Seal devices for filters

A filter element having an end cap is provided with a seal that can better accommodate non-round holes. The seal may be a chevron type seal and/or other similar seal having a sealing flange for forming a radial seal. Methods of replacing a filter having an O-ring gasket to improve upon sealing are provided as well as filtration systems employing the filter element.

FIELD OF THE INVENTION

This invention generally relates to filters, and in particular to filters having seals, and methods for installing the same.

BACKGROUND OF THE INVENTION

Fluid streams such as liquid flows and gaseous flows (e.g. air flows) often carry particulates that are often undesirable contaminants entrained in the fluid stream. Filters are commonly employed to remove some or all of the particulates from the fluid stream.

Seals such as o-rings are often provided to seal the filter to a surface of a filter housing, or to an inlet or outlet pipe, which carries the contaminated fluid or gas into or out of the filter. This sealing relationship helps prevent unfiltered fluid from bypassing the filter. Often, an imperfectly manufactured filter housing or pipe will have a sealing surface that is out of round or out of tolerance, thus making it more difficult for the seal to provide a full sealing relationship, and increasing the likelihood that contaminated fluid can bypass the filter. As such, filter housing makers will often attempt to tightly tolerance their sealing surfaces on housings. However, if that is not done, then a problem exists as typical O-ring gaskets can have sealing problems and therefore allow some leakage if the sealing surface is even 0.0005 inches out of round, or has an actual diameter even 0.010 greater than a design diameter. O-ring gaskets are also known to allow leakage if the sealing surface has a roughness of approximately 32 micro-inches or greater.

The invention provides improvements over the prior art relating to seals for filters. These and other advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.

BRIEF SUMMARY OF THE INVENTION

In one aspect, the invention provides a filter element. The filter element comprises a first end cap and a second end cap. The filter element further comprises a tubular ring of filter media, which extends between the first and second end caps and around a longitudinal axis. The first end cap carries a gasket, which has an annular sealing flange and an annular base portion. In a first embodiment, the annular sealing flange is spaced radially outside the annular base portion and an outer peripheral surface of the end cap. In an alternative embodiment, the annular sealing flange is spaced radially inside the annular base portion and an inner peripheral surface of the end cap. In either embodiment, the gasket is elastomeric with sufficient resiliency and flexibility to conform and seal to a non-round opening with up to at least 0.01 inch, more preferably up to 0.1 inch, and most preferably 0.25 inch in a diameter variance from round. The gasket also has sufficient resiliency and flexibility to conform to generally round openings having diameters that are up to 0.125 inches outside a design diameter, as well as to surfaces having a surface roughness of up to 90 micro inches. This sealing ability allows a filter to be sealed to imperfectly manufactured sealing surfaces, such as machined or stamped openings in filter housings.

In a preferred embodiment, the annular sealing flange extends at a canted angle of between 10 and 85 degrees relative to the longitudinal axis of the filter. The annular sealing portion thus defines an annular pocket with the annular base portion. In a more preferred embodiment, the gasket has an outer diameter with a design toleranced variance of greater than 1% and up to at least 5%, thus allowing design and lower cost flexibility to the gasket. The gasket is formed from a seal material having a Shore A durometer of between 30 and 80, and an elongation of between 100 and 400. The seal material may be made from a suitable sealing material such as at least one of buna-n (nitrile), fluoropolymer, silicone, fluorosilicone, and EPR (ethylene propylene rubber), although other suitable seal materials are contemplated.

In a more preferred embodiment, the annular base of the gasket has an axial thickness of between 0.1 inches and 0.75 inches, and a radial thickness of between 0.1 inches and 1 inch. The annular sealing flange spans a longitudinal length of between 0.1 inches and 1.25 inches, and spans a radial distance of between 0.1 inches and 1 inch. The annular pocket has a longitudinal depth of between 0.1 inches and 1 inch. It may wedge tightly into and against all three sides of a groove (the sidewalls and the bottom) formed in an end cap for appropriate support.

Also preferably, the filter has an outer diameter of between 2 and 10 inches, and a longitudinal length of between 4 and 80 inches. The filter element has a design maximum differential pressure of at least 50 PSID.

In another preferred embodiment, the first end cap is a plastic open end cap. The first end cap has an annular disc portion surrounding a central flow opening. The first end cap defines an outwardly opening annular groove, which retains the annular base portion of the gasket.

In another embodiment, the annular pocket faces axially toward an end of the filter element that provides the plastic open end cap. The filter element further comprises a porous outer support wrapper surrounding the tubular ring of filter media.

