Abstract:
A filter system has a housing and at least one detachable cover detachably connected to the housing to close off the housing. At least one exchangeable element is arranged within the housing and provided with a follower contour. The cover is provided with a follower tool which matches the follower contour of the at least one exchangeable element. The follower tool is disposed on the exterior side of the cover. The follower tool is a follower contour provided on the cover.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/815,214 filed: Apr. 23, 2013. This application claims foreign priority under 35 USC 119(b) to prior filed German patent applications 10 2013 002 274.6 filed Feb. 12, 2013; 10 2013 002 275.4 filed Feb. 12, 2013; 10 2013 002 277.0 filed Feb. 12, 2013; 10 2013 002 278.9 filed Feb. 12, 2013; and 10 2013 002 276.2 filed Feb. 12, 2013, the entire contents of the aforesaid U.S. Provisional Application and the aforesaid German patent applications being incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The invention concerns a filter system, in particular for use as an air filter in an internal combustion engine, as well as a filter element for installation in such a filter system. 
         [0003]    WO 2009/047196 A1 discloses a filter system for internal combustion engines in which a secondary element is provided which is arranged in an inner space of the filter element of the filter system. The secondary element has the task of keeping closed the outlet of the filter system when exchanging the filter element so that no dirt can penetrate into this area while the filter element is cleaned or replaced. In operation of the filter system the purified air flows through the secondary element which comprises a nonwoven layer on a support structure. The secondary element is connected by means of a screw thread to the outlet socket of the outlet and, at the same time, is sealed by an O-ring in this area. 
         [0004]    In principle, it is provided to exchange the filter elements of air filters after a certain operating time. Depending on the amount of dust that is collected, the service life of a filter element can be a few days (construction machinery) up to several months. In this context, the secondary element, arranged on the clean air side, remains usually within the filter system. However, when the secondary element is also strongly loaded with dirt, it must also be exchanged because otherwise the air throughput would be reduced too much. In this context, the reliable sealing action of filter element and secondary element in a housing ensuring safe operation is particularly important in order to protect the intake manifold of an internal combustion engine arranged downstream of the filter system from penetration of dirt. 
         [0005]    The object of the invention is to provide a filter system in which a service-friendly attachment and detachment of a secondary element from its fastening means in the housing is enabled. 
         [0006]    A further object of the invention is to provide a filter element and a secondary element for installation in such a filter system. 
       SUMMARY OF THE INVENTION 
       [0007]    In accordance with the present invention, the aforementioned objects are solved according to one aspect of the invention by a filter system that has a housing with at least one detachable cover that closes off the housing as well as at least one exchangeable element with a follower contour that is arranged within the housing, wherein the cover is provided with a follower tool which corresponds with or matches the follower contour of the exchangeable element. 
         [0008]    The service-related exchange of screw-on elements of a filter system such as filter elements and secondary elements is done usually by detaching and screwing on by hand. Particularly in case of large elements it becomes however more and more difficult to apply the required torque. Accordingly, it has become customary to employ separate tools in order to detach the elements and to screw them on again because greater torque can be applied by a greater lever action. This tool is now integrated into the cover of the system filter system so that it is available at any time in a service situation on site and cannot be lost. For example, the cover can have a follower contour that is provided also as a corresponding or matched negative shape on the exchangeable element so that it is sufficient to detach the cover from the filter housing, to turn it over, for example, in order to place the follower tool of the cover onto the element to be detached, and to unscrew the element by a rotational movement of the cover. In this case, the cover represents the tool or serves for handling the tool when the tool is used. 
         [0009]    Advantageously, the sealing action for the filter element and secondary element in the housing can be designed to be temperature-resistant and vibration-resistant. Even in facilities or devices that are exposed to strong vibrations or impacts, the sealing action for the filter element and secondary element can be ensured because the secondary element can be secured particularly safely and fast to the housing. In order to prevent an accidental detachment in operation, it is possible in case of screw connections to apply a satisfactory torque so that also an appropriate release torque must be applied for an exchange. Even when higher torque is required, the attachment and detachment of the secondary element by means of its screw connection can be realized without additional tools that have to be carried along. 
         [0010]    The follower contour that is complementarily provided on the secondary element and on the cover can be, for example, a polygon, a knurled structure, a rectangle and the like. When the follower contour is formed at the center of the cover, a relatively large diameter of the cover can provide an advantageous lever action. 
