Patent Description:
Filters are used to remove impurities from a flow of fluid such as a liquid or a gas. The filter will typically include porous filter media that traps the impurities as the fluid flows through the filter media.

One particular type of media is a fluted type media that is formed from a plurality of adjacent layers of filter media. The layers define a plurality of flutes that form either inlet or outlet flutes depending on which flutes are open at an inlet side and closed at the outlet side or closed at the inlet side and open on the outlet side of the filter. Typically, the layers of media are formed from a facer sheet secured to a corrugated or fluted sheet. This composite structure can then be wound to form a plurality of adjacent layers from a single continuous strip or can be cut into segments and then stacked to form a plurality of adjacent layers.

A seal arrangement is also typically attached to the filter media to releasably seal the filter media within a housing. This seal can be a radially directed seal or an axially directed seal. Typically, the seal is a relatively soft and compliant material so that it forms a good fluid tight seal with a corresponding surface of the housing. The seal arrangement is typically attached to an outer peripheral surface of the media.

A pressure differential will exist across the filter media to force the fluid to flow through the media. In many systems, the pressure differential is generated by a vacuum on a downstream side of the filter media. A vacuum across the media presents several problems, particularly with regard to the layered fluted type media.

This vacuum can cause radially inwardly directed compression of the filter media reducing the size of the outer periphery of the media. This reduction in size can cause several problems. This can cause the compliant seal to be drawn radially inward as well. If the seal is a radially directed seal, this can cause the seal to disengage from the housing sealing surface and create a leak path or, at a minimum, reduce the quality of the seal between the seal arrangement and housing.

Further, if the seal is an axial seal, the seal arrangement is often axially pinched between portions of the housing. When the filter media reduces in size while the seal is held firm between portions of the housing, this can cause the connection between the seal arrangement and media to become destroyed. Alternatively, it can cause the layers of the filter media to separate. Either of these problems can create undesirable leak paths.

A further problem particularly related to fluted media is that the pressure differential across the filter media can cause the adjacent layers to slip relative to one another, which is often referred as telescoping. This telescoping of the media can also create leak paths. Further, when the layers telescope, the problems relating to vacuum discussed above can be exacerbated.

Another type of media is pleated media that is typically a single continuous piece of filter media that is folded to form a plurality of adjacent panels interconnected by the folds. The interconnected panels form a plurality of peaks and valleys. One problem with this form of media is that the peaks on an inlet side of the filter may be directly exposed to impingement of impurities as well as another action that can cause cracking or damage to the filter media at the peaks.

Embodiments of the present invention are aimed at rectifying one or more of these problems or otherwise providing improvements over the art.

UK Patent Publication No. <CIT> discloses a method of manufacturing filter elements having integral frames. One filter element disclosed in the document is a rectangular filter element having an integral peripheral frame, with a rectangular panel of porous filter medium placed inside a flat shallow tray. A stream of viscous epoxy resin casting mixture is piped around the periphery of the panel through a nozzle, to form a bead. One or more trays each containing a panel of filter medium with a peripheral bead of resin mixture are then placed in a warm oven. When heated by the oven the resin mixture initially becomes more mobile and permeates down through the thickness of the peripheral portion of the panel under the influence of gravity and of capillary attraction. When the resin reaches the boundary of the filter medium it there comes into contact with the juxtaposed areas of the sides and bottom of the tray and adopts the configuration thereof. The resin subsequently polymerises on further heating and the panel of filter medium is thus provided with a rigid integral epoxy resin frame having three surfaces which are coplanar with the surface of the filter element, the side and bottom surfaces being moulded by the tray and the upper surface being defined by resin which has adhered to the upper surface of the panel after the resin had been caused to flow.

Japanese Patent Publication No. <CIT> discloses a method of forming a filter element by impregnating end edges of a flat filter material and a corrugated filter material with a reinforcing adhesive and subsequently filling the end edges of small through-holes obtained by the adhesive lamination of both filter materials with filler. The flat filter material and corrugated filter material are laminated and, prior to filling mountain parts at one end of the corrugated filter material or valley parts at the other end thereof with a filler, the filling corresponding end edges of the flat filter material and the corrugated filter material are impregnated with and fixed by a reinforcing adhesive.

