Fuel filter insert with a pre-filter element and a main filter element, as well as a fuel filter

Abstract

Fuel filter element (26) for a fuel filter (10), comprising: - a pre-filter element (28) and a main filter element (30), which are arranged one above the other in the direction of the longitudinal axis (34) of the fuel filter element (26), wherein at least one of the filter elements (28, 30) is permeable to fuel flow in a direction radial to the longitudinal axis (34), preferably from the outside to the inside;and- a flow channel (48) for the fuel pre-filtered by the pre-filter element (28), which is arranged in the axial direction between the pre-filter element (28) and the main filter element (30), wherein the flow channel (48) is directly bounded in the axial direction by mutually associated end disks (38, 40) of the pre-filter element (28) and the main filter element (30), characterized in that- the main filter element (30) has a water separation unit (60) for separating water contained in the fuel,- wherein the water separation unit (60) comprises a water separation gap (72) which is fluidically connected or connectable at one end to a water drain channel (74), wherein the water drain channel (74) extends at least sectionally through the pre-filter element (28) in the axial direction.;

Description

Technical field

[0001] The invention relates to a fuel filter insert with a pre-filter element and a main filter element, and to a fuel filter with such a fuel filter insert. State of the art

[0002] DE 10 2008 048 228 A9 discloses a fuel filter with a fuel filter element comprising a pre-filter element and a main filter element, which are arranged one behind the other in the axial direction along the longitudinal axis of the fuel filter. The fuel pre-filtered by the pre-filter element is pumped to the main filter element by means of a fuel pump arranged outside the filter housing.

[0003] From US Patent 3,900,400 B, a fluid filter with a filter housing is known in which two filter elements are arranged one above the other along the longitudinal axis of the fluid filter and can be replaced independently of each other. An inlet channel for the fluid is formed between the two filter elements, axially limited by an end plate of the lower of the two filter elements and by a housing clamping plate that is spring-loaded against the end plate. The housing clamping plate seals the upper of the two filter elements against a housing cover of the filter housing.

[0004] EP 0 852 158 A1 shows a fuel filter with two fluidically connected filter elements arranged one behind the other, which are arranged one above the other in the direction of the longitudinal axis of the fuel filter.

[0005] WO 2006 / 070221 A1 shows another fuel filter with a pre-filter element and a main filter element arranged concentrically to the longitudinal axis of the fuel filter.

[0006] Similar fuel filters are known from DE 20 2006 004 527 U1 and EP 1 485 605 B1.

[0007] The object of the invention is to provide a fuel filter insert with a pre-filter element and a main filter element, as well as a fuel filter with a fuel filter insert, which, with a compact and simplified design, enable further simplified handling and are also cost-effective to manufacture. Disclosure of the invention

[0008] The problem relating to the fuel filter element is solved by a fuel filter element according to claim 1. The fuel filter according to the invention has the features specified in claim 10.

[0009] The pre-filter element and the main filter element of the fuel filter cartridge reliably remove impurities from the fuel. The pre-filter element can advantageously be designed as a coarse filter for removing larger particulate contaminants, and the main filter element as a fine filter for removing smaller particulate contaminants from the fuel. In this respect, the filter media of the pre-filter and the main filter element can differ, particularly in their pore size. Furthermore, the fuel filter cartridge according to the invention can be implemented with a more compact design overall. This is achieved by the fact that the two corresponding end discs of the two filter elements, i.e.,Because the lower end disc of the main filter element and the upper end disc of the pre-filter element directly define the flow channel in the axial direction, the overall design of the fuel filter element is simplified. This allows for particularly cost-effective manufacturing of the fuel filter element. Furthermore, handling the fuel filter element during both installation and removal within the filter housing of a fuel filter is further simplified.

[0010] For particularly easy and safe replacement of the pre-filter and main filter elements, the corresponding end plates of the pre-filter and main filter elements, which define the flow channel, can be connected to each other for joint removal of the main and pre-filter elements, preferably formed as a single piece. Furthermore, this allows for a simplified implementation of a predetermined flow channel geometry as well as reliable positioning of the end plates within the filter housing relative to a fuel outlet of the filter housing. The two end plates can, in particular, be manufactured as a single injection-molded plastic part. This offers further cost and manufacturing advantages.

