Abstract:
A filtration system ( 10 ) for removing contaminants from a fluid is provided. The system includes a housing ( 44 ) having a convex shaped base ( 78 ) and a top ( 84 ), with filter media ( 46 ) disposed within the housing. The filter media may take the form of a roll having a first end formed by edges of the wound filter media and convex in shape. The system may further include a seal ( 56 ) adapted to impede channeling of the fluid in proximity to the core through substantially sealing annuluses formed between adjacent wraps of filter media by engaging the edges of the filter media in proximity to the core without substantially radially displacing the filter media. A fluid passageway may pass through the housing, wherein the passageway ( 20, 24, 40 , and/or  42 ) is sized sufficiently small in cross-sectional area to substantially impede the flow of fluid through the passageway due to gravity.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims the benefit of U.S. Patent Application No. 60/347,210, filed Jan. 8, 2002, priority from the filing date of which is hereby claimed under 35 U.S.C. § 120 and the disclosure of which is hereby expressly incorporated by reference. 

   FIELD OF THE INVENTION 
   The present invention relates generally to fluid filtration systems, and more particularly, to fluid filtration systems utilizing wound filtration media. 
   BACKGROUND OF THE INVENTION 
   Fluid filtration systems are commonly used in today&#39;s industrialized society to remove contaminants from a fluid. In one industry in particular, the automotive industry, fluid filtration is essential to ensuring the longevity and proper operation of internal combustion engines. More specifically, it has been found that the normal operation of an internal combustion engine results in the contamination of the lubricating oil and, consequently, increased wear/damage to the engine. Generally, contaminants are introduced into the lubricating oil by five primary sources: engine wear may introduce metal shavings; cylinder blow-by may introduce the products of combustion; water may enter from condensation or a leak in the cooling system; environmental dust may enter through the air intake system; and fuel may enter from fuel system leaks or an excessively rich intake mixture. 
   Typically, internal combustion engines are provided with a full flow filtration system to remove a portion of these contaminants. However, inasmuch as the full flow filtration system must handle a high rate of lubricating oil, typically in the range of 7 to 10 gallons per minute, the filter must be porous and therefore capable of removing only the larger-sized particulates, such as particulates having a size of 30 to 40 microns or larger. However, it has been found that 92% of all engine wear is the result of particulate matter sized between 7 and 40 microns, the majority of which are not removed by high-capacity full flow filtration systems. 
   One solution has been to provide a secondary by-pass filtration system that can remove the finer sized particulate matter. In a by-pass filtration system, a fraction of the full flow volume, such as one quart per minute for a 7- to 10-gallon flow rate system, is directed to a by-pass filter system. Typically, the by-pass filtration systems are designed to remove particles down to 1 to 6 microns. To assure maximum pressure differentials across the by-pass filter element, the return oil line is often routed directly back to the oil sump. 
   Another problem with existing full flow oil filtration systems is that they generally only have sufficient absorbent capacity to absorb a few teaspoons of water. Not only can water aid in the break down of the oil, limiting its lubricating properties, the water may combine with the products of combustion introduced by blow-by. Water mixed with the products of combustion may create sulfuric acid that can pit polished surfaces. In contrast, high-density by-pass filters can absorb substantially greater amounts of water, often a pint or more. When the oil heats up, the water evaporates and is released through the engine&#39;s breather conduit(s). 
   Commonly used by-pass filters are of one of two types. In the first type of by-pass filters, the oil passes through a perforated steel plate where all particles greater than approximately 3 microns are screened and trapped. Other by-pass filters use synthetics, paper, or polyester blends wound around a central core to create a microscopic screen to trap particles. Others use filter mediums constructed from organic materials, such as cotton or paper. While synthetics or organics will theoretically capture minute contaminants equally well, organic filtration often provides superior moisture absorption. As previously discussed, moisture mixed with soot (carbon from blow-by) forms acids. So, organic filtration may offer superior protection by trapping larger amounts of moisture in the filter so acid formation is reduced. 
