Abstract:
An oil filter assembly includes a pressure relief valve adaptable to wide variety of environments while maintaining ease of assembly and manufacture. The pressure relief valve of this invention also occupies a minimal amount of space within the filter assembly as compared to conventional valve arrangements. In the preferred embodiment, the three-piece filter system comprises a base, a deep pocket filtering media, and a housing shell. The unitary filtering media and cap member are formed as a replaceable component that seats into the housing shell without a center tube or other outside support. When the housing shell is threaded onto the base, the cap member is sandwiched between a ledge on the shell and a seal on the base. The pressure relief valve allows fluid to continue to flow in the event the filter element becomes clogged whereby the valve provides ease of assembly, reduced cost, and reduced valve size.

Description:
RELATED APPLICATION  
       [0001]     This is a continuation of application Ser. No. 10/445,263, filed May 27, 2003. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     This invention relates to filters for filtering fluids such as engine oil, coolant, fuel, hydraulic or transmission fluid.  
         [0004]     2. Description of Related Art  
         [0005]     Fluid filters are used to remove contaminants from fluid, such as engine oil. Internal combustion engines use oil to lubricate bearings and reduce friction. This oil is circulated through the engine and carries contaminants such as metal particles, carbon particles and dirt which may cause harm to the engine. In order to effectively lubricate the engine, engine oil is passed through a filter to remove the contaminants before the oil is recirculated into the engine. The typical oil filter is attached to an internal combustion engine at the oil filter receptacle.  
         [0006]     Engine oil passes through a discharge opening in the oil filter receptacle, into a fluid filter and then into the engine lubrication system through an oil inlet pipe. A filter element in the fluid filter removes contaminates from the oil before it reenters the engine through the oil inlet pipe. Because of the dynamic nature of this process, oil filters must be sealed to protect from oil leaking into the atmosphere.  
         [0007]     Oil filters have traditionally been of a disposable type creating a great environmental concern. Used oil filters are disposed of in landfills or by incinerating. Recent improvements in the art have separated the filter elements from the filter canister allowing users to dispose of only the filter element and thus reducing the quantity of waste material. However, a large volume of waste is still generated by disposing of the filter element.  
         [0008]     For both reusable and disposable filter assemblies, there is a need for a fluid filter having a pressure relief valve to allow fluid to continue to flow in the event the filter element becomes clogged whereby the valve provides ease of assembly, reduced cost, and reduced valve size.  
       SUMMARY OF THE INVENTION  
       [0009]     The present invention provides a unique oil filter assembly including a pressure relief valve that is adaptable to wide variety of environments while maintaining ease of assembly and manufacture. The pressure relief valve of this invention also occupies a minimal amount of space within the filter assembly as compared to conventional valve arrangements.  
         [0010]     In the preferred embodiment, a three-piece filtering system replaces the standard style of OE and aftermarket automotive liquid filters, whereby the filtering system provides an environmental approach with respect to recycling of the filter media portion. The three-piece filter system comprises a base, an end cap with a deep pocket filtering media, and a housing shell. A pressure relief valve is provided in the end cap to allow fluid to flow in the event the filter element becomes clogged.  
         [0011]     The base is adapted to be fitted/threaded onto an engine block, with a sealing surface that provides a seal with the engine block. The filtering media and cap member is placed pleated-media end down into the housing shell. The filtering media self centers and the housing shell with the filtering media attached is sealingly affixed to the base.  
         [0012]     The unitary filtering media and cap member are formed as a replaceable component that seats into the housing shell without a center tube or other outside support. When the housing shell is threaded onto the base, the cap member is sandwiched between a ledge on the shell and a seal on the base.  
         [0013]     The filter media itself is a solid block and has no center tube. The filter media is a solid pleated pocket design affixed to the cap member. In the preferred design, the filter element is square rather than round to increase surface area. The structure of the filter media eliminates the center tube and compression spring and bottom plate typically used inside the shell of a spin-on filter assembly; thus, the number of parts is reduced and assembly is simplified.  