[0011] The pre-filter and the main filter element can each have a filter medium arranged in a ring around the longitudinal axis of the fuel filter element. The filter medium is preferably supported on the inside by a grid-shaped support tube to prevent collapse of the filter medium when flowing through it from radially outside to radially inside. The filter media can each be designed as a star-shaped pleated filter bellows.

[0012] According to one embodiment of the invention, the two end discs are connected to each other by one or more spacer elements, which are arranged between the two end discs and attached to both end discs, in particular by integral part thereof. It is understood that the flow channel must not be completely obstructed in the radial direction by the spacer element(s).

[0013] The two end discs of the pre-filter and main filter elements, which define the flow channel, can each have a (radial) sealing element to ensure a reliable seal between the flow channel and the fuel filter housing. The sealing element is advantageously made of a (fuel-resistant) elastomer. Furthermore, the sealing element can compensate for manufacturing tolerances of the fuel filter element / filter housing or for contaminants adhering to the inside of the filter housing.

[0014] According to the invention, the main filter element can include a water separation unit for separating water contained in the fluid. This allows a combustion engine or fuel injection system powered by the fuel to be reliably protected from potentially harmful water content in the fuel.

[0015] The water separation unit of the main filter element preferably comprises a water separation gap that is fluidically connected at one end to a water drain channel extending axially, at least partially, through the pre-filter element. The water separated from the fuel can be discharged via the water drain channel and thus, for example, fed into a water collection chamber of the filter housing of a fuel filter. This allows the fuel filter element to be designed particularly compactly, enabling its use even in filter housings with limited installation space. The water separation gap can be arranged, in particular, between a filter medium of the main filter element and a perforated tube of the main filter element that functions as a final separator.

[0016] The water drainage channel is preferably radially bounded on the outside by a wall element attached, and in particular integrally formed, on the end plate of the main filter element that defines the flow channel. In this case, the wall element projects axially away from the main filter element and extends at least partially through the pre-filter element. Furthermore, the wall element can separate a low-pressure area of ​​the fuel filter element, encompassing the pre-filter element, from a high-pressure area of ​​the fuel filter element, encompassing the main filter element and the water separator unit. The wall element, being integrally formed with the end plate of the main filter element, allows for a more economical and simplified manufacturing process for the fuel filter element.

[0017] For maximum water separation efficiency, the water separation unit can include a coalescing medium, which is preferably arranged fluidically downstream of the filter medium of the main filter element. The coalescing medium can be single- or multi-layered, as required.

[0018] In a preferred embodiment, the aforementioned wall element, together with an end disc of the pre-filter element pointing away from the main filter element (i.e., the lower end disc of the pre-filter element), defines a receiving gap that is provided for the sealing reception of a housing or water outlet nozzle of a filter housing. The lower end disc of the pre-filter element, as well as the wall element, can each be provided with an elastomeric sealing element. Preferably, the elastomeric sealing elements have sealing surfaces oriented radially opposite each other.

[0019] As an alternative to forming a receiving gap, the wall element can be tightly connected to the lower end plate. In this case, sealing at a housing or water drain connection can be achieved, for example, via a sealing element arranged radially inside the wall element.

[0020] The fuel filter according to the invention comprises a filter housing and a fuel filter element as described above, which is arranged in the filter housing. The fuel filter element seals against the inside of the filter housing with its two end plates, which define the flow channel. The sealing contact of the fuel filter element with the filter housing can be axial or radial. A lateral fuel outlet is formed on the filter housing, through which the flow channel can be fluidically connected to a fuel pump in order to pump the fuel, pre-filtered by the pre-filter element, to the main filter element via a fuel inlet of the filter housing, preferably located laterally on the filter housing. The fuel filter can be implemented with high filtration performance in a compact design with a structurally simple filter housing. This offers cost advantages.

[0021] It is understood that the filter housing must be designed to allow for the replacement of the fuel filter element. For this purpose, the filter housing preferably has a filter bowl with a (single) insertion opening for the fuel filter element, which can be closed by means of a housing cover. The housing cover can be screwed onto the filter bowl or attached to it in some other way.

