Abstract:
A filter device includes a lid ( 6 ) configured for detachable mounting to a filter housing, an annular filter element ( 2 ) mounted to the lid ( 6 ), a closure part ( 13 ) embodied as a separate component from the filter element and the lid ( 6 ) with the closure part ( 13 ) detachably secured to at least one of the lid ( 6 ) and the filter element ( 2 ).

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a bypass continuation of international PCT application PCT/EP2012/051665 filed Feb. 1, 2012 and designating the United States of America. This application claims a priority date of Feb. 28, 2011, based on priority claimed in PCT/EP2012/051665 to prior filed German patent application No. 10 2011 012 633.3, the entire contents of the aforesaid international application and the German patent application being incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The invention concerns a filter device having an annular filter element. 
     BACKGROUND 
     EP 0 882 483 A2 discloses a filter device with an annular filter element that is arranged in a cup-shaped filter housing that is to be closed by a lid. The annular filter element is flowed through in radial direction from the exterior to the interior, the purified fluid is subsequently axially discharged. A central tube as a support body is integrated into the filter element and forms the wall of the axial interior through which the purified fluid is discharged. The end faces of the filter element are covered by a terminal disk. In addition, on the central tube a sealing bottom is provided on the end face that is facing the lid and closes the axial interior. The sealing bottom is secured fixedly to the lid by a tie anchor. 
     Mounting and demounting is relatively complex as a result of the anchor which penetrates the filter element axially through the interior space and is attached to the oppositely positioned housing bottom. 
     The invention has the object to simplify mounting of a filter device or the exchange of the filter element with simple constructive measures while providing an inexpensive manufacture. 
     SUMMARY OF THE INVENTION 
     The filter device according to the invention—a gas filter or a liquid filter—has an annular or hollow-cylindrical filter element which is flowed through in radial direction by the fluid to be filtered. The preferred flow direction is radial from the exterior to the interior wherein the purified fluid is axially discharged via the interior in the filter element. 
     The filter element is received in a filter housing which is closed off by a lid. For assembly, the filter element is inserted into the housing and closed off by the lid wherein the lid is to be connected to the filter element. 
     In the embodiment according to the invention, a closure part is provided that is embodied as a separate component and that is to be connected with the lid as well as with the filter element and that forms the connecting element between the lid and the filter element. The closure part is independent and discrete from the lid and from the filter element or from a component connected to the filter element. Moreover, it is provided that the closure part is releasably configured at least with one of the components, preferably with both components (lid and/or filter element). As a result of the releasability, mounting as well as demounting or exchange of the filter element is simplified. The filter element and the lid do not form a mandatorily connected component unit that must be inserted into the filter housing or must be removed therefrom as a whole. Instead, it is now possible to first insert the filter element into the housing and subsequently connect it by means of the closure part to the lid. 
     For servicing purposes, it is sufficient to exchange the filter element and to keep the lid. In this way, a significant cost reduction is achieved. 
     According to an expedient embodiment, it is provided that the closure part is supported rotatably in the lid and/or in the filter element. The rotatable arrangement has the advantage that the rotational movement can be used as a locking movement. Inasmuch as the closure part is rotatable relative to both components, during the locking movement the filter element as well as the lid remain in their stationary position relative to the housing so that only the closure part is rotated. Accordingly, the locking forces are significantly reduced because no rotational movement of the lid and/or of the filter element with high friction relative to a sealing element is required. 
     According to a further expedient embodiment, the closure part in the mounting position is connected with form fit to the lid and/or the filter element. The form fit connection can be produced or released in a simple way and advantageously without a tool. This is done, for example, in that a central recess is introduced into the lid into which the closure part is inserted, wherein the recess has a smaller diameter than the closure part. With respect to the filter element the connection with the closure part can be preferably realized in the form of a bayonet closure wherein by means of axial movement the closure part is first approached to the filter element and subsequently the closure part is rotated about the longitudinal axis of the filter element until the final locking position with form fit between the closure part and the filter element is reached. For realizing the bayonet closure, on the closure part at least one locking web can be arranged that engages in a mounted position a correlated locking web on the filter element. The locking webs are constructively designed such that upon a rotational movement an axial approach and fast clamping action can be achieved at the same time. Incidentally, in an alternative embodiment the lid with the closure part can be connected also like a bayonet closure. 
