Abstract:
The invention relates to a filter element ( 10 ) having a first fluid path ( 12 ) for filtering a first fluid and a second fluid path ( 14 ) having a fluid line ( 16 ) for carrying a second fluid, wherein a non-return valve ( 18 ) is arranged in the second fluid path ( 14 ), said non-return valve ( 18 ) closing the second fluid path ( 14 ) if a flow of the first liquid through the filter element ( 10 ) is interrupted. The invention further relates to a filter system ( 100 ) including such a filter element ( 10 ).

Description:
TECHNICAL FIELD 
       [0001]    The invention relates to a filter element for filtering a fluid and a filter system including said filter element, in particular a fuel filter of a motor vehicle. 
       BACKGROUND OF THE INVENTION 
       [0002]    A filter arrangement of the above-mentioned type is known from DE19519352A1, in which a hollow cylindrical filter insert is arranged in a cylindrical filter housing. The liquid to be filtered, for example fuel for an internal combustion engine, is guided in the radially outer chamber of the filter assembly, so that it can penetrate the filter insert from the outside into the inner cavity. The outlet for the filtered liquid is connected to the inner cavity. 
         [0003]    At the beginning of a liquid feed into the outer chamber of the filter arrangement, a certain amount of air upstream from the liquid is transported into the outer chamber. This amount of air is likewise pressed by the subsequent pressure of the liquid through the filter insert and thus also reaches the outlet of the filter arrangement. This is very disadvantageous, in particular in use as a fuel or oil filter, because the downstream units, such as the internal combustion engine, can be hindered during operation by air pockets in the fuel supply. 
         [0004]    A venting arrangement is therefore provided in DE19519352A1, which consists of a simple bore in a cap which is sealingly applied on the filter element, wherein the bore is connected with an outlet channel for the escaping air. This venting arrangement permits the escape of air contained in the filter arrangement, but also allows the inflow of air when no fuel is pumped into the internal combustion engine. Especially in internal combustion engines with start/stop systems, the internal combustion engine is often shut down and thus does not pump fuel, with the result that air may enter the fuel management system in the stop phase. 
         [0005]    The object of the invention is to design a filter element such that the ingress of air into the fuel management system is prevented in a stationary internal combustion engine. 
         [0006]    A further object of the invention is to provide a filter system for receiving such a replaceable filter element, which can prevent the entry of air into the fuel management system in a stationary internal combustion engine. 
         [0007]    The aforementioned objects are achieved according to one aspect of the invention in that, in a filter element for a filter system, in particular for a fuel filter, with a first fluid path for filtering a first fluid, in particular for filtering fuel, and a second fluid path with a fluid line for carrying a second fluid, in particular for ventilating the filter system, a non-return valve is arranged in the second fluid path, which non-return valve closes if a flow of the first fluid through the filter element is interrupted. The filter element is replaceably arranged in the housing of the filter system and has a filter media body through which the first fluid path leads. 
         [0008]    Advantageous embodiments and advantages of the invention result from the additional claims, the description and the drawings. 
       SUMMARY 
       [0009]    A filter element for a filter system, in particular for a fuel filter, with a first fluid path for filtering a first fluid, in particular for filtering fuel, and a second fluid path with a fluid line for carrying a second fluid, in particular for ventilating the filter system, wherein a non-return valve is arranged in the second fluid path, said non-return valve closing. The filter element is replaceably arranged in the housing of the filter system and has a filter media body through which the first fluid path leads. 
         [0010]    The non-return valve preferably closes the second fluid path when a predetermined system lower pressure limit is not met. In particular when the predetermined system lower pressure limit is not met on the raw side of the filter, which occurs in particular when an internal combustion engine is switched off, whereby a flow of the first fluid through the filter element is interrupted. 
         [0011]    Advantageously, most existing continuous ventilations of a filter element of an internal combustion engine may thus be equipped with a non-return valve. In this way, fuel is retained in an internal combustion engine which is turned off, for example in start/stop operation, and it can be prevented that any air which is possible in a tank return line enters the fuel management system of the internal combustion engine via the filter system. When the internal combustion engine is not running, the ventilation of the filter element may remain closed. If the internal combustion engine is started, and in start/stop operation a very short engine start time is typically desirable, the necessary system pressure in the fuel management system for an ignition release can be built up immediately in the fuel system. The system pressure which builds up in an outer region of the filter element enables an opening of the non-return valve and the filter element can once again be continuously ventilated. The great advantage is thus that short motor start times are made possible, in that the fuel remains in the filter system. 