         [0011]    The cover can cover the housing at the end face, for example, and can cover the opening through which the filter element is installed and removed. Conceivable are however also other housing parts which are detachably designed and are suitable for temporary detachment. 
         [0012]    In one embodiment, the follower tool can be designed as a recess in the cover when, for example, the follower contour in the element is designed as a corresponding projection. Accordingly, both parts are matched to each other and the element can be detached by turning the cover. 
         [0013]    In another embodiment, the configuration can be reversed so that the follower tool is designed as a projection on the cover when, for example, the follower contour in the element is designed as a matching recess. This also provides that both parts fit or match each other so that the tool functionality is fulfilled. 
         [0014]    Preferably, the follower contour is arranged on the exterior side of the cover, in particular centrally on the exterior side of the cover. This has, for example, also the advantage that the follower contour is not located within the interior of the housing and does not occupy therein flow space or construction space. 
         [0015]    In a beneficial embodiment, a filter system can comprise a housing with a longitudinal axis, a cover that closes off the housing at an end face, an inlet communicating with the interior of the housing and disposed at the housing for supplying a medium to be filtered, in particular air, and an outlet communicating with the interior of the housing and disposed at the housing for discharging the filtered medium, a filter element arranged within the housing, an exchangeable secondary element arranged in the inner space of the filter element and provided with a follower contour, wherein the cover has a follower tool complementary to the follower contour of the secondary element. The housing can be, for example, comprised of a housing wall and two opposed end faces. One of the end faces can be fixedly connected to the housing wall and the other end face can be embodied by the removable cover. The filter element as well as the secondary element arranged within the inner space of the filter element can be expediently concentrically arranged relative to the longitudinal axis of the housing. On the housing, concentric to the longitudinal axis, an outlet for discharging the filtered medium can be disposed. The filter element and the secondary element are usually exchangeably arranged in the housing of the filter system and are accessible after opening of the housing, for example, via the screw-on cover. With such an arrangement, the cover can be detached from the housing and can be used as a tool for detaching and tightening the secondary element by screwing; the cover represents at the same time a tool that is available at any time on site in a service situation and cannot be lost. 
         [0016]    Advantageously, the secondary element can be connected by a screw connection with the housing so that a rotation of the cover engaging the secondary element is sufficient in order to release the secondary element. 
         [0017]    Alternatively, the secondary element can also be connected by a rotary locking closure (bayonet coupling) with the housing. In this way, by engaging with the cover the secondary element and rotating the cover, the secondary element can be released from its locked position. 
         [0018]    Expediently, the secondary element connected with the housing can remain in the housing when the filter element is exchanged. In this way, it is ensured that the air guiding manifold that adjoins the outlet of the filter housing is protected from soiling during the exchange process. 
         [0019]    Advantageously, in the area of the inlet of the filter system a cyclone separator can be provided and a dirt outlet can be provided on the housing or on the cover. This cyclone separator is comprised of a guiding geometry that causes the medium to be filtered to rotate. Due to this rotation, the dirt in the area of the housing wall is concentrated and is then discharged at a suitable location by means of a dirt outlet. Due to the preseparation of most of the dirt from the air to be filtered, the service life of the actual filter element can be extended decisively. 
         [0020]    In a further advantageous embodiment, an inlet and/or dirt outlet arranged at the cover can be designed as a grip lever. In this way, it is possible by lever action to apply a greater torque onto the elements to be released upon rotation of the cover; this may be of great importance in particular for very large filter systems or greatly soiled filter systems where the screw connections may possibly be stuck (“frozen”). 
         [0021]    Expediently, the filter system can be used as an air filter, in particular an air filter of an internal combustion engine. Safe operation of internal combustion engines is also based on a reliable and favorable filtration of the intake air for combustion. The described filter element provides an economic possibility for this purpose. 
         [0022]    Advantageous is also the use of the filter system as a particle filter, in particular as an oil filter or fuel filter of an internal combustion engine. In this context, reliable mounting and economical replacement of the described filter element are of decisive importance. 
