fuel filter

Abstract

The invention relates to a fuel filter (1) for filtering fuel for a motor vehicle. The fuel filter (1) comprises a housing (2) and an outlet nozzle (4). The fuel filter (1) also includes a filter element (3) with a filter body (7) and two end discs (8a, 8b). The filter element (3) further comprises a sealing tube (10) which seals against one of the end discs (8a) on one side and against the outlet nozzle (4) on the other.

Description

[0001] The invention relates to a fuel filter for filtering a fuel for a motor vehicle, comprising a housing and a filter element according to the preamble of claim 1.

[0002] A fuel filter typically consists of a housing and a filter element located within the housing. The filter element comprises a filter body made of a filter material and divides the housing into a clean side and a raw side. The fuel to be filtered flows within the housing from the raw side to the clean side, passing over the filter material of the filter body and being filtered. The filter element is designed to be replaceable. A disadvantage is that when the filter element is removed, the unfiltered fuel from the raw side can enter the clean side. This can contaminate the already filtered fuel with the unfiltered fuel.

[0003] The object of the invention is therefore to provide an improved or at least alternative embodiment of a fuel filter of the generic type, in which the described disadvantages are overcome.

[0004] This problem is solved according to the invention by the subject matter of independent claim 1. Advantageous embodiments are the subject matter of the dependent claims.

[0005] The present invention is based on the basic idea of ​​relocating a sealing point between the raw side and the clean side in such a way that the fuel cannot reach the clean side when the filter element is removed.

[0006] The fuel filter according to the invention is designed for filtering fuel for a motor vehicle. The fuel filter comprises a housing having a first longitudinal end and a second longitudinal end with respect to its longitudinal center axis. Furthermore, the fuel filter comprises a filter element having a first end disc, a second end disc, and a hollow cylindrical filter body. The filter body is arranged between the axially aligned end discs. The filter element is arranged coaxially in the housing, with the first end disc of the filter element facing the first longitudinal end of the housing and the second end disc of the filter element facing the second longitudinal end of the housing. The fuel filter also comprises a hollow cylindrical outlet nozzle, which is arranged coaxially in the housing and in the filter element.The outlet nozzle is fluidically connected to an outlet of the housing at the first longitudinal end and has an inlet opening facing away from the first longitudinal end of the housing. According to the invention, the filter element comprises a sealing tube which is arranged coaxially within and to the filter body. On one side, the sealing tube is fluid-tightly connected to the first end plate, and on the other side, the sealing tube rests fluid-tightly against the outlet nozzle at a distance axially from the first end plate.

[0007] In a conventional fuel filter, the filter element, with its first end disc, forms a fluid-tight seal against the outlet nozzle. This creates a fluid separation between the clean side and the pipe side of the conventional fuel filter at a sealing point formed between the first end disc of the filter element and the outlet nozzle. When the filter element is removed during replacement in a conventional fuel filter, the unfiltered fuel settles at the first longitudinal end and can flow around the outlet nozzle above the sealing point. After the new filter element is inserted, the area above the sealing point is then on the clean side, and the unfiltered fuel reaches the clean side. In the fuel filter according to the invention, the filter element, with its sealing tube, forms a sealing seal against the outlet nozzle.This design fluidically separates the clean side and the pipe side at a sealing point formed between the sealing tube and the outlet nozzle. Unlike conventional fuel filters, the sealing point here is axially spaced from the first end plate or the conventional sealing point. When the filter element is removed from the fuel filter according to the invention for replacement, the unfiltered fuel settles at the first longitudinal end. The unfiltered fuel can only flow around the outlet nozzle in an area below the sealing point. After the new filter element is inserted, however, this area remains on the pipe side, and the unfiltered fuel cannot reach the clean side. Therefore, the filtered fuel cannot be contaminated by the unfiltered fuel when the filter element is replaced.

[0008] The filter element can, in particular, comprise the filter body made of a filtering material – such as nonwoven fabric and / or paper. The filter body can be axially bonded to the end discs on both sides – for example, by gluing. The sealing tube and / or the first end disc and / or the second end disc and / or the outlet nozzle and / or the housing can be made of plastic. The sealing tube can be bonded to the first end disc, preferably by welding. One side of the fuel filter can extend around the filter body, between the first end disc and the first longitudinal end of the housing, and between the outlet nozzle and the sealing tube, from the first end disc to a sealing point formed between the sealing tube and the outlet nozzle.A clean side of the fuel filter can extend within the filter body as well as between the filter body and the sealing tube.

[0009] The sealing tube can form a fluid-tight seal at the outlet nozzle between the outlet nozzle's inlet opening and the first end plate and / or the first longitudinal end of the housing. In other words, the outlet nozzle can protrude axially from the filter element's sealing tube, facing away from the first longitudinal end of the housing. The outlet nozzle's inlet opening can be located outside the filter element's sealing tube. This allows the inlet opening to be situated within an interior space of the filter element, enabling the filtered fuel to flow from this interior space through the inlet opening into the outlet nozzle and onward to the housing outlet.

