Abstract:
A fluid filter has an annular filter element and a particular annular seal, which has axial first and second surfaces, an outer circumferential surface, and an inner circumferential surface. The seal includes a sealing protrusion, defined by the axial first surface of the annular seal, with a section forming an axially oriented seal surface, as well as a filter element receptacle defined by the axial second surface. The receptacle receives an axial end of the annular filter element therein. To assist with installation, a feature defining a helix is included as part of the inner circumferential surface of the annular seal, and forms part of a radially oriented seal, surface.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention concerns fluid filters, useful in automotive applications, having features facilitating installation of filter elements into associated filter housings. While the fluid mentioned is typically air, the invention, of course, should not be considered limited solely to air filtering applications. 
         [0003]    2. Description of Related Art 
         [0004]    U.S. Pat. No. 5,547,480 to Coulonvaux discloses a cylindrical air filter including a ring-like end cap molded over ends of a cylindrical pleated paper filter element and liners between which that paper filter element is mounted. The end cap has a radially inward facing surface adapted to engage an outer surface of the tubular portion of an air filter outlet. 
         [0005]    Conventional seals disposed between annular air filter elements and housings for such elements utilize axially extending sealing faces that either are cylindrical or have concentric rings. U.S. Pat. No. 5,556,440 to Mullins et al., for example, discloses several embodiments of a pressure-actuated radial air filter seal. 
         [0006]    In one embodiment, the seal has a straight inside axial face that is deflected and placed in tension around a generally cylindrical center post, while, in another embodiment, the seal has an inside axial face with a concave radiused portion located between protruding radial ribs or lips that are deflected and placed in tension around the post. 
         [0007]    The disclosures of both the Coulonvaux (&#39;480) patent and the Mullins et al. (&#39;440) patent are incorporated herein by reference as non-essential subject matter. 
       SUMMARY OF THE INVENTION 
       [0008]    A new end cap or seal design includes a helical or spiral feature on one of its sealing surfaces to ease installation. The helical or spiral feature is used instead of the usual concentric rings to produce a seal against the neck of an air filter housing outlet. 
         [0009]    One aspect of the invention concerns a fluid filter having an annular filter element and a particular annular seal, which has axial first and second surfaces, an outer circumferential surface, and an inner circumferential surface. The seal includes a sealing protrusion, defined by the axial first surface of the annular seal, including a section forming an axially oriented seal surface, as well as a filter element receptacle defined by the axial second surface, the receptacle receiving an axial end of the annular filter element therein. A feature defining a helix is included as part of the inner circumferential surface of the annular seal and forms part of a radially oriented seal surface. In the particular embodiments described and illustrated, the helix referred to is a conical helix. 
         [0010]    The feature mentioned could be a protruding thread, a ledge, or a step, and can extend either partially or completely along the axial extent of the inner circumferential surface of the annular seal. The invention, more generally, also relates to a filter arrangement for an automotive vehicle including a filter housing with an annular end wall and a neck forming a fluid outlet, and a fluid filter including an annular filter element and an annular seal such as that mentioned, as well as to a process of mounting the fluid filter in such a filter housing. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a perspective view from above an annular air filter seal according to a first embodiment of the invention. 
           [0012]      FIG. 2  is a top view of the seal shown in  FIG. 1 . 
           [0013]      FIG. 3  is a side view of the seal shown in  FIG. 1 . 
           [0014]      FIG. 4  is a view of the seal shown in  FIG. 2  along section line  4 - 4 . 
           [0015]      FIG. 5  is a part-sectional view similar to that provided by  FIG. 4 , but of a second embodiment of the air filter seal. 
           [0016]      FIG. 6  is a view similar to that provided by  FIG. 4 , but of a third filter seal embodiment. 
           [0017]      FIG. 7  is a part-sectional view similar to that provided by  FIG. 4 , but of a fourth filter seal embodiment. 
