Patent Description:
Engine air filtration systems often comprise filter housings, precleaners, primary and/or secondary filter elements. Sometimes the secondary filter element may not be employed and/or a precleaner may not be employed. <CIT> provides a holding frame for one removable filter cartridge for hot air applications. <CIT> provides filter assemblies including filter housings and filter elements for the housing. <CIT> provides a replaceable filter package for a filter housing. <CIT> provides a filter element for a filter housing and corresponding air cleaner assemblies.

The present invention pertains to various improvements relating to such various air filtration systems.

The present invention relates to filter assembly including a filter element as defined in claim <NUM>.

According to an embodiment of the present invention, the air filter element includes a filter media pack comprising filter media. The filter media pack has an inlet face and an outlet face. Fluid can flow from the inlet face to the outlet face by passing through the filter media to filter the fluid. The air filter element also includes a gasket arranged in surrounding relation of one of the inlet face and the outlet face. The gasket extends about a perimeter of the filter media pack to form a complete ring. The gasket has first and second opposed end surfaces and an outer perimeter surface extending between the first and second opposed end surfaces. A receiving channel is recessed into the first end surface of the gasket in surrounding relation of the filter media pack.

According to a more particular embodiment, the receiving channel is formed by seal material of the gasket and the receiving channel is surrounded by a continuous rib formed by the seal material.

According to a more particular embodiment, the gasket is at least partially raised above the inlet face and the seal material is integrally molded to the filter media pack to secure and seal the gasket to the filter media pack and prevent leakage of unfiltered fluid flow therebetween.

In a more particular embodiment, the air filter element is a panel filter, with the filter media pack being pleated with a plurality of pleat tips at the inlet face and a plurality of pleat tips at the outlet face.

In a more particular embodiment, a screen member extends across the inlet face and is embedded in the seal material of the gasket.

In a more particular embodiment, the air filter element is incorporated into a filter assembly that further comprises a secondary filter element comprising a casing. The casing includes a casing body surrounding the filter media pack and extending between the inlet face and the outlet face. The casing includes a flange projecting radially outwardly from the casing body. The flange is received in the receiving channel and a sealed position in the receiving channel whereby a continuous seal surrounding the filter media pack is formed between the projecting flange and the gasket. The secondary filter further comprises a filter member (screen or other filter) carried by the casing body and extending over the outlet face of the filter media pack.

In a more particular embodiment, the filter member comprises a planar mesh screen material, and the filter media comprises a non-woven fibrous media comprising at least one of glass, cellulose or polymer material.

In a more particular embodiment, the air filter element and the secondary filter element are both quadrilateral.

In a more particular embodiment, the air filter element and the secondary filter element have at least one variable dimension that is either a depth dimension that varies from the inlet face to the outlet, or a width or length dimension that varies between opposed sides of the quadrilateral.

In a more particular embodiment, the secondary filter element is gasket free and utilizes only the gasket of the air filter element.

According to another embodiment of the present invention, the filter element comprises a casing that includes a casing body extending from a first end to a second end and having a hollow interior defining a cavity for receiving another filter element. The filter element further comprises a filter member carried by the casing body at the second end and over the cavity, such that fluid cannot flow from the cavity through the second end without passing through the filter member.

In a more particular embodiment, the filter member comprises a planar mesh screen material.

In a more particular embodiment, the casing is formed of plastic material. The plastic material can be integrally molded to planar mesh screen material and thereby permanently secures the planar mesh screen material to the casing.

According to the invention, the filter element is incorporated into a filter assembly that further comprises an air filter installed into the cavity and sealingly engaged at a periphery to the casing.

According to the invention, the filter assembly includes a gasket that seals between the filter element and the air filter.

The gasket has a quadrilateral shape and engages a quadrilateral flange of the filter element.

The gasket is integrally provided by the air filter.

