Abstract:
A filter element for filtering a fluid, particularly oil, in which the filter element has at least two individual elements ( 10 ), that are interconnected by a connector ( 11 ). The individual elements ( 10 ) each include two end disks ( 13 ) and a filter medium ( 12 ) arranged therebetween. The connector ( 11 ) has a radially circumferential sealing bead ( 23 ), which communicates with the end disk ( 13 ) of an individual element ( 10 ) so as to form a seal and ensures a tight seal between the individual element ( 10 ) and the connector ( 11 ).

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The invention relates to a filter element for filtering a fluid, particularly oil, having at least two individual elements that are interconnected by a connector.  
         [0002]     U.S. Pat. No. 2,313,307 (=GB 542,339) discloses a filter element that is composed of a plurality of individual elements. The individual elements each have two end disks and a filter medium and are interconnected by a connector. The connector is a tubular member and has a cylindrical center section. The connector is conical in the region of the end faces, such that the cone tapers toward the end face. To connect the individual elements, the connector is inserted into the end disk, so that the cone interlocks with the end disks. To this end, the end disk is provided with corresponding clips. To prevent unfiltered fluid from flowing between the individual elements, an additional seal is disposed in the region of the cylindrical center section and is clamped axially between the individual elements. A drawback in this embodiment is that the individual elements must always be axially prestressed to ensure a tight seal between the individual elements. The additional assembly time required and the costs for the seal are a further drawback.  
       SUMMARY OF THE INVENTION  
       [0003]     It is an object of the invention to provide an improved filter element for filtering a liquid.  
         [0004]     Another object of the invention is to provide a filter element which does not require axial prestress.  
         [0005]     A further object of the invention is to provide a filter element which can be quickly assembled at minimal cost.  
         [0006]     These and other objects are achieved in accordance with the present invention by providing a filter element for filtering a fluid comprising at least two individual elements interconnected by a connector, wherein the individual elements each comprise two end disks and a filter medium arranged between the end disks, and wherein the connector has a radially circumferential sealing bead which sealingly engages an end disk of an individual element.  
         [0007]     The filter element according to the invention is intended to filter a liquid, particularly oil, or a gaseous fluid. The filter element comprises at least two interconnected individual elements. By connecting a plurality of individual elements it is possible to produce filter elements of any length and to combine mass-produced, inexpensive standard elements. This reduces the number of different filter element sizes which must be produced and maintained in inventory. Connecting the individual elements into a long filter element gives the filter element relatively great stability. Each individual element comprises two end disks and an annularly closed filter medium disposed therebetween. The filter medium can be made, for example, from cellulose paper, a nonwoven glass fiber material, a nonwoven polyester material, a laminated and/or multilayer construct or a combination of different fiber materials. The filter medium may, for example, be wound or fan-folded and annularly closed.  
         [0008]     The end disks are tightly connected to the filter medium. Preferably, the end disks are constructed as circular annular disks. In advantageous embodiments, the end disk is made of a flexible material with adequate shape stability. Synthetic resin materials, such as thermoplastics or elastomers are suitable for this purpose, for example. In one advantageous embodiment, the end disk is made of a thermally reactive rubber, particularly nitrile rubber.  
         [0009]     The individual elements are interconnected by a connector, which has a circumferential sealing bead. The interior of the tubular connector is permeable to the fluid to be filtered. Both the interior and the exterior can have any geometric configuration. The connector can have any cross section, e.g., rectangular, elliptical, triangular or polygonal. The sealing bead may be disposed either on the lateral surface and face outward or in the interior and face inward. If disposed on the lateral surface, the sealing bead communicates with an opening in the end disk. If disposed in the interior, the sealing bead communicates with the outer surface of the end disk.  
         [0010]     The sealing bead communicates with the end disk of an individual element so as to form a seal, whereby a linear or planar contact is produced between the end disk and the connector. A radial seal running along the circumference is produced in this region. Because a relatively elastic end disk is paired with a relatively rigid connector, the sealing bead presses into the end disk to produce a reliable seal between the end disk and the connector.  
         [0011]     It is advantageous if the connector has a latching ring in the form of an undercut, for example, which fixes the connector in its position and prevents it from falling out during handling.  
         [0012]     According to another advantageous embodiment of the invention, the cylindrical connector is inserted into the end disk of the individual element. The sealing bead has an outside diameter (D) greater than the inside diameter (d) of the end disk. The elasticity of the end disk allows the inside diameter to expand slightly, so that the sealing bead can be pushed into the inside diameter of the end disk. As a result of the elasticity of the end disk, the inside diameter of the end disk fits tightly against the sealing bead of the connector to form a seal.  
         [0013]     It is advantageous if the connector comprises an intermediate disk disposed between two sealing beads. This prevents the end disks of the individual elements from being pushed over the sealing bead or the region provided for mounting. In this embodiment the individual elements are pushed onto the connector, such that the intermediate disk serves as a limit stop for the respective end disk. This ensures that the end disk is positioned exactly on the sealing bead and cannot slip once it is mounted.  
         [0014]     According to yet another advantageous embodiment of the invention, the diameter of the intermediate disk substantially corresponds to the outside diameter of the end disk. Thus, the end disk of each individual element can contact and rest against the intermediate disk over its full area.  
         [0015]     According to yet another advantageous embodiment of the invention, the intermediate disk is non-releasably coupled, particularly adhesively bonded, to the adjoining end disks to produce a firm union between the mating members (end disk and connector). This prevents the individual elements from accidentally slipping off the connector.  