         [0023]    The invention concerns as a further aspect a filter element for installation in a filter system as described above, wherein the filter element is exchangeably arranged in the housing of the filter system. Advantageously, in a service situation for exchange of the filter element, a tool integrated into the cover of the housing of the filter system can be used for releasing and tightening the filter element. In this way, the tool is always available on site in a service situation and cannot be lost. 
         [0024]    Furthermore, the invention concerns a secondary element for installation in a filter system as described above, wherein the secondary element is exchangeably arranged in the housing of the filter system. Advantageously, when exchanging the secondary element in a service situation, a tool which is integrated into the cover of the housing of the filter system can be utilized for releasing and tightening the secondary element. In this way, the tool is always on site in a service situation and cannot be lost. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0025]    Further embodiments and advantages of the invention can be taken from the claims, the description, and the drawing. Advantages are disclosed in the following description of the invention wherein embodiments of the invention are illustrated in the drawings. The drawings, the description, and the claims contain numerous features in combination. A person of skill in the art will also expediently consider these features individually and will combine them to other meaningful combinations. 
           [0026]      FIG. 1  shows in a perspective view a filter system according to one embodiment of the invention with tangential inlet, central outlet, and dirt outlet at the bottom. 
           [0027]      FIG. 2  shows in a perspective view a filter system according to another embodiment of the invention with radial inlet and central outlet. 
           [0028]      FIG. 3  shows in a perspective view the filter system according to  FIG. 1 , looking onto the cover with the follower tool being visible. 
           [0029]      FIG. 4  is a longitudinal section view of the filter system according to  FIG. 1 . 
           [0030]      FIG. 5  is a perspective view of the filter system according to  FIG. 1  with removed cover and with the follower contour of a secondary element. 
           [0031]      FIG. 6  shows a perspective view of the filter system according to  FIG. 1  with removed and turned-over cover before the follower tool of the cover and the follower contour of the secondary element are brought into engagement. 
           [0032]      FIG. 7  is a perspective view of the filter system of  FIG. 1  with the cover as a tool engaging the secondary element. 
       
    
    
       [0033]    In the Figures, same or functionally the same components are identified with same reference characters. The Figures show only examples and are not to be understood as limiting the invention. 
       DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0034]      FIG. 1  shows in a perspective illustration a filter system  100  according to one embodiment of the invention with tangential inlet  102 , central outlet  104 , and dirt outlet  106  at the bottom. Illustrated is a round filter configuration which is comprised of a housing  108  that is closed off by cover  110 . In case of an air filter system, dust-laden air flows into the inlet  102  that is arranged tangentially to the air filter element installed in the interior of the housing so that the air in the interior of the housing  108  is caused to rotate due to an incoming flow protector provided at the filter element. Filter element and incoming flow protector are not illustrated in the drawing. Due to the cyclone effect that is caused by the rotational movement of the air, centrifugal forces act on the dirt particles of the inflowing air so that the dirt particles are partially separated at the housing wall and can be discharged through the dirt outlet  106  from the filter system  100 . In this way, the filter element is loaded less with dirt. The purified air can be discharged via the central outlet  104  from the housing  108 . 
         [0035]      FIG. 2  shows a perspective view of a filter system  100  of an embodiment with radial inlet  102  and central outlet  104 . Illustrated is also a round filter configuration that is comprised of a housing  108  that is closed off by cover  110 . The inlet through which dust-laden air flows into the housing is in this case arranged centrally above the filter element arranged in the interior. The outlet  104  by means of which the purified air can flow out is also centrally arranged, as shown also in  FIG. 1 . 
         [0036]      FIG. 3  shows a perspective view of a filter system  100  according to  FIG. 1  illustrated in a view onto the cover with visible follower tool contour. It can be seen that in the cover  110  a follower contour  118  in the form of a recess is provided which, after removal of the cover  110  from the housing  108 , can be used as a follower tool for releasing a secondary element of the filter system. 