         [0012]    In the case of a particularly preferred embodiment, the filter element comprises the fluid line of the second fluid path. The fluid line is replaceable with the filter element. In particular, it is undetachably connected to the (rest of) the filter element. The element-side fluid line can therefore also be configured so as to be fixed to the element. The fluid line is preferably an integral component of the filter element. In particular, a non-destructive separation of the fluid line from the (rest of) the filter element cannot occur. 
         [0013]    The element-side fluid line may preferably be formed as a rigid tube, which contributes to the stability of the filter element. 
         [0014]    In the installed state of the filter element, the element-side fluid line advantageously opens above the filter media body, so that, for example, fuel flows through the fluid line only when the filter media body is supplied completely with fuel, i.e. the air is displaced from the fuel filter so far that the fuel level extends above the filter media body. 
         [0015]    A variant is particularly preferred in which the fluid line leads from one end face of the filter element, in particular the upper end face of an installed filter element, to the opposite (lower) end face. In this way, a discharge of the air from the filter may occur in a convenient manner via the housing bottom. 
         [0016]    A particularly compact design is obtained in that the fluid line extends through an inner region surrounded by the filter media body. For example, the filter media body has a filter media web, preferably a star-pleated filter media web, for particle filtration. A coalescer medium, for example wound, is preferably provided within the filter media web. A water separating element, for example with a hydrophobic mesh fabric, follows the coalescer medium in the direction of flow, which water separating element is arranged for example within the coalescer medium and at the height thereof. An annular water discharge gap is formed between the coalescer medium and the water separating element. The fluid line is guided through the inner region surrounded by the water separating element. 
         [0017]    In a particularly preferred variant, the filter element is provided with a non-return valve port, by means of which the element-side fluid line can be connected to the non-return valve, during installation of the filter element in the housing of the filter system. This variant enables a particularly preferred embodiment, in which the non-return valve is arranged on the housing side. Thus, it need be not replaced when changing the filter element. 
         [0018]    A particularly robust construction of a non-return valve port results, for example, through a design as a stub-shaped protrusion of the fluid line. A non-return valve port designed as a stub-shaped protrusion can also be easily arranged above the rest of the filter element, in particular above the filter media body. It preferably protrudes at one end face of the filter element, in particular the upper end face. 
         [0019]    For the purpose of ease of assembly of the filter element, the non-return valve port is arranged coaxially to a longitudinal element axis. Thanks to this measure, the filter element can be installed in any rotational position about its longitudinal element axis. 
         [0020]    In a particularly preferred embodiment, the non-return valve port is provided with a sealing element for sealing engagement with the non-return valve. Straight sealing elements are subject to considerable wear, so it is advantageous to provide the sealing element on the non-return valve port, which is regularly replaced along with the filter element. 
         [0021]    Advantageous sealing behavior and installation forces arise in that the sealing element is preferably formed as a circumferential sealing element directed radially outward. An O-ring applied to the element-side connection stub has proven useful in practice. 
         [0022]    The filter element may further comprise an outflow port, by means of which the element-side fluid line can be connected to a housing-side outflow channel during installation of the filter element in the housing of the filter system. The outflow port may preferably be designed such that it contributes to the holding and support of the filter element in the housing. The outflow channel may preferably be connected to a tank return. 
         [0023]    A particularly robust construction results through a design of the outflow port as a stub-shaped protrusion of the fluid line. 
         [0024]    Comparable to the conditions of the non-return valve port, the outflow port may also be provided with a sealing element for sealing engagement on the housing-side outflow channel, which is, in particular, a circumferential sealing element directed radially outward. An O-ring applied on the outflow-side connection stub can be regarded as a proven example. 
         [0025]    For assembly reasons, a coaxial arrangement of the outflow port to a longitudinal element axis is advantageous. 
