Abstract:
A filter is disclosed that includes a filter cup, a filter insert inserted into the filter cup and having a substantially cylindrical shape and a terminal disk arranged at an end face of the filter insert and connected to an end of the filter cup. The terminal disk includes a circumferential rim configured to engage the end of the filter cup and is provided with locking means that positive-lockingly connects the terminal disk and the filter cup.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit under 35 USC 119 of foreign application DE 20 2008 004 288.7 filed in Germany on Mar. 27, 2008. 
       TECHNICAL FIELD 
       [0002]    The invention relates to a filter comprising a filter cup and a filter insert received therein and having a substantially cylindrical shape as well as a terminal disk arranged at the end face of the filter insert and connected to the end face of the filter cup. 
       BACKGROUND OF THE INVENTION 
       [0003]    Filters are comprised in general of a filter cup and a filter insert received therein. This filter insert is often of a substantially cylindrical configuration so that the fluid to be filtered flows through the filter insert radially from the exterior to the interior. For attaching the filter insert and for closing off the end face, a terminal disk is provided that is connected to the end face of the filter cup. 
         [0004]    Such filters are often used as elements for removing oil from air especially in stationary and movable compressor devices. The compressors provided for this purpose require oil for lubricating and sealing the moving parts so that oil-containing gases are generated. In order to recapture most of this oil and in order to purify the air, oil-removing elements are used that, during the course of maintenance of the device, must be exchanged regularly. 
         [0005]    It is therefore an object of the present invention to provide a filter of the aforementioned kind that is simple with regard to its configuration and can be produced inexpensively. 
       SUMMARY OF THE INVENTION 
       [0006]    An object of the present invention to provide a filter of the aforementioned kind that is simple with regard to its configuration and can be produced inexpensively. In accordance with the present invention, this is achieved by designing the terminal disk at its circumferential rim in such a way that it engages across the end of the filter cup and is provided with locking means for a positive-locking connection of the terminal disk and the filter cup. 
         [0007]    According to an advantageous embodiment of the invention, at the circumferential rim of the terminal disk ring segments are provided that axially engage the end of the filter cup and have radially inwardly oriented snap-on hooks wherein on the filter cup includes at least one radially outwardly oriented projection that is arranged to be engaged by the snap-on hooks. In this way, mounting of the terminal disk on the filter cup is very simple because the terminal disk does not need to be aligned and instead is simply attached by being pressed on. Rotation of the terminal disk relative to the housing is still enabled in this way. 
         [0008]    Moreover, it is expedient that openings are provided in the end face of the ring segments. These openings enable the manufacture of an inexpensive terminal disk with snap-on hooks by injection molding because in this way the injection mold can mold the undercuts for the snap-on hooks. The snap-on hooks are formed as undercuts only below the openings and are demolded through these openings. Below the closed areas between the openings no snap-on hooks are formed. Other methods, for example, forced demolding or other geometries are also possible. Moreover, it is advantageous that on the exterior side of the filter cup a circumferentially extending projection is arranged so that between the free end of the ring segments and the projection a circumferentially extending groove for receiving a sealing ring is formed. In this way, the sealing ring is automatically secured in its position by mounting the terminal disk without requiring additional measures. The sealing ring projects relative to its circumference somewhat past the outer circumference of the ring segments so that the sealing ring rests against the inner wall of a filter head that is to be attached to the filter cup and therefore effects the sealing action. 
         [0009]    In order for the terminal disk to be secured at the end of the filter cup in a fixed or play-free way, it is expedient that the terminal disk in the area of its outer circumference has an axial section that rests seal-tightly on the inner wall of the filter cup. Expediently, the filter is configured as an air oil separator box and has a collecting chamber for the separated oil. In this connection it is expedient that in the terminal disk a pre-separator is integrated wherein this pre-separator is comprised of a plurality of guiding elements that are curved in the axial direction of the filter insert and are arranged between the axial section and a socket that is positioned coaxially thereto. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The accompanying Figures, where like reference numerals refer to identical or functionally similar elements throughout the separate views and which together with the detailed description below are incorporated in and form part of the specification, serve to further illustrate various embodiments and to explain various principles and advantages all in accordance with the present invention. 
           [0011]    Features of the present invention, which are believed to be novel, are set forth in the drawings and more particularly in the appended claims. The invention, together with the further objects and advantages thereof, may be best understood with reference to the following description, taken in conjunction with the accompanying drawings. The drawings show a form of the invention that is presently preferred; however, the invention is not limited to the precise arrangement shown in the drawings. 
           [0012]      FIG. 1  depicts a side view of a filter cup and of a terminal disk, consistent with the present invention; 
           [0013]      FIG. 2  presents a longitudinal section of the filter of  FIG. 1 ; and 
           [0014]      FIG. 3  depicts detail III of  FIG. 2 . 
       
    
    
       [0015]    Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention. 
       DETAILED DESCRIPTION 
       [0016]    Before describing in detail embodiments that are in accordance with the present invention, it should be observed that the embodiments reside primarily in combinations of apparatus components related to a filter apparatus. Accordingly, the apparatus components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. 
