FULL FLOW/BYPASS FILTER ASSEMBLY

Abstract: A filter of the type having first annular filter media comprising a generally columnar stack of annular filter media lamina for providing filtration for one circuit, a harness for retaining the filter media lamina in stacked columnar alignment comprising a generally circular end piece having a diameter somewhat greater than the diameter of the filter media lamina engaging one end lamina, an annular portion engaging the opposite end lamina, a plurality of elongated strips integral with and extending from the periphery of the annular portion with the end piece receiving and retaining the free ends of the elongated strips. There is a second filter media providing filtration for another circuit. The two filter media are housed adjacent to one another in a hollow cylindrical shell closed at one end. An annular retainer is integral with the shell near the other shell end for engaging the second media and retaining both media axially within the shell. The annular retainer has a plurality of apertures for providing an inlet to the common path. A grommet defines an intermediate generally annular path from within the annulus of the second media to the end of the cylindrical shell opposite the closed one end. The grommet cooperates with a base member when installed thereon to isolate the inlet, common path, annular path and central path each from the other.

Description: FU L FLOW/BYPASS FILTER ASSEMBLY The present invention relates generally to methods and apparatus for removing undesirable particles from lubricants and more particularly to an improved filter cartridge or head member of a type having at least two dissimilar filtering media therein and including a multifunction grommet and improved filter media retaining device. It is desirable to provide separate lubricant circuits in certain internal combustion engines and to do so with but a single filter cartridge. So-called full flow/bypass filters are well known in the literature and are commercially available. Known dual media filters of this type employ a metal end plate and two gaskets to define the full flow circuit exit from the filter cartridge or head and to isolate the full flow circuit from the bypass circuit filter exit and from the common lubricant inlet. It would be highly desirable to reduce this number of parts and thereby simplify the assembly of such a filter cartridge. The known dual media filters of this type frequently employ a stack of felt or paper disks or other laminae as the bypass circuit media. These lamina may be circular, hexagonal, octagonal, or of other geometries. The term "lamina" as used herein is intended to cover any of these disk-like shapes. Likewise, "diameter" describes the greatest diagonal in case the lamina is polygonal. The lamina typically include one or more holes and may be either aligned or staggered, but in either case, they assume a columnar form with interior filtered lubricant pathways. These stacks are held in compression by several rods which extend between opposed end plates which are also called pressure plates. There are two plates and three or more rods. It would also be highly desirable to reduce this number of parts and thereby simplify the assembly of such a filter cartridge. A compression spring typically lies between the closed end ofthe filter cartridge case or shell and one end plate ofthe stack. During cartridge assembly, this spring is difficult to properly position. One solution in the past has been to employ a more costly than necessary spring of maximum diameter nearly as great as that ofthe shell. It would be highly desirable to reduce the cost of this spring while retaining the ease of positioning the spring during assembly. The present invention provides solutions to the above problems by providing a harness for retaining filter media disks in stacked cylindrical or columnar alignment having a lubricant impervious end piece with a diameter somewhat greater than the diameter ofthe filter media disks The end piece engages one end filter media disk An annular portion engages the opposite end filter media disk The annular portion has a plurality of elongated strips integral therewith and extending from the periphery thereof The end piece includes peripherally disposed portions for receiving and retaining the free ends ofthe elongated strips In accordance with another aspect ofthe invention, a grommet within a filter cartridge shell defines an intermediate lubricant path from within an annulus of one filter media to the end ofthe cylindrical shell which mates with a base member The grommet cooperates with the base member when installed thereon to isolate a lubricant inlet, a common lubricant path, the intermediate lubricant path and a central lubricant path each from the other The grommet includes an outer radial portion interposed between a retainer portion ofthe shell and one end ofthe one filter media, an outer cylindrical portion having an inner surface for seaiingly engaging a full flow circuit fitting on the base member, an inner cylindrical portion having a first inner cylindrical surface seaiingly engaging a standpipe which forms a portion ofthe central lubricant path, and a second inner cylindrical surface for seaiingly engaging a bypass circuit fitting on the base member BRIEF DESCRIPTION OF THE DRAWING Figure 1 is an isometric view of a stack of filter media disks illustrating a prior art technique for compressing the stack, Figure 2 is an isometric view