[0010] The sealing tube can have at least one rib circumferentially around its longitudinal center axis on the side facing the outlet nozzle, and this rib can then abut the outlet nozzle in a sealing manner. Alternatively or additionally, the outlet nozzle can have at least one rib circumferentially around its longitudinal center axis on the side facing the sealing tube, and this rib can then abut the sealing tube in a sealing manner. The respective rib can, in particular, improve the sealing connection between the sealing tube and the outlet nozzle. It is conceivable that the sealing tube has exactly two axially spaced ribs and the outlet nozzle has exactly one rib. The rib of the outlet nozzle can then be arranged axially between the two ribs of the sealing tube.

[0011] The axial height of the outlet nozzle can be more than 10%, preferably more than 30%, and particularly preferably more than 50%, of the axial height of the housing. The outlet nozzle can extend from the first longitudinal end of the housing to the second longitudinal end of the housing, particularly across an axial center of the housing. Alternatively or additionally, the axial height of the sealing tube can be more than 10%, preferably more than 30%, and particularly preferably more than 50%, of the axial height of the filter body. In particular, the sealing tube can extend from the first end disc to the second end disc of the filter element at least to the axial center of the filter body. This allows a sealing point between the sealing tube and the outlet nozzle to be positioned sufficiently far from the first longitudinal end of the housing, thereby reliably preventing contamination of the filtered fuel with unfiltered fuel when changing the filter element.

[0012] The housing can have a first housing part at its first longitudinal end and a second housing part at its second longitudinal end. The first and second housing parts can be detachably connected to each other at a joint circumferentially around the longitudinal center axis of the housing, for example, by screws. The sealing tube can then extend axially from the first end plate to the second end plate of the filter element across this joint. Therefore, if the joint is loosened and the filter element is removed for replacement, the unfiltered fuel can only fill the first housing part up to an edge of the first housing part or up to the loosened joint. Since the sealing tube extends axially across this joint, the unfiltered fuel cannot flow around a sealing point between the sealing tube and the outlet nozzle.This reliably prevents the filtered fuel from becoming contaminated with unfiltered fuel when changing the filter element.

[0013] The filter element can have a hollow cylindrical support frame with radial flow through it. The support frame can be arranged coaxially with the filter body within the filter body. The support frame can be positioned between the filter body and the sealing tube such that the filter body is supported radially inwards by the support frame, and the support frame is supported by the sealing tube. The filter body can rest against the support frame and be bonded to it – for example, by adhesive. A gap between the support frame and the sealing tube can be, for example, 0.5 mm. The support frame can be made of, for example, plastic. The support frame can be connected to the end plates of the filter element – ​​for example, by bonding. This can increase the rigidity of the filter element and reduce the risk of its collapse.

[0014] Between the support frame and the sealing tube and / or between the support frame and the filter body, axially flowable channels can be formed to allow the fuel to flow through. The fuel, flowing axially through the filter body relative to the sealing tube, can be directed axially through these channels to the inlet opening of the outlet nozzle.

[0015] In the context of the present invention, the terms "axial," "radial," "coaxial," and "circumferential" always refer to the longitudinal center axis of the housing. In the fuel filter, the housing and / or the filter body and / or the support frame and / or the sealing tube and / or the outlet nozzle can be aligned coaxially with one another. The phrase "within a hollow cylindrical element" is synonymous with the phrase "in a cavity formed within the hollow cylindrical element."

[0016] Further important features and advantages of the invention will become apparent from the dependent claims, the drawings and the associated description of the figures based on the drawings.

[0017] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or on their own, without leaving the scope of the present invention.

[0018] Preferred embodiments of the invention are shown in the drawings and are explained in more detail in the following description, wherein identical reference numerals refer to identical or similar or functionally identical components.

[0019] They show, schematically, each one Fig. 1 a sectional view of a fuel filter according to the invention; Fig. 2 a sectional view of the fuel filter according to the invention during the replacement of a filter element; Fig. 3 a sectional view of the filter element of the fuel filter according to the invention; Fig. 4 a sectional view of a sealing tube of the filter element of the fuel filter according to the invention; Fig. 5 a sealing point of the fuel filter according to the invention.

[0020] Fig. Figure 1 shows a sectional view of a fuel filter 1 according to the invention for filtering fuel for a motor vehicle. The fuel filter 1 comprises a housing 2, a hollow cylindrical filter element 3, and a hollow cylindrical outlet nozzle 4. Fig. 1 The fuel filter 1 is aligned in an operational manner with respect to the force of gravity G.

[0021] The housing 2 has a first longitudinal end 2a and a second longitudinal end 2b, which are axially spaced apart from each other with respect to a longitudinal center axis LMA of the housing 2. The housing 2 also comprises a first housing part 5a with the first longitudinal end 2a and a second housing part 5b with the second longitudinal end 2b, which are detachably connected to each other at a circumferential connection point 6 – here screwed together.

