Abstract:
A filter element ( 32 ) and a filter device ( 10 ). The filter element ( 32 ) can be arranged in a filter housing ( 16 ) of the filter device. The filter element ( 32 ) has an annular closed filter medium ( 34 ) connected with at least at one end face with an end member ( 36, 38 ). An annular anti-drain membrane ( 44 ) opens and closes at least one fluid opening ( 26 ) of the filter housing ( 16 ) amd is arranged on the side of the at least one end member ( 38 ) that is facing away from the filter element ( 34 ). The surface of the contact section ( 60 ) of the anti-drain membrane ( 44 ) has at least one relief-like adhesion disturbance area ( 64 ) for disturbing an adhesion of the anti-drain membrane ( 44 ) to the contact section ( 60 ).

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims the benefit of prior filed German patent application no. 102011117173.1 filed in Germany on Oct. 28, 2011, the entire disclosure of which is incorporated herein by reference. 
       TECHNICAL FIELD 
       [0002]    The invention concerns a filter element of a filter device for filtering a fluid, in particular oil or fuel, in particular of an internal combustion engine, particularly of a motor vehicle, that can be arranged in a filter housing of the filter device, comprising an annular closed filter medium that is connected at least at one end face with an end member and comprising an annular anti-drain membrane, arranged on the side of the at least one end member that is facing away from the filter medium, for opening and closing at least one fluid opening of the filter housing. 
         [0003]    The invention moreover concerns a filter device for filtering a fluid, in particular oil or fuel, in particular of an internal combustion engine, particularly of a motor vehicle, comprising a filter element that is arranged in a filter housing of the filter device and that comprises an annular closed filter medium that is connected at least at one end face with an end member and comprising an annular anti-drain membrane, arranged on the side of the at least one end member that is facing away from the filter medium, for opening and closing at least one fluid opening of the filter housing. 
       BACKGROUND OF THE INVENTION 
       [0004]    WO 2009/060072 Al discloses a filter element for use in a filter housing that can be opened. The filter element has an annular closed filter medium that is connected at the end faces with an upper end disk and a lower end disk. An anti-drain membrane is arranged such at the lower end disk that it covers within the filter housing an inlet opening. In normal operation of the liquid filter, the fluid to be purified flows through the inlet opening and lifts a sealing rim of the anti-drain membrane off the surface of a housing bottom part. 
       SUMMARY OF THE INVENTION 
       [0005]    An object of the invention is to design a filter element and a filter device of the aforementioned kind such that reliability, in particular response behavior of the anti-drain membrane, is further improved. In particular, the susceptibility to wear should be reduced as possible. 
         [0006]    This object is solved according to the invention in that, in a maximum open state, the anti-drain membrane is resting flat with a back that is facing the at least one end member against a surface of a contact section of the at least one end member that is facing this back and the surface of the contact section that is facing the back of the anti-drain membrane has at least one relief-like adhesion disturbance area for disturbing adhesion of the anti-drain membrane to the contact section of the at least one end member. 
         [0007]    According to the invention, the surface of the contact section is thus not continuously smooth but provided with at least one relief-like adhesion disturbance area. In this way it is prevented that the back of the anti-drain membrane upon contacting the contact section can tightly adhere like a suction cup or gets stuck in a different way. In this way, the response behavior of the anti-drain membrane is improved in particular upon transition from the maximum open state into the closed state. The relief-like adhesion disturbance area can advantageously have volumes that are open toward the back of the anti-drain membrane. The open volumes interrupt the surface of the contact section that is otherwise approximately uniform and in particular smooth. In this way, adhesion by suction of the back of the anti-drain membrane to the contact section of the least one end member can be counteracted. Since the adhesion disturbance area is arranged on the at least one end member, the back of the anti-drain membrane can be designed to be otherwise uniform, in particular smooth. This has a positive effect on its flexibility. 