[0022] According to the invention, the filter housing can have a vent pipe for the main filter element in order to counteract malfunctions of the fuel filter during operation caused by compressible gases.

[0023] According to one embodiment of the invention, the vent pipe is permanently attached to the filter housing and can, in particular, be locked into place therein. Thus, even when the pre-filter and main filter elements are replaced, the vent pipe remains in the filter housing as a lifetime component. This offers cost advantages and conserves resources.

[0024] In a preferred embodiment, the vent pipe with its inlet opening can project axially beyond an upper end disc of the main filter element or be flush or substantially flush with the upper end disc of the main filter element. This ensures reliable venting of the main filter element.

[0025] The vent pipe preferably opens at the other end into a fuel return line of the filter housing, through which the fuel can be returned to a fuel tank. The vent pipe can optionally be fitted with a restrictor to prevent backflow of contaminants into the area of ​​the main filter element.

[0026] In the case that the filter element has a water separator unit as described above, the vent pipe may have a pipe element by which the water drain channel of the water separator unit of the fuel filter element arranged in the operating position within the filter element is limited on the inside in a radial direction.

[0027] According to the invention, the filter housing can have a water drain nozzle that extends axially and sealingly into the receiving gap between the wall element and the lower end disc of the pre-filter element. This allows the protruding low-pressure area and the high-pressure area of ​​the fuel filter element to be sealed against each other.

[0028] For replacing the fuel filter element, a preferred embodiment of the invention provides a fuel drain channel in the filter housing located below the filter element. In the operating position of the filter element within the filter housing, the raw side of each pre-filter element and main filter element is sealed against the fuel drain channel by a sealing contact between the filter element and the filter housing. The raw side of the main filter element can be fluidically connected to the fuel drain channel by axially moving the filter element out of its operating position via the raw side of the pre-filter element. This prevents unfiltered fuel from entering the clean side of the fuel filter. Furthermore, this design results in a particularly simple fuel filter construction. Brief description of the drawings

[0029] The drawing shows:

[0030] Fig. 1 a fuel filter with a filter housing and a filter element arranged therein with a pre-filter element and a main filter element in a perspective sectional view;

[0031] Fig. 2. Remove the fuel filter Fig. 1 in a longitudinal section; and

[0032] Fig. 3. Remove the filter insert Fig. 1 in a cutaway view. embodiment(s) of the invention

[0033] In the Fig. 1 and Fig. 2 is a fuel filter 10 shown for filtering out impurities contained in fuel, especially diesel fuel. The fuel filter 10 It is suitable, for example, for use in commercial vehicles with combustion engines.

[0034] The fuel filter 10 includes an openable filter housing 12 with a filter pot 14 with an insertion opening16 and with a case cover 18 to close the filter pot 14 The filter lid 18 can go into the filter pot 14 to be screwed in. A different type of fastening for the filter cover. 18 on the filter pot 14 is conceivable. The filter housing 12 It can be made of metal or plastic, for example. At the bottom of the filter housing. 12 is a so-called filter pot 20 trained. The fuel filter 10 It is therefore designed in a manner known per se for a standing arrangement in operation.

[0035] The filter housing 12 has a fuel inlet 22 on, which supplies the fuel to be filtered, for example from a fuel tank (not shown), to the fuel filter 10 It serves as a fuel return line. 24The filter housing serves to return contaminated fuel, e.g. to the aforementioned fuel tank.

[0036] Inside the filter housing 12 is a fuel filter insert 26 arranged. The fuel filter element 26 includes a pre-filter element 28 and a main filter element 30 The two filter elements 28 , 30 are in the direction of the longitudinal axis 32 of the fuel filter stacked on top of each other in the filter housing 12 arranged. The longitudinal axis 32 the fuel filter falls with the longitudinal axis 34 of the fuel filter element 26 together. The main filter element 30 is the pre-filter element 28 The filter element is arranged fluidically downstream. In other words, during operation, the fuel to be filtered first flows through the pre-filter element located at the bottom of the filter housing. 28and subsequently the area above the pre-filter element 28 arranged main filter element 30 .