         [0037]    In  FIG. 4 , a cross-section of the filter system  100  according to the embodiment with tangential inlet  102 , central outlet  104 , and dirt outlet  106  at the bottom is illustrated. The housing  108  of the filter system  100  is closed off by cover  110 . A filter element  10  that is comprised of concentrically arranged support tube  14  and filter medium  12  is closed off at two oppositely positioned end faces with a first terminal disk  16  and a second terminal disk  18 . The second terminal disk  18  has support knobs  20  which are arranged in a circular shape and extend axially in outward direction; upon insertion into the housing  108 , they contact an inner cover contour  114  of the cover  110  in axial direction, engage in outward direction the contour  114 , and in this way are supported on the housing  108  axially and radially. On the oppositely positioned end face of the filter element  10 , a radial seal  26  is provided on the first terminal disk  16 . By means of the seal  26  the filter element  10  is supported radially on the housing  108 ; the seal  26  seals off the unfiltered air chamber relative to the filtered air chamber. The filter element  10  is thus axially clamped as well as radially clamped twice relative to the housing  108 . 
         [0038]    Dust laden air can flow in through the inlet  102  which in this embodiment is illustrated as a tangential inlet that enables the cyclone operation by the effected rotational movement of the air. Dust particles can be partially preseparated by the rotational movement and deposited on the housing wall; they can be discharged from the filter system  100  through the dirt outlet  106  by the force of gravity when the filter housing  108  is installed with the dirt outlet  106  pointing in downward direction. 
         [0039]    After partial separation of the dust particles in operation, the air flows through the filter medium  12  into the inner space of the filter element. Dust particles are retained within the filter medium starting at a certain size that depends on the filter medium. Depending on the dust load, the filter element must therefore be exchanged after a certain operating time. At the outlet end of the filter element  10 , between support tube  14  and outlet  104 , a secondary element  28  is provided that is comprised of a relatively permeable filter medium and, when the filter element  10  is exchanged, remains in the housing  108  as a protection for the downstream air guiding manifold of the internal combustion engine against penetration of dust particles and other objects. The secondary element  28  has at the closed end of the body  52  an end face  54  where a follower contour  56  is provided as a projection and can be used for release of the screw connection  32  at the housing  108 . In the cover  110  of the housing  108  a follower contour  118  is illustrated as a recess. This follower contour  118  can be used as a follower tool after detaching the cover  110  from the housing  108  and after turning over the cover  110  and placing it on the follower contour  56  of the secondary element  28  so as to provide a follower tool. In this way, it is possible to apply a greater torque for release of the screw connection  32 . The use as a follower tool is also possible in case that for the connection of the secondary element  28  to the housing  108  a rotary locking connection  58  (bayonet coupling) is used. 
         [0040]    Alternatively, the follower contour  56  can also be designed in the secondary element  28  as a recess at the end face  54  when the follower contour  118  of the cover  110  is designed as a projection. 
         [0041]      FIG. 5  shows a perspective view of a filter system  100  according to  FIG. 1  with removed cover and visible follower contour of the secondary element. Here, the secondary element  28  can be seen that is screwed into the housing  108  of the filter system  100  and comprises body  52 , end face  54 , and follower contour  56 ; the follower contour  54  is designed in this case as a projection. 
         [0042]    In  FIG. 6 , a perspective view of a filter system  100  according to  FIG. 1  with removed and turned-over cover  110  is illustrated before the follower contours of the cover and the secondary element are being contacted and engaged. This illustrates the utilization of the cover  110  as a follower tool by means of the follower contour  118 , designed as a recess in this embodiment and matched with its negative shape to the follower contour  56  of the secondary element  28  at the end face  54  of the body  52 . 
         [0043]      FIG. 7  shows furthermore the use of the cover  110  as a follower tool in a perspective view of the filter system  100  according to  FIG. 1  with the cover  110  attached as a tool to the secondary element. The cover  110  is positioned with its follower contour  118  directly on the follower contour  56  of the secondary element  28  at the end face  54  of the body  52 . For releasing the screw connection of the secondary element  28  from the housing  108 , the cover  110  can be rotated so that the cover  110  entrains the secondary element  28  upon rotation. In this way, it is possible by means of the lever action of the cover  110  to apply a greater torque onto the screw connection and to thereby release the connection more easily. 
         [0044]    Advantageously, an inlet and/or dirt outlet provided at the cover  110  can be designed as a grip lever so that by means of it upon rotation of the cover  110  an even greater torque can be applied onto the screw connection of the secondary element  28 . Such a dirt outlet  106  is, for example, illustrated in  FIGS. 1 and 3 . In this way, an even easier release of the connection between secondary element  28  and housing  108  is possible. 
         [0045]    While specific embodiments of the invention have been shown and described in detail to illustrate the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.