Abstract:
A filter may include ac over defining a chamber and an annular filter element arranged within the chamber. The filter may also include a housing and at least one intermediate piece arranged between the cover and the housing when the cover is screwed to the housing. An inlet duct may be in communication with an untreated side of the filter element and an outlet duct may be in communication with clean side of the filter side of the filter element and an outlet duct may be in communication with a clean side of the filter element. A drainage duct may be arranged in the housing for draining the chamber during removal of the cover. A closure device may be arranged in the intermediate piece and have a closure element configured to close the drainage duct.

Description:
CROSS-REFERENCES TO RELATED APPLICATION 
       [0001]    This application claims priority to German Patent Application 10 2009 030 503.3 filed on Jun. 24, 2009 and PCT/EP2010/058620 filed on Jun. 18, 2010, which are hereby incorporated by reference in their entireties. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to a filter device for fluids, in particular an oil filter for the cleaning of lubricating oil for internal combustion engines of motor vehicles 
       BACKGROUND 
       [0003]    Filter devices, in particular oil filters for internal combustion engines of motor vehicles usually have a so-called annular filter element, by means of which a fluid flowing through the filter device is filtered. Periodically, this annular filter element must be exchanged in order to be able to always ensure the filtering action of the filter device. By removal of a filter device from the housing, the annular filter element is also removed. Owing to the constantly increasing environmental specifications, the exchange of the annular filter element must be possible here without fluid, in particular oil, arriving into the environment. For this reason, conventional filter devices have in their housing, in addition to an inlet duct which communicates with an untreated side of the annular filter element and an outlet duct which communicates with a clean side of the annular filter element, also a drainage duct, through which a receiving chamber, in which the annular filter element is arranged, can be drained on unscrewing of the filter device. Of course, this drainage duct must be closed off when the filter device is ready for operation, because otherwise the clean side and the untreated side of the annular filter element would be short-circuited with each other and thereby the filter device could not deploy its filtering action. 
       SUMMARY 
       [0004]    The present invention is concerned with the problem of indicating for a filter device an improved or at least a different embodiment which makes possible an automatic opening or respectively closing off of a drainage duct on dismantling or respectively installing a filter device. 
         [0005]    This problem is solved according to the invention by the subject matter of the independent Claim  1 . Advantageous embodiments are the subject matter of the dependent claims. 
         [0006]    The invention is based on the general idea of providing an intermediate piece between a filter device, arranged vertically, and a housing arranged therebeneath, into which intermediate piece a closure device is integrated. The closure device is constructed here so as to be rotatable about the filter axis of the annular filter element, wherein the annular filter element itself is arranged in a receiving chamber, which is delimited by a filter housing cover. On the housing side, an inlet duct and an outlet duct are provided, wherein the inlet duct communicates with an untreated side of the annular filter element and the outlet duct communicates with a clean side of the annular filter element. A drainage duct is likewise provided in the housing, through which the receiving chamber can be drained on unscrewing of the filter device, so that no filter fluid, in particular no oil, can arrive into the environment. The closure device, which is arranged so as to be rotatable about the filter axis, has a closure element, by means of which the drainage duct can be closed off when the filter device is screwed fully onto the housing. Generally, the closure device is constructed so that, on screwing on of the filter device on the housing, it is fixed in a precisely defined position in which the closure element is arranged aligned to the drainage duct and is able to be adjusted into a position closing off the drainage duct by the screwing on of the filter device. In contrast to this, the closure device on unscrewing of the filter device from the housing is twisted and is moved at the same time axially away from the housing, so that the closure element on unscrewing of the filter device from the housing frees the drainage duct and makes possible a drainage of the receiving chamber containing the annular filter element. Through the closure device according to the invention, which can be constructed for example as a favourably-priced plastic part with a closure element made of a different plastic, it is possible in the technically simplest manner to reliably close off the drainage duct with the filter device screwed on fully on the housing, and thereby to ensure a problem-free functioning of the filter device, wherein on an unscrewing of the filter device from the housing the drainage duct is automatically opened, so that the receiving chamber for the annular filter element can drain and no filter fluid arrives into the environment. A separate opening or respectively closing of the drainage duct, connected with the possibility of forgetting this, can be reliably ruled out by the filter device according to the invention, whereby the maintenance process is to be arranged to be distinctly more reliable and in addition easier to arrange. Through the precisely fixed position of the closure device during the screwing-on process of the filter device on the housing, furthermore a laborious positioning or respectively aligning of the closure element with respect to the drainage duct which is to be closed off can be dispensed with, wherein it is always ensured that the drainage duct is reliably closed off with the filter device fully screwed on on the housing. 