         [0008]    During opening and closing, it can therefore be uniformly deformed, in particular curved, and can enable a uniform opening process and closing process. In a view from the at least one fluid opening, the anti-drain membrane can advantageously be shaped concavely in the rest state in which it can seal the at least one fluid opening. A fluid flow through the fluid opening toward the anti-drain membrane can lift the anti-drain membrane off the at least one fluid opening. The anti-drain membrane can be bent by the fluid flow elastically toward the at least one end member. The concave shape has the effect that the anti-drain membrane is then elastically tensioned. The anti-drain membrane in the open state can be resting flat with its back on the contact section. The contact section can serve as a stop for the anti-drain membrane in order to prevent a further folding over of the anti-drain membrane. The flat contact also prevents that the anti-drain membrane is deformed. This reduces wear. Moreover, it is prevented in this way that the anti-drain membrane resting flat against the contact section flutters within the fluid flow; this also has a positive result on wear of the anti-drain membrane. Upon interruption of the fluid flow or a reversal of the fluid flow the mechanical tension has the effect that the anti-drain membrane is automatically returned into the rest state and closes the at least one fluid opening. In this way, a return flow of fluid into the at least one fluid opening is prevented. Advantageously, the at least one end member can be an end disk. An end disk can be realized in a simple and space-saving way. Advantageously, the anti-drain membrane can be connected in radial direction inwardly or outwardly with the at least one end member. 
         [0009]    In an advantageous embodiment, the at least one adhesion disturbance area can have at least one recess and/or at least one projection. Recesses and projections can be formed integrally in a simple way in particular when molding the at least one end member in a single working step. They can also be shaped or molded subsequently. Recesses can be simply cut, drilled, etched or milled into the surface of the end member. Projections can be adhesively attached or welded on. Recesses can be designed simply such that, when the anti-drain membrane is resting flat on the contact section, they cause smaller deformations of the back of the anti-drain membrane than projections. In this way, the wear of the anti-drain membrane can be further reduced. 
         [0010]    Advantageously, the at least one recess can be channel-like. Channel-like recesses have an elongate extension wherein their length is greater than their width. Channel-like recesses can extend within the contact section and connect fluidically various areas within the contact section with each other. With respect to its width on either side of the at least one channel-like recess, the back of the anti-drain membrane can be supported on the surface of the contact section. Deformations of the anti-drain membrane when resting on the contact section of the at least one end member can thus be reduced further. 
         [0011]    Advantageously, a plurality of channel-like recesses can extend in the contact section in radial direction from an inward area to an outward area. The channel-like recesses can advantageously be distributed circumferentially. They can be uniformly distributed so that the disturbance of the adhesion is as homogenous as possible across the entire contact section. This may further improve the response behavior of the anti-drain membrane. 
         [0012]    According to a further advantageous embodiment, the adhesion disturbance area can provide a fluid connection in an area outside of the contact section; optionally, the at least one channel-like recess can extend past the contact section. In this way, upon contacting of the anti-drain membrane on the contact section, a possibly resulting underpressure, which may cause the anti-drain membrane to adhere by suction on the contact section, can be counteracted in that fluid from the exterior of the contact section can flow to the contact section through the at least one channel-like recess. 
         [0013]    Advantageously, a width of the at least one recess can be smaller than 1 mm, preferably approximately 0.5 mm, and its depth can be smaller than 1 mm, preferably approximately 0.4 mm. In this way, a flat uniform contacting of the anti-drain membrane on the contact section can be enabled. In this way, with the at least one recess an optimal pressure compensation can be realized for preventing underpressure between the anti-drain membrane and the contact section. 
         [0014]    The object is solved further according to the invention by the filter device in that, in the maximum open state, the anti-drain membrane is resting flat with a back that is facing the at least one end member against a surface of the contact section of the end member that is facing this back and the surface of the contact section that is facing the back of the anti-drain membrane has at least one relief-like adhesion disturbance area for disturbing adhesion of the anti-drain membrane to the contact section of the at least one end member. The advantages and features that have been discussed in connection with the filter element according to the invention apply likewise to the filter device according to the invention and its advantageous embodiments. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    Further advantages, features and details of the invention result from the following description in which an embodiment of the invention will be explained in more detail with the aid of the drawing. A person of skill in the art will consider the features disclosed in combination in the drawing, the description and the claims also expediently individually and combine them to other meaningful combinations. It is shown schematically in 
           [0016]      FIG. 1  schematically shows a section of an oil filter of an internal combustion engine of a motor vehicle with an exchangeable round filter element that comprises an anti-drain membrane at a lower end disk; 
           [0017]      FIG. 2  schematically shows the round filter element of  FIG. 1  showing one half in section; 
           [0018]      FIG. 3  is an isometric schematic illustration of the round filter element of  FIGS. 1 and 2  looking onto the lower end disk with the anti-drain membrane; 
           [0019]      FIG. 4  is a detail view of the lower end disk with the anti-drain membrane of the round filter element of  FIGS. 1 to 3 ; and 
           [0020]      FIG. 5  schematically depicts the oil filter of  FIG. 1  wherein the anti-drain membrane is shown in the open state. 