In a more particular embodiment, such an assembly can comprise a filter housing defining a housing cavity comprising an outlet port and an inlet opening. The air filter can be a primary filter element that is received in the filter housing through the inlet opening. The primary filter element comprises filter media that comprises a non-woven fibrous media comprising at least one of glass, cellulose or polymer material. The filter element can be a secondary filter element for downstream use with the primary filter element. Further the assembly comprises a gasket member sealing simultaneously between the filter housing, the primary filter element, and the secondary filter element.

In a more particular embodiment of an assembly, the gasket is integrally provided by the primary filter element and defines a channel receiving a flange of the secondary filter element.

In an embodiment where the gasket is provided by the air filter, the gasket may integrally molded to the filter media.

Preferably in an more particular embodiment, the primary filter element or air filter comprises a pleated filter media pack.

In a more particular embodiment, such an assembly can further comprise a precleaner having an inlet port. The precleaner has at least an air cleaning device that utilizes air flow to separate larger particles prior to reaching the primary filter element. The precleaner can be mounted to the filter housing and can enclose the primary filter element and the secondary filter element therein.

According to another embodiment of the present invention, a filter assembly comprises a filter housing defining a housing cavity comprising an outlet port and an inlet opening. The filter assembly further comprises a primary filter element received in the filter housing through the inlet opening. The primary filter element comprising filter media that comprises a non-woven fibrous media comprising at least one of glass, cellulose or polymer material. The filter element further comprises a secondary filter element. The secondary filter element includes a casing that includes a casing body extending from a first end to a second end and having a hollow interior defining a cavity receiving the primary filter element. A filter member is carried by the casing body at the second end and over the cavity downstream of the primary filter element, such that fluid cannot flow from the cavity through the second end without passing through the filter member. The filter assembly further comprises a precleaner having an inlet port. The precleaner has at least an air cleaning device that utilizes air flow to separate larger particles prior to reaching the primary filter element, and is mounted to the filter housing and encloses the primary filter element and the secondary filter element therein. The filter element further comprises a gasket member sealing simultaneously between the filter housing, the primary filter element, the secondary filter element and the precleaner.

In a more particular embodiment, the gasket member is a single gasket member permanently attached to the primary filter element.

In a more particular embodiment, the filter housing, the primary filter element, the secondary filter element and the precleaner all have a quadrilateral shape. The filter housing defines a quadrilateral body wall surrounding the primary filter element and the secondary filter element, and an end wall defining the outlet port enclosing a first end of the quadrilateral body wall. The filter housing includes at a second end of the quadrilateral body wall a quadrilateral step comprising a planar ledge and a surrounding containment wall, and the single gasket member extends outward from the filter media and is seated on the quadrilateral step.

In a more particular embodiment, the precleaner has an axially extending quadrilateral flange facing the quadrilateral step and engaging the gasket member.

In a more particular embodiment, manually actuated latches removably secure the precleaner and the filter housing.

According to another embodiment of the present invention, a filter assembly comprises a filter housing defining a housing cavity, an outlet port and an inlet opening. The filter housing has a seating surface surrounding the housing cavity. The assembly further comprises a primary filter element received in the housing cavity and into the filter housing through the inlet opening along an install axis. The primary filter element comprises filter media that comprises a non-woven fibrous media comprising at least one of glass, cellulose or polymer material. The primary filter element has filter media extending between an inlet face and an outlet face, and a filter media depth along the install axis that is not constant and which extends between the inlet face and the outlet face. The filter media depth is shallower proximate the outlet port and deeper as the filter media transitions away from the outlet port.

In a more particular embodiment, the air filter element is a panel filter. The filter media pack is pleated with a plurality of pleat tips at the inlet face and a plurality of pleat tips at the outlet face. The pleat tips at the inlet face form a plane, and the pleat tips at the outlet face are stepped to form an incline relative to the plane at the inlet face.

In a more particular embodiment, the incline is at least <NUM> degrees relative to the plane at the inlet face, and the pleat tips are stepped at the outlet face to form said incline.