[0037] The pre-filter element 28 and the main filter element 30 are each as round filter elements with a longitudinal axis 34 the filter medium arranged in a ring shape as a filter insert 36 executed. The filter medium 36 of the pre-filter element 28 as well as the main filter element 30 are in a direction relative to the longitudinal axis of the fuel to be filtered 34 of the fuel filter element 26 The filter media allow flow in a radial direction from the outside to the inside. 36 are each designed as a star-shaped folded filter bellows and are sandwiched between a lower and an upper end disc 38 , 40 the respective filter element is held in place. The upper end disc 40 of the main filter element 30is via a bayonet connection 41 (snap connection or similar) with the housing cover 18 Detachably coupled or coupled. For radial inner support of the filter media. 36 of the pre-filter element 28 as well as the main filter element 30 Each uses a grid-shaped support tube. 42 The filter media 36 They lie on the inside of the respective support tube, preferably directly against it.

[0038] The corresponding end disks 38 , 40 of the pre-filter element and the main filter element, i.e. the lower end disc 38 of the main filter element 30 and the upper end disc 40 The two end plates of the pre-filter element are spaced apart from each other in the axial direction. 38 , 40 Each lies above sealing elements 43 The two end discs seal against the inside of the filter housing (fluid-tight).38 , 40 They thus serve as sealing discs, through which the filter housing is axially sealed inside in a direction that aligns with the pre-filter element. 28 featuring pre-filter chamber 44 and a main filter chamber containing the main filter element 46 is divided. Between the upper end disc 40 of the pre-filter element 28 and the lower end disc 38 of the main filter element 30 is a flow channel 48 for the pre-filter element 28 Pre-filtered fuel is arranged. The flow channel 48 is formed by the mutually assigned end discs 38 , 40 the pre- and main filter element is directly limited in the axial direction.

[0039] The upper end disc 40 of the pre-filter element 28 and the lower end plate 38 of the main filter element 30 are for the joint expansion of the main and pre-filter element30 , 28 connected to each other, in particular formed in one piece, and can in particular be manufactured as a plastic injection molded part. As can be seen from the Fig. 1 and Fig. As can be seen from point 2, there are spacer elements between the two end discs. 50 arranged, each of which is attached to, in particular molded onto, the two end discs.

[0040] The flow channel 48 is essentially ring-shaped and is aligned radially with the inner wall 52 of the filter housing 12 Fluidically connected. The flow channel 48 It has a side (radially) arranged fuel outlet on the output side. 54 of the filter housing 12 Fluidically connected. To the fuel outlet. 54 is a fuel pump 56 connectable. The fuel pump 56 It serves to direct the contaminated fuel into the pre-filter chamber. 44and through the pre-filter element 28 to vacuum and remove it from the filter housing 12 the pre-filtered fuel is passed through a system with 58 designated fuel inlet of the filter housing 12 into the main filter chamber 46 of the filter housing 12 to pump the pre-filtered fuel through the filter medium. 36 of the main filter element 30 to lead to the fuel inlet. 58 is relative to the fuel outlet 54 of the filter housing 12 axially offset arrangement.

[0041] The main filter element 30 It features a water separator unit for separating water contained in the fuel. 60 up. The water separator unit 60 includes a coalescing medium 62 , which is ring-shaped around the longitudinal axis 34 of the fuel filter element 26 is arranged. The coalescing medium 62can, as is shown in the Fig. 1 and Fig. 2 is shown, the filter medium 36 of the main filter element 30 especially if it is arranged downstream in a fluidic manner. The coalescing medium 36 It is advantageously located on the inside of a central tube 64 so that it can be pressurized during the operation of the fuel filter. 10 did not collapse. The center tube 64 is inside the support tube 42 and coaxial to the longitudinal axis 34 of the fuel filter element 26 arranged. The coalescing medium 62 is therefore between the middle tube 64 and the support tube 42 of the filter medium 36 of the main filter element 30 arranged. The coalescing medium 62 It can be constructed in one or more layers as needed and, for example, consist of a non-woven fabric.