         [0016]     In another advantageous embodiment, the filter element has individual elements that are provided with insertion members on the end faces opposite the connector. These insertion members communicate with the end disk to form a seal. The insertion members may be constructed as a cover or a connection for the individual element. As described above with reference to the connector, the insertion member may include a cylindrical region with a sealing bead. The sealing bead of the insertion member can have the same features as the connector.  
         [0017]     In another embodiment of the novel filter element, the insertion member is non-releasably connected to the end disk. Thus, the insertion member cannot become accidentally detached from the end disk because of unfavorable pressure conditions inside the filter element. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]     The invention will be described in further detail hereinafter with reference to illustrative preferred embodiments shown in the accompanying drawing figures, in which:  
         [0019]      FIG. 1  is a partially sectional view of a filter element according to the invention;  
         [0020]      FIG. 2  is an enlarged detail view of the filter element shown in  FIG. 1 , and  
         [0021]      FIG. 3  is an even more enlarged detail of the filter element of  FIG. 1 .  
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0022]     The filter element depicted in  FIG. 1 , which is preferably used for filtering liquids, such as oils, comprises two individual elements  10  that are interconnected by a connector  11 . The individual elements  10  each have a fan-folded or pleated filter medium  12 , which is annularly closed. The filter medium  12  is encircled by a spirally wound cord  22 , which is fixed to the tips of the folds of the filter medium  12  by a hot-melt adhesive. End disks  13  are arranged on the end faces of the filter medium  12  and are connected to the filter medium  12  so as to form a seal.  
         [0023]     The end disks  13 , which are configured as circular annular disks, have an elasticity that allows the inside diameter I to expand. Within the annularly closed filter medium  12  is disposed a support tube  14 , which supports the filter medium  12  and is permeable to the fluid to be filtered or the filtered fluid. The support tube  14  is likewise connected to the end disk  13  so as to form a seal. In this embodiment, the end disk  13  is made of a nitrile rubber, such that the filter medium  12  and the support tube  14  are enclosed by the material of the end disk  13  at their end faces.  
         [0024]     The individual elements  10  are coupled to the connector  11 , such that the connector is inserted into the inside diameter of the end disks  13 . The connector  11  comprises an intermediate disk  15  with the same or substantially the same outside diameter as the end disks  13 . The connector  11  furthermore has a tubular section with a fluid-permeable interior  16 . In this embodiment the interior  16  is a hollow cavity. In other embodiments (not shown) the interior  16  may have struts or structures to increase stability. The interior  16  may also have a filling (not shown), which is permeable to the fluid and can serve as an additional filter unit.  
         [0025]     A cover member  17  that closes the end face of the individual element  10  is disposed on the end disk  13  of the individual element  10  that is not connected to the connector  11 . The cover member  17  is preferably made of a thermoplastic material. On its one side the cover member  17  has an insertion diameter  18 , which is inserted into the inside diameter I of the end disk  13 . On the other side the cover member  17  has a centering device  19 , which may be positioned and secured inside a housing (not shown). The cover member  17  is non-releasably bonded to the end disk  13  to prevent accidental detachment of the cover member  17 .  
         [0026]     The other individual element  10  has a coupling member  20 , which is non-releasably connected to the end disk  13 . For this purpose, the coupling member  20  is inserted with its insertion diameter  18  into the inside diameter I of the end disk  13  and is bonded to the end disk. The coupling member  20  has a fitting  21 , which is connectable to a filtered fluid line (not shown).  
         [0027]     The fluid to be filtered flows radially through the individual elements  10  of the filter element from the outside to the inside. The cord  22  fixes the folds of the filter medium  12  to prevent them from contacting each other. The filtered fluid is located in the annular space enclosed by the filter medium  12 . The fluid filtered by the lower individual element  10  flows through the interior  16  of the connector  11  into the annular space of the upper individual element  10 . From this upper annular space the fluid flows out of the filter element through the coupling member  20  and the fitting  21 .  
         [0028]      FIG. 2  shows a partially cutaway detail of the filter of  FIG. 1  in the region around the connector  11 . Components corresponding to those of  FIG. 1  are identified by the same reference numerals. The connector  11  has two sealing beads  23  disposed on both sides of the intermediate disk  15 . The sealing bead  23  communicates with the end disk  13  placed onto the connector  11  so as to form a seal. Because of its elasticity the end disk  13  expands somewhat during assembly, so that the sealing bead  23  is seated against the end disk  13  to form a seal. The intermediate disk  15  is bonded over its full area to each of the outer faces of the end disks  13 , so that the connector  11  cannot detach itself from the individual element  10 .  
         [0029]      FIG. 3  is a partially cutaway view of an enlarged detail X of  FIG. 1  showing the region around the connector  11 . Again, components corresponding to those depicted in  FIG. 1  are identified by the same reference numerals. The connector  11  has an additional latching ring  24  in the form of an undercut in the material of the connector  11 . This latching ring  24  interlocks with the end disk  13  as it is connected to the individual element  10 . This fixes the connector  11  in its position relative to the individual elements  10  and prevents the connector  11  from falling out during handling of the filter element. If the filter element is handled incorrectly or if the connector  11  is separated from the individual element  10  by force, the end disk  13  may be destroyed. This is an additional safety aspect because it virtually precludes used individual elements from being reused. It is also advantageous that once the individual elements are mated with the connector, the parts can no longer become detached, which enhances handling safety.  
         [0030]     The foregoing description and examples have been set forth merely to illustrate the invention and are not intended to be limiting. Since modifications of the described embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed broadly to include all variations within the scope of the appended claims and equivalents thereof.