In a preferred embodiment, the gasket is a chevron seal.

In another aspect, the invention provides a filter system. The filter system includes filter element and a housing with an inlet and an outlet, and fluid flows from the inlet to the outlet. The housing further comprises a radial seal housing surface. The filter element comprises a first end cap and a second end cap. The filter element further comprises a tubular ring of filter media, which extends between the first and second end caps and around a longitudinal axis. The first end cap carries a gasket, which has an annular sealing flange and an annular base portion. In a first embodiment, the annular sealing flange is spaced radially outside the annular base portion and an outer peripheral surface of the end cap. In an alternative embodiment, the annular sealing flange is spaced radially inside the annular base portion and an inner peripheral surface of the end cap. In either embodiment, the gasket is elastomeric with sufficient resiliency and flexibility to conform and seal to a non-round opening with up to at least 0.01 inch, more preferably up to 0.1 inch, and most preferably 0.25 inches in a diameter variance from round. The gasket also has sufficient resiliency and flexibility to conform to generally round openings having diameters that are up to 0.125 inches outside a design diameter, as well as to surfaces having a surface roughness of up to 90 micro inches. This sealing ability allows a filter to be sealed to imperfectly manufactured sealing surfaces, such as machined or stamped openings in the filter housing.

Preferably, the housing includes a vessel having an inlet and an outlet. The inlet and outlet are separated by a partition wall having an array of flow openings. A plurality of sleeves are mounted to the partition wall and aligned with the flow openings. Each sleeve defines one of the radial seal surfaces. A plurality of filter elements are arranged in parallel circuit with each other. Each filter element extends at least partly into one of the sleeves, and radially seals thereto.

In yet another aspect, the invention provides a method of replacing a filter element in a filter system. According to this aspect, the filter system has an inlet and an outlet, with fluid flow from the inlet to the outlet. The housing has an original filter element therein with an original endcap carrying an O-ring gasket. The O-ring gasket is sealed against a radial seal housing surface of the housing. One step in the method includes installing a replacement filter element into the housing. The replacement filter element has a first end cap and a second end cap and a tubular ring of filter material extending between the end caps and around a longitudinal axis.

The aspect further includes a step of sealing between the first end cap and the radial seal housing surface. The seal is formed with a gasket having an annular sealing flange and an annular base portion. The annular base portion is carried by the first end cap, and the annular sealing flange extends radially beyond an inner peripheral surface or outer peripheral surface of the first end cap.

DETAILED DESCRIPTION OF THE INVENTION

With reference toFIGS. 1 and 2, a filter10having seal to accommodate non-round openings is provided (accommodating openings with up to at least 0.01 inch, more preferably up to 0.1 inch, and most preferably 0.25 inches in a diameter variance from round), which may take the form of a chevron seal110as discussed in embodiments below. The filter10includes an open end cap12and a closed end cap14. Filter media16extends between the end caps12and14and around a longitudinal axis30such that the filter10is generally hollow and defines an inner cavity24. In a preferred embodiment, the filter media16is a pleated filter media, although other types of filter media are contemplated such as depth media for example. The filter10may further include a support wrapper18, which is made of a suitable porous somewhat-rigid material. The open end cap12defines a central flow opening22and an outwardly opening annular groove20(shown inFIG. 8), which carries the chevron seal110(shown in more detail inFIGS. 4-7).

In a preferred embodiment, the outer diameter of the filter10is between 2 inches and 10 inches, and the longitudinal length L is between 4 inches and 80 inches. The filter10preferably has design maximum differential pressure of at least 50 PSID.

Turning now toFIG. 3, one embodiment of the filter10having a chevron seal110is shown installed in a filter vessel50. The filter vessel50has an inlet52and an outlet54. The filter vessel50is separated into an inlet area56having a high pressure and an outlet area58having a low pressure by a partition wall62. The partition wall62defines various flow openings64, having sleeves66extending therefrom into the outlet area58. The sleeves66are adapted to receive the open end cap12of the filter10such that the fluid to be filtered flows first into the inlet area56through the inlet52and then through the flow openings64into the filters10. The contaminated fluid then flows through the filter media16, and contaminants are attempted to be removed therefrom. The filtered fluid then flows out of the filter media16, into the outlet area58, and lastly through the outlet54. As such, the filters10shown inFIG. 3are configured to filter fluid in an “inside to outside” direction.