         [0014]     The end cap member includes a one-piece, U-shaped pressure relief valve assembly to allow fluid to continue to flow in the event the filter element becomes clogged. The one-piece valve is constructed so that different sizes, materials, thicknesses, and preloading of the valve can produce different pressure relief settings. Additionally, the angle of the valve with respect to the end cap member can adjust the pre-load to allow for varying pressure settings.  
         [0015]     Further features and advantages of the invention are pointed out with the description of the preferred embodiment, drawings and claims of this application. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]      FIG. 1  is a detail section view of a reusable three-piece fluid filter including the base, the housing shell, and the filtering element.  
         [0017]      FIG. 2  is a side view of the reusable fluid filter media and associated cap member.  
         [0018]      FIG. 3   a  is a side view of the cap member of this invention.  
         [0019]      FIG. 3   b  is a top view of the cap member illustrated in  FIG. 3   a.    
         [0020]      FIGS. 4   a - 4   d  show various views of the preferred design of the filter assembly according to the present invention as described above.  
         [0021]      FIG. 5  is a schematic bottom view of an alternate embodiment of the cap member of  FIG. 2  including a pressure relief valve.  
         [0022]      FIG. 6  is a perspective view of one embodiment of the valve plate according to the present invention. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0023]     One form of the invention is illustrated and described herein as an oil filter on an engine.  FIG. 1  illustrates reusable fluid filter comprising a housing shell  10 , a filter element  20 , and a threaded base  30 .  
         [0024]     As illustrated in  FIG. 1 , the threaded base  30  has external threads  32  and internal threads  34 . External threads  32  are used to threadably mount the base  30  to a standard reusable filter housing shell  10 . Internal threads  34  are machined to allow the fluid filter to be adapted to a wide variety of engines produced by various manufacturers. An engine block (not shown) typically has an oil filter stub (not shown) to allow a fluid filter to be threadably attached via internal threads  34 . Filtered oil port  36  is formed in base  30  to allow filtered fluid to exit the reusable fluid filter after passing through the cap member  22 . Threaded base  30  is designed to be an inexpensive device to allow the reusable oil filter to be adapted to a wide variety of engine blocks. Internal threads  34  are formed to fit OEM threads of the oil filter stub (not shown) and adapts the reusable fluid filter to a wide variety of engines while reducing the costs to manufacture, package and distribute reusable fluid filters.  
         [0025]     The base  30  has an inside face  30   a  and an outside face  30   b . Outside face  30   b  has an annular flat surface and an annular channel cut  31  formed in the annular flat surface. O-ring  37  is mounted in annular channel  31  to form an oil tight seal between base  30  and the engine block when base  30  is threadably attached to filter stub. A second annular channel (not shown) in outside face  30   a  may also be used to form an oil tight seal with a second o-ring mounted in the second channel to adapt the base  30  to additional manufacturers engines. Unfiltered oil leaves engine block through unfiltered oil ports in the filter stub. Unfiltered fluid channel  42  is formed in outside face  30   a  and allows unfiltered oil to pass through unfiltered fluid inlet orifices  44 , through base  30  and into the unfiltered fluid compartment  48  defined between the base  30  and the cap member  22 . Unfiltered fluid channel  42  helps fluid filter  22  adapt to a wide variety of engines and other fluid systems.  
         [0026]     Assuming normal pressure conditions and operation of the filter, the unfiltered oil passes from the compartment  48  through passageways formed at the peripheral edges of the cap member  22  and into a canister area  11  between the housing shell  10  and filter element  20 .  
         [0027]     Unfiltered fluid inlet orifices  44  may be formed at an angle to the axis of canister  10  in order to create a turbine or a swirling motion of unfiltered fluid in the unfiltered fluid compartment  48 .  