[0022] The filter element 3 comprises a hollow cylindrical filter body 7, a first end plate 8a and a second end plate 8b, a hollow cylindrical support frame 9, and a sealing tube 10. The sealing tube 10 is located within the support frame 9, and the support frame 9 is located within the filter body 8. The filter body 7, the support frame 9, and the sealing tube 10 are arranged coaxially with each other and axially between the end plates 8a and 8b, which are oriented perpendicular to the longitudinal center axis (LMA). The filter body 7 and the support frame 9 extend over the entire axial height of the filter body 7 and are connected to the end plates 8a and 8b. The filter body 7 is supported radially inward by the support frame 9, and the support frame 9 is supported radially inward by the sealing tube 10. The sealing tube 10 is connected to the first end disc 8a - for example by welding - and extends approximately over an axial center of the filter body 7.The filter element 3 is arranged coaxially in the housing 2, so that the filter body 7, the support frame 9 and the sealing tube 10 are aligned coaxially to the housing 2.

[0023] The outlet nozzle 4 is located partially within the sealing tube 10 of the filter element 3 and is aligned coaxially with the housing 2 and the filter element 3. The outlet nozzle 4 is fluidically connected at its first axial end 4a to an outlet 11 of the housing 2 formed at its first longitudinal end 2a, and protrudes from the sealing tube 10 at its second axial end 4b. At the second end 4b, the outlet nozzle 4 has an inlet opening 12 that leads from an interior space 17 of the filter element 3 into the outlet nozzle 4. The sealing tube 10 rests against the outside of the outlet nozzle 4, forming a circumferential sealing surface 13 between the sealing tube 10 (or the filter element 3) and the outlet nozzle 4. A vent pipe 14 of the fuel filter 1 is also arranged coaxially within the outlet nozzle 4.The vent pipe 14 connects the outlet 11 of the housing 2 with the environment at the second longitudinal end 2b of the housing 2.

[0024] The fuel filter 1 is designed to filter the fuel. The fuel flows onto a raw side 15a of the housing 2 and through the filter body 7 of the filter element 3 onto a clean side 15b of the housing 2. The raw side 15a of the housing 2 comprises a region surrounding the outside of the filter element 3 and a region located between the first longitudinal end 2a of the housing 2 and the end plate 8a of the filter element 3. Furthermore, the raw side 15a comprises a region located between the sealing tube 10 and the outlet nozzle 4, extending axially from the first end plate 8a to the sealing point 13.

[0025] Fig. Figure 2 shows a sectional view of the fuel filter 1 according to the invention during the replacement of the filter element 3. Here, the second housing part 5b is detached from the first housing part 5a at the connection point 6, and the filter element 3 is removed from the housing 2. Fig. 2. The fuel filter 1 is aligned in a manner appropriate for operation with respect to the force of gravity G.

[0026] When changing fuel filter 1, filter element 3 is removed – as in Fig. As shown in Figure 2, the unfiltered fuel settles downwards in the first housing part 5a. The sealing point 13 is designed such that the unfiltered fuel can only flow around the outlet nozzle 4 in the area below the sealing point 13. When the new filter element 3 is inserted into the housing 2 – as shown in Figure 2 – the unfiltered fuel settles downwards in the first housing part 5a. The sealing point 13 is designed such that the unfiltered fuel can only flow around the outlet nozzle 4 in the area below the sealing point 13. Fig. As shown in Figure 1, the area of ​​the outlet nozzle 4 around which the unfiltered fuel flows is located on the raw side 15b. This prevents the unfiltered fuel from reaching the clean side 15b even when the filter element 3 is changed, thus protecting the filtered fuel from contamination.

[0027] Fig. Figure 3 shows a sectional view of the filter element 3 of the fuel filter 1 according to the invention. As can be seen particularly well here, the sealing tube 10 does not extend over the entire axial height of the filter body 7. It can also be seen that the support frame 9 comprises several radial openings 16. Through the openings 16, the fuel filtered in the filter body 7 can enter the interior 17 of the filter element 3 and flow via the inlet opening 12 of the outlet nozzle 4 into the outlet nozzle 4 and to the outlet 11 of the housing 2.

[0028] Fig. Figure 4 shows a sectional view of the sealing tube 10 of the filter element 3 of the fuel filter 1 according to the invention. As shown in Fig. As is particularly evident in Figure 4, the sealing tube 10 has two circumferential ribs 18 that are axially spaced apart from each other. The ribs 18 are formed on the sealing tube 10 facing the outlet nozzle 4.

[0029] Fig. Figure 5 shows the sealing point 13 in the fuel filter 1 according to the invention. As can be seen here, the outlet nozzle 4 includes a circumferential rib 19, which is arranged axially between the ribs 18 of the sealing tube 10. The ribs 18 and 19 ensure a particularly reliable seal of the clean side 15b.

Images