         [0017]    In this document, relational terms such as first and second, top and bottom, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element preceded by “comprises . . . a” does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element. 
         [0018]      FIG. 1  shows a side view of a substantially cylindrical filter cup  1  and a terminal disk  2  of a filter  3  that is to be connected thereto. In the illustrated embodiment, the filter  3  is an air oil separator box that is in particular used in connection with air compressors. The filter cup  1  has at its end face  4  an outwardly oriented radial projection  5  that, in the direction toward the terminal disk  2 , tapers conically and has a radial projection  6  on the side that is facing the filter cup  1 . The projection  5  is designed to extend about the entire circumference of the filter cup  1 . At a spacing to the projection  5 , a sealing ring  7  is provided on the circumference of the filter cup  1  and resting against a circumferential projection  8 . 
         [0019]    The terminal disk  2  comprises an axial section  9  whose circumference is designed such that it can be inserted at the end face into the filter cup  1 , as illustrated by the arrows  10  indicating the mounting direction. The terminal disk  2  has at its top side shown in  FIG. 1  a connecting socket  11  with a groove  12  for receiving a seal. The outer circumferential rim of the terminal disk  2  has several ring segments  13  that are separated from one another by narrow radial slots  14 . As will be explained, the ring segments  13  of the terminal disk  2  engage in the mounted state, (i.e., after assembly according to the arrows  10 ), the filter cup  1  in that the projection  5  is received in a groove that is formed in the ring segments  13 . 
         [0020]      FIG. 2  shows a longitudinal section of the filter  3 . In the filter cup  1  a filter insert  15  is concentrically arranged and is comprised of two cylindrical layers  16 ,  17  of filter material and a support grid  18  that is positioned inside the radially inner layer  17 . At the end face of the filter insert  15  the terminal disk  2  is arranged. On the socket  11  an axially inwardly extending sleeve section  19  is integrally formed and projects into the end of the support grid  18  and therefore centers the filter insert  15 .  FIG. 2  shows also a seal  22  arranged in groove  12 . 
         [0021]    The terminal disk  2  has at its circumferential rim several ring segments  13  that are separated from one another only by narrow radial slots  14 . By means of the radial slots  14  a sufficient elasticity or flexibility is provided in order to provide together with the radial projection  5  of the filter cup  1  a snap-on connection whose configuration will be explained in more detail infra. In the mounted stated according to the illustration of  FIG. 2  the spacing of the ends of the rings segments  13  facing the filter cup  1  relative to the projection  8  provides a circumferential groove  20  in which the sealing ring  7  is arranged. Several openings  21  are provided in the end face of the ring segments  13 . Neighboring the ring segments  13  a pre-separator is arranged at the radial inner side. 
         [0022]    In  FIG. 3  a detail illustration of the detail III of  FIG. 2  is shown. This illustration shows that the ring segments  13  have an axial section  24  with which they engage the end of the filter cup  1 . The terminal disk  2  comprises also the axial section  9 , as already described in connection with  FIG. 1 , which axial section rests seal-tightly against the inner wall of the filter cup  1 . Between the axial sections  9  and  24  an axial groove  25  is formed in which the axial end of the filter cup  1  is received. At the free end of the axial section  24  of the ring segment  13  there is a radially inwardly oriented snap-on hook  26  that upon mounting of the terminal disk  2  on the filter cup  1  is pushed across the circumferential projection  5  and locks on the radial projection  6 . For demolding the snap-on hook when producing the terminal disk  2  by injection molding openings  21  are provided at its end face. 
         [0023]    As can be seen in  FIG. 3 , the sealing ring  7  is positioned in the spacing between the ring segment  13  and the projection  8 . The pre-separator  23  is comprised of a plurality of guiding elements  27  that are curved in the axial direction and are arranged between the axial section  9  and the coaxially positioned socket  28 . The pre-separator  23  forces a change of direction of the oil-containing air stream. This change of direction has the effect that the oil components are separated partially because, as a result of their greater mass, they have a tendency to maintain their direction of movement. This causes the formation of droplets that drop down or flow along the inner wall of the filter cup  1  in the downward direction. The oil components that are still contained in the air stream are separated at the layers  16  and  17  (compare  FIG. 2 ). For same parts the same reference numerals are used in  FIGS. 2 and 3 . 
         [0024]    By means of the present invention, in comparison to prior art filters, the mounting expenditure for insertion of the sealing ring can be reduced. The utilization of the filter is independent of its position. Mounting of the filter cup is facilitated in that the rotation between terminal disk and filter cup is still maintained. A further advantage resides in that the terminal disk can be combined in a simple way with a pre-separator. 
         [0025]    In the foregoing specification, specific embodiments of the present invention have been described. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the present invention as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present invention. The benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential features or elements of any or all the claims. The invention is defined solely by the appended claims including any amendments made during the pendency of this application and all equivalents of those claims as issued.