In other embodiments, such as the filter system shown inFIG. 3A, a filter11is adapted to filter fluid in an outside to inside direction. In this embodiment, the fluid flows through an inlet53of a vessel51into an inlet area57having high pressure. The unfiltered fluid then flows through the filter11, which is received by a sleeve67. Each sleeve67extends from a flow opening65in a partition wall63, which separates the vessel51into the inlet area57and an outlet area59. The filtered fluid then flows through a flow opening65into the outlet area59having low pressure, and through an outlet55.

The chevron seal shown inFIG. 1is adapted to radially seal the open end cap12of the filters10,11to the sleeves66,67such that contaminated fluid in the inlet area56,57cannot bypass the filters. Because the filters10,11may be desired to be used in sealing relation with imperfectly manufactured components, i.e. a sleeve66or67that is not perfectly round, the filters10and11having the chevron seal110that can seal to a non-round opening is an improvement over seals currently available in the art as applied to filters having end caps. Typically, the chevron seal will be wedged tightly into a groove on the end cap—positively engaging all three sides (sidewalls and groove bottom) when mounted thereon (seeFIG. 11). While discussed in association with a chevron seal, it is understood that the embodiments may more generally have a mounting base portion for the end cap (which seals an end of the filter media ring), and a flange (seals even if not “chevron seals” are thus encompassed under broader claimed aspects). However, embodiments discussed herein are typically referred to as chevron seal.

Turning now toFIGS. 4-7, the chevron seal is discussed in greater detail. The chevron seal110has an annular sealing flange112and an annular base portion114, defining a pocket116therebetween that opens at an angle α.

The chevron seal110has an inner diameter I.D. adapted to be retained by the outwardly opening groove20of the filter10. In a preferred embodiment, the chevron seal110has a outer diameter O.D. with design tolerance variance of up to 5% of the total outer diameter.

In a preferred embodiment, the annular base portion114has an axial thickness Tba of between 0.1 inches and 1.5 inches, and a radial thickness Tbr of between 0.1 inches and 1 inch. The annular sealing portion112has a thickness Ts of between 0.02 and 0.25 inches. The terminating end118of the annular sealing portion112is radially spaced from the annular base portion114by a distance X of between 0.1 inches and 1.25 inches. The annular sealing portion112spans a longitudinal length Y of between 0.1 inches and 1.25 inches. The angle α of the pocket116is between 10 degrees and 85 degrees, and the pocket116has an axial depth D of between 0.1 inches and 1 inch.

The chevron seal110is preferably made from an appropriate sealing material such as buna-n (nitrile), fluoropolymer, silicone, fluorosilicone, or EPR (ethylene propylene rubber), although other appropriate sealing materials are contemplated. A preferred embodiment of the chevron seal110has a Shore A durometer of between 30 and 80.

The preferred characteristics discussed above allow the filter10having a chevron seal110to form a seal with a non-round opening. A method of measuring a variance from round in an opening involves measuring the maximum and minimum diameters of the opening with a measuring tool such as a set of calipers, and subtracting the minimum diameter from the maximum diameter. The chevron seal110is adapted to seal to openings with up to at least 0.25 inches variance from round in preferred embodiments and certainly better than typical O-ring gaskets that may be prone to sealing problems with non-round surfaces as described above.

The preferred characteristics discussed above also allow the filter10having a chevron seal110to form a seal with a generally round opening that is formed having a diameter that is at least up to 0.125 inches outside a design diameter of the opening (certainly greater than the 0.01 inches that is reliably provided by an o-ring). A filter10having a chevron seal110can also form a seal with a generally round opening that has a surface roughness of at least up to 90 micro-inches (and greater than the typical—ring maximum roughness of 32 micro-inches). This sealing ability provides significant improvements over an O-ring gasket, which may not be able to form a seal with openings being 0.010 inches out of tolerance, or surfaces with a surface roughness of over 32 micro-inches.

Embodiments of the present invention may thus be set for greater performance than an o-ring with a variance of between 0.01 inches and 0.125 inches or more from a designed diameter of the opening, preferably higher in the range. Embodiments of the present invention may thus also be set to conform to a surface roughness of between 32 micro inches and 90 micro inches or more, and again higher in the range is preferable. This allows for maximum design and manufacturing flexibility.

Turning now toFIGS. 8-10, the sealing ability of the chevron seal110is further discussed. In a first embodiment, shown inFIG. 8, the open end cap12defines the outwardly opening groove20on an outer peripheral surface of the end cap12. The outwardly opening groove20retains the annular base portion114of the chevron seal110such that the annular base portion114fits snugly within the groove20, i.e. the chevron seal110is slightly compressed within the groove20and thus contacts each of the surfaces of the groove20.

