Abstract:
The invention relates to a filter element, comprising a filter medium ( 10 ) having a concentric shape and pleated in a zig-zag shape, a first open or closed end disk ( 11 ) arranged on a face and a second end disk ( 12 ) arranged on the opposing face. The end disk ( 12 ) comprises a concentric opening ( 13 ) and extends in a substantially annular shape over the pleats of the filter medium. The end disk ( 12 ) further comprises a first ring bead ( 14 ) extending axially to the outside and a sealing groove ( 16 ). The ring bead ( 14 ) comprises outer faces ( 18, 19 ), which are supported on radially extending ribs ( 20, 21 ) of a housing receiving the filter element or on a flat surface having channels.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is US National Stage Entry of international patent application no. PCT/EP2010/050615, filed Jan. 20, 2010 designating the United States of America. Priority is claimed based on German patent application no. 10 2009 008 450.9, filed Feb. 11, 2009. 
     TECHNICAL FIELD 
     The invention concerns a filter element and a filter system, in particular for the intake air of an internal combustion engine. 
     PRIOR ART 
     U.S. Pat. No. 4,720,292 discloses an air filter with the following features: a housing with an axial outlet opening and a substantially open second end that is closable by a removable cover. On the circumference of the housing an air inlet opening is arranged. A substantially cylindrical filter element is arranged in the housing and has an inner support pipe, a filter with an outer support pipe, wherein the filter element is coaxially arranged in the housing. The sealing action of the filter element relative to the housing is realized by an annular end disk that is provided with a substantially cylindrical surface that is inwardly oriented in radial direction and is pushed across an inner section of the outlet part. 
     It is known that filter inserts of air filters are exchanged after a certain service life. Depending on the dust load, the service life of an air filter can be a few days (construction machinery) up to several months. 
     The filter insert disclosed in the above-mentioned U.S. patent as well as other conventionally employed filter inserts are comprised of a combination of materials wherein in particular for the support pipes sheet steel or plastic material is used. The filter medium is paper or a synthetic nonwoven. The end disks are comprised of plastic material, for example, of a soft elastomer. 
     Especially in case of frequent exchange of filter elements a reliable and process-safe sealing action of the filter element in a housing is important. The sealing action should be designed to be temperature-resistant and resistant to vibrations. In facilities or devices that are subjected to strong vibrations or shaking action, the sealing action of the filter element must also be ensured. At the same time, however, the filter element itself should have no metallic elements so that it can be thermally disposed off without problems. 
     SUMMARY OF THE INVENTION 
     The invention therefore has the object to provide a filter element and a filter system with excellent filtration properties and a reliable sealing action between the area of the unfiltered and the area of the filtered medium. This object is solved by the features of the independent claim. 
     The important advantage of the invention resides in that by the configuration of the seals of the filter element with two annular bead-shaped arrangements and a sealing groove positioned therebetween it is ensured that, on the one hand, a high sealing effect and, on the other hand, an excellent support action of the filter element in a housing are achieved. Particularly when using plastic material for the seal on vibration-loaded elements, a design is required that operates reliably even under extreme temperature fluctuations. 
     According to the invention, the housing can also have passages that are arranged on the flat surface on which the annular bead is resting. These passages, for example, have the task of discharging dust. 
     According to a further embodiment of the invention the end disk that supports the seal is comprised of polyurethane. Of course, there is also the possibility to produce the end disk of a soft elastomer or of several components, for example, by means of in-mold assembly by injection molding, wherein the component that forms the seal is comprised of an elastomer and the component that produces the connection to the filter medium is a thermoplastic material. The latter can be fused or glued to the filter medium. 
     In a further embodiment of the invention, it is proposed to arrange dust passages on the filter system where it is required to keep the sealing surfaces, in contact with the filter element, free of dust. 
     According to a further embodiment, ribs can be arranged on the filter-receiving housing or also on a web. There is also the possibility to arrange ribs and/or grooves on the housing at locations where this support action or passing-through of certain materials through the grooves is required. 
     The invention concerns moreover a filter system with a filter element. This filter system serves in particular for filtration of intake air of an internal combustion engine and is comprised of a housing and a cover for receiving the filter element. In an advantageous way, the filter system is provided with two annular grooves that, in the area of the seal, communicate with the sealing contours of the filter element. At the same time, in this area additional support webs or grooves are provided that extend, for example, radially and have a support action or a through-opening function. 
     These and further features are not only disclosed in the claims but can also be taken from the figure description and the figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be explained in the following in more detail with one embodiment. It is shown in: 
         FIG. 1  a section through a filter system; 
         FIG. 1   a  a detail view of  FIG. 1 ; and 
         FIG. 2  the detail illustration in the sealing area of the filter housing. 
     
    
    
     DETAILED DESCRIPTION 
     The filter system according to  FIG. 1  is comprised of a housing  26  that is substantially concentrically configured and has an inlet  28 . The filter system serves for filtering intake air of an internal combustion engine. By means of the inlet  28  the air to be purified is supplied according to arrow  38 , flows through a cyclone pre-separator  34  and is imparted therein with a rotary flow action. As a result of this rotary flow action, particles that are entrained in the air reach the outer housing walls and are transported from there to the exterior through a dirt outlet  35  that can be closed off by a suitable valve. 
     On the housing  26  a central part  37  is arranged. The latter is also concentrically designed and is coupled with the housing in the area  40 , for example, by means of a weld connection. On the central part  37  there is a cover  27 . The latter is detachably connected to the central part by means of clamp closure devices or another suitable closure system. Cover, central part and housing therefore provide a closed system that has an outlet  29  for discharging the purified air. 
