suitable mating bores in the annular flange 27, so that self-tapping screws can even be used for securing purposes. The way in which the liquid filter 21 operates is explained as follows: the fuel which is to be cleaned moves past the first connection opening 23 at the outer circumference of the upper, second end plate 13, on to the dirty side 33 of the liquid filter 21. The fuel then flows through the filter element 11 in the radial direction and reaches the clean side 34 in cleaned form. The cleaned fuel can flow out via the passage 14 to the second connection opening 24 in the connection module 22. The two annular ribs 19 in the fir-tree profile 18 are responsible not only for the holding function but also for the sealing function, so that internal sealing between clean side 34 and dirty side 33 takes place without an additional component. Figure 4 shows a simplified illustration of a partial longitudinal section through a liquid filter 40 in which the filter insert 10 shown in figure 1 is installed, the filter insert 10 being illustrated on a reduced scale. The liquid filter 40 is in this case designed as a line filter which has a housing 41 made from aluminum and in which a cover 42 and a cup-shaped housing part 43 are connected to one another in a sealed and fixed manner. The two connection pieces 44 on the cover 42 and 45 on the housing part 43 lie coaxially. The cover 42 in this case performs the function of the connection module, and for this purpose on its inner side has a matching connection opening 46, which lies coaxially with respect to the connection piece 44 and into which the connection piece 17 of the filter insert 10 is fitted, the fir-tree profile 18 being responsible for both the holding function and the sealing. Of course, modifications to the embodiments shown are possible without departing from the basic idea of the invention. Although a circular design of the filter insert 10 is particularly advantageous, the fact that the filter insert 10 is fitted and removed in the axial direction means that the tubular connection piece 17 may also have a different cross-sectional shape, for example may be square, rectangular or triangular or of any other desired shape, should this prove expedient for the installation conditions. The number, shape and design of the ribs 19 in the fir-tree profile 18 can also be varied with regard to the holding and sealing functions which are to be fulfilled. The structural form of the housing 26 and the securing means 29 can also be modified without departing from the basic idea of the invention. For example, the filter insert can also be used in other housing filters, cartridge or box filters, line filters and also in disposable filters, especially since it requires fewer components and is easier to handle. Furthermore, as an alternative to the aluminum housing shown in figure 4, it is also possible to produce a housing from steel sheet or plastic. Also, the housings may be designed in such a way that the receiving opening for the connection piece of the filter insert is arranged in the other housing part, i.e. for example in the cup-shaped housing part. WE CLAIM: 1. A filter insert for a liquid filter for fuels, having a substantially hollow-cylindrical filter element, in particular made from filter material which has been folded into a star shape, which filter element is arranged in a sealed manner between end-side end plates and through which filter element the liquid which is to be filtered can flow in the radial direction with respect to the longitudinal axis of the filter insert the first end plate being of closed design, while the other, second end plate has a central passage which runs through an outwardly projecting, tubular connection piece, to which connection means for securing the filter insert to a connection module and sealing means for providing an inner seal between a dirty side and a clean side are arranged, characterized in that the connection piece (17), on its outer circumference, has a fir-tree profile (18) with ribs (19), which is responsible for the functions of the connection means and the sealing means, with the result that the centrally arranged connection piece (17) of the filter insert (10) can be plugged longitudinally into a connection opening (24) in a connection module (22). 2. The filter insert as claimed in claim 1, wherein the second end plate (13) with the tubular connection piece (17) consists of plastic, in particular polyamide. 3. The filter insert as claimed in claim 1 or 2, wherein the second end plate (13) with the tubular connection piece (17) is designed in the shape of a circular ring. 4. The filter as claimed in any one of claims 1 to 3, wherein the fir-tree profile (18) has at least two annular ribs (19). 5. The filter as claimed in any one of claims 1 to 4, wherein the second end plate (13) is responsible only for internal sealing (19) between dirty side (23) and clean side (24). 6. The filter insert as claimed in any one of claims 1 to 5, wherein the first end plate (12) consists of plastic and the filter element (11) consists of filter paper. 7. The filter insert as claimed in any one of claims 1 to 6, wherein the second end plate (13) is of two-part structure, having an annular inner part (16), which comprises the connection piece (17) with the profile (18), and an outer ring (15), which is fixedly connected to the inner part and holds the filter material (11) in a fixed and sealed manner, both parts consisting of plastic. 8. The filter insert as claimed in any one of claims 1 to 7, wherein its tubular connection piece (17) projects into an associated connection opening (24) in the connection module (22), the connecfion module (22) having an addifional connection opening (23) for the feed, and in that the filter insert (10) and the two connecfion openings (23, 24) in the connecfion module (22) are covered by a pot-shaped housing (26), which is secured in a sealed manner to the connection module (22) by means of its edge (27) which lies at the open end. 9. The filter insert as claimed in claim 8, wherein the filter insert (10) is internally supported on the housing (26) by means of its first end cap (12). 10. The filter insert as claimed in any one of claims 8 and 9, wherein the housing (26) is releasably secured to the connection module (22), in particular by screw connections (29), an inserted sealing ring (32) being responsible for sealing the interior of the housing (26) with respect to the outside. 11. The filter device as claimed in any one of claims 8 to 10, wherein the connection module (22) has a substantially planar mounting surface (25), into which the connection openings (23, 24) open out. 12. The filter insert as claimed in any one of claims 8 to 11, wherein the flange (27) of the housing (26) has an encircling annular groove (31) which accommodates the sealing ring (32). 13. The filter insert as claimed in any one of claims 8 to 12, wherein the housing (26) is secured to the connection module (22) with the aid of a plurality of screw connections (29) which are distributed along the circumference, the screw connections (29) centering the housing (26) relative to the connection module (22). 14. The filter insert as claimed in any one of claims 1 to 7, wherein its tubular connection piece (17) projects into an associated connection opening (46) in the connection module, which is designed as one of the parts of a two-part housing (41) oaf line filter (40). 15. The filter insert as claimed in claim 14, wherein the cover (42) of the housing (41) is used as the connection module. 16. The filter insert as claimed in claim 14 or 15, wherein the connection pieces (44, 45) on the cover (42) and on the cup-shaped housing part (43) and the connection piece (17) of the filter insert (10) and its associated receiving opening (46) are arranged coaxially with respect to one another. 17. The filter insert as claimed in any one of claims 14 to 16, wherein the line filter is designed as a disposable filter with a housing consisting of plastic. 18. A filter insert for a liquid filter for fuels, substantially as hereinabove described and illustrated with reference to the accompanying drawings.

Documents:

in-pct-2002-1165-che abstract-duplicate.pdf

in-pct-2002-1165-che abstract.jpg

in-pct-2002-1165-che abstract.pdf

in-pct-2002-1165-che claims-duplicate.pdf

in-pct-2002-1165-che claims.pdf

in-pct-2002-1165-che correspondence-others.pdf

in-pct-2002-1165-che correspondence-po.pdf

in-pct-2002-1165-che description (complete)-duplicate.pdf

in-pct-2002-1165-che description (complete).pdf

in-pct-2002-1165-che drawings-duplicate.pdf

in-pct-2002-1165-che drawings.pdf

in-pct-2002-1165-che form-1.pdf

in-pct-2002-1165-che form-19.pdf

in-pct-2002-1165-che form-26.pdf

in-pct-2002-1165-che form-3.pdf

in-pct-2002-1165-che form-5.pdf

in-pct-2002-1165-che pct.pdf