         [0026]    In a particularly preferred embodiment, the filter element has two circumferential sealing elements in the region of that end face which is arranged below in the installed state of the filter element. For example, in a fuel filter with a clean-side water separation, these sealing elements may be used to seal a raw fluid-side annular space, which surrounds the filter element, from a clean fluid-side water collection area below the filter element. Two sealing elements are provided in order to control the outflow of fuel from the raw fluid-side annular space during removal of the filter element in order to avoid or at least reduce a contamination of the clean-side water collection area with raw fluid from the outer annular space. In particular, one of the sealing elements is used for sealing the raw fluid-side annular space against an emptying area. The other sealing element is used for sealing the emptying area against the clean-side water collection area. The emptying area may preferably be connected to a tank return. 
         [0027]    In a particularly preferred variant, the two sealing elements are arranged in the region of that end face on which the outflow port of the element-side fluid line is also provided. 
         [0028]    For the purpose of lower assembly forces and a compact construction, one of the sealing elements is oriented radially outward and/or one of the sealing elements is oriented radially inward. The two sealing elements are preferably of different diameters and/or are arranged coaxially to each other. 
         [0029]    In a particularly preferred embodiment, the filter element has a clean fluid outlet in the region of that end face on which the outflow port is arranged. The various ports may thus be advantageously integrated into the housing container. 
         [0030]    A further advantageous measure for avoiding the contamination of the clean side of the filter with unfiltered fluid is obtained in that the clean fluid outlet is provided with a stub-shaped protrusion, which preferably surrounds the outflow port. 
         [0031]    In one embodiment, in which the filter element is designed as a fuel filter and has a water separation, a water outlet is preferably provided for water separated from the first fluid in the region of that end side on which the outflow port is arranged. A mixing of the separated water with the filtered fuel is thus avoided, in that the water outlet surrounds the stub-shaped protrusion which surrounds the clean fluid outlet. 
         [0032]    Alternatively or in addition to a variant with a housing-side non-return valve, a non-return valve is fixed on the fluid line, which is preferably firmly attached to the element. A construction in which the non-return valve is integrated into the fluid line is particularly compact. 
         [0033]    Another aspect of the invention relates to a filter system, in particular a fuel filter, with a first fluid path for filtering a first fluid, in particular for filtering fuel, and a second fluid path with a fluid line for carrying a second fluid, in particular for ventilating a filter system, wherein a non-return valve is arranged in the fluid line of the second fluid, which non-return valve closes if a flow of the first fluid through the filter element is interrupted, wherein the filter system is equipped with a filter element according to the variants described hereinabove and hereinbelow. 
         [0034]    In the case of a particularly preferred embodiment of the filter system, the non-return valve is arranged above the filter media body of the filter element. 
         [0035]    It is particularly advantageous if the non-return valve is fixed on a housing cover of the filter system. This may be releasably or permanently connected to the housing cover, for example snapped on. 
         [0036]    The non-return valve preferably has a recess for an element-side non-return valve port. 
         [0037]    Conveniently, the filter element may be provided at least on one side with a cover or an end plate, wherein the fluid line may be accessible through the cover and the non-return valve may be arranged above or in the cover. In this way, a simple installation and also possible interchangeability of the non-return valve is provided in case of failure. 
         [0038]    A further advantageous design possibility is to form the filter element such that a non-return valve is alternatively or additionally arranged within the fluid line. The fluid line, which can often be realized in a support tube of the filter element, may thus be directly connected with the non-return valve, which can reduce the number of components and further simplify installation. 
         [0039]    It may be generally advantageous that the non-return valve can be fixed with a snap connection and sealed with an O-ring seal. The non-return valve, which can be advantageously arranged in a valve support in this embodiment, can thus be easily inserted during assembly. For example, the cover of the filter element may be held in place by means of the snap connection and a housing cover of the filter system may likewise be held by means of the snap connection. In addition, the non-return valve can easily be exchanged by means of such an arrangement, which is sealed by means of an O-ring seal, in case of failure of the non-return valve. 
         [0040]    Advantageously, the filter element may have a hollow cylindrical design, and the first fluid path may lead radially through a filter wall portion of the filter media body of the hollow cylindrical filter element. The first fluid path may advantageously lead radially from outside to inside into the filter element. This arrangement allows an inflow, for example of fuel, from the outside across the diameter of the filter element. The fuel may then flow through the filter element to the inside and may be led via the inner part of the filter element into the fuel supply of an internal combustion engine. 