[0042] As from the Fig. 1 and Fig. As can be seen from Figure 2, there is a sieve tube inside the central tube. 66 arranged. The sieve tube 66 Functionally, it serves as a final separator for the water contained in the fuel. The sieve tube 66 is to the longitudinal axis 34 of the fuel filter element 26 Arranged coaxially. The interior of the sieve tube 66 is above a fuel drain channel 68 , which extends partially through the pre-filter element in the axial direction 28 extended through, with a fuel channel 70 of the filter housing 12 Fluidically connected. The pre- and main filter element 28 , 30 Filtered fuel, at least partially freed from water, flows from inside the sieve tube during operation. 66 via the fuel drain channel 68 and the fuel channel 70 of the filter housing 12 downwards from the fuel filter insert 26 away.

[0043] Between the sieve tube 66 and the coalescing medium 62 or the middle tube 64 is an annular water separation gap 72 formed. The water separation gap 72 It is open at the bottom and has a longitudinally extended water drainage channel at one end. 74 fluidically connected.

[0044] On the lower end disc 38 of the main filter element 30 is essentially a tubular wall element 76 attached, in particular molded, extending in the axial direction from the lower end disc 38 of the main filter element 30 extended away towards the filter head, i.e. downwards. The wall element 76 extends in the axial direction up to the level of the lower end disc 38 of the pre-filter element 28 into the pre-filter element. The wall element 76 The pre-filter chamber is limited 44in a radial direction on the inside and separates it from the water drainage channel 74 of the fuel filter element 26 off. The drainage channel 74 In other words, the water separated from the fuel passes radially through the outside of the tubular wall element. 76 immediately limited.

[0045] The wall element 76 This separates the pre-filter element in total. 28 comprehensive low-pressure range 78 and one of the main filter element 30 comprehensive high-pressure range 80 of the fuel filter element 26 against each other.

[0046] The drainage channel 68 can pass completely or partially through the pre-filter element in the axial direction 28 extend through and is accessible via a housing or water drain nozzle. 82 of the filter housing 12 with a water drainage channel or water collection chamber84 of the filter housing 12 fluidically connected.

[0047] The tubular wall element 76 and the lower end plate 38 of the pre-filter element 28 together limit a recording gap 86 , into which the housing or water drain nozzle 82 protrudes inwards in the axial direction. The wall element 76 lies over a sealing element 43 inside at the water drain spout 82 and the lower end plate 38 of the pre-filter element 28 via another sealing element 43 on the outside of the water drain spout 82 sealing. This creates a low-pressure area or pre-filter chamber. 44 opposite the high-pressure area or the water drainage channel 74 sealed.

[0048] The drainage channel 74 is in the radial direction on the inside by a pipe element 88limited. The pipe element 88 It also forms a radial outer boundary of the fuel drain channel. 68 The pipe element 88 is at one end via a longitudinal axis of the fuel filter insert 34 diagonally arranged and fenestrated (not shown) connecting section 90 on a centrally located vent pipe 92 of the fuel filter 10 molded in place. Alternatively, the pipe element can also be part of the sieve tube. 66 of the fuel filter element 26 be trained.

[0049] A free end section of the sieve tube 66 is a sealing lip or a sealing collar 94 formed and is located on the pipe element 88 fully sealed on the outside. The pipe element 88 of the vent pipe 92 On the other hand, i.e. at its lower end, it has a fuel drain nozzle. 96of the filter housing 12 latched (or screwed) and rests against this via a sealing element. 43 sealing on the inside.

[0050] The vent pipe 92 It serves to vent the main filter element. 30 or the main filter chamber 46 and extends coaxially to the longitudinal axis 34 of the fuel filter element through it. The vent pipe 92 can with its inlet opening 98 one end over the upper end plate 40 of the main filter element 30 protrude axially. The inlet opening 98 of the vent pipe 92 In this case, it is between the upper end disk 40 of the main filter element 30 and the case lid 18 arranged. It goes without saying that the vent pipe 92 also flush or substantially flush with the upper end plate 40the main filter element can be located there. The vent pipe 92 On the other end, it protrudes into a vent. 100 of the filter housing 12 sealing inside. The vent pipe 100 can be used with the fuel return line 24 of the filter housing 12 are fluidically connected. During the operation of the fuel filter. 10 This allows in the area of ​​the main filter chamber 46 Air contained in the fuel or fuel vapors via the vent pipe 92 and the fuel return 24 of the filter housing 12 from the filter housing 12 be evacuated. The vent pipe 92 For safety reasons, for example in the area of ​​its inlet opening, 98 , with a throttle 102 be provided.