   The operation of a typical wound filter media by-pass filter will now briefly be described. Oil at high pressure is injected at a low flow rate to a first end of the filter. The oil runs parallel with the windings between the annulus formed between the inner central core and the outer canister wall. As the lubricating oil travels from the first end to a second end of the filter, contaminants from the oil are removed. Once the oil passes the entire length of the canister, the oil is directed through a central core of the filter to return to the oil sump. 
   Although existing by-pass filtration systems may be effective, they are not without their problems. Often, the by-pass filters are subject to what is known in the art as channeling, where preferential paths form in the filter media. These preferential paths allow the oil to pass preferentially through the media without significant filtering. Typically, channeling is most pronounced along the inner wall of the canister and along the outer surface of the central core. 
   Further, changing of the by-pass filter system often results in spillage of the lubricating oil contained within the canister. Not only does the spill create a mess that must be cleaned, it also presents a slipping hazard, may harm the environment, and may lead to the violation of environmental regulations. 
   Still further, existing by-pass filter systems are subject to substantial pressures over a large surface area. Existing by-pass filter systems often utilize canisters having flat end shapes, which do not efficiently contain the pressure exerted on their surfaces; therefore the canister ends require more material, are heavier, and are more expensive to manufacture. 
   Thus, there exists a need for a by-pass filter system that reduces channeling, impedes the spillage of oil during removal, and has a canister design that efficiently contains the pressure within the canister. 
   SUMMARY OF THE INVENTION 
   In accordance with one embodiment formed in accordance with the present invention, a fluid filtration system for removing contaminants from a fluid of a machine is provided. The fluid filtration system includes a housing having a first open end and a second open end. A top is coupled to the first open end of the housing so as to close off the first open end. A base is coupled to the second open end of the housing so as to close off the second open end, wherein the base is convex in shape when viewed from within the housing. The filtration system also includes filter media disposed within the housing. 
   In accordance with another embodiment formed in accordance with the present invention, a filter cartridge for removing contaminants from a fluid when placed in a canister of a filter is provided. The filter cartridge includes a core disposed along a longitudinal axis of the filter cartridge. A length of filter media is wound around the core to form a roll having a cylindrical outer surface and a first end formed by successive adjacent edges of the wound filter media. The first end is convex in shape when viewed from the center of the roll. 
   In accordance with still another embodiment formed in accordance with the present invention, a fluid filtration system for removing contaminants from a fluid of a machine is provided. The fluid filtration system includes a housing with filter media disposed within the housing. The fluid filtration system also includes a first fluid passageway in fluid communication with the filter media and operable to be in fluid communication with the machine. At least a portion of the first fluid passageway is sized sufficiently small in cross-sectional area to substantially impede the flow of fluid due to gravity out of the housing when the fluid is at atmospheric pressure and below a selected temperature. 
   In accordance with an additional embodiment formed in accordance with the present invention, a fluid filtration system for removing contaminants from a fluid of a machine is provided. The fluid filtration system includes a housing and a core disposed within the housing. A length of filter media is wound around the core to form a roll having a cylindrical outer surface and a first end formed by successive adjacent edges of the wound filter media. A seal is adapted to impede channeling of the fluid in proximity to the core through substantially sealing annuluses formed between adjacent wraps of filter media. The seal engages the edges of adjacent wraps of the filter media in proximity to the core without substantially radially displacing the adjacent wraps of filter media. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
       FIG. 1  is an exploded perspective view of one embodiment of a fluid filtration system formed in accordance with the present invention; 
       FIG. 2  is a longitudinal cross-sectional view of the fluid filtration system depicted in  FIG. 1 , showing the assembled elements of the fluid filtration system; 
       FIG. 3  is a planar view of the end that faces the canister of one embodiment of a mounting plate formed in accordance with the present invention and suitable for use with the fluid filtration system depicted in  FIG. 1 ; and 
       FIG. 4  is a planar view of the end which faces away from the canister of the embodiment of the mounting plate depicted in  FIG. 3 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIGS. 1 and 2  illustrate one embodiment of a fluid filtration system  10  formed in accordance with the present invention. For illustrative purposes, the illustrated embodiment of the present invention will be described as a by-pass lubricating oil filtration system for an internal combustion engine of a motor vehicle; however, one skilled in the relevant art will appreciate that the disclosed fluid filtration system has wide application and is not to be construed as limited to application with a motor vehicle nor solely with lubricating oil. 