     Moreover, it can be expedient to arrange on the closure part at least one locking hook which in the mounted position engages from behind a correlated locking section on the lid. Accordingly, the closure part is connected with form fit to the lid in both axial directions. For releasing the closure part, it is sufficient to press the bendable locking hook into the disengaged position and at the same time remove the closure part axially from the lid. 
     A component of the annular filter element is expediently a central or support tube that is introduced, for improvement of the stability, into the filter element and forms the wall of the cylindrical interior of the filter element. According to a preferred embodiment, the closure part is connected to the central tube that for this purpose has corresponding locking elements that are embodied so as to correspond with the locking elements on the closure part. In the mounted position, the lid is seated immediately on the end face of the central tube. 
     In general, both end faces of the filter element are covered by terminal disks which are also a component of the filter element. Optionally, the connection between filter element and closure part is realized by one of the terminal disks that is provided for this purpose with locking elements. It may also be expedient to provide at least one terminal disk and the central tube in monolithic embodiment and to realize the locking action with the closure part either with the terminal disk or the central tube. 
     According to a further expedient embodiment, it is provided that on the lid a cylindrical collar is provided that surrounds the central recess that is introduced into the lid and that extends axially in the form of a socket. The collar projects in the mounted position into the central tube and facilitates positional fixation of the lid in relation to the filter element. It can be expedient to provide a rib or the like on the collar as a mounting aid which engages a correlated groove on the inner wall of the central tube. In this way, the rotational position of the lid relative to the filter element is positively determined. 
     According to a further advantageous embodiment, it is provided that the lid is designed as a closed disk and, on the inner side of the lid that is facing the filter element, form fit elements are arranged for connecting with the closure part. As in the embodiment with central recess in the lid, the form fit elements can be designed as locking webs which upon relative rotational movement assume a locking position relative to each other so that the components in axial direction are secured with form fit and safely on each other. In the embodiment of the lid without central recess, the form fit elements at the lid are expediently provided on the inner side of a collar that projects in axial direction past the inner side of the lid and correspond with form fit elements on the exterior side of a ring of the closure part. 
     It can be expedient to provide on the closure part a snap hook for limiting the relative rotational movement between lid and closure part so that with engagement of the form fit elements across a limited angle segment a relative rotational movement between lid and closure part is possible. This relative rotational movement can be used for locking or unlocking the component, comprised of the lid and the closure part, on the filter element or the central tube of the filter element. At the same time, the snap hook prevents an accidental unintentional detachment of the closure part from the lid. Inasmuch as a detachment of the closure part from the lid is desired, the snap hook can be force-loaded into its opening positions so that the form fit elements on the closure part and on the lid can be disengaged from each other. 
     Moreover, it can be expedient to provide on the lid and on the filter element or a component connected to the filter element, in particular the central tube, axially oriented positioning elements that are serving for securing the relative rotational position between the lid and the filter element. The axially oriented positioning elements engage each other upon axial placement of the lid onto the filter element or the central tube so that the relative rotational position is determined positively. A plurality of such positioning elements can be distributed about the circumference, respectively, and can be designed, for example, as recess or ribs, wherein the number of positioning elements enables a corresponding number of rotational positions between lid and filter element or central tube. 
     For an easier actuation and manipulation of the closure part, the latter can be provided with a central actuating grip. In particular in the closed embodiment of the lid without a central recess, the actuating grip is curved and projects in the mounted state of the filter device into the interior of the filter element in order to facilitate engagement and actuation, in particular rotation of the closure element. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further advantages and expedient embodiments can be taken from the further claims, the figure description, and the drawings. It is shown in: 
         FIG. 1  a perspective view of a filter device with an annular filter element that in the area of an end face is closed by a lid which is a component of a filter housing; 
         FIG. 2  the filter element, shown by itself, with a view of the end face where the lid is to be arranged; 
         FIG. 3  the lid in perspective illustration; 
         FIG. 4  a central tube which is inserted into the filter element, shown by itself; 
         FIG. 5  a closure part by means of which the lid is connected with the central tube of the filter element, illustrated in perspective view; 
         FIG. 6  the closure part in a further illustration; 
         FIG. 7  a section through the filter element with the lid, including closure part, attached at the end face, shown in perspective illustration; 
         FIG. 8  a further section illustration through the filter device; 
         FIG. 9  the connecting area with central tube, closure part, and lid in enlarged illustration; 
         FIG. 10  a detail view of the area of the upper terminal disk with integrally formed sealing lip; 
         FIG. 11  the upper terminal disk in mounted position; 
         FIG. 12  a perspective view of the filter device in a further embodiment, illustrated with end face lid element; 
         FIG. 13  the lid element in a perspective individual illustration; 
         FIG. 14  a closure part in individual illustration which is to be connected to the lid part according to  FIG. 13 ; 
         FIG. 15  lid and closure part in connected position; 
         FIG. 16  the central tube of the filter element in a first perspective view; 
         FIG. 17  the central tube in a second perspective view; 
         FIG. 18  the filter element with end face terminal disk in a first perspective view; 
         FIG. 19  the filter element with second axially oppositely positioned terminal disk in a further perspective view; 
         FIG. 20  a section view of the filter device; 
         FIG. 21  the sectioned filter device in a perspective view from above. 