         [0007]    Expediently, the closure device is constructed as a plate and has at least one rib facing the dome belonging to the housing, which rib, on screwing on of the filter device lies against the at least one incline on the housing side and thereby is fixed with respect to its position so that the closure element is in alignment to the drainage duct and by a further screwing on of the filter device is able to be adjusted into its position closing off the drainage duct. The rib ensures here on screwing on that the rib is in contact with a stop, which is formed by the incline on the housing side, and hence does not prevent the closure device from a further rotational movement, but delays its axial movement. If the filter device is screwed on further, then a compression of the spring element takes place, whereby an axial displacement of the closure element towards the drainage duct is delayed until the gaps between the ribs receive the inclines and the gaps between the inclines receive the ribs, so that that the closure element rests on an opening of the drainage duct, and namely so that the drainage duct is tightly closed off 
         [0008]    In a further advantageous embodiment of the solution according to the invention, the intermediate piece is constructed from a closure device in the manner of a plate and an outer cap, wherein on the outer edge of the closure device at least one detent element is provided, which engages into a matching counter detent element on the inner side of the cap and therefore only permits rotation in one direction. The cap is securely connected with the filter housing cover and the closure device is rotatable therein. 
         [0009]    In a further advantageous embodiment of the solution according to the invention, between the intermediate piece and the annular filter element arranged thereabove, a disc-like base and a simple spring element are provided, wherein the base has several through-openings distributed in circumferential direction. The co-rotation of the closure device on unscrewing of the filter housing cover from the housing brings about a lifting of the closure element and hence an axial displacement of the closure device together with the closure element, so that the closure element frees the opening of the drainage duct. The closure device therefore behaves completely differently in the screwing process or respectively unscrewing process of the filter device on/from the housing. 
         [0010]    On screwing of the filter device on the housing, the closure device, i.e. the spring arranged between closure device and base, is compressed until the closure element, arranged on the closure device, lies tightly on the drainage duct. Thereby, on screwing of the filter device on the housing, a reliable closing off of the drainage duct can be brought about, and on unscrewing of the filter device from the housing, a reliable opening and hence draining of the receiving chamber can be brought about. This ensures, on the one hand, a high functional reliability of the filter device, and on the other hand an emergence of filter fluid into the environment can be reliably avoided, because the drainage duct is preferably already fully opened with few rotations of the filter device, so that the receiving chamber can drain completely before the filter device is removed. 
         [0011]    Further important features and advantages of the invention will emerge from the sub-claims, from the drawings and from the associated description of figures with the aid of the drawings. 
         [0012]    It is to be understood that the features mentioned above and to be explained further below are able to be used not only in the respectively indicated combination, but also in other combinations or in isolation, without departing from the scope of the present invention. 