       
    
    
       [0021]    In the Figures same components are identified with the same reference numerals. 
       DETAILED DESCRIPTION 
       [0022]    In  FIGS. 1 and 5 , an oil filter  10  of a motor oil circuit of an internal combustion of a motor vehicle is illustrated in section. The oil filter  10  serves for filtering the motor oil. 
         [0023]    The oil filter  10  comprises a housing bottom part  12  and a housing top part  14  of a the filter housing, referenced as a whole by  16 . The housing bottom part  12  has a cup  18  that is open at the top and is provided with an inner thread  20  at its inner wall. An outer thread  22  of the housing top part  14  engages this inner thread  20  so that the housing parts  12  and  14  are detachably secured to each other. For sealing between the housing parts  12  and  14  an O-ring  24  is provided. 
         [0024]    In the interior of the housing bottom part  12  a plurality of inlet openings  26  for the motor oil to be filtered and a central outlet opening  28  for filtered motor oil are arranged. The outlet opening  28  is connected with the interior of a central tube  30 . The central tube  30  is arranged coaxial to a filter axis  31 . The inlet openings  26  are located relative to the filter axis  31  radially outside of the central tube. When in the following “radial”, “axial” or “circumferential” is used, this is relating to the filter axis  31  if nothing different is explicitly mentioned. 
         [0025]    On the central tube  30  an exchangeable round filter element  32  is positioned coaxially. The round filter element  32  has a zigzag-shaped folded and annular closed filter medium  34 . At its end face, the filter medium  34  is seal-tightly connected by means of an adhesive connection with an upper end disk  26  and a lower end disk  38 , respectively. The upper end disk  36  is resting tightly on the support collar  39  of the central tube  30  supporting the filter medium  34 . The central tube  30  has a plurality of penetrations  40  that are permeable for the motor oil. At the lower end disk  38 , on the side that is facing away from the filter medium  34 , a downwardly projecting continuous annular projection  42  is arranged. On the projection  42  an elastic annular anti-drain membrane  44  is injection-molded. The anti-drain membrane  44  is illustrated in detail also in  FIGS. 2 to 4 . 
         [0026]    The anti-drain membrane  44  is concavely curved when viewed from the inlet openings  26 . In radial direction outwardly, it has a circumferentially extending sealing rim  46  which, in the closed state that is also the rest state, is supported on a circumferentially extending sealing surface  48  of the housing bottom part  12 , as illustrated in  FIG. 1 . The sealing surface  48  surrounds the inlet openings  26  outwardly in radial direction. On the radial inner circumferential side of the projection  42  a radial sealing section  50  is arranged which is seal-tightly supported on the radial outer circumferential side of the central tube  30 . In this way, a seal-tight separation between a raw side  52  and a clean side  54  of the round filter element  32  is provided. The clean side  54  is located in the interior of the round filter element  32 , the raw side  52  outside. 
         [0027]    The anti-drain membrane  44  is designed such that, upon flow of the motor oil through the inlet openings  26 , indicated in  FIG. 5  by arrows  58 , it can be bent towards the lower end disk  38 . A back  56  of the anti-drain membrane  44  that is facing away from the inlet openings  26  can then rest flat against the surface of a contact section  60  of the lower end disk  38  that is facing it. The contact section  60  extends circumferentially, on the one hand, and in radial direction from the projection  42  in radial direction outwardly to the level of the sealing rim  46  of the anti-drain membrane  44 , on the other hand. The contact section  60  extends thus across the area in which the back  56  of the anti-drain membrane  44  in its maximum open state, illustrated in  FIG. 5 , can rest against the lower end disk  38 . 
         [0028]    In the contact section  60  a plurality of relief-like adhesion disturbance areas in the form of channel-like recesses  64  is arranged. The recesses  64  are shown in  FIGS. 2 to 4  in detail. The recesses  64  are distributed in groups circumferentially in the surface of the lower end disk  38 . The recesses  64  extend radially to the filter axis  31  approximately from the projection  42  to the radial outer rim of the lower end disk  38 . They are open toward the radial outer circumferential side of the lower end disk  38 . The recesses  64  thus extend past the contact section  60  toward the raw side  52 . 