   Referring to  FIG. 1 , the elements of the fluid filtration system  10  will now be described. The fluid filtration system  10  includes a mounting plate  12  and a housing or canister  14 . The mounting plate  12  is a circular shaped, generally solid body having a thickness. Disposed on the mounting plate  12  is an inlet fitting  16  and an outlet fitting  18 . As shown best in  FIG. 2 , the inlet and outlet fittings  16  and  18  are comprised of internally threaded, perpendicularly oriented bores that extend partially through the thickness of the mounting plate  12 . The outlet fitting  18  is located at the center of the circular shaped mounting plate  12  and the inlet fitting  16  is located along a radius that extends outwardly from the center of the circular shaped mounting plate  12 . The inlet fitting  16  permits the coupling of the mounting plate  12  in fluid flow communication with the high pressure side of the engine&#39;s lubricating system, thereby allowing lubricating oil requiring filtering to be introduced into the fluid filtration system  10 . Similarly, the outlet fitting  18  permits the coupling of the mounting plate  12  in fluid flow communication with the engine, thereby allowing filtered oil to return to the low pressure side of the engine&#39;s lubricating system. Preferably, the outlet fitting  18  is coupled in fluid flow communication with the location in the engine&#39;s lubricating system having the lowest pressure, such as the oil sump, to provide a maximum pressure differential between the inlet and outlet fittings  16  and  18  and thereby across a filter media  46  housed in the canister  14  in the manner described below. 
   Referring now to  FIGS. 2-4 , the inlet fitting  16 , which is located on an outer end surface  28  of the mounting plate  12 , is in fluid flow communication with an inlet fluid passageway  20 . The inlet fluid passageway  20  is concentrically located within the bore of the inlet fitting  16  and passes through the thickness of the mounting plate  12 , terminating in an annular groove  22  machined on the opposite (inner) end surface  30  of the mounting plate  12 . The annular groove  22  is concentrically oriented with respect to the center of the mounting plate  12 . The inlet fluid passageway  20  has a diameter substantially less than the diameter of the inlet fitting  16 , the significance of which will be described in further detail below. 
   Still referring to  FIGS. 2-4 , the outlet fitting  18  is in fluid flow communication with an outlet fluid passageway  24 , which is concentrically located within the bore of the outlet fitting  18 . The outlet fluid passageway  24  is in fluid flow communication with the outlet fitting  18  and a second outlet fluid passageway  40  that is bored through the center of an externally threaded fastener  32 . The second outlet fluid passageway  40  is in fluid flow communication with a third outlet fluid passageway  42 , perpendicularly bored through a base  78 . Therefore, any fluid contained in the central tube  50  may be transferred to the outlet fitting  18  by passing through the aligned outlet fluid passageways  42 ,  40  and  24  formed in the base  78 , externally threaded fastener  32 , and mounting plate  12 , respectively. As with the inlet fluid passageway  20 , the outlet fluid passageways  24 ,  40  and  42  have a diameter substantially less than the diameter of the outlet fitting  18 , the significance of which will be described in further detail below. 