         [0013]    Preferred example embodiments of the invention are illustrated in the drawings and are explained in further detail in the following description, wherein identical reference numbers refer to identical or similar or functionally identical components. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    There are shown, respectively diagrammatically: 
           [0015]      FIG. 1  shows an external view of the filter device according to the invention 
           [0016]      FIG. 2  shows a detail of the external view 
           [0017]      FIG. 3  shows the detail as exploded illustration 
           [0018]      FIG. 4  shows a detail in plan view from below 
           [0019]      FIG. 5  shows a housing 
           [0020]      FIG. 6  shows the details of  FIG. 3   
           [0021]      FIG. 7  shows the detail of  FIG. 4  in oblique view 
           [0022]      FIG. 8  shows the detail of  FIG. 5  in section 
           [0023]      FIG. 9  shows a first stage of the interplay of the inclines on screwing on 
           [0024]      FIG. 10  shows a second stage of the interplay of the inclines on screwing on 
           [0025]      FIG. 11  shows the mounted filter device 
           [0026]      FIG. 12  shows a detail of  FIG. 11   
       
    
    
     DETAILED DESCRIPTION 
       [0027]    In  FIG. 1  the filter device  1  can be seen from the exterior. It consists of a filter housing cover  2 ; the latter forms in its interior a receiving chamber  5  in which the annular filter element  6  is arranged so that it separates a clean side from an untreated side. The internal structure is that of a conventionally used exchangeable filter which is suitable for the filtering of oil. An intermediate piece  3  is situated on the side of the filter device  1  facing the housing  4 . The housing  4 , on which the filter device  1  is securely screwed, can be, for example, a motor block housing or a cylinder housing. For the sake of simplicity, it is only named as housing  4 . The housing  4  is configured so that it has a dome  15  with thread, an incline  22  adjacent to the dome  15 , and the inlet duct  7 , the outlet duct  8  and the drainage duct  9  (see  FIGS. 7 and 8 ). 
         [0028]    In  FIG. 2  the intermediate piece  3  is shown, which is tightly flanged with the filter housing cover  2  at the transition of the two parts. The intermediate piece  3  consists of an outer cap  37  and internal plate  11 . 
         [0029]    In  FIG. 3  the individual parts which together form the intermediate piece  3 , and further parts are illustrated. A base  16 , which has through-openings  33  through which oil can arrive into the receiving chamber  5 , forms the closure of the receiving chamber  5 . The central opening  34  has a thread or a threaded hollow pin, so that the filter device  1  can be screwed securely on the dome  15  of the housing  4 . Between the base  16  and plate  11  there is a spring element  17 , a conventional spiral spring in the example which is shown, but any suitable spring element  17  can be used. The spring element  17  has a bearing surface internally on the plate  11 . The plate  11  has a central opening  39  and a lateral edge  21  on which detent elements  19  are situated. The lower edge  32  of the detent elements  19  forms at the same time the mounting of the plate  11  in the cap  37 . For this purpose, the cap  37  has an unbent edge  38  at the lower end. The plate  11  also has a flat annular groove on the side facing the housing, into which the closure element  12  is inserted in the form of a flat O-ring seal. The sealing material can also be injected into the annular groove. The precise shape of the closure element  12  is dependent on the respective case of application. 
         [0030]    All the named parts of the filter device  1 , except for the annular filter element  6  and the seals, can be made from metal or else from suitable plastics; in the latter case, however, the cap  37  would not be flanged with the filter housing cover  2 , but welded. 
         [0031]    The cap  37  and the plate  11  are illustrated again in detail in  FIG. 4 . At least one detent nose  18  is situated in the cap  37 , on which the detent hooks  19  of the lateral edge  21  of the plate  11  engage. Thereby, the plate  11  is only rotatable in one direction in the cap  37 . In the other direction, through the engaging of the detent elements  18  and  19  into each other it is moved together with the cap  37  and hence with the filter device  1 . 
         [0032]      FIG. 5  also shows the plate  11  in detail, however from a different perspective. It can be seen here that the ribs  13  are arranged offset with respect to the closure element  12  and that beneath the detent hooks  19  elongated openings  40  are provided, through which the oil can run off out from the receiving chamber  5  via the drainage duct on unscrewing of the filter device  1 . 