[0051] The pre-filter chamber 44 is downwards through a case base 104 of the filter housing 12limited. The pre-filter element 28 is in its shown installed state from the bottom of the housing 104 axially spaced apart. This creates a gap between the lower end disk 38 of the pre-filter element 28 and the case bottom 104 a fuel drain channel 106 formed or defined. The fuel drain channel 106 encompasses the longitudinal axis 32 of the fuel filter housing 12 and is for the fuel return 24 of the filter housing 12 open, i.e., fluidically connected to it.

[0052] The filter pot 14 has an internal cross-section that extends axially towards the bottom of the housing 102 , i.e. in the direction of insertion 108 The fuel filter element is progressively tapered. The filter housing 12 This indicates that in the area of ​​its inner wall 52 Sealing surface sections 110 for the sealing of the end discs38 , 40 of the fuel filter element, which increases with distance from the inlet opening 16 of the filter housing 12 towards the bottom of the housing 104 from the longitudinal axis 34 of the fuel filter element 26 are spaced less far apart. The sealing elements 43 the lower end disc 38 of the main filter element 30 as well as the two end discs 38 , 40 of the pre-filter element 28 are in a corresponding manner to the longitudinal axis 34 of the fuel filter insert 26 They are spaced at different distances and are located in the operating position of the fuel filter element shown. 26 in the filter housing 12 at the sealing surface sections 110 of the filter pot 20 sealing. This allows the fuel filter element to be used. 26 simplified and without unnecessary strain on its sealing elements43 to be inserted into its operating position in the filter housing.

[0053] For replacing the fuel filter element 26 This is done in the opposite direction of insertion. 108 axially from the filter pot 14 moved out. As soon as the fuel filter element is removed, it will be removed. 112 ( Fig. 2) the designated axial path is moved from its shown installation position to a drainage position, the sealing elements 43 the lower and upper end discs 38 , 40 of the pre-filter element 28 as well as the lower end disc 38 of the main filter element 30 from their respective sealing position on the filter housing 12 or the water drain nozzle 82 removed. Consequently, the main filter chamber is 46 via the pre-filter chamber 44 with the fuel drain channel 106Fluidically connected. This allows the raw fuel to escape from the main filter chamber. 46 via the pre-filter chamber 44 together with the fuel located on the raw side – following gravity – into the fuel drain channel 106 flow. Via the fuel drain channel 106 Can the fuel return line 24 drain away.

[0054] It should be noted that the axial length of the housing-side water drain nozzle 82 is dimensioned in such a way that the sealing element 43 of the wall element 76 in the drainage position of the fuel filter element 26 still at the water drain nozzle 82 It seals tightly. This ensures that fuel is not drawn from the pre-filter chamber. 44 not on the clean side of the fuel filter 10 , here the water drain (stem) or the fuel drain stem 96 of the fuel channel 70reached.

[0055] Fig. 3 shows the fuel filter element from the Fig. 1 and Fig. 2 in a cut-out view and in a longitudinal section. The grid structure of the sieve tube. 66 This is clearly visible in this illustration. The sieve tube 66 is with the upper end plate 40 of the main filter element 30 connected, e.g., latched. The sealing collar 94 The sieve tube can be made of an elastically deformable (plastic) material. The sealing collar 94 This can be used when inserting the fuel filter element axially. 26 into the filter housing ( Fig. 1 and Fig. 2) guided by the diagonally running connecting section 90 of the vent pipe 92 on the pipe element 88 The lower end disc must be pushed on tightly to seal. 38 of the main filter element 30 has a retaining rib on the inner circumference114 up. The landing stage 114 stands from the lower end disc 38 axially towards the upper end disk 40 of the main filter element 30 away and supports the center tube 64 from the inside.