US Patent Publication No. <CIT> discloses a method for fabricating a filter element including a media pack having alternating layers of a face sheet material and a convoluted filter material, with the alternating layers forming substantially longitudinally oriented flutes that extend axially past a radially acting seal. The media pack includes a layer of resin at an outlet end of the filter element. The layer of cured resin, in alternating closed ends of the flutes, tends to partially impregnate corrugated filter material and face sheets that form the flutes, and forms a rigid web within the outlet end of the filter element which provides radial support for the outlet end to react radially and axially directed forces.

US Patent Publication No. <CIT> discloses a filter including a filter element having a filter medium pleated in a zigzag manner, with a raw side and a clean side. Filter medium sections, which extend on either side of the raw-side pleat tips to adjoining raw-side pleat bases, include a first bend toward the raw side, and behind that a second bend toward the clean side, in each case viewed from the raw-side pleat tips.

European Patent Publication No. <CIT> discloses a filter element comprising a filter jacket, a fluted filter media, and an internal seal. The filter jacket defines a filter jacket inner surface, a gravitational bottom, an upstream end, and a downstream end. The fluted filter media resides within the filter jacket and defines a filter media outer surface. The fluted filter media comprises a planar sheet and a fluted sheet intermittently bonded together and collectively coiled to form a plurality of flutes. First and second selected ones of the plurality of flutes are closed proximate the upstream and downstream ends, respectively. The internal seal is formed between the filter jacket inner surface and the filter media outer surface. The internal seal is disposed within the filter jacket between the upstream and downstream ends.

The invention is defined by appended claim <NUM>. Optional features are defined the appended dependent claims. In the invention, a new and improved method of reinforcing a media pack is provided. The method includes forming a media pack to have an inlet face and an outlet face. The method includes applying a reinforcing agent to the media pack. The reinforcing agent is applied in a flowable state. The method also includes hardening the reinforcing agent to form a reinforcing structure to reinforce the media pack.

In some methods, the reinforcing agent is applied proximate at least one of the inlet face and the outlet face.

In one method, applying the reinforcing agent includes immersing at least one of the inlet face and the outlet face in the reinforcing agent. This may be done using a bath housing the reinforcing agent in the flowable state.

In one method, applying the reinforcing agent includes immersing less than the entire media pack in the reinforcing agent.

The reinforcing agent is in the flowable state, a liquid.

In one method, hardening the reinforcing agent includes exposing the reinforcing agent to predetermined wavelength of a light.

In one method, hardening the reinforcing agent includes heating the reinforcing agent.

In one method, hardening the reinforcing agent includes drying the reinforcing agent without heating the reinforcing agent.

The media pack is z-media having a plurality of adjacent layers of fluted filter media defining the inlet face and the outlet face. Each layer includes a corrugated sheet and a facer sheet attached to the corrugated sheet to form a plurality of inlet and outlet flutes extending between the inlet and outlet faces.

The inlet flutes have an open end proximate the inlet end and a closed end proximate the outlet end. The outlet flutes have a closed end proximate the inlet end and an open end proximate the outlet end, the reinforcing agent does not close the open ends of the flutes.

The inlet flutes are open proximate the inlet end and closed proximate the outlet end by outlet end sealant and the outlet flutes are closed proximate the inlet end by inlet end sealant and open proximate the outlet end. The reinforcing agent is different than the inlet end sealant and outlet end sealant.

The inlet and outlet end sealant has a higher viscosity than the reinforcing agent when in a flowable state.

In one method, the method further includes attaching a seal member to the media pack adjacent the reinforcing agent. The seal member may provide a radially outward directed seal surface. The seal member may provide an axially directed seal surface.

In one method, the seal member is molded directly to an outer periphery of the media pack.

In one method, a portion of the seal member overlaps with a portion of the reinforcing agent.

In one method, the reinforcing agent is applied to only a portion of the cross-section of the media pack. In one method, the reinforcing agent is applied proximate an outer periphery of the corresponding face of the filter media pack.

In one method, applying the reinforcing agent includes absorbing the reinforcing agent into media of the media pack. In one method, applying the reinforcing agent includes coating surfaces of filter media of the media pack with the reinforcing agent.

In one method, coupling a plurality of layers of media together occurs by winding a single strip of media to form a coiled media pack.

In one method, coupling a plurality of layers of media together occurs by stacking a plurality of strips or segments of media to form a stacked media pack.

Each layer of the media pack includes a fluted sheet and a facer sheet attached to the fluted sheet to form a plurality of inlet and outlet flutes extending between the inlet and outlet faces.