   The externally threaded fastener  32  mentioned above extends perpendicularly outward from the center of the inner end surface  30  of the mounting plate  12 . The externally threaded fastener  32  has a threaded portion that is sized and dimensioned to correspondingly couple with an internally threaded fastener  34  centrally located in the base  78  that encloses an open end  38  of the canister  14  in the manner described below. The outlet fluid passageway  40  is perpendicularly bored through the center of the externally threaded fastener  32 . 
   Referring now to  FIGS. 1-4 , the mounting plate  12  also includes four mounting holes  36 . The mounting holes  36  are bored perpendicularly into the thickness of the mounting plate  12  from the outer end surface  28 . The mounting holes  36  are internally threaded to allow the outer end surface  28  of the mounting plate  12  to be coupled by well known threaded fasteners (not shown) to a mounting bracket (not shown), which in turn is typically attached to the engine or frame of the vehicle, as is well known in the art. 
   Preferably, the mounting plate  12  also includes a seal  90 . The seal  90  is circular in shape and is mounted within an annular seal mounting groove  92  formed in the inner end surface  30  of the mounting plate  12 . The annular seal mounting groove  92  is concentrically located in the inner end surface  30 , outside of the annular groove  22 , i.e., the diameter of the annular seal mounting groove  92  is substantially greater than the annular groove  22 . When the mounting plate  12  is coupled to the base  78  of the canister  14  in the manner herein described, the seal  90  is compressed between the inner end surface  30  of the mounting plate  12  and the base  78 , thereby sealing the mounting plate  12  to the base  78 . The seal  90  aids in impeding the pressurized oil contained within the annular groove  22  from escaping to the environment. Although the illustrated embodiment depicts a rectangular type of seal (cross-section), it should be apparent to one skilled in the art that the present invention may also be practiced without such a seal, or alternately with other types of seals, such as O-ring seals or flat gaskets. 
   In one actual embodiment of the present invention, the mounting plate  12  is formed from aluminum and the threaded fastener  32  from steel. However, it should be apparent to one skilled in the art that other materials may be used and fall within the scope of the invention. 
   Referring to  FIGS. 1 and 2 , the elements of the canister  14  will now be discussed. The canister  14  includes a hollow housing  44  containing filter media  46 . The hollow housing  44  is cylindrical in shape, having opposing open ends closed by an integral top  84  and a base  78 . The integral top  84  is concave, when viewed from inside of the canister  14 . The shape and thickness are sufficient to contain the pressure produced within the canister  14 . The concave shape allows the canister  14  to be formed with less material, creating a canister  14  that is light and less expensive to manufacture, while still retaining its ability to adequately withstand the pressures exerted against its inner surface. 
   Similarly, the base  78  is convex in shape, when viewed from inside of the canister  14 . The shape and thickness are adequate to contain the pressure produced within the canister  14 . The convex shape allows the canister to be formed with less material, creating a canister that is light and less expensive to manufacture, while still retaining its ability to withstand the pressures exerted against its inner surface. Preferably, the canister housing  44  and the base  78  are formed of iron and are joined together along the outer periphery of the base  78  by welding or press fitting the parts together. 
   The base  78  has an inlet fluid passageway  72  bored perpendicularly through its thickness. The inlet fluid passageway  72  is positioned radially outward from the center of the base  78  so as to be in alignment with the annular groove  22  in the mounting plate  12 . With the inlet fluid passageway  72  positioned as described, the inlet fluid passageway  72  will always be in fluid flow communication with the annular groove  22 , regardless of the relative rotational position of the mounting plate  12  with respect to the end plate  78  of the canister  14 . 
   The base  78  further includes a centrally located, internally threaded fastener  34 , sized to receive the externally threaded fastener  32 . The internally threaded fastener  34  extends perpendicularly inward from the inner end surface  30  of the base  78 . The outer diameter of the threaded fastener  34  is sized to slidably fit with the inside wall of the central tube  50 , thereby allowing the threaded fastener  34  to be received within the central tube  50 . An annular channel  80  is circumferentially disposed on the outer surface of the threaded fastener  34 . The annular channel  80  is sized and dimensioned to receive an O-ring  82 . The O-ring  82  sealingly engages the inner surface of the central tube  50 , thereby impeding the passage of oil between the threaded fastener  34  and the central tube  50 . The outlet fluid passageway  42  extends through the center of the fastener  34 , thereby completing a passageway between the outlet fitting  18  and the central tube  50 . 