illustrating compression ofthe media stack of Figure 1 according to one form ofthe present invention, Figure 3 is a plan view ofthe top end piece and integral strips of Figure 2, Figure 4 is a plan view showing one modification to the end piece of Figure 3, Figure 4a is a plan view of a bottom pressure plate modified for use in conjunction with the end piece of Figure 4, Figure 5 is a side elevation view of a filter media stack employing the end piece of Figure 4 along with a compression spring and stand pipe ready to be assembled into a cartridge shell, Figure 6 is a side elevation view similar to Figure 5, but illustrating modified top and bottom end plates, Figure 7 is a plan view ofthe top end plate of Figure 6; Figures 8a and 8b are cross-sectional views of a peripheral portion ofthe bottom end plate of Figure 6 showing how it joins to the depending strips ofthe top end plate; Figure 9 is a diametral cross-sectional view ofthe bottom end plate of Figure 6; Figure 10 is an end view of a full flow, bypass and common inlet defining grommet according to the present invention; Figure 11 is a view in cross-section along lines 1 1- 1 1 of Figure 10; and Figure 12 is a partially cross-sectioned side view of a filter cartridge incoφorating the grommet of Figures 10 and 11 and the media stack assembly of Figure 6. Corresponding reference characters indicate corresponding parts throughout the several views ofthe drawing. DESCRIPTION OF THE PREFERRED EMBODIMENT In Figure 1 upper 1 1 and lower 13 pressure plates engage the outermost lamina in a stack 14 of filter media elements. The pressure plates are held in place by three index rods 15, 17 and 19 having enlarged a irregular ends The rods pass through holes such as 21 in the upper pressure plate and engage notches such as 23 in the lower pressure plate thereby holding the stack in a columnar form during filter assembly. This structure employs an excessive number of parts and requires an excessive assembly time. In Figure 2, the upper pressure plate 11 and the three index rods 15, 17 and 19 have been eliminated and those four parts replaced by a single elastic harness 25. The harness 25 includes a flat pliable gasket or end piece 27 which is generally circular and lubricant impervious. End piece 27 has a diameter somewhat greater than the lateral extent ofthe filter media lamina and is adapted to engage one end filter media lamina 50. The harness 25 end portion 27 has three integral elastic retaining strips 29, 31 and 33 extending from the periphery ofthe annular portion 27 and terminating at remote free ends. This annular portion 27 and the elongated strips 29, 31 and 33 are formed of a resilient material to exert an axial compressive force on the stack of filter media lamina, thus, tension on the elastic strips squeezes the media lamina together. The bottom pressure plate 13 is unchanged and includes three notches such as 23 which are peripherally disposed about the end piece for receiving and retaining the free ends ofthe elongated strips. Bottom pressure plate 13 engages an end filter media lamina 52. The strip free ends include transverse tabs 35, 37 and 39 which engage the pressure plate 13 holding the lamina stack 14 in a compressed state. The number of parts and assembly time is thereby reduced with the annular portion, elongated strips and end piece cooperating to form a cage about the stack of filter media lamina compressing the lamina and retaining the lamina in a stacked columnar alignment. The end portion 27 includes a centrally located aperture 41 for passing filtered lubricant from within the lamina and through a standpipe such as 43 of Figure 5. When the filter media stack is assembled into a hollow cylindrical shell which is closed at one end, there is a helical compression coil spring 45 disposed between the shell closed end and the end piece 13 for axially compressing the media stack. It is difficult to properly position this spring, so one modification according to the present invention includes a retaining strap 47 extending from one elongated strip free end as depicted in Figure 4 This strap may be passed underneath the slightly modified pressure plate 51 of Figures 4a and 5 to engage the helical spring 45 temporarily holding the spring in position adjacent the end piece 51 during filter assembly. The end or tip 53 ofthe retaining strap 47 which is remote from the elongated strip free end 55 is selectively engagable with the slot 57 in the end piece 51. This slot 57 is diametrically opposite the strip end 55 from which it extends when assembled as in Figure 5. In Figure 5, the standpipe 43 is a separate piece, however, additional economies may be achieved by forming the standpipe 59 as an integral part ofthe end piece 61 as shown in Figures 6 and 7. Standpipe 59 is formed integral with the annular portion 69 along the inner periphery thereof and provides a lubricant path from within the filter media lamina to the end ofthe cylindrical shell opposite the closed one end. In Figure 6 relatively rigid strips 63, 65 and 67 have been substituted for the elastic strips 29, 31 and 33. The annular portion 69 and integral elongated strips 63, 65 and 67 are formed as a flat sheet of relatively rigid material of generally uniform thickness. There is a transverse relieved portion 71, 73 and 75 along each strip adjacent to the annular portion 69 to form a flexible integral hinge between the annular portion and the corresponding elongated strip. This "living hinge" allows