         [0028]     Filter element  20  comprises a reusable filter media  21  and cap member  22 . The reusable filter media  21  comprises a disposable element having a first end  21   a , a second end  21   b , and an outside wall  21   c . The first end  21   a  of the deep pocket filter media  21  is attached to the cap member  22 . Unlike conventional filter media of conventional oil filters, the filter media  21  is a pleated pocket design similar to conventional panel air filtration systems. The filter media  21  is in the form of a solid block of a filter material having no central opening therethrough. In other words, the block of the filter media  21  substantially occupies a central portion of the outer shell  10 . In the preferred embodiment, the filter media  21  is square—rather than round—when viewed from the top to increase surface area. Moreover, as illustrated in  FIGS. 3   b  and  4   a - 4   d , the block of filter media  21  includes a continuous series of pleats extending across an entire width thereof such that no substantial void (or opening) exists in or through the central portion of the outer shell  10 . In a conventional round-type, media style filter for spin-on liquid filter assembly, the typical area of the filter media is 357.4 in 2 . Of course, these dimensions relate to only one example of a filter size; other filter sizes achieve similar benefits. For the solid, square pleat block of this invention, the corresponding filter area is 410.6 in 2  to fit the same size housing shell. With the solid square structure of the filter media  21 , the stability and rigidity of the filter media is enhanced. In other words, the spacer/comb design provides even pleat spacing under pressure while giving rigidity to the deep pocket media element  21 . As a result, the solid structure of the filter media  21  eliminates the central opening therethrough as well as the compression spring and bottom plate typically used inside the shell of a spin-on filter assembly. Thus, the number of parts is reduced with the design of this invention.  
         [0029]     In a preferred embodiment, the filter media  21  may be torn away from or otherwise removable from the cap member  22  to further enhance the environmental benefits of this invention. In one embodiment of this invention, the filter media  21  is provided with a disposable mesh  25  (see  FIG. 2 ), which is woven from a material such as metallic wire.  
         [0030]     The cap member  22  is preferably metal or plastic but other suitable materials may be used without departing from this invention.  
         [0031]     As shown in  FIG. 1 , the unitary filtering media  21  and cap member  22  are formed as a replaceable assembly that seats into the housing shell  10  without a center tube or other outside support. The cap member  22  is formed with a rim portion  23  defining a mounting surface  24 , which is adapted to rest on the inwardly projecting surface or ledge  12  provided on the inner surface of the housing shell  10 . When the housing shell  10  is threaded onto the base  30 , the cap member  22  is sandwiched between the ledge  12  on the housing shell  10  and a seal  50  adjacent the base  30 . Alternately, the seal  50  may be omitted in favor of the friction force provided by the inner seal  39  disposed adjacent the filtered oil port  36 , whereby the cap member  22  is sandwiched between the ledge  12  on the housing shell  10  and the inner seal  39  at the filtered oil port  36 . It is within the scope of this invention to provide any type of retention system to maintain the filter media  21  and cap member  22  in fixed position within the housing shell  10  and base  30 .  
         [0032]     With reference to  FIGS. 3   a  and  3   b , the cap member  22  is shown with an emphasis on the shape and function of the mounting surface  24 . As shown in  FIG. 3   b , the mounting surface  24  may be formed as a wave-shaped edge  24   a  to permit flow of the unfiltered oil from the unfiltered oil compartment  48  through the passageways defined by the wave-shaped edge  24   a  formed at the periphery of the cap member  22  and into the canister area  11  between the housing shell  10  and filter element  20 . The ledge  12  is correspondingly formed to permit flow of unfiltered oil around the peripheral edge  24   a  of the cap member  22 . Alternatively, suitable passageways may be provided at the interface of the rim  23  and ledge  12 . The wave shaped edge  24   a  shown in  FIG. 3   b  provides sufficient support for the cap member  22  and filter media  21  while permitting sufficient flow of oil from the compartment  48  to the canister area  11 .  
         [0033]     It should be understood that if filter element  12  becomes clogged with contaminants, pressure in the unfiltered fluid compartment  48  becomes very great due to oil being forced into canister area  11  through passageways at the periphery of the cap member. Therefore, this invention includes a pressure relief valve to provide a by-pass path for the unfiltered oil when the filter element becomes clogged. As the filter media becomes clogged, pressure builds up within the compartment  48  upstream of the valve holes  100   a ,  100   b . As illustrated in  FIGS. 3   a ,  3   b ,  4   a  and  4   c , the valve holes  100   a ,  100   b  are radially spaced and axially offset from a central aperture  101  through the cap member  22 . When the pressure differential reaches a predetermined force, pressure against valve holes  100   a ,  100   b  overcomes a mounting force of a pressure relief valve plate  102  causing a direct fluid communication through valve holes  100   a ,  100   b  between unfiltered fluid compartment  48  and hollow core leading to the filter oil port  36 . This arrangement will allow unfiltered fluid to flow directly from the unfiltered fluid inlet orifices  44  through the unfiltered fluid compartment  48  and into port  36  to return to engine block through filtered oil tube.  