         [0041]    Advantageously, the second fluid path may likewise extend into the interior of the filter element, wherein a separate tube is provided for the airflow, which can be realized for example, in order to save components and reduce the complexity of the filter element, in a central support tube of the filter element. 
         [0042]    As mentioned above, the first fluid path may advantageously be used for filtering fuel. The use of such a configuration is also conceivable for the use of oil filters. Of course, filter systems for other liquid fluids which must be filtered are typically provided with ventilation systems, so that the use of such a non-return valve is also conceivable in the filtering of other fluids. 
         [0043]    As also mentioned above, the second fluid path may be used for ventilating a fuel management system of an internal combustion engine. Especially in internal combustion engines, in which the starting process should take place in a relatively short time, as is the case in modern internal combustion engines in start/stop operation, such a ventilation system is of great advantage, as it retains the fluid in the filter system when the internal combustion engine is turned off and thus enables short start times. 
         [0044]    A further advantageous embodiment may provide an arrangement of the fluid line in a support tube for receiving the filter element. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0045]    Further advantages appear from the following description of drawings. The drawings illustrate exemplary embodiments of the invention. The drawings, description and claims contain numerous features in combination. A person skilled in the art will expediently also consider the features individually and combine them into appropriate further combinations. 
           [0046]      FIG. 1  shows a longitudinal section through a filter system according to one embodiment for fuel filtration in a motor vehicle; 
           [0047]      FIG. 2  shows an enlarged view of the upper part of the longitudinal section of  FIG. 1  with details of the arrangement of a non-return valve in a cover of a filter element; 
           [0048]      FIG. 3  shows a longitudinal section through a filter system according to another embodiment for fuel filtration in a motor vehicle with a direct arrangement of a non-return valve in a fluid line; 
           [0049]      FIG. 4  shows an enlarged view of the upper part of the longitudinal section of  FIG. 3  with details of the arrangement of a non-return valve in a fluid line; 
           [0050]      FIG. 5  shows a longitudinal section through a filter system according to a further embodiment for fuel filtration in a motor vehicle with a direct arrangement of a non-return valve in a fluid line; 
           [0051]      FIG. 6  shows an enlarged view of the upper part of the longitudinal section of  FIG. 5  with details of the arrangement of a non-return valve in a fluid line; 
           [0052]      FIG. 7  shows a longitudinal section through a filter system according to a further embodiment for fuel filtration in a motor vehicle with an arrangement of a non-return valve on a housing cover; 
           [0053]      FIG. 8  shows a longitudinal section through the filter element of the filter system according to  FIG. 7 , and 
           [0054]      FIG. 9  shows a longitudinal section through a filter system according to a further embodiment for fuel filtration in a motor vehicle with an arrangement of a non-return valve in the fluid line fixed to the element. 
       
    
    
     DETAILED DESCRIPTION 
       [0055]    In the figures, identical or similar components are provided with the same reference characters. The figures are only exemplary and are not meant to be limiting. 
         [0056]    The invention is illustrated with reference to a fuel filter, however it may also be provided for other filter systems with corresponding adaptation of the construction. 
         [0057]      FIG. 1  shows a longitudinal section through a filter system  100  according to one embodiment of the invention for fuel filtration in a motor vehicle. The filter system  100  comprises a central housing in two parts, an upper part  102  and a lower part  104 . A hollow cylindrical filter element  10  sits centrally arranged in the housing, through which correspondingly flows a first fluid, in particular fuel, radially from outside to inside by means of the first fluid path  12 , marked by an arrow, said fluid thereby being filtered. The filtering takes place here in the filter wall portion of a filter media body of the hollow cylindrical filter element  10 . The filter media body has, for example, by means of a star-folded filter media web, which is used for particle filtration. Within the star-folded filter media web is provided, for example, a wound coalescer medium. A water separating element, for example with a hydrophobic mesh fabric, which is arranged below the star-folded filter media web and the coalescer medium, follows the coalescer medium in the direction of flow. 
         [0058]    In an embodiment not shown, a reverse direction of flow from inside to outside is also conceivable with a corresponding adjustment of the positions of the respective components. 