[0056] During the operation of the fuel filter 10 The unfiltered fuel drawn in by the fuel pump flows through the fuel inlet. 22 of the filter housing into the pre-filter chamber 44 and flows through the filter medium 36 of the pre-filter element 28 in a radial direction from the outside inwards. Through the tubular wall element 76 The fuel passes through the main filter element via the flow channel. 48 and the side fuel outlet 54 of the filter housing into the fuel pump 56 . By means of the fuel outlet 54 and the fuel inlet 58The pre-filtered fuel is pumped into the main filter chamber via a fluidically connected fuel pump. 46 of the filter housing 12 pumped. The pre-filtered fuel flows through the filter medium. 36 of the main filter element 30 , the coalescing medium 62 and the sieve tube in a direction perpendicular to the longitudinal axis 34 of the fuel filter element 26 radially from the outside to the inside. In this process, the water contained in the fuel is at least partially separated from the fuel and flows away from the water separation gap under the influence of gravity. 72 via the drainage channel 68 down into the water collection chamber 84 of the filter housing 12 The fuel, now freed from impurities, flows through the fuel channel. 70 from the fuel filter 10 out and can be fed to an internal combustion engine or a fuel injection pump.

[0057] To replace the fuel filter element 26 In the first step, the housing cover will be removed. 18 from the filter pot 20 removed. The bayonet connection 41 between the case cover 18 and the fuel filter insert 26 is closed or is closed by the screwing motion of the housing cover. 18 Closed. The fuel filter element. 26 The screw movement as a whole moves axially in the direction of the longitudinal axis 32 of the filter housing 12 from its installation position ( Fig. 1 and Fig. 2) moved. As soon as the filter element is in the drainage position, the raw-side (pre-filtered) fuel flows out of the main filter chamber. 46 of the filter housing 12 into the pre-filter chamber 44 of and together with the raw-side fuel arranged there via the fuel drain channel 106 into the fuel return line 24and possibly a fuel tank fluidically connected to it. Upon further twisting or lifting of the housing cover 18 from the filter pot 14 together with the fuel filter insert 26 The inner sealing element will also be replaced. 43 of the wall element 76 as well as the one at the water drain nozzle 82 adjacent sealing element 43 the lower end disc 38 of the pre-filter element 28 from their sealing system at the water outlet nozzle 82 It moves. Any liquid level of a fuel-water mixture that may be present on one side can then flow radially outwards into the fuel drain channel. 106 flow and via the fuel return line 24 from the filter housing 12 drain away. After completely removing the fuel filter element. 26 from the filter pot, this is removed from the housing lid 18 disconnected and a new fuel filter insert26 on the case lid 18 attached. The fuel filter element 26 is subsequently inserted into the filter pot in the direction of introduction 14 inserted and secured by screwing the housing cover down. 18 on the filter pot 14 transferred to its installation position ( Fig. 1 and Fig. 2). QUOTES INCLUDED IN THE DESCRIPTION

[0058] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0059] DE 102008048228 A9

[0002] US 3900400 B

[0003] EP 0852158 A1

[0004] WO 2006 / 070221 A1

[0005] DE 202006004527 U1

[0006] EP 1485605 B1

[0006]