In a more particular embodiment, the filter housing, the primary filter element, the secondary filter element and the precleaner all have a quadrilateral shape. The filter housing defines a quadrilateral body wall surrounding the primary filter element and the secondary filter element, and an end wall defining the outlet port enclosing a first end of the quadrilateral body wall. The filter housing includes at a second end of the quadrilateral body wall a quadrilateral step comprising a planar ledge and a surrounding containment wall. The primary filter cartridge is sealed against the planar ledge by a gasket. The containment wall defines a terminating edge that lies in a plane that is inclined relative to the planar ledge.

In accordance with a first embodiment not according to the invention, it is provided a filter element, comprising: a casing, the casing including a casing body extending from a first end to a second end and having a hollow interior defining a cavity for receiving another filter element, and a filter member carried by the casing body at the second end and over the cavity, such that fluid cannot flow from the cavity through the second end without passing through the filter member.

In accordance with a second embodiment not according to the invention, which is related to the first embodiment, it is provided the filter element, wherein the filter member comprises a planar mesh screen material.

In accordance with a third embodiment not according to the invention, which is related to the second embodiment, it is provided the filter element, wherein the casing is formed of plastic material, and wherein the plastic material is integrally molded to planar mesh screen material and thereby permanently secures the planar mesh screen material to the casing.

In accordance with a fourth embodiment not according to the invention, which is related to the first embodiment, it is provided a filter assembly including the filter element, further comprising an air filter installed into the cavity and sealing engaged at a periphery to the casing.

In accordance with a fifth embodiment not according to the invention, which is related to the fourth embodiment, it is provided the filter assembly, further comprising a gasket sealing between the filter element and the air filter, wherein the gasket has a quadrilateral shape and engages a quadrilateral flange of the filter element.

In accordance with a sixth embodiment not according to the invention, which is related to the fifth embodiment, it is provided the filter assembly, wherein the gasket is integrally provided by the air filter.

In accordance with a seventh embodiment not according to the invention, which is related to the fourth embodiment, it is provided the filter assembly, further comprising a filter housing defining a housing cavity comprising an outlet port and an inlet opening, the air filter being a primary filter element received in the filter housing through the inlet opening, the primary filter element comprising filter media that comprises a non-woven fibrous media comprising at least one of glass, cellulose or polymer material; the filter element being a secondary filter element; and a gasket member sealing simultaneously between the filter housing, the primary filter element, and the secondary filter element.

In accordance with an eighth embodiment not according to the invention, which is related to the seventh embodiment, it is provided the filter assembly, wherein the gasket is provided by the primary filter element and defines a channel receiving a flange of the secondary filter element.

In accordance with a ninth embodiment not according to the invention, which is related to the eighth embodiment, it is provided the filter assembly, wherein the gasket is integrally molded to the filter media.

In accordance with a tenth embodiment not according to the invention, which is related to the seventh embodiment, it is provided the filter assembly, wherein the filter media comprises a pleated filter media pack.

In accordance with an eleventh embodiment not according to the invention, which is related to the seventh embodiment, it is provided the filter assembly, further comprising a precleaner having an inlet port, the precleaner having at least an air cleaning device that utilizes air flow to separate larger particles prior to reaching the primary filter element, the precleaner mounted to the filter housing and enclosing the primary filter element and the secondary filter element therein.

In accordance with a twelfth embodiment not according to the invention, it is provided a filter assembly, comprising: a filter housing defining a housing cavity comprising an outlet port and an inlet opening; a primary filter element received in the filter housing through the inlet opening, the primary filter element comprising filter media that comprises a non-woven fibrous media comprising at least one of glass, cellulose or polymer material; a secondary filter element, comprising a casing, the casing including a casing body extending from a first end to a second end and having a hollow interior defining a cavity receiving the primary filter element, a filter member carried by the casing body at the second end and over the cavity downstream of the primary filter element, such that fluid cannot flow from the cavity through the second end without passing through the filter member; a precleaner having an inlet port, the precleaner having at least an air cleaning device that utilizes air flow to separate larger particles prior to reaching the primary filter element, the precleaner mounted to the filter housing and enclosing the primary filter element and the secondary filter element therein; and a gasket member sealing simultaneously between the filter housing, the primary filter element, the secondary filter element and the precleaner.