   Housed within the canister  14  is the filter media  46 . The filter media  46  is wound around a tubular core  48 , which may be constructed from a rigid material, such as cardboard. Concentrically located within the tubular core  48  is the central tube  50 , which is constructed from a rigid material, such as steel. The outer diameter of the central tube  50  is substantially equal to the inner diameter of the tubular core  48 , whereby the outer surface of the central tube  50  substantially sealingly engages the inner surface of the tubular core  48 . 
   The central tube  50  has a flared end  52 . The flaring restrains a flat washer  54  mounted on the central tube  50 . The flat washer  54  engages a flat seal  56  and acts as a rigid backing member. In an assembled configuration, the force exerted by a coil spring  86  presses the flat washer  54  against the flat seal  56 . The flat seal  56  is thereby pressed against the edges of successive adjacent inner layers of the filter media  46  and the circular end surface of the tubular core  48  to impede channeling between the central tube  50 , the filter media tabular core  48 , and the filter media  46 , as described in more detail below. As shown in  FIG. 2 , preferably the end of the filter media adjacent to the flat seal  56  tapers away from the center of the flat seal. Although the illustrated embodiment utilizes the force provided by the coil spring  86  to compress the flat seal  56  and provide axial compressive forces upon the filter media, it should be apparent to one skilled in the art that other methods of compressing the flat seal  56  against the filter media  46  can be used and fall within the scope of the invention. 
   The filter media  46  is formed from any suitable filter material well known in the art, such as cotton-based low porosity paper impregnated with cellulose. The filter media  46  is tightly wound around the tubular core  48 , and a sufficient amount of filter media is wound so the outer surface of the filter media engages the inside wall  70  of the housing  44  of the canister  14 . Further, as is apparent from viewing  FIG. 2 , the width of the outer layers gradually increases (as compared to the inner layers) from a first width to a second width as the layers approach the canister wall, to form a convex first end having an annular ring  64  with a tapered wall  66  at the end of the filter media  46  that faces the base  78 . In operation, the oil pressure within an inlet cavity  68  creates a force that presses the tapered wall  66  against the inside wall  70  of the housing  44  of the canister  14 , thereby impeding channeling along the inside wall  70 , as described in more detail below. 
   More specifically and in regard to the variable width of the filter media, the width of the filter media decreases from a first width measured in proximity to the core to a second width, and increases from the second width to a third width greater than the first width, the third width measured in proximity to the cylindrical outer surface and the second width measured between the points at which the first and third widths are measured. By varying the width as described, the convex first end is formed, along with an opposite concave second end. Although the illustrated convex first end and concave second end are shown as formed in specific shapes, it should be apparent to those skilled in the art that other shapes are suitable for use with and are within the spirit and scope of the present invention. Further, it should be apparent to those skilled in the art, that the terms concave and convex as used within this detailed description, include convex and concave ends formed in a linear manner, arcuate manner, or combination thereof. 
   An optional well-known wire mesh  88  is also shown in  FIG. 2 . The wire mesh  88  is formed to have a shape similar to the integral top  84  of the canister  14 . The wire mesh  88  is sandwiched between the coil spring  86  and the top  84  of the canister  14 . As will be apparent to one skilled in the art, the wire mesh  88  may be used in instances where the filter media  46  is wound or placed in the canister  14  in such a manner that the filter media  46  engages the integral top  84 , thereby impeding the discharge of oil from the filter media  46 . In such instances, the wire mesh  88  will space the filter media  46  from the integral top  84 , by an amount sufficient to provide flow paths for oil to exit the filter media  46  and enter the central tube  50 . 