each rigid strip to be pivoted to the positions shown in Figure 6 where they cooperate with the pressure plate 77 to confine the lamina stack 79. It will be noted that each strip free end includes a ratch in the form of a series of notches or grooves such as 81 and 83. Peripherally disposed about the end piece 77 are three pawl containing structures such as 85 for receiving and retaining the free ends ofthe elongated strips. These pawls 82 engage a corresponding ratch as best seen in Figure 8b to securely fasten the opposed pressure plates together. The pawl and strip are freely movable in the stack collapsing direction, however, motion between a pawl and strip in the opposite direction is prevented When assembled and in use, the stack 79 axially yields under the urging of spring 87 Since the strips 63, 65 and 67 are rigid, as the stack axially yields, the pawl is moved upwardly relative to the strip as shown by the arrow 89 and the pawl moves into engagement with a new notch thereby latching the stack in successive positions of reduced axial extent. The ratch and pawl arrangement is similar to a "zip-tie" and is also visible in Figure 9 As noted earlier, there is difficulty maintaining springs 45 or 87 in position during filter cartridge assembly. As an alternative to the strap 47, pressure plate 77 may be provided with a spring receiving socket 89 in which the spring may be retained by friction, a series of detents or a helical thread. The media stack 79, spring 87 and harness 61, 77 with its integral standpipe 59 have been assembled into a multi-media lubricant filter head in Figure 12. The stack of Figure 6 is illustrative and the stacks of Figures 2 or 5 may be assembled into such a filter head in the same way. The generally columnar stack 79 of flat filter media lamina provide filtration for one lubricant circuit while a second filter media 91 provides filtration for another lubricant circuit. The hollow cylindrical shell 93 is closed at the left end as viewed and receives the first 79 and second 91 filter media axially adjacent to one another with the first filter media 79 adjacent the closed one end. There are annular spaces 95 and 97 between the outer periphery of each filter media and the shell for providing a common lubricant path to the outer peripheries ofthe filter media. Standpipe 59 provides a central lubricant path from within the annulus or central part ofthe filter media 79 to the right end ofthe cartridge. An annular retainer 99 is formed integral with the shell 93 near the right shell end for engaging the media 91 and retaining both media axially within the shell. The engagement may be direct or through an intermediary such as the grommet rim 115 The annular retainer 99 has a plurality of apertures 101 and 103 for providing a lubricant inlet to the common lubricant path between the shell 93 and the outside ofthe two filter media Lubricant flow paths through the filter head are shown by arrows. A grommet 105 separates the annular full-flow circuit 107 from the central by¬ pass circuit 109 Grommet 105 defines or separates the intermediate generally annular lubπcant path 107 from within the annulus ofthe media 91 to the end ofthe cylindrical shell This grommet cooperates with a base member (not shown) when installed thereon to isolate the lubricant inlet (arrow 1 1 1), common lubricant path (arrow 1 13), intermediate or annular lubricant path (arrow 107) and central lubricant path (arrow 109) each from the other This grommet is best seen in Figures 10 and 1 1 and includes an outer radial portion 1 15 to be inteφosed between the retainer 99 and one end ofthe filter media 91 , an outer cylindrical portion 1 17 having an inner surface 1 19 for seaiingly engaging a full flow circuit fitting on the base member, an inner cylindrical portion 121 having a first inner cylindrical surface 123 for iealingly engaging the standpipe 59 and a second inner cylindrical surface 125 for seaiingly engaging a bypass circuit fitting on the base member There are a plurality of apertures such as 127 and 129 in the grommet radially intermediate the inner and outer cylindrical portions forming a part ofthe annular intermediate lubricant path from within the annulus ofthe media 91 The diameter ofthe inner cylindrical surface 123 is greater than the diameter ofthe cylindrical surface 125 and an abutment 131 is formed at their junction Axial movement ofthe grommet 105 onto the standpipe 59 is limited by the abutment 131

Claims: WHAT IS CLAIMED IS: 1. In a multi-media lubricant filter ofthe type having a generally columnar stack of flat filter media lamina for providing filtration for one lubricant circuit, means for axially compressing the stack of filter media lamina, and other filter media providing filtration for another lubricant circuit; a harness for retaining the filter media lamina in stacked columnar alignment comprising a generally circular lubricant impervious end piece having a diameter somewhat greater than the lateral extent ofthe filter media lamina, the end piece adapted to engage one end filter media lamina, an annular portion for engaging the opposite end filter media lamina, a plurality of elongated strips integral with and extending from the periphery ofthe annular portion and terminating at remote free ends, and means peripherally disposed about the end piece for receiving and retaining the free ends ofthe elongated strips. 