     
    
    
     In the Figures, the same components are identified with the same reference characters. 
     DETAILED DESCRIPTION OF THE INVENTION 
     As can be seen in  FIGS. 1 and 2 , the filter device  1  has an annular filter element  2  whose end faces each are sealed off by terminal disks  4  and  5 , respectively. In the filter element  2  a plastic central tube  3  as a support frame is integrated that forms at the same time the inner wall of the interior of the filter element  2 . The filter element  2  is flowed through radially from the exterior to the interior by the fluid to be purified that subsequently is discharged in purified form out of the interior in axial direction. 
     A lid  6  belongs to the filter housing and is to be connected to an end face of the filter element  2 . 
     As can be seen in  FIG. 2 , on the terminal disk  5  which is facing in the mounted state the lid  6 , axially projecting support webs  7  that serve for supporting the lid  6  are provided. Moreover,  FIG. 2  shows that in the central tube  3 , on the side which is neighboring the terminal disk  5 , locking webs  8  extending in circumferential direction are arranged at a minimal axial spacing to the end face and are located on the inner side of the central tube  3  and are monolithically formed therewith. Distributed about the circumference, several such locking webs  8  are provided that each extend across a limited angular segment and preferably all have the same axial spacing to the end face. The locking webs  8  serve for providing a form fit locking action in the manner of a bayonet closure with a closure part that is illustrated in  FIGS. 5 and 6 . 
     As can be seen in the view of the lid  6  according to  FIG. 3 , a central recess  10  is incorporated into the lid  6  and is delimited by an axially projecting socket-shaped collar  9 . On the exterior side of the collar  9  there are, regularly spaced, axially extending ribs  11  which are monolithically formed with the collar  9  and serve as a mounting aid. In the mounted state the ribs  11  project into correlated grooves  12  which, as can be seen in  FIG. 4 , are introduced on the inner side into the central tube  3  adjacent to the end face of the central tube. By means of engagement of the ribs  11  in the grooves  12  a precise orientation of the lid in the rotation direction is provided. 
       FIGS. 5 and 6  show a closure part  13  in two different perspective illustrations. The closure part  13  serves as a connecting element for connecting the lid  6  with the filter element  2  or the central tube  3  in the filter element. The closure part  13  has a radially expanded collar  14  and an axially projecting collar  15  that has, relative to the collar  14 , a smaller diameter. The collar  15  supports locking webs  16  that are distributed about the circumference adjacent to the free end face on the exterior side of the collar. The locking webs  16  interact in the mounted position with the locking webs  8  on the inner wall of the central tube  3  in the manner of a bayonet closure. A portion of the locking webs  16  on the closure part  13  has a curved section that upon rotational movement of the closure part  13  about the axis of the filter device facilitates pushing onto the correlated locking webs  8  on the central tube  3 . The closure part  13  is also provided with an actuating grip  17  which spans the central recess in the sleeve-shaped closure part  13  and is designed to facilitate easier handling of the closure part. 
     The collar  14  has a greater diameter than the central recess  10  of the lid  6  so that, upon insertion of the closure part  13  into the recess  10  of the lid  6 , the lid and the closure part are connected to each other with form fit in axial direction. 