           [0018]      FIG. 8  illustrates an air filter seal according to any of the four embodiments mentioned when the seal is located, in place, in the interior of a filter housing. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    A first embodiment of an air filter seal  10  according to the invention is illustrated in  FIGS. 1-4 . This seal  10  may be a one piece elastomeric seal, a seal formed of another suitable material, or a seal formed of an appropriate combination of materials. The perspective view provided by  FIG. 1  shows the seal to be generally annular overall. The seal  10  has an axial first surface  12 , an axial second surface  14 , best visible in  FIG. 4 , an outer circumferential surface  16 , and an inner circumferential surface  18 . The axial first surface  12  illustrated includes a radially outer flat section  12   a , a first upstanding seal flange side section  12   b , a second upstanding seal flange side section  12   c , a substantially flat, axial seal flange sealing section  12   d  interposed between the seal flange side sections  12   b  and  12   c , and a radially inner flat section  12   e  immediately adjacent a central opening  19  surrounded by the inner circumferential surface  18  of the seal  10 . 
         [0020]    Referring now to the cross sectional view provided by  FIG. 4 , the axial second surface  14  is composed of a substantially flat, radially inner annular section  14   a  immediately adjacent the central opening  19 , a substantially cylindrical, axially extending section  14   b  adjacent to the inner annular section  14   a , a substantially cylindrical, axially extending section  14   c  radially outside of and roughly parallel to the axially extending section  14   b , a substantially flat, radially intermediate section  14   d  located between the axially extending sections  14   b  and  14   c , and a radially outer annular section  14   e  defining an outer edge of the axial second surface  14 . A sealing protrusion or flange  13  ( FIG. 1 ) is delimited by the surface sections  12   b ,  12   c , and  12   d . Flat sections  12   a  and  12   e  may be positioned at the same distance from the intermediate section  14   d  of the surface  14 , for a consistent thickness on opposite sides of the sealing protrusion or flange  13 , or, as shown in  FIG. 4 , at different distances from the section  14   d , so that the width or thickness of the seal  10  differs on opposite sides of the sealing protrusion or flange  13 . In the first seal embodiment, the outer circumferential surface  16  of the seal  10  extends approximately axially between a radial outermost location of the outer flat section  12   a  and a radial outermost location of the annular section  14   e , and thus is approximately cylindrical. 
         [0021]    As shown in  FIGS. 1 ,  2 , and  4 , the inner circumferential surface  18  of the annular seal  10  includes an approximately conical surface section  18   a  and a conical helix section  18   b  formed by a feature, such as the upstanding thread illustrated, protruding radially inwardly from the surface  18  relative to the section  18   a . In the configuration shown in  FIGS. 1-4 , the thread section  18   b  is provided over the full axial extent of the surface  18 , from the radially inner flat section  12   e  of the axial first surface  12  to the radially inner annular section  14   a  of the axial second surface  14 . The thread section  18   b  may define a thread having a cross sectional shape that is semispherical, part oval, part triangular, part square, or part rectangular, or that is of any other suitable form. 
         [0022]      FIG. 5  is a cross sectional view similar to that provided by  FIG. 4 , but of a second embodiment of the air filter seal  10 . Reference numbers used in  FIG. 5  to identify structures that are the same as, essentially the same as, or similar to structures discussed in connection with  FIGS. 1-4  are increased by 10 relative to the reference numbers used in  FIGS. 1-4 . In the embodiment of  FIG. 5 , the inner substantially cylindrical, axially extending section  24   b  is elongated so as to differ significantly in axial extent from that of the outer substantially cylindrical, axially extending section  24   c . An inwardly protruding thread section  28   b  of the inner circumferential surface  28 , moreover, forms a conical helix extending only partially over the extent of that surface  28 , with a termination point  28   c  that is axially displaced from the radially inner annular section  24   a . The thread section  28   b , again, may define a thread having a cross sectional shape that is semispherical, part oval, part triangular, part square, or part rectangular, or that is of any other suitable appropriate form. The outer circumferential surface  26  is shown in  FIG. 5  as slightly conical, as opposed to the substantially cylindrical outer circumferential surface  16  illustrated in  FIGS. 1-4 . 