In one method, applying the reinforcing agent includes spraying the reinforcing agent onto the filter media pack. Applying the reinforcing agent may include wiping the reinforcing agent onto the filter media.

In one method, hardening the reinforcing agent includes applying a second material to the reinforcing agent to cure the reinforcing agent. In a more particular embodiment, the reinforcing agent and second material are a multipart epoxy.

The filter media is fluted media (also referred to as z-media).

On the contrary, the intent is to cover all alternatives, modifications and equivalents as included within the spirit and scope of the invention as defined by the appended claims.

<FIG> show a first embodiment of the present invention in the form of a filter element <NUM> adapted for insertion into a filter housing for removing particulate matter from a flow of fluid passing through the filter housing. The term fluid as used herein is intended to include fluids in either liquid or gaseous forms; however, the embodiments shown herein illustrate an air filter of the type used for filtering intake air for engines and air compressors. It is understood that inventive features may also be applicable to liquid applications.

The filter element <NUM> of the first embodiment is generally shown in <FIG> as an annular shape with a race-track-like cross section. The term "annular" is used herein in accordance with the common dictionary definition to describe a variety of ring-like shapes disposed about an axis or centerline. Annular shapes, as contemplated by the inventors, may include, but are not limited to, shapes that are round, rectangular, oval, or race-track-like with two generally straight and parallel sides joined by rounded ends.

To generally introduce different components, the filter element <NUM>, as shown in <FIG>, includes a filter media pack <NUM> and a seal arrangement <NUM> for sealing with a housing in which the filter element <NUM> is to be mounted.

The filter media pack <NUM> of the illustrated embodiment has opposed flow faces in the form of an inlet face <NUM> and an outlet face <NUM>.

In the illustrated embodiment, with additional reference to <FIG>, the filter media pack <NUM> is a fluted media pack formed from a plurality of adjacent layers of filter media, which may include a flat sheet layer and a fluted or corrugated layer. The fluted filter media forms a plurality of inlet flutes <NUM> that have an open inlet end <NUM> adjacent the inlet face <NUM> and a closed outlet end <NUM> adjacent the outlet face <NUM>. The closed outlet end <NUM> is closed by a sealing bead <NUM>. The fluted filter media also forms a plurality of outlet flutes <NUM> that have a closed inlet end <NUM> that is closed by a sealing bead <NUM> adjacent the inlet face <NUM>. The outlet flutes <NUM> have an open outlet end <NUM> adjacent the outlet face <NUM>. Fluid to be filtered enters the filter media pack <NUM> through the open inlet ends <NUM> of the inlet flutes <NUM> passes through the porous filter media to the outlet flutes <NUM> and out the open outlet ends <NUM> of the outlet flutes <NUM> through the outlet face <NUM>.

With reference to <FIG>, the fluted filter media includes a facer sheet <NUM> of porous filter media and a fluted sheet <NUM> (also referred to as a corrugated sheet) of porous filter media secured together to form a layer of fluted filter media. Typically, the facer sheet <NUM> is attached to the fluted sheet <NUM> by a first bead of sealant that also forms one of the inlet or outlet sealing beads <NUM>, <NUM> that closes one of the ends of either the inlet or outlet flutes <NUM>, <NUM>.

The fluted sheet <NUM> may be formed by any appropriate process, such as corrugating or pleating, but preferably by gathering as described in <CIT>, entitled "Gathered Filter Media for an Air Filter and Method of Making Same,". The term "facer sheet", as used herein, is intended to encompass any form of sheet or strip of generally flat, porous or non-porous, material attached to the fluted sheet of porous filter material. In most embodiments of the invention, the facer sheet would preferably be formed of a porous filter material. Further, the facer sheet would typically be flat, but could be corrugated or otherwise shaped as well.

The fluted filter media for the filter element <NUM> of <FIG> is wound around a winding core <NUM> to provide the plurality of adjacent layers. As the fluted filter media is wound, a second bead of sealant is applied between the facer sheet of one layer and the fluted sheet of the adjacent layer. This second bead of sealant is axially offset from the first bead of sealant along the flutes and is typically located proximate the opposite end of the flutes. This second bead of sealant will form the other one of the outlet or inlet sealing beads <NUM>, <NUM> that closes the other end of the outlet or inlet flutes <NUM>, <NUM>.

The winding core <NUM> can take various shapes and dimensions. One example of the winding core <NUM> is disclosed in <CIT>, entitled "Fluid Filter Apparatus Having Filter Media Wound About a Winding Frame,". In alternative embodiments, the fluted filter media pack <NUM> may be formed without using a winding core.