     On the collar  14  several locking hooks  18  are distributed about the circumference and extend each in axial direction and are arranged at a minimal radial spacing relative to the outer wall of the collar  15 . The locking hooks  18  serve for clamping fast a correlated locking section on the lid  6  wherein the locking section is preferably the collar  9  on the lid  6 . Accordingly, it is possible, by axial insertion of the collar  15  into the central recess  10  in the lid  6 , and by the locking action of the locking hooks  18  on the end face of the collar  9  on the lid  6 , to secure with from fit the two components in opposite axial directions. For release of the connection, the locking hooks  18  must be bent slightly in the direction toward the collar  15  on the closure part  13  until the locking hooks become disengaged from the collar  9  on the lid  6  and the closure part can be removed again in axial direction from the central recess  10  in the lid  6 . 
     As can be seen further in  FIGS. 5 and 6 , on the outer circumference of the collar  14  of the closure part  13 , a looking hook  19  is arranged which upon mounting delimits the rotational movement of the closure part  13 . The locking hook  19  upon rotational movement contacts a correlated locking member on the lid  6 . 
     In  FIGS. 7 to 9 , section illustrations of the filter device  1  with the filter element  2  and the lid  6  mounted with the aid of the closure part  13  are illustrated. In the central recess in the lid  6  the closure part  13  is inserted wherein the radially extended collar  14  of the closure part  13 , as a result of its diameter being greater than the central recess, securely holds the lid  6  of the filter element  2 . The collar  15  of the closure part  13  engages with the locking webs  16  the correlated locking webs  8  on the central tube  3  ( FIG. 9 ). Accordingly, the closure part  13  together with the lid  6  is securely held with form fit in axial direction on the central tube  3  and thus on the filter element  2 . 
     As can be seen in  FIGS. 8 and 9 , the locking hooks  18  which are monolithically formed on the closure part  13  are in the locking position in which the locking hook  18  engages from behind the end face edge of the collar  9  on the lid  6 . 
     The support webs  7  which are monolithically formed with the terminal disk  5  on the filter element  2  are positioned in mounted position so as to contact the inner side of the lid  6 . The support webs  7  are located radially outside of the closure part  13  and effect an additional stabilization of the lid  6 . 
     As can be seen in  FIGS. 10 and 11 , monolithically with the upper terminal disk  4  a sealing lip  20  is formed which projects axially past the topside of the terminal disk  4  and is of an annular configuration. The sealing lip  20  which is arranged on the radial inner side of the annular terminal disk  4  is also shown in  FIG. 1 . In the mounted position, the sealing lip  20  is seal-tightly resting on a housing component  21  of the filter device, for example, on the bottom of the cup-shaped part of the housing, as can be seen in  FIG. 11 . The sealing lip  20  is designed to be elastically deformable and upon assembly is pressed against the housing component  21  and is thereby deformed. The force which is generated by the deformation and which is based on the inherent elasticity of the sealing lip serves as a sealing force with which the sealing lip  20  presses against the housing part  21 . 
     It may be expedient to provide on each of the two terminal disk such sealing lips. 
     The terminal disk  4  and the sealing lip  20  which is formed monolithically with the terminal disk are comprised, for example, of polyurethane (PUR) or of another material that has a defined elasticity for elastic deformation of the sealing lip. 
       FIGS. 12 to 21  show a further embodiment of a filter device which is designed similarly to the preceding embodiment but differs in particular in regard to the lid and the closure element. 
     As can be seen in  FIG. 12 , the annular filter element  2  of the filter device  1  is closed off at the end face by the lid  6  which, in contrast to the first embodiment, has no central recess but is configured as a closed disk. As can be seen in the perspective view of the lid  6  according to  FIG. 13 , on the inner side of the lid an annular collar  9  projects in axial direction and has on its end face several ribs  22  distributed about the circumference and projecting in axial direction and forming positioning elements for securing the rotational position of the lid relative to the filter element. The ribs  22  correspond with correlated positioning elements in the form of recesses  23  ( FIG. 17 ) which are introduced adjacent to the lower end face into the central tube  3 . Distributed about the circumference there are a total of six ribs  22  or recesses  23  with uniform spacing so that positioning of the lid on the central tube is possible in six different rotational positions at a respective angular distance of 60 degrees relative to each other. 
     The radial outer surface of the collar  9  forms a sealing surface on which the lower terminal disk which closes off the filter element is resting seal-tightly. 
     On the radial inner side of the collar  9 , uniformly distributed about the circumference, a total of four webs  24  extending in circumferential direction are arranged that constitute form fit elements for a form fit connection with the closure part. 