     Within the system as a whole there is a filter element  39 . The latter is comprised of a zigzag-shaped folded filter medium  10  and is designed of a concentric shape. On the end faces the filter element  39  has end disks  11 ,  12 . While one end disk  12  has a concentric opening  13 , the other end disk  11  is closed off by means of a closure member  24 . There is also the possibility to provide the additional end disk with a concentric opening that is closed off by a socket at the cover  27 . The air to be purified flows according to arrow  41  through the filter element and according to arrow  42  exits purified through the outlet  29  to an internal combustion engine, not illustrated here. The filter element has at the end disk  12  arranged to the right a first annular bead  14  and a second annular bead  15 . Therebetween a sealing groove  16  is located. 
     Within the end disk  12  a reinforcement plate  17  is provided. The latter has penetrations  22 . The reinforcement plate is provided in the outer area, i.e., outside of the sealing material area, with an annular surface  23 . The latter serves for shielding the filter medium or the element during assembly or when knocking off dust or when being manually handled in other ways. 
     The annular bead  14  as well as the annular bead  15  impact on ribs  20 ,  21  and define thus the axial position of the filter element in the housing. The axial bead end faces ( 18 ,  19 ) of the annular beads ( 14 ,  15 ) can lie in the same plane and abut against and be supported on the radially outwardly extending ribs ( 20 ,  21 ) of a housing receiving the filter element or on a planar surface with passages. 
     In an alternative embodiment, not limited to this example, the position of the filter element can be defined by engagement of the annular beads  14  and  15  in annular grooves  31  and  32 —without contacting the ribs  20 ,  21 . Alternatively, also other locations can be used for additional axial and/or radial fixation. 
     The ribs are illustrated in more detail in  FIG. 2 ; they are so-called double ribs, i.e., two neighboring ribs  20   a ,  20   b ,  20   c  that are arranged at the groove bottom of the annular groove  31  and at the groove bottom of the annular groove  32  and, for example, have a height of 3 to 6 mm. 
     The sealing web  33  is provided in the upper area with one or several grooves or webs. There is also the possibility, as indicated by reference character  61 , to provide a web  61  additionally on one side of the sealing web  33  or, as indicated with reference character  62 , a groove on the web  33 . Of course, basically one has to take care that a circumferentially extending sealing action of the filter element in the housing is ensured. The illustrated webs as well as the grooves are only examples for the support action at certain locations, in particular a support action of the filter element, or a passage configuration that is expedient for discharging dirt or the like. 
     The illustrated features of  FIG. 2  can also be grooves  20   a ,  20   b ,  20   c  or  21   a ,  21   b ,  21   c  that are arranged in any arrangement in the sealing area. The filter element is supported reliably in the sealing area. An arrangement of ribs prevents a rotation of the filter element in case of transverse frequency excitation. The sealing structure improves at the same time the entire connection between the housing and the filter element. 
     The sealing web  33  that is located between the two annular grooves has the sealing area provided on its flanks; here, the end disk  12  seals with its sealing groove  16 . Therefore, there is a double sealing principle by means of these two flanks. The sealing groove  16  is minimally deeper than the sealing web  33  so that a certain axial tolerance is possible in this area. As already mentioned, the end disk is comprised of a polyurethane foam or another elastomer whose hardness is selected such that, on the one hand, it provides the required sealing forces and, on the other hand, also ensures good positioning of the filter element in the filter housing. By means of the two-flank sealing action and the support action of the annular beads  14 ,  15  on the ribs  20 , a relatively minimal mounting force and also minimal release force for exchange of the filter element is required. 
     In an alternative embodiment, not limited to this example, the sealing web  33  has at its axial end an additional sealing bead, for example, an annular structure that is extending on the sealing web  33  and is axially oriented into the interior of the housing. In this way, an additional axial sealing action can be achieved without affecting the pressing force when mounting the filter element in the filter housing. This can be provided, for example, by means of a sealing bead that is thin in comparison to the sealing web  33 . 
     The end disk  11  is provided with support noses  43 ,  44 . The latter are supported on the cover  27  and ensure thus a satisfactory axial force in the direction of the end disk  12  and thus a reliable sealing action. In the end disk  12  a closure member  24  is embedded. It separates the raw air space from the clean air space. Within the filter element there is a secondary element  36  that surrounds the interior  25 . The purified air flows through the secondary element that usually comprises a nonwoven pad  45 . The nonwoven pad is attached to a thermoplastic or metallic base member  46 . The secondary element  36  is attached by means of a thread  47  on the outlet socket of the outlet  29  and, at the same time, sealed by means of an O-ring  48  in this area. 
     The housing  26  is provided with an inner wall  49 . This inner wall has a minimal spacing relative to the annular surface  23 . At this inner wall a clamping element  50  is provided. 
     This clamping element is comprised of spring steel that is shaped at several locations and projects into the mounting space of the filter element. The shaped locations are illustrated in  FIG. 1  and are identified by reference character  51 . Upon insertion of the filter element the shaped locations are pushed outwardly and serve for centering the filter element. Should a filter element without the annular surface  23  be inserted into the housing, there is no possibility of centering the filter element. In this case, the filter element or the filter medium would possibly be damaged. Therefore, the clamping element serves as a protection against accidental installation of a wrong or faulty filter element.