Claims

[1] Fuel filter element ( 26 ) for a fuel filter ( 10 ), comprehensive: – a pre-filter element ( 28 ) and a main filter element ( 30 ), which in the direction of the longitudinal axis ( 34 ) of the fuel filter element ( 26 ) are arranged one above the other, with at least one of the filter elements ( 28 , 30 ) of the fuel in a direction perpendicular to the longitudinal axis ( 34 ) radial direction, preferably from outside to inside, through which flow is possible; and – a flow channel ( 48 ) for the pre-filter element ( 28 ) pre-filtered fuel, which flows in the axial direction between the pre-filter element ( 28 ) and the main filter element ( 30 ) is arranged, wherein the flow channel ( 48 ) in the axial direction by mutually associated end disks ( 38 , 40 ) of the pre-filter element ( 28 ) and the main filter element ( 30) is immediately limited. [2] Fuel filter element according to claim 1, characterized by that the two end discs ( 38 , 40 ) of the pre-filter element ( 28 ) and the main filter element ( 30 ), which forms the flow channel ( 48 ) limit, are connected to each other for the joint expansion of the main and pre-filter elements, in particular are formed in one piece together. [3] Fuel filter element according to claim 1 or 2, characterized by that between the two end discs ( 38 , 40 ) Distance elements ( 50 ) are arranged, preferably the spacer elements ( 50 ) on both end discs ( 38 , 40 ) attached, in particular molded on. [4] Fuel filter element according to any one of the preceding claims, characterized by that the main filter element ( 30 ) a water separator unit ( 60) for separating water contained in the fuel. [5] Fuel filter element according to claim 4, characterized by that the water separator unit ( 60 ) a water separation gap ( 72 ) includes, at one end with a water drainage channel ( 68 ) is fluidically connected or connectable, wherein the water drainage channel ( 68 ) in the axial direction at least sectionally through the pre-filter element ( 28 ) extends through it. [6] Fuel filter element according to claim 5, characterized by that the drainage channel ( 68 ) in a radial direction on the outside through a wall element ( 76 ) is limited, which is located at the flow channel ( 48 ) limiting end disk ( 38 , 40 ) of the main filter element ( 30 ) attached, in particular molded on. [7] Fuel filter element according to claim 5 or 6, characterized by that the wall element ( 76) together with a lower end plate ( 38 , 40 ) of the pre-filter element ( 28 ) a recording slot ( 86 ) for the installation of a water drain nozzle ( 82 ) of a filter housing ( 12 ) forms. [8] Fuel filter element according to any one of the preceding claims, characterized by that the water separator unit ( 60 ) a coalescing medium ( 62 ) exhibits a filter medium ( 36 ) of the main filter element ( 30 ) is preferably fluidically connected downstream. [9] Fuel filter element according to any one of the preceding claims, characterized by that the pre-filter element ( 28 ) and / or the main filter element ( 30 ) each a filter medium ( 36 ) exhibit that is attached to a support tube on the inside ( 42 ) is supported. [10] Fuel filter ( 10 ) comprising a filter housing ( 12 ) and one in the filter housing ( 12) arranged fuel filter insert ( 26 ) according to any of the preceding claims, characterized by that the fuel filter element ( 26 ) with the two end discs ( 38 , 40 ), which forms the flow channel ( 48 ) limit, at the filter housing ( 12 ) seals against the inside, with the filter housing ( 12 ) a side fuel outlet ( 54 ) is formed, over which the flow channel ( 48 ) with a fuel pump ( 56 ) is fluidically connectable to the pre-filter element ( 28 ) pre-filtered fuel via a, preferably laterally, on the filter housing ( 12 ) trained, fuel inlet ( 58 ) to the main filter element ( 30 ) to pump. [11] Fuel filter according to claim 10, characterized by that the filter housing ( 12 ) a vent pipe ( 92 ) exhibits, which is characterized by the fuel filter insert ( 26) extends at least partially through it. [12] Fuel filter according to claim 11, characterized by that the vent pipe ( 92 ) a drainage channel ( 74 ) a water separator unit ( 60 ) of the fuel filter element ( 26 ) radially limited on the inside. [13] Fuel filter according to claim 12, characterized by that the vent pipe ( 92 ) one end into a fuel return line ( 24 ) of the filter housing ( 12 ) to return the fuel to a fuel tank, leads to. [14] Fuel filter according to one of claims 10 to 13 in combination with claim 7, characterized by that the filter housing ( 12 ) a water drain ( 82 ) exhibits, which extends into the recording gap ( 86 ) between the wall element ( 76 ) and the lower end plate ( 38 ) of the pre-filter element ( 28 ) extends inwards in a sealing manner. [15] Fuel filter according to any one of claims 10 to 14, characterized by that the filter housing ( 12 ) below the fuel filter element ( 26 ) a fuel drain channel ( 106 ) exhibits, wherein in the operating position of the fuel filter element ( 26 ) in the filter housing ( 12 ) each raw side of the pre-filter element ( 28 ) and the main filter element ( 28 ) through a sealing system of the filter element ( 26 ) on the filter housing ( 12 ) opposite the fuel drain channel ( 106 ) are sealed and wherein the raw side of the main filter element ( 30 ) by axially moving the filter insert outwards ( 26 ) from its operating position via the raw side of the pre-filter element ( 28 ) with the fuel drain channel ( 106 ) is fluidically connectable.

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