Fluid filtration system

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.

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'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'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.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIGS. 1 and 2illustrate one embodiment of a fluid filtration system10formed 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 toFIG. 1, the elements of the fluid filtration system10will now be described. The fluid filtration system10includes a mounting plate12and a housing or canister14. The mounting plate12is a circular shaped, generally solid body having a thickness. Disposed on the mounting plate12is an inlet fitting16and an outlet fitting18. As shown best inFIG. 2, the inlet and outlet fittings16and18are comprised of internally threaded, perpendicularly oriented bores that extend partially through the thickness of the mounting plate12. The outlet fitting18is located at the center of the circular shaped mounting plate12and the inlet fitting16is located along a radius that extends outwardly from the center of the circular shaped mounting plate12. The inlet fitting16permits the coupling of the mounting plate12in fluid flow communication with the high pressure side of the engine's lubricating system, thereby allowing lubricating oil requiring filtering to be introduced into the fluid filtration system10. Similarly, the outlet fitting18permits the coupling of the mounting plate12in fluid flow communication with the engine, thereby allowing filtered oil to return to the low pressure side of the engine's lubricating system. Preferably, the outlet fitting18is coupled in fluid flow communication with the location in the engine's lubricating system having the lowest pressure, such as the oil sump, to provide a maximum pressure differential between the inlet and outlet fittings16and18and thereby across a filter media46housed in the canister14in the manner described below.

Referring now toFIGS. 2-4, the inlet fitting16, which is located on an outer end surface28of the mounting plate12, is in fluid flow communication with an inlet fluid passageway20. The inlet fluid passageway20is concentrically located within the bore of the inlet fitting16and passes through the thickness of the mounting plate12, terminating in an annular groove22machined on the opposite (inner) end surface30of the mounting plate12. The annular groove22is concentrically oriented with respect to the center of the mounting plate12. The inlet fluid passageway20has a diameter substantially less than the diameter of the inlet fitting16, the significance of which will be described in further detail below.

Still referring toFIGS. 2-4, the outlet fitting18is in fluid flow communication with an outlet fluid passageway24, which is concentrically located within the bore of the outlet fitting18. The outlet fluid passageway24is in fluid flow communication with the outlet fitting18and a second outlet fluid passageway40that is bored through the center of an externally threaded fastener32. The second outlet fluid passageway40is in fluid flow communication with a third outlet fluid passageway42, perpendicularly bored through a base78. Therefore, any fluid contained in the central tube50may be transferred to the outlet fitting18by passing through the aligned outlet fluid passageways42,40and24formed in the base78, externally threaded fastener32, and mounting plate12, respectively. As with the inlet fluid passageway20, the outlet fluid passageways24,40and42have a diameter substantially less than the diameter of the outlet fitting18, the significance of which will be described in further detail below.

The externally threaded fastener32mentioned above extends perpendicularly outward from the center of the inner end surface30of the mounting plate12. The externally threaded fastener32has a threaded portion that is sized and dimensioned to correspondingly couple with an internally threaded fastener34centrally located in the base78that encloses an open end38of the canister14in the manner described below. The outlet fluid passageway40is perpendicularly bored through the center of the externally threaded fastener32.

Referring now toFIGS. 1-4, the mounting plate12also includes four mounting holes36. The mounting holes36are bored perpendicularly into the thickness of the mounting plate12from the outer end surface28. The mounting holes36are internally threaded to allow the outer end surface28of the mounting plate12to 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 plate12also includes a seal90. The seal90is circular in shape and is mounted within an annular seal mounting groove92formed in the inner end surface30of the mounting plate12. The annular seal mounting groove92is concentrically located in the inner end surface30, outside of the annular groove22, i.e., the diameter of the annular seal mounting groove92is substantially greater than the annular groove22. When the mounting plate12is coupled to the base78of the canister14in the manner herein described, the seal90is compressed between the inner end surface30of the mounting plate12and the base78, thereby sealing the mounting plate12to the base78. The seal90aids in impeding the pressurized oil contained within the annular groove22from 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 plate12is formed from aluminum and the threaded fastener32from 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 toFIGS. 1 and 2, the elements of the canister14will now be discussed. The canister14includes a hollow housing44containing filter media46. The hollow housing44is cylindrical in shape, having opposing open ends closed by an integral top84and a base78. The integral top84is concave, when viewed from inside of the canister14. The shape and thickness are sufficient to contain the pressure produced within the canister14. The concave shape allows the canister14to be formed with less material, creating a canister14that is light and less expensive to manufacture, while still retaining its ability to adequately withstand the pressures exerted against its inner surface.

Similarly, the base78is convex in shape, when viewed from inside of the canister14. The shape and thickness are adequate to contain the pressure produced within the canister14. 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 housing44and the base78are formed of iron and are joined together along the outer periphery of the base78by welding or press fitting the parts together.

The base78has an inlet fluid passageway72bored perpendicularly through its thickness. The inlet fluid passageway72is positioned radially outward from the center of the base78so as to be in alignment with the annular groove22in the mounting plate12. With the inlet fluid passageway72positioned as described, the inlet fluid passageway72will always be in fluid flow communication with the annular groove22, regardless of the relative rotational position of the mounting plate12with respect to the end plate78of the canister14.