In the illustrated embodiment, the seal arrangement <NUM> is provided proximate the inlet face <NUM> of the filter media pack <NUM>. The seal arrangement <NUM> includes a seal member <NUM> for engaging a housing having a sealing surface (not shown). In the illustrated embodiment, the seal member <NUM> provides an axial seal. However, in other embodiments, the seal member <NUM> could be configured to provide a radial seal.

The seal member <NUM> has a sealing surface <NUM> configured to seal against the sealing surface of the filter housing to form an axial seal between the filter housing and the filter element <NUM>. When the filter element <NUM> is placed in the filter housing, the seal member <NUM> is compressed against the sealing surface of the filter housing such that the sealing surface <NUM> of the seal member <NUM> and the sealing surface of the filter housing provide a seal between the filter element <NUM> and the housing to prevent any unfiltered air from bypassing the filter media pack <NUM> while flowing through the filter housing. The seal member <NUM> may be formed of any suitable sealing materials including but not limited to polymeric materials and polymer foams, preferably, urethane foam. Expandable materials such as urethane are particularly advantageous because they are resilient to provide a sealing function and can be molded directly to the filter media pack <NUM> or onto a seal support member <NUM>, such as illustrated in <FIG>. Further yet, the seal member <NUM> could be separately formed and then adhesively or otherwise secured to the filter media pack <NUM> or the seal support member <NUM>.

When mounted in an air supply system, such as an air intake system for an engine, these filters are typically exposed to a suction applied at the outlet face <NUM> as illustrated by suction force S in <FIG>. This suction force S tends to cause the filter media and layers of filter media to compress radially inwardly as illustrated by arrows <NUM>.

This inward compression can pose several problems. First, this can cause the layers of filter media to separate and create possible leak paths. Further, this can cause the filter media to separate from the seal arrangement <NUM> depending on the rigidity of the seal arrangement <NUM> or how tightly the seal arrangement <NUM> is axially engaged with the housing in an axial sealing configuration. Further, if the seal arrangement <NUM> provides a radial seal with the housing, the inward compression of the filter media pack <NUM> can likewise draw the seal arrangement radially inward reducing the seal engagement between the seal arrangement <NUM> and the sealing surfaces of the filter housing. This is particularly true if the seal arrangement <NUM> is merely the seal member <NUM> secured to the filter media pack <NUM> without any more rigid support member.

A further problem associated with the pressure differential across the filter element <NUM> and flow of air through the filter element <NUM> is that the layers of filter media can telescope axially. More particularly, adjacent layers of the filter media will slip axially relative to one another which can create leak paths as well as exacerbate the issues relating to radial compression discussed previously.

With reference to schematic illustrations of <FIG> and <FIG>, embodiments of the invention incorporate a reinforcing structure <NUM> to reinforce the layers of fluted media to prevent one or more of the problems identified above.

The reinforcing structure <NUM> in <FIG> is located adjacent the inlet face <NUM>. However, it could be located adjacent the outlet face <NUM> or multiple structures could be provided, such as one adjacent the inlet face <NUM> and one adjacent the outlet face <NUM>. Further, a reinforcing structure could be axially offset from the inlet and outlet faces <NUM>, <NUM> and be positioned axially inward therefrom.

The reinforcing structure is a composite structure formed from a reinforcing component formed from a reinforcing agent <NUM> and the sheets of filter media including the face and fluted sheets <NUM>, <NUM>. Preferably, the reinforcing agent is impregnated into the face and fluted sheets <NUM>, <NUM>. In <FIG> and <FIG>, the reinforcing agent <NUM> is shown as an outer layer of material around the filter media of sheets <NUM>, <NUM> with an exaggerated thickness for ease of illustration.

Typically, the reinforcing agent <NUM> will be applied as a liquid and then operably hardened, and more preferably hardened to a solid to provide reinforcement of the media pack <NUM>. In the liquid form, the reinforcing agent <NUM> will be absorbed into and preferably entirely through the pores of portions of the various sheets of media <NUM>, <NUM> to further reinforce the media pack <NUM>. This is illustrated by the cross-hatching of the reinforcing agent <NUM> extending into the cross hatching of the sheets <NUM>, <NUM> and entirely therethrough such as at regions <NUM> and <NUM> in <FIG>. Typically, at regions <NUM> there is no adhesive between the facer sheet <NUM> and the fluted sheet <NUM> proximate this end of the media pack <NUM>. As such, by using the reinforcing agent <NUM> an adhesive bond between these two sheets <NUM>, <NUM> is now provided to further support and strengthen the media pack <NUM>.