In accordance with a thirteenth embodiment not according to the invention, which is related to the twelfth embodiment, it is provided the filter assembly, wherein the gasket member is a single gasket member permanently attached to the primary filter element.

In accordance with a fourteenth embodiment not according to the invention, which is related to the thirteenth embodiment, it is provided the filter assembly, wherein the filter housing, the primary filter element, the secondary filter element and the precleaner all have a quadrilateral shape, and wherein the filter housing defines a quadrilateral body wall surrounding the primary filter element and the secondary filter element, and an end wall defining the outlet port enclosing a first end of the quadrilateral body wall, the filter housing including at a second end of the quadrilateral body wall a quadrilateral step comprising a planar ledge and a surrounding containment wall, the single gasket member extending outward from the filter media and seated on the quadrilateral step.

In accordance with a fifteenth embodiment not according to the invention, which is related to the fourteenth embodiment, it is provided the filter assembly, wherein the precleaner has an axially extending quadrilateral flange facing the quadrilateral step and engaging the gasket member.

In accordance with a sixteenth embodiment not according to the invention, which is related to the twelfth embodiment, it is provided the filter assembly, further comprising manually actuated latches removably securing the precleaner and the filter housing.

In accordance with a seventeenth embodiment not according to the invention, it is provided an air filter element, comprising: a filter media pack comprising filter media, the filter media pack having an inlet face and an outlet face, wherein fluid is adapted to flow from the inlet face to the outlet face by passing through the filter media to filter the fluid; a gasket arranged in surrounding relation of one of the inlet face and the outlet face, the gasket extending about a perimeter of the filter media pack to form a complete ring; the gasket having first and second opposed end surfaces and an outer perimeter surface extending between the first and second opposed end surfaces; a receiving channel recessed into the first end surface of the gasket in surrounding relation of the filter media pack.

In accordance with an eighteenth embodiment not according to the invention, which is related to the seventeenth embodiment, it is provided the air filter element, wherein the receiving channel is formed by seal material of the gasket and wherein the receiving channel is surrounded by a continuous rib formed by the seal material.

In accordance with a nineteenth embodiment not according to the invention, which is related to the eighteenth embodiment, it is provided the air filter element, wherein the gasket is at least partially raised above the inlet face and wherein the seal material is integrally molded to the filter media pack to secure and seal the gasket to the filter media pack and preventing leakage of unfiltered fluid flow therebetween.

In accordance with a twentieth embodiment not according to the invention, which is related to the nineteenth embodiment, it is provided the air filter element, wherein the air filter element is a panel filter, the filter media pack being pleated with a plurality of pleat tips at the inlet face and a plurality of pleat tips at the outlet face.

In accordance with a twenty-first embodiment not according to the invention, which is related to the twentieth embodiment, it is provided the air filter element, further comprising a screen member extending across the inlet face and embedded in the seal material of the gasket.

In accordance with a twenty-second embodiment not according to the invention, it is provided a filter assembly comprising the air filter element of the seventeenth embodiment and further comprising: a secondary filter element comprising a casing, the casing including a casing body surrounding the filter media pack and extending between the inlet face and the outlet face, the casing including a flange projecting radially outwardly from the casing body, the flange received and having a sealed position in the receiving channel whereby a continuous seal surrounding the filter media pack is formed between the projecting flange and the gasket, and further comprising a filter member carried by the casing body and extending over the outlet face of the filter media pack.

In accordance with a twenty-third embodiment not according to the invention, which is related to the twenty-second embodiment, it is provided the filter assembly, wherein the filter member comprises a planar mesh screen material, and wherein the filter media comprises a non-woven fibrous media comprising at least one of glass, cellulose or polymer material.