2. The harness of Claim 1 wherein the filter includes a hollow cylindrical shell closed at one end and the means for axially compressing the stack comprises a helical compression spring to be disposed between the shell closed end and the end piece, and further including a retaining strap extending from one elongated strip free end for engaging the helical spring and holding the spring in position adjacent the end piece during filter assembly. 3. The harness of Claim 2 wherein an end ofthe retaining strap remote from the elongated strip free end is selectively engagable with the end piece diametrically opposite the strip end from which it extends. 4. The harness of Claim 1 wherein the annular portion and the plurality of elongated strips are formed of a resilient material for exerting an axial compressive force on the stack of filter media lamina when assembled thereto. 5. The harness of Claim 1 wherein the elongated strip free ends include transverse tabs and the means peripherally disposed about the end piece for receiving and retaining the free ends ofthe elongated strips comprise notches for receiving corresponding strips and engaging the tabs, the annular portion, elongated strips and end piece cooperating to form a cage about the stack of filter media lamina when assembled thereto. 6. The harness of Claim 1 wherein the filter includes a hollow cylindrical shell closed at one end and the means for axially compressing the stack comprises a helical compression spring to be disposed between the shell closed end and the end piece, and wherein the annular portion and integral elongated strips are formed as a flat sheet of relatively rigid material of generally uniform thickness with a transverse relieved portion along each strip adjacent to the annular portion to form a flexible integral hinge between the annular portion and the corresponding elongated strip. 7. The harness of Claim 6 wherein each elongated strip free end includes a ratch and the means peripherally disposed about the end piece for receiving and retaining the free ends ofthe elongated strips comprises a like plurality of pawls for engaging a corresponding ratch whereby when the stack of filter media yields axially under the urging ofthe compression spring, the ratches and pawls latch the stack in successive positions of reduced axial extent. 8. The harness of Claim 1 wherein the filter includes a hollow cylindrical shell closed at one end and the means for axially compressing the stack comprises a helical compression spring to be disposed between the shell closed end and the end piece, and wherein the annular portion and integral elongated strips are formed of a relatively rigid material of generally uniform thickness with a transverse relieved portion along each strip adjacent to the annular portion to form a flexible integral hinge between the annular portion and the corresponding elongated strip, the filter further comprising a standpipe integral with the annular portion along the inner periphery thereof for providing a lubricant path from within the filter media lamina to the end ofthe cylindrical shell opposite the closed one end. 9. The harness of Claim 1 wherein the filter includes a hollow cylindrical shell closed at one end and the means for axially compressing the stack comprises a helical compression spring to be disposed between the shell closed end and the end piece, the end piece including a socket for receiving and retaining the compression spring in position during filter assembly 10. In a multi-media lubricant filter ofthe type having first annular filter media for providing filtration for one lubricant circuit, second filter media providing filtration for another lubricant circuit, a hollow cylindrical shell closed at one end for receiving the first and second filter media axially adjacent to one another with the first filter media adjacent the closed one end and with annular spaces between the outer periphery of each filter media and the shell for providing a common lubricant path to the outer peripheries ofthe first and second filter media, a standpipe for providing a central lubricant path from within the first filter media to the end ofthe cylindrical shell opposite the closed one end, and an annular retainer integral with the shell near the other shell end for engaging the second media and retaining both media axially within the shell, the annular retainer having a plurality of apertures for providing a lubricant inlet to the common lubricant path; the improvement comprising a grommet defining an intermediate generally annular lubricant path from within the annulus ofthe second media to the end ofthe cylindrical shell opposite the closed one end, the grommet cooperating with a base member when installed thereon to isolate the lubricant inlet, common lubricant path, intermediate lubricant path and central lubricant path each from the other. 11. The improvement of Claim 10 wherein the grommet includes an outer radial portion inteφosed between the retainer and one end ofthe second filter media, an outer cylindrical portion having an inner surface for seaiingly engaging a full flow circuit fitting on the base member, an inner cylindrical portion having a first inner cylindrical surface seaiingly engaging the standpipe and a second inner cylindrical surface for seaiingly engaging a bypass circuit fitting on the base member. 12. The improvement of Claim 1 1 wherein the intermediate lubricant path from within the annulus ofthe second media includes a plurality of apertures in the grommet radially intermediate the inner and outer cylindrical portions. 