     In  FIG. 14  the closure part is illustrated in an individual illustration,  FIG. 15  shows the connection of the lid  6  and closure part  13 . The closure part  13  is annularly designed and has a bracket-shaped web  17  which in the mounted state projects past the inner side of the lid  6  and facilitates engagement and rotation of the closure part. On the radial outer surface of the ring of the closure part  13  there are webs  25  and  26  which constitute form fit elements for form fit connection with the lid  6 . The webs  25  and  26  correspond with the webs  24  on the inner side of the collar  9  on the lid  6  ( FIG. 13 ). On an end face of the web  25  there is a snap hook  27  which forms together with the web  26 , positioned above and axially displaced, an insertion opening for the web  24  on the lid  6 . The snap hook  27  enables insertion of the web  24  in circumferential direction into the area of the web  25  on the closure part  23  but it prevents an accidental release of the lid  6  and closure part  13  by rotation in opposite direction so that the web  24  on the lid  6  can move only up to the point of reaching the snap hook  27  that forms a stop. A second stop is provided by a wall  25   a  which is formed on the oppositely positioned side of the web  25 . Accordingly, the relative rotational movement between closure part  13  and lid  6  is delimited by the wall  25   a  and the snap hooks  27 . At the same time, this relative rotational movement enables transfer of the closure part  13  between a locking position on the central tube and a release position or removal position without this rotational movement also requiring a rotational movement of the lid. Instead, the lid can remain stationary during the relative rotational movement of the closure part  13  on the filter element or central tube. 
       FIG. 16  shows the central tube  3  in a perspective view from above,  FIG. 17  in a perspective view from below wherein the lower side of the lid  6  is to be closed. Adjacent to the lower end face on the inner side of the central tube  3 , locking webs  8  extending in the circumferential direction are distributed about the circumference. Between two locking webs each that are positioned at a spacing to each other there is a recess  23  which is embodied to be open toward the end face and which forms a positioning element that interacts with the axially projecting rib  22  on the collar  9  of the lid  6  ( FIG. 13 ). The locking webs  8  enable together with the locking webs  16  on the closure part  13  ( FIG. 14 ) a locking action of the closure part on the central tube  3 . The locking webs  16  on the closure part  13  are located, like the webs  25  and  26 , on the radial outer surface of the ring of the closure part  13 . The locking webs  16  interact with the webs  26  on the outer side of the ring, the locking webs  16  and the webs  26  having the same extension in circumferential direction but the locking webs  16  displaced axially relative to the webs  26  and providing a passage for receiving the locking webs  8  on the central tube. 
       FIG. 16  in combination with  FIG. 21  shows that on the inner side of the central tube  3  adjacent to the locking webs  8  or the recesses  23  there are markings  28  which are intended to indicate the locking or release position of the closure part  13 . Markings  29  on the closure part  13  that are arranged in the locking webs  16  correspond with the markings  28  on the central tube  3 . Two such markings displaced in circumferential direction on the inner side of the central tube  3  indicate a locking position and a release position, respectively. In the mounted state, the marking  29  of the closure part  13  points to the locking marking  28 ; for unlocking, the locking part  13  must be rotated so far that the marking  29  points to the release marking on the central tube  3 . 
       FIG. 18  shows the filter device  1  in a perspective view from above,  FIG. 19  from below but without the lid being put on. The filter element  2  on both end faces is covered by a terminal disk  4  and  5 , respectively, wherein on each terminal disk an annular sealing lip  30  or  31  is projecting in axial direction. The radial inner surface of the annular terminal disk  4  or  5  forms a sealing surface, respectively. 
     In the  FIGS. 20 and 21 , the filter device  1  is illustrated with mounted lid  6  as well as closure element  13 . As shown in  FIG. 20 , the radial inner side of the terminal disk  5  forms a sealing surface and is positioned seal-tightly on a section of the lid  6  which in this area is conically shaped and connects an approximately disk-shaped, in radial direction outwardly positioned section with a circular inwardly positioned section of the lid. The sealing lip  31  on the lower terminal disk  5  contacts the inner side of the lid  6 . 
     In  FIG. 21  the closure element  6  is illustrated in the locked position in which the marking  29  on the closure element  13  is pointing directly onto the locking marking  28  on the inner side of the central tube  3 . For unlocking, the closure element  13  by actuation of the actuating grip  17  must be rotated to such an extent that the marking  29  points to the second marking  28  which corresponds to the release position.