In accordance with a twenty-fourth embodiment not according to the invention, which is related to the twenty-third embodiment, it is provided the filter assembly, wherein the air filter element and the secondary filter element are both quadrilateral.

In accordance with a twenty-fifth embodiment not according to the invention, which is related to the twenty-fourth embodiment, it is provided the filter assembly, wherein the air filter element and the secondary filter element have at least one variable dimension that is either a depth dimension that varies from the inlet face to the outlet, or a width or length dimension that varies between opposed sides of the quadrilateral.

In accordance with a twenty-sixth embodiment not according to the invention, which is related to the twenty-second embodiment, it is provided the filter assembly, wherein the secondary filter element is gasket free and utilizes only the gasket of the air filter element.

In accordance with a twenty-seventh embodiment not according to the invention, it is provided a filter assembly, comprising: a filter housing defining a housing cavity and comprising an outlet port and an inlet opening, the filter housing having a seating surface surrounding the housing cavity; a primary filter element received in the housing cavity and into the filter housing through the inlet opening along an install axis, the primary filter element comprising filter media that comprises a non-woven fibrous media comprising at least one of glass, cellulose or polymer material, the primary filter element having filter media extending between an inlet face and an outlet face, a filter media depth along the install axis that is not constant and that extends between the inlet face and the outlet face, and wherein the filter media depth is shallower proximate the outlet port and deeper as the filter media transitions away from the outlet port.

In accordance with a twenty-eighth embodiment not according to the invention, which is related to the twenty-seventh embodiment, it is provided the filter assembly, wherein the air filter element is a panel filter, the filter media pack being pleated with a plurality of pleat tips at the inlet face and a plurality of pleat tips at the outlet face, wherein the pleat tips at the inlet face form a plane, and wherein the pleat tips at the outlet face are stepped to form an incline relative to the plane at the inlet face.

In accordance with a twenty-ninth embodiment not according to the invention, which is related to the twenty-eighth embodiment, it is provided the filter assembly, wherein the incline is at least <NUM> degrees relative to the plane at the inlet face, and wherein the pleat tips are stepped at the outlet face to form said incline.

In accordance with a thirtieth embodiment not according to the invention, which is related to the twenty-seventh embodiment, it is provided the filter assembly, wherein the filter housing, the primary filter element, the secondary filter element and the precleaner all have a quadrilateral shape, and wherein the filter housing defines an quadrilateral body wall surrounding the primary filter element and the secondary filter element, and an end wall defining the outlet port enclosing a first end of the quadrilateral body wall, the filter housing including at a second end of the quadrilateral body wall a quadrilateral step comprising a planar ledge and a surrounding containment wall, the primary filter cartridge being sealed against the planar ledge by a gasket, and wherein the containment wall defines a terminating edge that lies in a plane that is inclined relative to the planar ledge.

Turning to <FIG>, an engine filtration assembly <NUM> is illustrated which includes a filter housing <NUM>, a primary filter element <NUM>, a secondary filter element <NUM> and a precleaner <NUM>.

The filter housing <NUM> defines a housing cavity <NUM> that is sized to receive the primary filter element <NUM> and the secondary filter element <NUM>. Housing cavity <NUM> also comprises an outlet port <NUM> for conveying filtered air to an engine (or other such filtered air application) and an inlet opening <NUM> through with the primary filter element <NUM> and the secondary filter element <NUM> can be installed and removed when desired for replacement. The primary filter element <NUM> is received in filter housing through the inlet opening <NUM>, as is the secondary filter element <NUM>.

The primary filter element <NUM> comprises filter media that comprises a non-woven fibrous media comprising at least one of glass, cellulose or polymer material.

Typically the primary filter element <NUM> will have a filtration efficiency of at least <NUM>% for removing <NUM> micron particles in some applications (or larger or smaller particles and higher efficiencies in other applications).

