Abstract:
A filter assembly includes a housing including a first cover and a second cover, a grid located in the housing including interconnected ribs and strips, and filter media integral with the grid, including a peripheral width located between the covers.

Description:
BACKGROUND OF THE INVENTION  
       [0001]    1. Field of the Invention 
         [0002]    This invention relates generally to a suction filter for automatic transmission fluid incorporating filter media with an overmolded tray. 
         [0003]    2. Description of the Prior Art 
         [0004]    A transmission suction filter having a single media layer trapped between upper and lower housings provides marginal filtration capacity coupled with functional limitations in efficiency and pressure drop. 
         [0005]    To improve filtration efficiency, improved filter elements with bag-type configurations and non-planar elements were developed. However, these designs require greater internal volume and packaging space and are still limited in their functional performance. 
         [0006]    Continued improvement in filtration technology has resulted in suction filters with dual media allowing for high media packaging density, high dirt holding capacity, high filtration efficiency, packaging flexibility for irregular shaped housings, and low cost. These designs utilize media configurations that require premium packaging space and add extra components into the filtration system. 
         [0007]    A need exists to increase the media packing density while using less packaging space. 
       SUMMARY OF THE INVENTION  
       [0008]    A filter assembly includes a housing including a first cover and a second cover, a grid located in the housing including mutually interconnected ribs and strips, and filter media integral with the grid, including a peripheral width located between the covers. 
         [0009]    Combining the rib-strip tray with the filter media, specifically high efficiency media, through an over-molding process reduces the number of components in the filter assembly, allows for a more optimized flow distribution, improves rigidity of the high efficiency filter media, reduces the volume of resin required for the rib-strip ray and reduces the size of the filter assembly. 
         [0010]    The filter assembly reduces the cost of the filter, improves the package density of the filter media, improves filter media configurations and increases the filter area. 
         [0011]    The scope of applicability of the preferred embodiment will become apparent from the following detailed description, claims and drawings. It should be understood, that the description and specific examples, although indicating preferred embodiments of the invention, are given by way of illustration only. Various changes and modifications to the described embodiments and examples will become apparent to those skilled in the art. 
     
    
     
       DESCRIPTION OF THE DRAWINGS  
         [0012]    The invention will be more readily understood by reference to the following description, taken with the accompanying drawings, in which: 
           [0013]      FIG. 1  is a perspective external view showing a filter assembly; 
           [0014]      FIG. 2  is perspective exploded view of the filter assembly of  FIG. 1 ; 
           [0015]      FIG. 3  is a perspective transverse cross sectional view of the filter assembly; 
           [0016]      FIG. 4  is a perspective longitudinal cross sectional view of the filter assembly; and 
           [0017]      FIG. 5  is a perspective view of the showing an integral, overmolded subassembly including a tray and filter media. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0018]      FIGS. 1 and 2  shows a filter assembly  10 , which includes an upper cover  12  formed with an exit tube  14 , a lower cover  15 , mating upper and lower flanges  16 ,  18  formed on the covers. The covers  12 ,  15  form a housing containing an overmolded subassembly  20  comprising a filter media  22  and a grid of intersecting longitudinal ribs  24  and lateral strips  30 . 
         [0019]    Overmolding is an injection molding process wherein one material, such as a thermoplastic elastomer (TPE), is molded integrally with a secondary material, typically a rigid plastic or metal. The overmolded TPE forms a strong bond with secondary material without joints or fasteners. Use of primers or adhesives is not required to achieve a bond between the two materials. In the filter assembly  10  the secondary material is filter media  22 . 
         [0020]    A hole  26  is formed in the lower cover  15  preferably near the end of the filter  10  that is opposite the end where the exit tube  14  is located. Automatic transmission fluid (ATF) drawn from a fluid sump through hole  26 , flows through the filter media  22  and exits the filter assembly  10  though exit tube  14 , due to suction produced at the entrance of a hydraulic pump, which communicates with the exit tube  14 . 
         [0021]      FIGS. 3 and 4  show that a width  23  around the periphery of filter media  22  is supported on the lower flange  18  and is overlapped by the upper flange  16 . 
         [0022]    The subassembly  20  is overmolded such that the ribs  24  are interlocked with the filter media  22  by strips  30  and buttons  32 , the ribs and strips forming a tray or grid. Located at longitudinally spaced locations along the length of each rib  24  and formed integrally with each rib are strips  30 , which extent laterally and interconnect the five ribs forming the tray, which supports the filter media  22 . Also located at longitudinally spaced locations along the length of each rib  24  and formed integrally with each rib are buttons  32 , each button located at the intersection of each rib  24  and each strip  30 . Each button  32  is spaced from the corresponding strip  30  by a vertical gap directed along the depth of the ribs. The filter media  22  is located in the gaps and overmolded with the tray or grid. Each strip  30  is located immediately below the lower surface of the filter media  22  and each button  32  is located immediately above the upper surface of the filter media. 
         [0023]    The thickness of the filter media  22  is located in the vertical space between each button  32  and each strip  30 . The filter media  22  and the ribs  24  are overmolded together forming a one-piece subassembly  20 , which includes no mechanical fasteners or subsequent bonded connections to connect the ribs  24  and the filter media  22  after the subassembly  20  is overmolded. 
         [0024]    Differential pressure across the filter media  22 , ATF located in the lower cover  12 , flanges  16 ,  18  gripping the edges of the filter media  22 , lateral and longitudinal stiffness of the tray formed by the rib  24  and strips  30 , and the close tolerance fit between the upper surface  34  of each rib  24  and the lower surface  36  of the upper cover  12  supports and holds the filter media  22  in a substantially level plane in the assembly  10 . 
         [0025]    Combining the rib-strip tray with the filter media  22 , specifically high efficiency media, through an over-molding process reduces the number of components in the filter assembly  10 , allows for a more optimized flow distribution, improves rigidity of the high efficiency filter media, reduces the volume of resin required for the rib-strip ray and reduces the size of the filter assembly  10 . 
         [0026]    In accordance with the provisions of the patent statutes, the preferred embodiment has been described. However, it should be noted that the alternate embodiments can be practiced otherwise than as specifically illustrated and described.