13. The improvement of Claim 11 wherein the diameter ofthe first inner cylindrical surface is greater than the diameter ofthe second cylindrical surface, the inner cylindrical surfaces being joined at an annular abutment adapted to limit axial movement ofthe grommet onto the standpipe. 14. The improvement of Claim 10 wherein the first filter media comprises a generally cylindrical stack of annular filter media lamina for providing filtration for the one lubricant circuit and means for axially compressing the stack of filter media lamina, the improvement further including a harness for retaining the filter media lamina in stacked columnar alignment comprising a generally circular lubricant impervious end piece having a diameter somewhat greater than the diameter ofthe filter media lamina, the end piece adapted to engage one end filter media lamina, an annular portion for engaging the opposite end filter media disk, a plurality of elongated strips integral with and extending from the periphery ofthe annular portion and terminating at remote free ends, and means peripherally disposed about the end piece for receiving and retaining the free ends ofthe elongated strips. 15. The improvement of Claim 14 wherein the means for axially compressing comprises a helical compression spring disposed between the shell closed end and the end piece, and further including a retaining strap extending from one elongated strip free end for engaging the helical spring and holding the spring in position adjacent the end piece during filter assembly. 16. The improvement of Claim 15 wherein an end ofthe retaining strap remote from the elongated strip free end is selectively engagable with the end piece diametrically opposite the strip end from which it extends. 17. The improvement of Claim 14 wherein the annular portion and the plurality of elongated strips are formed of a resilient material for exerting an axial compressive force on the stack of filter media lamina when assembled thereto. 18. The improvement of Claim 14 wherein the elongated strip free ends include transverse tabs and the means peripherally disposed about the end piece for receiving an'! retaining the free ends ofthe elongated strips comprise notches for receiving the strips and engaging the corresponding tabs. 19. The improvement of Claim 14 wherein the means for axially compressing the stack comprises a helical compression spring disposed between the shell closed end and the end piece, and wherein the annular portion and integral elongated strips are formed as a flat sheet of relatively rigid material of generally uniform thickness with a transverse relieved portion along each strip adjacent to the annular portion to form a flexible integral hinge between the annular portion and the corresponding elongated strip. 20. The improvement of Claim 19 wherein each elongated strip free end includes a ratch and the means peripherally disposed about the end piece for receiving and retaining the free ends ofthe elongated strips comprises a like plurality of pawls for engaging a corresponding ratch whereby when the stack of filter media yields axially under the urging ofthe compression spring, the ratches and pawls latch the stack in successive positions of reduced axial extent. 21 The harness of Claim 14 wherein the means for axially compressing the stack comprises a helical compression spring disposed between the shell closed end and the end piece, the end piece including a socket for receiving and retaining the compression spring in position during filter assembly, and wherein the annular portion and integral elongated strips are formed of a relatively rigid material of generally uniform thickness with a transverse relieved portion along each strip adjacent to the annular portion to form a flexible integral hinge between the annular portion and the corresponding elongated strip, the filter further comprising a standpipe integral with the annular portion along the inner periphery thereof for providing a lubricant path from within the filter media lamina to the end ofthe cyhndπcal shell opposite the closed one end 22 A harness for compressing a stack of filter media lamina comprising a relatively flat pressure plate for engaging one end filter media lamina, an end portion for engaging the opposite end filter media lamina, a plurality of elongated strips integral with and extending from the periphery ofthe end portion and terminating at remote free ends, and means peripherally disposed about the pressure plate for receiving and retaining the free ends of the elongated elastic strips 23 The harness of Claim 22 wherein the end portion is flexible and the elongated strips are elastic 24 The harness of Claim 23 wherein the end portion includes a centrally located aperture 25 The harness of Claim 22 wherein the elongated strip free ends include transverse tabs and the means peripherally disposed about the end piece for receiving and retaining the free ends ofthe elongated strips comprise notches for receiving corresponding strips and engaging the tabs, the annular portion, elongated strips and end piece cooperating to form a cage about the stack of filter media lamina when assembled thereto

Inventors: BILSKI GERARD WALTER, KNOPP RALPH ALLEN, LANGSDORF BRIAN JAMES, BILSKI, GERARD, WALTER, KNOPP, RALPH, ALLEN, LANGSDORF, BRIAN, JAMES
Applicants: ALLIED SIGNAL INC, ALLIEDSIGNAL INC.
Application year: 1996
Main classification: B01D27
IPC codes: B01D25, B01D27, B01D29, F01M11