The secondary filter element <NUM>, when employed, will typically remove larger particles and not smaller particles as will typically be removed by the primary filter element <NUM>. The secondary filter element <NUM> is used to avoid and limit clumps of dirt or large particles, leaves or other debris from entering into the outlet port <NUM> at the outlet end of the housing, such as when the primary filter element <NUM> is removed during service intervals or otherwise. As such, a planar screen member made of metal wire mesh or even plastic wire mesh with a defined pore size can be used as a surface or barrier filter.

In an embodiment, the secondary filter element comprises a casing <NUM> including a casing body <NUM> extending from a first end <NUM> to a second end <NUM> and having a hollow interior defining a cavity <NUM> receiving the primary filter element <NUM>. A filter member <NUM> is carried by the casing body <NUM> at the second end <NUM> and over the hollow interior cavity <NUM> downstream of the primary filter element <NUM>, such that fluid cannot flow from the cavity <NUM> through the second end without passing through the filter member.

The precleaner <NUM> has an inlet port <NUM> to receive raw unfiltered air flow from the external environment that is often laden with dust, debris and other particulates. The precleaner has at least an air cleaning device that utilizes air flow to separate out larger particles prior to reaching the primary filter element <NUM>. For example, the precleaner <NUM> may use centrifugal or change of direction cleaners such as shown in Lindstone, <CIT> entitled "precleaner for combustion engines" or utilize a bank of vortex separators such as in Durre, <CIT>, entitled "Aircleaner Apparatus", the entire disclosures of which are hereby incorporated by reference in their entireties.

In an embodiment where a precleaner is used, the precleaner <NUM> is mounted to the filter housing <NUM> and encloses the primary filter element <NUM> and the secondary filter element <NUM> therein.

In accordance with an inventive aspect, a gasket member <NUM> seals simultaneously between the filter housing <NUM>, the primary filter element <NUM>, the secondary filter element <NUM> and the precleaner <NUM>.

With this sealing arrangement, unfiltered air flow passes first through the precleaner <NUM>, next through the primary filter element <NUM>, then through the secondary filter element <NUM>, whereby clean filtered air flow is received and ducted through the outlet port <NUM>. Preferably, gasket member <NUM> is carried by and more preferably permanently attached (e.g. such as by integrally molded or adhesively attached) to the primary filter element <NUM> such that the gasket is replaced fresh each time.

Advantageously, the gasket member <NUM> may be a single gasket member permanently attached to the primary filter element <NUM> as illustrated.

While other shapes are possible, the filter housing <NUM>, the primary filter element <NUM>, the secondary filter element <NUM> and the precleaner <NUM> all have a quadrilateral shape which may be rectangular or non-rectangular. The housings/bodys/casings for the filter housing, the secondary filter element and the precleaner may all be molded plastic material.

With the quadrilateral shape, the filter housing <NUM> defines an quadrilateral body wall <NUM> surrounding the primary filter element <NUM> and the secondary filter element <NUM>, and an end wall <NUM> (opposite of inlet opening <NUM>) defining the outlet port <NUM> enclosing a first end of the quadrilateral body wall <NUM>. The filter housing <NUM> may include at a second end of the quadrilateral body wall <NUM> a quadrilateral step <NUM>. The step <NUM> can comprise a planar ledge <NUM> and a surrounding seal containment wall <NUM>. In use, the single gasket member <NUM> extends outward from the filter media of the primary filter element <NUM> and is seated on the quadrilateral step <NUM> (either by an axial seal engagement with the ledge <NUM> or a radial seal engagement with the wall <NUM>, or both; compression of the seal member <NUM> may also cause bulging of the seal member to create a radial seal).

When used with a precleaner or cover, the precleaner or cover has an axially extending quadrilateral seal engagement flange <NUM> facing the quadrilateral step <NUM> and engaging the gasket member <NUM>.