In the embodiment shown inFIG. 8, the annular terminating end118of the chevron seal110is spaced radially outside the annular base portion114. A diameter of an inner peripheral surface of the sleeve66is smaller than the outer diameter of the chevron seal110and larger than the diameter of the outer peripheral surface of the open end cap12. As such, when the filter10is received within the sleeve66, the chevron seal110is in a radially compressed state.

The pocket116of the chevron seal110opens toward the high pressure inlet area56. As such, the high pressure fluid exerts pressure inside the pocket116on both the annular sealing portion112and the annular base portion110. This pressure urges the pocket116open, causing further radial sealing engagement between the annular sealing portion112of the chevron seal110and the sleeve66, as well as between the annular base portion114of the chevron seal110and the open end cap12. The radially compressed state of the chevron seal110and the beneficial orientation of the pocket116helps prevent fluid in the high pressure area from bypassing the filter, even when the inner surface of the sleeve66is not perfectly round.

The filter10having a chevron seal110shown inFIG. 8is adapted to filter fluid flowing in through its central flow opening22and outward through the filter media16toward the outer periphery of the filter10such that the filter removes contaminants from fluid flowing in an “inside to outside” direction, as illustrated inFIG. 3.

In other embodiments, such as the embodiment illustrated inFIG. 9, a filter410having a chevron seal110may filter fluid flowing into the filter410through the outer periphery of the filter media16and out of the filter410through the central flow opening422in the open end cap412, in an “outside to inside” direction. In this alternative embodiment, a high pressure inlet area surrounds the outer periphery of the filter410, and a low pressure outlet area is positioned within the inner cavity424of the filter410. As such, the chevron gasket110is oriented such that the pocket116opens toward the area having high pressure. In this alternative embodiment, a cross-section of the chevron seal110is oriented generally upside down from the orientation illustrated inFIG. 8.

The embodiment illustrated inFIG. 9may further include a perforated tube404that carries the filtered fluid from the inner cavity424from the filter410. Also, this embodiment includes an end cap412having a disc portion bonded to the end of the filter medium, and a projecting tube and cylinder portion having a groove to receive the chevron gasket in spaced relation from the axial end of the filter media ring.

In another alternative embodiment, shown inFIG. 10, a filter210having a chevron seal310is adapted to receive an inlet pipe280. In this embodiment, the open end cap212defines an inwardly opening groove220on an inner peripheral surface of the end cap212. The inwardly opening groove220retains the annular base portion314of the chevron seal310such that the annular base portion314is seated snugly within the groove220. In this alternative embodiment, the annular terminating end318is spaced radially inside the annular base portion314. In this embodiment, an outer diameter of the inlet pipe280is larger than an inner diameter of the chevron seal and smaller than a diameter of the inner peripheral surface of the end cap212. As such, when the inlet pipe280is received by the end cap central flow opening222, the chevron seal310is in a compressed state.

Similarly to the embodiment shown inFIG. 8, the embodiment shown inFIG. 10is also adapted to filter fluid in an “inside to outside” direction. Also similarly to the embodiment of the filter10shown inFIG. 8, the pocket316opens toward a high pressure area, this time within the inner cavity224of the filter210. As such, high pressure unfiltered fluid urges the pocket316open wider, causing further radial sealing engagement between the annular sealing portion312of the chevron seal310and the inlet pipe280, as well as between the annular base portion314of the chevron seal310and the open end cap212. The radially compressed state of the chevron seal310and the beneficial orientation of the pocket316helps prevent fluid in the high pressure area from bypassing the filter, even when an outer surface of the inlet pipe280is not perfectly round.

Having discussed the structural attributes of several embodiments of the present invention, a method of replacing a filter element10having a chevron seal110in a filter system will be discussed. Referring to the FIGs. generally, an original filter element having an O-ring gasket is removed from the vessel50. The filter10having a chevron seal110is then installed in the vessel50, such that the chevron seal110seals the open end cap12to the sleeve66of the vessel50. The filter10is positioned such that the pocket116of the chevron seal110is open toward the high pressure inlet area56of the vessel50.

One particular advantage is using filter elements with a Chevron seal to replace existing elements in the field employing O-ring gaskets (that may be circular or other shape in cross section). Various current applications suffer from leakage and sealing inefficiencies where O-rings are employed. By substituting elements with Chevron gaskets on the end caps, the non-roundness and sealing problems experienced can be eliminated or greatly diminished if there is a serious non-round problem with a given hole (of many holes) in a partition wall.