         [0059]    The filter element  10  replaceably designed. The filter system  100  can be opened for replacement, for example, via the two-part housing  102 ,  104 . The filtered fluid flows downward via the inner region  36  of the filter element  10  and is conveyed further, for example to the injection system of an internal combustion engine. An end plate or cover  20  is mounted on the upper end of the filter element  10 , said cover being flatly and sealingly applied on the filter element  10  and to which cover is adjoined a fluid line  16  in the inner region  36  of the filter element. The fluid line  16  is advantageously designed simultaneously as a part of a support tube  24  of the filter system  100 , in order to represent a constructed receptacle for the filter element  10 . A non-return valve  18  is centrally arranged in the cover  20 . A second fluid path  14 , which may serve for ventilating the filter system  100 , thus leads via the outer region  44  of the filter element  10  into the non-return valve  18  and through a bore  38  in the cover  20 , which serves as a throttle bore for setting a defined flow resistance and which is preferably designed with a size of 0.5 mm, into the fluid line  16 . Air which has been entrained with the fuel from a tank system may thus be led back out of the filter system  100  by means of the non-return valve  18  and the fluid line  16  via an outlet  40 . If an internal combustion engine connected to the filter system  100  is turned off, for example in start/stop operation, and as a result no fuel is resupplied from the corresponding tank system, the non-return valve  18  may thus close. The pressure in the filter element  10  is thereby maintained, and the fuel remains in the filter system  100 . This provides the conditions for a rapid start of the internal combustion engine. After the re-opening of the non-return valve  18 , the ventilation of the filter system  100  again begin to operate. 
         [0060]      FIG. 2  shows an enlarged view of the upper part of the longitudinal section of  FIG. 1  with details of the arrangement of the non-return valve  18  in the cover  20  of the filter element  10 . The non-return valve  18  itself is embedded with its valve body  30  in a valve support  32 , for example pressed thereinto. The valve support  32 , in turn, is inserted by means of an O-ring seal  34  in a corresponding receptacle  42  of the cover  20  and thus establishes a sealed connection to the cover  20 . The cover  20 , in turn, sits sealingly on the filter element  10  and has a connection via the bore  38  to the support tube  24  designed as the fluid line  16 . In cross-section, the valve body  30  displays the usual design of a non-return valve with a ball  26 , which is pressed into a valve seat by means of a spring  28 . The second fluid path  14  for ventilating the filter system  100  thus leads via the outer region  44  of the filter element  10  through the non-return valve  18  via the bore  38  into the fluid line  16  of the support tube  24 . 
         [0061]      FIG. 3  shows a longitudinal section through a filter system  100  according to another embodiment of the invention for fuel filtration in a motor vehicle with a direct arrangement of a non-return valve  18  in a fluid line  16 . The construction of the filter system  100  is similar to the filter system shown in  FIG. 1  with a flow direction from the outside to the inside, which is indicated by the radial arrows from the outside to the inside through the filter element  10 . 
         [0062]    A hollow cylindrical filter element  10  is arranged in a two-part housing  102 ,  104 , wherein the filter element  10  can be designed to be replaceable. The filter system  100  can be opened for replacement, for example, via the two-part housing  102 ,  104 . A first fluid path  12  shows the route of the first fluid to be filtered, for example fuel, from an outer region  44  of the filter element  10  radially through the periphery into an inner region  36 . In contrast to the filter system shown in  FIG. 1 , however, the non-return valve  18  here is arranged directly in the fluid line, which in turn is formed as a support tube  24 . The filter element  10  is fitted over the support tube  24  and completes a radial seal with the support tube  24  by means of a sealing element  34 . The second fluid path  14  for ventilating the filter system  100  leads in a manner analogous to  FIG. 1  from the outer region  44  of the filter element  10  through the non-return valve  18  into the fluid line  16 , which likewise opens into an outlet (not shown). 