To provide for ready servicing by a mechanic, the assembly further comprises manually actuated latches <NUM> removably securing the precleaner <NUM> and the filter housing <NUM> to allow for replacement of the primary filter element <NUM> (and optionally the secondary filter element) when desired and/or at regular service intervals. When serviced, the secondary filter element <NUM> may stay situated and in place while the primary filter is removed. The secondary filter element <NUM> can then be manually inspected and while installed helps prevent debris or dust created by the mechanic from entering the outlet port <NUM>.

Another feature can be provided by virtue of a canted installation and/or canted shape to the primary and/or secondary filter elements.

The primary filter element <NUM> has filter media <NUM> extending between an inlet face <NUM> and an outlet face <NUM> with a filter media depth along the install axis that is not constant and that extends between the inlet face and the outlet face. To provide greater air flow near the outlet port and not create restriction, the filter media depth can be shallower proximate the outlet port <NUM> and deeper as the filter media <NUM> transitions away from the outlet port <NUM>, in the installed position.

Preferably, the primary filter element <NUM> is a panel filter as shown, the filter media being in a pleated filter media pack <NUM> with a plurality of pleat tips <NUM> at the inlet face <NUM> and a plurality of pleat tips <NUM> at the outlet face <NUM>. The pleat tips at the inlet face may form a plane in a typical arrangement. To provide for variable depth, the pleat tips <NUM> at the outlet face <NUM> can be stepped to form an incline relative to the plane at the inlet face <NUM>.

These types of variable dimension filter media packs are shown for example in Tate et al, <CIT>, entitled Filter Media Packs, Methods of Making and Filter Media Presses, the entire disclosure of which is hereby incorporated by reference. This shows that one or more dimensions of depth, width and length can be varied to achieve advantage.

In some embodiments, the incline of the outlet face is at least <NUM> degrees and preferably at least <NUM> degrees relative to the plane at the inlet face, and wherein the pleat tips are stepped at the outlet face to form said incline.

Another feature may be directed to inclined installation. The filter housing <NUM> includes at the quadrilateral step <NUM>, the planar ledge <NUM> and the surrounding seal containment wall <NUM>. With the primary filter cartridge being sealed against the planar ledge by the gasket, the containment wall <NUM>, as shown, can define a terminating edge <NUM> (e.g. facing the precleaner <NUM> or cover) that lies in a plane that is inclined relative to the planar ledge <NUM>.

The primary filter element <NUM> and/or gasket member <NUM> as illustrated also provides inventive features. The gasket member <NUM> is arranged in surrounding relation of one of the inlet face <NUM> and the outlet face <NUM> (and preferably and in this instance the inlet face <NUM>). The gasket member <NUM> extends about a perimeter of the filter media pack <NUM> to form a complete ring.

The gasket member <NUM> has first and second opposed end surfaces <NUM>, <NUM> that may be flat top and bottom surfaces, and an outer perimeter surface <NUM> extending between the first and second opposed end surfaces <NUM>, <NUM>.

Further, the gasket member <NUM> may include a receiving channel <NUM> recessed into the first end surface <NUM> (such as the bottom surface or surface opposite of the inlet face) of the gasket member <NUM> and in surrounding relation of the filter media pack <NUM>.

Preferably, the recessed channel is formed by seal material of the gasket member <NUM> with the recessed channel <NUM> being surrounded by a continuous rib <NUM> also formed by the seal material.

The rib <NUM> has a flat bottom wall and the recessed channel <NUM> has a flat bottom wall in an embodiment, with the rib <NUM> and channel bottom connect by an axially extending wall (e.g. that may be vertical).

As shown, the gasket member <NUM> can be at least partially raised above the inlet face <NUM>. Preferably, the seal material of seal member <NUM> is integrally molded to the filter media <NUM> to secure and seal the gasket to the filter media pack and preventing leakage of unfiltered fluid flow therebetween.

Additionally, the filter element <NUM> may include a screen member <NUM> extending across the inlet face and embedded in the seal material of the gasket member <NUM>. The screen member <NUM> may be expanded wire mesh and larger mesh than that provided by the screen member of the secondary filter element <NUM>.