         [0034]     As shown in  FIGS. 3   a  and  3   b , the end cap member  22  is shown with a pair of bypass valve holes  100   a ,  100   b  and the valve plate  102 .  FIGS. 4   a - 4   d  show various views of the preferred design of the filter assembly according to the present invention as described above.  
         [0035]      FIG. 5  illustrates the valve plate  102  as mounted on the underside of the end cap member  22 .  
         [0036]     With reference to  FIG. 6 , the valve plate  102  is preferably formed as a flat plate member having a central mounting section  105  and a pair of valve fingers  107   a ,  107   b . Flex points  109   a ,  109   b  are disposed between the central mounting section  105  and the valve fingers  107   a ,  107   b ; respectively. In the preferred embodiment, each valve finger  107   a ,  107   b  is provided with a sealing coating  110  disposed on a side of each valve finger  107   a ,  107   b  facing the respective valve hole  100   a ,  100   b . The sealing coating  110  serves to enhance the sealing effect provided by the valve fingers  107   a ,  107   b  on the valve holes  100   a ,  100   b.    
         [0037]     The valve plate  102  is mounted to the underside of the cap member  22  at the central mounting section  105  via a number of suitable methods including but not limited to welding, adhesive/epoxy, or a heat staking method. In the heat staking method, the underside of the plastic cap member  22  is formed with a protrusion during the plastic injection molding process. Thereafter, the valve plate  102 , which—in this mounting arrangement—is formed with a central aperture at the central mounting section  105 , is positioned on the protrusion. Then, the protrusion is melted to secure the valve member  102  onto the underside of the cap member  22 .  
         [0038]     With the valve plate  102  affixed to the cap member  22 , the valve fingers  107   a ,  107   b  are positioned over the valve holes  100   a ,  100   b  to sealingly close the valve holes  100   a ,  100   b.    
         [0039]     The flex points  109   a ,  109   b  resiliently bias the valve fingers  107   a ,  107   b  against the valve holes  100   a ,  100   b  to selectively close the valve holes  100   a ,  100   b  and prevent flow of unfiltered oil from the unfiltered fluid compartment  48  through the valve holes  100   a ,  100   b  and into the hollow core leading to the filter oil port  36 . The flex points  109   a ,  109   b  also serve to prevent deformation, wear and breakage of the valve plate  102  due to movement of the valve fingers  107   a ,  107   b.    
         [0040]     When the filter media  21  begins to clog, a pressure gradient is created in the unfiltered fluid compartment  48 . As the pressure gradient reaches a predetermined level, the pressure level overcomes a closing force created by the valve plate  102  closing the valve holes  100   a ,  100   b . When the pressure overcomes the closing force of the valve fingers  107   a ,  107   b , unfiltered oil begins to flow through the bypass valve holes  100   a ,  100   b ; thereby, the unfiltered oil bypasses the filter media  21 .  
         [0041]     The sealing force generated by the valve plate  102  is determined by a number of factors including the size and number of the valve holes  100   a ,  100   b , the size/thickness of the valve plate  102 , the material forming the valve plate  102 , and angle of the valve plate with respect to the pressure force. Specifically, the valve plate may be formed with an angle between the valve fingers  107   a ,  107   b  and the central mounting section to provide a non-planar arrangement between these components. In such a case, the closing force will be increased because the valve fingers are bent toward the valve holes and there is an increased closing force when the valve  20  plate  102  affixed to the end cap member  22 .  
         [0042]     It is significant to note that the dual valve hole and finger arrangement shown in the drawings is not intended to limit this invention because a single valve hole and a single valve finger may define the pressure relief valve of this invention. In such a case, the valve plate  102  has a mounting section for mounting the valve member to the end cap member  22  and single flex point between the mounting section and the single valve finger.  
         [0043]     The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and it is therefore desired that the present embodiment be considered in all respects as illustrative and not restrictive, reference being made to the appended claims rather than to the foregoing description to indicate the scope of the invention.