The base78further includes a centrally located, internally threaded fastener34, sized to receive the externally threaded fastener32. The internally threaded fastener34extends perpendicularly inward from the inner end surface30of the base78. The outer diameter of the threaded fastener34is sized to slidably fit with the inside wall of the central tube50, thereby allowing the threaded fastener34to be received within the central tube50. An annular channel80is circumferentially disposed on the outer surface of the threaded fastener34. The annular channel80is sized and dimensioned to receive an O-ring82. The O-ring82sealingly engages the inner surface of the central tube50, thereby impeding the passage of oil between the threaded fastener34and the central tube50. The outlet fluid passageway42extends through the center of the fastener34, thereby completing a passageway between the outlet fitting18and the central tube50.

Housed within the canister14is the filter media46. The filter media46is wound around a tubular core48, which may be constructed from a rigid material, such as cardboard. Concentrically located within the tubular core48is the central tube50, which is constructed from a rigid material, such as steel. The outer diameter of the central tube50is substantially equal to the inner diameter of the tubular core48, whereby the outer surface of the central tube50substantially sealingly engages the inner surface of the tubular core48.

The central tube50has a flared end52. The flaring restrains a flat washer54mounted on the central tube50. The flat washer54engages a flat seal56and acts as a rigid backing member. In an assembled configuration, the force exerted by a coil spring86presses the flat washer54against the flat seal56. The flat seal56is thereby pressed against the edges of successive adjacent inner layers of the filter media46and the circular end surface of the tubular core48to impede channeling between the central tube50, the filter media tabular core48, and the filter media46, as described in more detail below. As shown inFIG. 2, preferably the end of the filter media adjacent to the flat seal56tapers away from the center of the flat seal. Although the illustrated embodiment utilizes the force provided by the coil spring86to compress the flat seal56and 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 seal56against the filter media46can be used and fall within the scope of the invention.

The filter media46is formed from any suitable filter material well known in the art, such as cotton-based low porosity paper impregnated with cellulose. The filter media46is tightly wound around the tubular core48, and a sufficient amount of filter media is wound so the outer surface of the filter media engages the inside wall70of the housing44of the canister14. Further, as is apparent from viewingFIG. 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 ring64with a tapered wall66at the end of the filter media46that faces the base78. In operation, the oil pressure within an inlet cavity68creates a force that presses the tapered wall66against the inside wall70of the housing44of the canister14, thereby impeding channeling along the inside wall70, 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 mesh88is also shown inFIG. 2. The wire mesh88is formed to have a shape similar to the integral top84of the canister14. The wire mesh88is sandwiched between the coil spring86and the top84of the canister14. As will be apparent to one skilled in the art, the wire mesh88may be used in instances where the filter media46is wound or placed in the canister14in such a manner that the filter media46engages the integral top84, thereby impeding the discharge of oil from the filter media46. In such instances, the wire mesh88will space the filter media46from the integral top84, by an amount sufficient to provide flow paths for oil to exit the filter media46and enter the central tube50.

The operation of the illustrated embodiment of the present invention will now be described. Referring toFIG. 2, the inlet fitting16is 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 fitting18is 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 fitting16. From the inlet fitting16the oil passes through the inlet fluid passageway20and into the annular groove22. The oil passes along the annular groove22until it reaches the inlet fluid passageway72, where it enters the canister14. Once in the canister14, the oil begins its tortuous travel through the filter media46in the direction of the arrow indicated by the reference numeral74. As the oil passes through the filter media46, 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 media46, the oil enters an end cavity75. From the end cavity75, the oil enters the central tube50, flowing in the direction of the arrow indicated by reference numeral76. The oil leaves the canister14via the outlet fluid passageways24,40and42to the outlet fitting18, which returns the filtered oil to the low pressure side of the engine lubricating system.

Once the expected useful life of the filter media46has been reached, the canister14is simply rotated until the internally threaded fastener34of the canister14is disengaged from the externally threaded fastener32of the mounting plate12. As discussed above, the inlet fluid passageway72and the outlet fluid passageways24,40and42each have a diameter substantially less than the inner diameter of the inlet and outlet fittings16and18, respectively. The small diameter of the inlet fluid passageway72and the outlet fluid passageways24,40and42reduces, if not entirely eliminates, the spillage of oil during removal of the canister14.

Preferably, the diameters of the inlet fluid passageway72and the outlet fluid passageways24,40and42are one-tenth (0.1) of an inch or less. In one actual embodiment of the present invention, the diameters of the inlet fluid passageway72and the outlet fluid passageways24,40and42are 50 thousandths (0.05) of an inch. The diameters of the inlet fluid passageway72and the outlet fluid passageways24,40and42are 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 passageway72or outlet fluid passageways24,40and42, are sufficient to overcome the forces, such as gravity, tending to force the oil out through the inlet fluid passageway72and outlet fluid passageways24,40and42when 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 canister14during removal of the canister14from the mounting plate12.

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 canister14will 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.