         [0029]    The extension of the recesses  64  in the circumferential direction, i.e., their width, is smaller than 1 mm, preferably approximately 0.5 mm, respectively. Their depth in axial direction is smaller than 1 mm, preferably approximately 0.4 mm, respectively. In this way, the back  56  of the anti-drain membrane  44  can rest flat against the contact section  60  without the anti-drain membrane  44  being deformed in the area of the recesses  64 . The contact area of the anti-drain membrane  44  at the contact section  60  in relation to the width of the recesses  64  is so large that the anti-drain membrane  44  cannot be pressed into the recesses  64 . 
         [0030]    In operation of the oil filter  10 , the motor oil to be purified that is flowing in through the inlet openings  26  forces the anti-drain membrane  44  into the maximum opening state, as illustrated in  FIG. 5 , against the contact section  60  and thus releases the inlet openings  26 . The anti-drain membrane  44  in the open state is under mechanical tension. The motor oil flows to the raw side  52  and from the radial outward position through the filter medium  34 , where it is purified, in radial direction inwardly, indicated in  FIG. 5  by arrow  66 , and through the passages  40  into the interior of the central tube  30 . From here, the purified motor oil, indicated by arrow  68  and arrow  70 , flows through the outlet opening  28  out of the filter housing  16  and is supplied to the motor oil circuit. 
         [0031]    In the rest state, when no motor oil flows through the inlet openings  26 , the sealing rim  46  rests sealingly on the sealing surface  48 , as indicated in the  FIG. 1 , and prevents in this way that motor oil can flow from the raw side  52  back into the inlet openings  26 . Because of the anti-drain membrane  44  a complete drainage of the filter housing  16  is thus prevented so that, when starting the internal combustion engine anew, motor oil is available immediately. 
         [0032]    Upon transfer from the open state into the rest state, for example, upon interruption of the oil flow, as is the case, for example, upon operational stop of the internal combustion engine, the anti-drain membrane  44  as a result of its mechanical tension is bent from the contact section  60  back to the sealing surface  48 . The recesses  64  prevent in this connection that the back  56  of the anti-drain membrane  44  can become attached by suction on the contact section  60 . Because of the recesses  64 , motor oil from the raw side  52  outside of the contact section  60  can flow to the area between the contact section  60  and the back  56  of the anti-drain membrane  44 . Underpressure that may occur is counteracted in this way. This inflow of motor oil via the recesses  64  enhances also the return movement of the anti-drain membrane  44  toward the sealing surface  48 . 
         [0033]    In the above described embodiment of an oil filter  10  and a round filter element  32 , the following modifications are possible inter alia: 
         [0034]    The invention is not limited to an oil filter  10  of internal combustion engines of motor vehicles. It can also be used in other types of liquid filters, for example, for water or fuel. Instead of an internal combustion engine for motor vehicles, it can also be used in other types of internal combustion engines, for example, industrial motors. 
         [0035]    The invention can also be used in connection with oil filters  10  that cannot be opened and a filter element  32  that is not exchangeable. 
         [0036]    The anti-drain membrane  44 , instead of being injection-molded onto the projection  42 , can also be connected in a different way to the lower end disk  38 . For example, it can be glued, welded or monolithically formed on the lower end disk  38 . 
         [0037]    The anti-drain membrane  44 , instead of being connected in radial direction inwardly, can also be connected in radial direction outwardly with the lower end disk  38 . 
         [0038]    In addition to or instead of the channel-type recesses  64 , the relief-like adhesion disturbance area can have also other relief-like structures. 
         [0039]    In addition or instead of the recesses  64 , also projections can be provided on the surface of the lower end disk  38  in the area of the contact section  60  in order to realize the relief-like adhesion disturbance area. 
         [0040]    The recesses  64 , instead of being radial, can also extend from the radial inner position to the radial outer position in a slanted, curved or meandering fashion. 
         [0041]    The recesses  64 , instead of extending past the contact section  60 , can also be arranged entirely within the contact section  60 . 
         [0042]    The upper end disk  36  and/or the lower end disk  38  can also be connected seal-tightly with the filter medium  34  in a different way than by a respective glue connection. It is also possible to provide only a lower end disk  38 . 
         [0043]    The anti-drain membrane  44 , instead of being arranged at the lower end disk  38 , can also be arranged at the upper and disk  36 . 
         [0044]    Instead of the end disks  36  and  38 , also other types of end members can be provided. 
         [0045]    The filter medium  34 , instead of being folded in a zigzag shape, can also be annularly closed in a different way. 
         [0046]    Instead of the round filter element  32 , a different annular, for example, oval or angular, filter element can be used also.