Screen member <NUM> can add support to the pleated filter media pack <NUM> and also serve to intercept large objects such as leaves or other debris to attempt to avoid impact or damage to the pleated filter media pack <NUM>. Additionally and contrary to many panel filters, this arrangement may provide the screen member <NUM> at the inlet face <NUM> and not the outlet. The outlet face <NUM> can be supported by the secondary filter element <NUM> if desired, or alternatively when embossed and made according to the aforementioned Tate et al, <CIT>, has embossments that maintain pleat spacing to prevent blinding off.

A further feature and aspect pertains to the secondary filter element <NUM>. The secondary filter element <NUM> comprises a casing <NUM>, the casing including a casing body <NUM> surrounding the filter media pack <NUM> and extending between the inlet face and the outlet face <NUM>, <NUM> as generally illustrated or can be inferred from the drawings.

The casing <NUM> is shown to include a flange <NUM> projecting radially outwardly from the casing body <NUM>, the flange <NUM> received and having a sealing engaged position in the receiving channel <NUM> whereby a continuous seal surrounding the filter media pack is formed between projecting flange <NUM> and gasket member <NUM>.

The filter member <NUM> of the secondary filter element <NUM> may be a filter screen member carried by the casing body <NUM> and extending over the outlet face of the primary filter element.

Preferably, the filter member <NUM> comprises a planar mesh screen material, in contrast to the filter media of the primary filter element that typically comprises a non-woven fibrous media comprising at least one of glass, cellulose or polymer material.

As alluded to above, the primary air filter element and the secondary filter <NUM> element can have at least one variable dimension that is either depth dimension that varies from the inlet face to the outlet, or a width or length dimension that varies between opposed sides of the quadrilateral.

An advantage in the present embodiment is that the secondary filter element <NUM> can be gasket free and utilizes only the gasket member <NUM> of the primary air filter element <NUM>. As such, the secondary filter element <NUM> can be reused while a fresh seal supplied by the primary may be realized during primary filter element <NUM> replacement.

Further, the arrangement of the secondary filter element <NUM> surrounding the primary filter element <NUM> is a feature. The casing <NUM> includes the casing body <NUM> extending from a first end to a second end and having a hollow interior defining a cavity <NUM> for receiving another filter element such as the primary filter element <NUM>. At the same time, the casing body <NUM> carries the filter member <NUM> at the second end and over the cavity <NUM>, such that fluid cannot flow from the cavity through the second end without passing through the filter member <NUM>.

As noted, the filter member <NUM> preferably comprises a planar mesh screen material, which is planar (and not pleated as per the primary filter element <NUM>).

Further, with the casing <NUM> being formed of plastic material in an embodiment, casing plastic material can be integrally molded to the planar mesh screen material of filter member <NUM> as shown and thereby permanently securing the planar mesh screen material to the casing.

With this arrangement, the primary filter element <NUM> can be installed into the cavity <NUM> and sealing engaged at a periphery to the casing <NUM>.

Claim 1:
A filter assembly including a filter element (<NUM>), comprising:
a casing (<NUM>), the casing including a casing body (<NUM>) extending from a first end (<NUM>) to a second end (<NUM>) and having a hollow interior defining a cavity (<NUM>) for receiving another filter element (<NUM>), comprising an air filter (<NUM>) installed into the cavity (<NUM>) and sealing engaged at a periphery to the casing (<NUM>) and a gasket (<NUM>) sealing between the filter element (<NUM>) and the air filter (<NUM>), wherein the gasket (<NUM>) has a quadrilateral shape and engages a quadrilateral flange of the filter element (<NUM>), characterized in that
a filter member (<NUM>) is carried by the casing body (<NUM>) at the second end (<NUM>) and over the cavity (<NUM>), such that fluid cannot flow from the cavity (<NUM>) through the second end (<NUM>) without passing through the filter member (<NUM>), and that the gasket (<NUM>) is integrally provided by the air filter (<NUM>).