         [0033]    In  FIG. 6  a view is illustrated of the plate  11  from below. The detent elements  19  situated on the lateral edge  21  can be seen, which occur on the entire circumference of the lateral edge  21  of the plate  11 . At least two ribs  13  are arranged at the central opening  39  on the inner side. They are therefore ribs, because they have a short, not too steep inclination only at one end  24 , whereas the remainder of the ribs  13  runs flat. As can be seen from  FIG. 5 , the ribs  13  are not arranged at the height of the closure element  12 , but rather lie slightly offset hereto. Between the at least two ribs  13  at least two gaps are situated, the ends of the respective ribs  13  are spaced apart with respect to each other. 
         [0034]    In  FIG. 7  an oblique top view is to be seen onto the housing  4 . The inlet duct  7 , the outlet duct  8  and the drainage opening  9  can be seen, and also at least two inclines  22  which are configured matching the ribs  13  on the plate  11 , i.e. inverted. 
         [0035]    In  FIG. 8  the housing  4  is illustrated in section. The incline  22  is situated adjacent to the dome  15 . It has a first part  35  with a small inclination and a second part  25  which is without inclination. Between the at least two inclines  22  at least two gaps  41  are situated, into which, with the filter device  1  screwed on, the ribs  13  of the plate  11  come to lie. The geometry of the ribs  13  and inclines  22  and also of the gaps lying respectively between two inclines must be ideally coordinated with each other. This is shown in  FIGS. 9 and 10 . On screwing the filter device  1  tightly on the housing  4 , firstly the thread of the base  16  or of a threaded hollow pin engages into the thread of the dome  15 . By the rotating of the filter device  1 , the plate  11  is therefore moved axially together with the filter device  1  in the direction of the housing  4 . When the flat piece of the ribs  13  is placed on the part  25  of the incline  22 , the spring element  17  is compressed. On further rotating of the filter device  1 , the ribs  13  and inclines  22  slide along each other until the ribs  13  can enter into the gaps  41  between the inclines  22 . At this stage, the plate  11  can rotate further without moving axially; only when the ribs  13  engage into the gaps  41  can the plate not rotate further, it is prevented from this by the inclines  22 . The elastic force of the spring element  17  now acts and presses the plate  11  downwards in the direction of the housing  4 . The filter device  1  is now screwed securely by further rotation and is now screwed tightly on the housing  4 . The elastic force of the spring element  17  causes a tight closing off of the drainage opening of the drainage duct  9 . 
         [0036]    On unscrewing of the filter device  1  from the housing  4 , the plate  11  is positively moved together with the filter device  1  owing to the detent elements  18  and  19  acting as detent hooks, which are arranged on the plate  11  and on the cap  37  (see  FIG. 4 ). 
         [0037]    In  FIGS. 11 and 12  the mode of operation of the ribs  13  and of the inclines  22  is illustrated on unscrewing of the filter device  1 ; rotation is carried out in the other direction, e.g. anti-clockwise. By the rotating of the filter device  1 , the ribs  13  move out from the gaps  41  towards the incline  22  until the two oblique surfaces of the ribs  13  and of the inclines  22  come into contact. The plate slides by means of the oblique part of the ribs  13  along the incline  22  in the housing  4 , thereby the plate  11  is pressed against the spring element  17 , the latter is compressed again and the drainage opening of the drainage duct  9  is freed, so that the oil can flow off out from the receiving chamber  5  of the filter device  1  via the drainage duct  9  before the filter device  1  is unscrewed from the housing. 
         [0038]      FIG. 12  shows how the two oblique surfaces of the ribs  13  on the one hand and of the incline  22  on the other hand slide over each other. With the movements of the ribs  13  and of the inclines  22  relative to each other, no crumbs of material arise, because they both have surfaces which have no sharp edges. 
         [0039]    On the cap  37 , on the outer circumference close to the connection site between filter housing cover  2  and cap  37  there is situated a further seal, not shown, which seals the filter device  1  with respect to the housing  4  after screwing on, so that no oil can arrive into the environment during operation.