         [0023]      FIG. 6  is another cross sectional view similar to that provided by  FIG. 4 , but of a third filter seal embodiment. Reference numbers used in  FIG. 6  to identify structures that are the same as, essentially the same as, or similar to structures discussed in connection with  FIGS. 1-4  are increased by 20 relative to the reference numbers used in  FIGS. 1-4 . The seal  10  shown in  FIG. 6  has an inner substantially cylindrical, axially extending section  34   b  of the axial second surface  34  that is similar to the section  24   b  of  FIG. 5 , in that it is significantly greater in axial extent than the outer substantially cylindrical, axially extending section  34   c  of the surface  34 . Here, the helical feature is a ledge or step  38   b , configured as a conical helix, that actually defines the inner circumferential surface  38  of the annular seal. The innermost corner of the ledge or step  38   b , which may optionally be beveled, operates in a way, to be described, that is essentially the same as the conical helix thread sections  18   b  and  28   b  discussed in connection with  FIGS. 1-4  and  FIG. 5 , respectively. The outer circumferential seal surface  36  shown in  FIG. 6  is slightly conical, similar to the outer cylindrical surface  26  shown in  FIG. 5 . 
         [0024]      FIG. 7  is yet another cross sectional view similar to that provided by  FIG. 4 , but of a fourth air filter seal embodiment. The seal  10  illustrated in  FIG. 7  is nearly identical to that illustrated in  FIG. 6 , except that the ledge or step  48   b , again configured as a conical helix and again defining the inner circumferential surface  48  of the annular seal, terminates at a location that is displaced from the substantially flat, radially inner annular section  44   a  of the axial second seal surface  44 . Accordingly, the inner circumferential surface  48  includes an approximately cylindrical terminal portion  48   a  adjacent the annular section  44   a  mentioned. 
         [0025]      FIG. 8  illustrates an air filter seal  10  according to any of the four embodiments mentioned when the seal is located, in place, in the interior  52  of a filter housing  50 . Although the following discussion is equally applicable to each of the four embodiments mentioned above, to simplify this discussion, it will be presumed that the particular air filter seal  10  shown in  FIG. 8  is a seal according to the first embodiment illustrated in  FIGS. 1-4 . 
         [0026]    Referring now to both  FIG. 1  and  FIG. 8 , when a filter element  54  and the seal  10  are assembled, sections  14   b ,  14   c , and  14   d  of the axial second seal surface  14  are adhesively bonded or secured in some other fashion to an end of the element  54 . Another seal, an end cap, or some other type of end support may be utilized at an end of the filter element  54  opposite that to which the seal  10  is secured, and appropriate liners (not shown) are provided to supply the overall filter  56  with adequate structural rigidity. The particular configuration of the filter element  54  itself does not matter in the context of the present invention; the element  54  could be formed of pleated fabric, for example, or of any other type of material appropriate for automotive air filtering applications. 
         [0027]    Once the filter element  54  and the seal  10  are joined together and the overall filter  56  is ready for use, a neck  58  of the housing  50  and the central seal opening  19  are aligned, and both a torque (i.e., a twisting force) and an axial pressure or force are applied to at least one of the filter housing  50  and the filter  56  to rotate the seal  10  and, at the same time, displace the seal  10  relative to the neck  58  towards an end wall  60  of the filter housing. In one arrangement in which the invention is appropriate for use, the neck  58  forms an outlet for air that has been filtered upon passing through the element  54 . 
         [0028]    As the seal  10  is twisted and displaced relative to the neck  58  towards the end wall  60  of the filter housing, the neck forces the conical helix originally defined by the threads of the spiral thread section  18   b  to approach a strictly helical configuration, approximating threads of a screw, to facilitate interconnection between the seal  10  and the filter housing  50 . The inner circumferential seal surface  18 , including the surface and thread sections  18   a  and  18   b , is at this time radially expanded and placed into tension, so that the thread section  18   b  and, to a slightly lesser degree, the surface section  18   a  press tightly against the annular outer surface of the neck  58  to form a radial seal. Under the combined action of the torque and the axially applied pressure or force, the inner surface  18  and the outer surface of the neck  58  are relatively rotated and relatively axially displaced until the sealing section  12   d  of the surface  12  is axially pressed against an end wall  54  of the filter housing  50  to a desired degree, thereby forming an axial seal. The necessary sealing between of the filter  56  and the filter housing  50  is thus automatically provided. 
         [0029]    The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, and the invention should be construed to include everything within the scope of the invention ultimately claimed.