         [0063]      FIG. 4  shows an enlarged view of the upper part of the longitudinal section of  FIG. 3  with details of the arrangement of the non-return valve  18  in the fluid line  16 . The non-return valve  18  is embedded with its valve body  30  directly in the fluid line  16 , for example pressed thereinto, said fluid line being formed as a support tube  24  and being radially sealed with a sealing element  34  with respect to the filter element  10 . The second fluid path  14  for ventilating the filter system  100  thus leads in an analogous manner to the filter system shown in  FIG. 1  from the outer region of the filter element  10  via the non-return valve  18 , the function of which is represented by a ball  26  which is pressed into a valve seat by means of a spring  28 , via a bore  38 , which serves as a throttle bore for setting a defined flow resistance and which is preferably designed with a typical size of approximately 0.5 mm, into the support tube  24  which is formed as a fluid line, from where the air can be redirected back into the tank system. The manner of operation of the non-return valve  18  occurs in an analogous manner to the filter system shown in  FIG. 1 . If an internal combustion engine connected to the filter system  100  is turned off, for example in start/stop operation, and as a result no fuel is resupplied from a tank system, the non-return valve  18  may thus close. The pressure in the filter element  10  is thereby maintained, the fuel remains in the filter system  100 . This provides the conditions for a quick start of the internal combustion engine. After re-opening of the non-return valve  18 , the ventilation of the filter system  100  again begin to operate. 
         [0064]      FIG. 5  shows a longitudinal section through a filter system  100  according to a further embodiment of the invention for fuel filtration in a motor vehicle with a direct arrangement of a non-return valve  18  in a fluid line  16 . The construction of the filter system  100  is similar to the filter system shown in  FIG. 3  with a flow direction from outside to inside, which is indicated by arrows from outside to inside into the filter element  10 , and differs from the embodiment shown in  FIG. 3  by a support tube  24  which is differently formed in the upper part, which has a fluid line  16  with a significantly larger diameter than the fluid line  16  shown in  FIG. 3 , and thus a better ventilating behavior. The other functional behavior of the filter system  100  according to the embodiment shown in  FIG. 5  corresponds to the embodiment shown in  FIG. 3 . 
         [0065]    A hollow cylindrical filter element  10  is arranged in a two-part housing  102 ,  104 , wherein the filter element  10  can be designed to be replaceable. The filter system  100  can be opened for replacement, for example, via the two-part housing  102 ,  104 . A first fluid path  12  shows the route of the first fluid to be filtered, for example fuel, from an outer region  44  of the filter element  10  radially through the periphery into an inner region  36 . As in the filter system shown in  FIG. 3 , the non-return valve  18  here is arranged directly in the fluid line, which is formed as a two-piece support tube  24 . The non-return valve  18  is seated in the upper part of the support tube  24 . The filter element  10  is fitted over the support tube  24  and completes a radial seal with the support tube  24  by means of a sealing element  34 . The second fluid path  14  for ventilating the filter system  100  leads in a manner analogous to  FIG. 3  from the outer region  44  of the filter element  10  through the non-return valve  18  into the fluid line  16 , which opens into an outlet  40 . 
         [0066]      FIG. 6  shows an enlarged view of the upper part of the longitudinal section of  FIG. 5  with details of the arrangement of the non-return valve  18  in the fluid line  16 . The non-return valve  18  is embedded with its valve body  30  directly in the fluid line  16 , for example pressed thereinto, said fluid line being formed as the upper part of the support tube  24  and being radially sealed with a sealing element  34  with respect to the filter element  10 . The second fluid path  14  for ventilating the filter system  100  thus leads in an analogous manner to the filter system shown in  FIG. 3  from the outer region of the filter element  10  via the non-return valve  18 , the function of which is represented by a ball  26  which is pressed into a valve seat by means of a spring  28 , via a bore  38 , which serves as a throttle bore for setting a defined flow resistance and which is preferably designed with a typical size of approximately 0.5 mm, into the support tube  24  which is formed as a fluid line  16 , from where the air can be redirected back into the tank system. The manner of operation of the non-return valve  18  occurs in an analogous manner to the filter system shown in  FIG. 3 . If an internal combustion engine connected to the filter system  100  is turned off, for example in start/stop operation, and as a result no fuel is resupplied from a tank system, the non-return valve  18  may thus close. The pressure in the filter element  10  is thereby maintained, the fuel remains in the filter system  100 . This provides the conditions for a quick start of the internal combustion engine. After re-opening of the non-return valve  18 , the ventilation of the filter system  100  again begin to operate. 