   The operation of the illustrated embodiment of the present invention will now be described. Referring to  FIG. 2 , the inlet fitting  16  is coupled in fluid flow communication with the pressurized side of the engine lubricating system by any suitable conduit means well known in the art. Likewise, the outlet fitting  18  is coupled in fluid flow communication via another suitable conduit with the low pressure side of the engine lubricating system, and preferably to the oil sump. Oil to be filtered is delivered through the inlet line to the inlet fitting  16 . From the inlet fitting  16  the oil passes through the inlet fluid passageway  20  and into the annular groove  22 . The oil passes along the annular groove  22  until it reaches the inlet fluid passageway  72 , where it enters the canister  14 . Once in the canister  14 , the oil begins its tortuous travel through the filter media  46  in the direction of the arrow indicated by the reference numeral  74 . As the oil passes through the filter media  46 , particulates bind with the filter media and are removed from the oil by methods well known in the art. 
   After the oil has traveled the entire length of the filter media  46 , the oil enters an end cavity  75 . From the end cavity  75 , the oil enters the central tube  50 , flowing in the direction of the arrow indicated by reference numeral  76 . The oil leaves the canister  14  via the outlet fluid passageways  24 ,  40  and  42  to the outlet fitting  18 , which returns the filtered oil to the low pressure side of the engine lubricating system. 
   Once the expected useful life of the filter media  46  has been reached, the canister  14  is simply rotated until the internally threaded fastener  34  of the canister  14  is disengaged from the externally threaded fastener  32  of the mounting plate  12 . As discussed above, the inlet fluid passageway  72  and the outlet fluid passageways  24 ,  40  and  42  each have a diameter substantially less than the inner diameter of the inlet and outlet fittings  16  and  18 , respectively. The small diameter of the inlet fluid passageway  72  and the outlet fluid passageways  24 ,  40  and  42  reduces, if not entirely eliminates, the spillage of oil during removal of the canister  14 . 
   Preferably, the diameters of the inlet fluid passageway  72  and the outlet fluid passageways  24 ,  40  and  42  are one-tenth (0.1) of an inch or less. In one actual embodiment of the present invention, the diameters of the inlet fluid passageway  72  and the outlet fluid passageways  24 ,  40  and  42  are 50 thousandths (0.05) of an inch. The diameters of the inlet fluid passageway  72  and the outlet fluid passageways  24 ,  40  and  42  are preferably selected so forces well known in the field of fluid mechanics, such as friction and surface tension effects created by the interaction of the fluid with the exposed surfaces of the inlet fluid passageway  72  or outlet fluid passageways  24 ,  40  and  42 , are sufficient to overcome the forces, such as gravity, tending to force the oil out through the inlet fluid passageway  72  and outlet fluid passageways  24 ,  40  and  42  when the oil is at atmospheric pressure and below selected temperature, such a normal operating temperature or room temperature. When appropriate diameters are chosen, a substantial majority of the oil remains within the canister  14  during removal of the canister  14  from the mounting plate  12 . 
   It is well known to those skilled in the art that the fluid mechanical properties of a fluid vary between fluids, and also vary for the same fluid based on changes in other variables, such as temperature. Therefore, the maximum size of fluid passageways, which substantially eliminate discharge, is dependent on the individual properties of a specific fluid and upon various variables defining the fluid, such as temperature. For example, the maximum fluid passageway size that will still substantially eliminate flow from the canister  14  will be significantly smaller for heated oil as relative to the same oil at a lower temperature, and likewise significantly smaller for water as compared to a viscous lubricating oil of an equal temperature. Therefore, although preferred diameters are disclosed for one embodiment of the present invention, it is to be understood that other diameters fall within the scope of the present invention. 
   While the preferred embodiment of the invention has been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.