         [0067]      FIG. 7  shows a longitudinal section through a filter system  100  according to a further embodiment for fuel filtration in a motor vehicle with an arrangement of a non-return valve  18  on a housing cover  102 . A replaceable filter element  10  is arranged in the housing  102 ,  104  of the filter system  100 . A first fluid path  12  shows the route of the first fluid to be filtered, for example fuel, from an outer region  44  of the filter element  10  radially through a filter media body  119  of the filter element  10  into an inner region  36 . The non-return valve  18  is arranged above the filter media body  119  of the filter element  10  and is fixed on the housing cover  102  by means of a snap connection  120 . The non-return valve  18  has a receptacle  121  for an element-side non-return valve port  122 . The second fluid path  14  for ventilating the filter system  100  leads from the outer region  44  of the filter element  10  through the non-return valve  18  into the fluid line  16  fixed to the element, which opens into an outlet  40  in the form of a housing-side outflow channel. In general, the manner of function of the non-return valve  18  corresponds to that of the already-described embodiments. 
         [0068]    The fluid line  16  is part of the replaceable filter element  10 . It extends from the end face of the filter element  10 , which is arranged above in the installed state, to the opposite, lower end face through the inner region  36  surrounded by the filter media body  119 . 
         [0069]    Similarly to the embodiment according to  FIGS. 1 and 2 , the filter media body  119  has a star-folded filter media web  123 , which is used for particle filtration. A wound coalescer medium  124  is likewise provided within the star-folded filter media web  123 . A water separating element  125 , for example with a hydrophobic mesh fabric, in turn follows the coalescer medium  124  in the direction of flow, which water separating element is however arranged for example within the coalescer medium  124  and at the height thereof. An annular water discharge gap  126  is formed between the coalescer medium  124  and the water separating element  125 . The annular water discharge gap  126  is connected below with a water collection area  127  of the filter system  100 . The inner region  36  surrounded by the water separating element  125  is provided on the lower end face with a clean fuel outlet  128 . 
         [0070]    In  FIG. 8 , the filter element  10  of the filter system  100  according to  FIG. 7  is shown in isolation. The non-return valve port  122  is formed as a stub-shaped protrusion of the fluid line  16 , which protrudes on the upper end face of the filter element  10  and is arranged coaxially to the longitudinal element axis  129 . It is provided with a sealing element oriented radially outward in the form of an applied O-ring  130  for sealing against the non-return valve  18 . 
         [0071]    The filter element  10  comprises an outflow port  131  on the lower end face, by means of which the fluid line  16  can be connected to the discharge  40  during installation of the filter element  10  in the housing  102 ,  104  of the filter system  100 . The outflow port  131  is also designed as a stub-shaped protrusion of the fluid line  16 , which is arranged coaxially to the longitudinal element axis  129 . It has a circumferential sealing element which is oriented radially outward in the form of an applied O-ring  132 . 
         [0072]    In addition, the filter element  10  has two circumferential sealing elements  133 ,  134  on the lower end face, wherein the sealing element  133  is oriented radially outward and the sealing element  134  is oriented radially inward. The sealing element  133  abuts against the inner housing wall and is used for sealing the outer annular space  44  from an emptying area  135  formed as a groove ( FIG. 7 ). The other sealing element  134  abuts against a housing stub  136  and is used for sealing the water collection area  127  against the emptying area  135 . The element-side clean fuel outlet  128  is surrounded by a stub-shaped protrusion  137 , which additionally surrounds the outflow pot  131  and is mounted on a housing-side stub  138 , which encloses an annular channel of the fuel outlet  108 . 
         [0073]      FIG. 9  shows a longitudinal section through a filter system  100  according to a further embodiment of the invention for fuel filtration in a motor vehicle with an arrangement of a non-return valve  18  in the fluid line  16  fixed to the element. The fluid line  16  is formed in this example from a section  141  provided through the cover  20  of the filter element  10  and a section  142  extending in the inner region of the filter media body  119 . As in the example according to  FIG. 7 , the fluid line  16  is exchanged together with the filter element  10 , wherein at the same time the non-return valve  18  integrated in section  141  is also exchanged. The filter system  100  according to  FIG. 9  is similar to the other embodiments in construction and function, so that reference is made in general to the preceding descriptions, wherein advantageous differences also arise from  FIG. 9 .