After application, the reinforcing agent <NUM> will harden to form a matrix that penetrates the pores of the media and encapsulates the material of the media, such as fibers thereof. The media thus provides a substrate of the composite structure. This hardened reinforcing structure <NUM> provides additional bonding between the various sheets to increase the rigidity of the media pack <NUM>. The reinforcing structure <NUM> will provide additional axial reinforcement to prevent telescoping or slipping of adjacent layers, such as along axis <NUM> that is typically not present in fluted media, i.e. such as at location <NUM>. The reinforcing structure <NUM> will also provide further rigidity to provide radial support and strength to prevent or inhibit radial compression or expansion of the media pack <NUM> toward or away from axis <NUM> depending on whether the media pack <NUM> is exposed to a positive or negative differential pressure.

The reinforcing agent <NUM> is applied to the filter media pack in a flowable state. Typically, the reinforcing agent <NUM> will be a liquid having a low viscosity. Preferably, the viscosity will be below <NUM> centipoise. More preferably, the viscosity is less than <NUM> centipoise. Even more preferably, the viscosity is between <NUM> and <NUM> centipoise and even more preferably between <NUM> and <NUM> centipoise. However, it is contemplated that viscosities less than <NUM> centipoise would provide very positive wicking characteristics. Other embodiments (not according to this invention) could use a powder material that is applied to the media pack <NUM>. The powder material could then be converted to a rigid structure by a secondary process such as heating or applying a curing or hardening agent.

The viscosity of the reinforcing agent <NUM> will be substantially less than the viscosity of the sealant for the first and second beads <NUM>, <NUM>. This is because it is desired that the reinforcing agent does not plug or restrict flow of fluid through the flutes. The sealant for the first and second beads <NUM>, <NUM> may be formed from numerous different materials but is often formed from a hot melt. When dispensed, the sealant for the first and second beads <NUM>, <NUM> will often be above <NUM>,<NUM> centipoise, and in some instances much more viscous such as above <NUM>,<NUM> centipoise. The sealant for beads <NUM>, <NUM> will become more viscous as the sealant cures and hardens after being applied to the media as the sealant cools, particularly when a hot melt type product is used. The higher viscosity of the sealant beads <NUM>, <NUM> is used such that the sealant beads <NUM>, <NUM> are sufficient to seal off and close desired ones of the flutes, as illustrated in <FIG> and <FIG>.

With reference to <FIG>, the media pack <NUM> is first formed from the filter media. This could be done by winding a continuous layer of media formed from a facer sheet and a fluted sheet to form a plurality of adjacent layers or stacking a plurality of segments of layers to form the media pack <NUM>.

The media pack <NUM> is then dipped into a bath <NUM> of liquid or otherwise flowable reinforcing agent <NUM>, such as illustrated by arrow <NUM> along axis <NUM> and perpendicular to the inlet and outlet faces <NUM>, <NUM>. The dipping may be to a dipping depth d1 (also referred to as an emersion depth) that is equal to or less than the ultimate depth d2 (see <FIG>) of the reinforcing agent <NUM> from the corresponding flow face <NUM>, <NUM> of the media pack <NUM>. The ultimate depth d2 may also be referred to as the reinforced distance. Typically, the dipping depth d1 will be less than the ultimate depth d2 as the reinforcing agent <NUM> will wick axially into the media pack <NUM> further than the dipping depth d1. For instance, with some products that have been tested, the dipping depth d1 was approximately <NUM>/<NUM> the of the ultimate depth d2 of the reinforcing agent <NUM>.

During this dipping process, the flowable reinforcing agent <NUM> will preferably penetrate into and through the pores within the media to increase the strength of the ultimate reinforcing structure <NUM> when completed. However, in other embodiments, the reinforcing agent <NUM> could merely coat the outer surfaces of the media.

The media pack <NUM> will then be axially lifted out of the bath <NUM>, illustrated by arrow <NUM>.

After the media pack <NUM> is removed from the bath <NUM>, the liquid reinforcing agent <NUM> applied to the filter media will be hardened. Prior to hardening, in some embodiments, forced air is blown through the filter element to help clear excess reinforcing agent <NUM> from the open ended flutes.

<FIG> illustrates the reinforcing agent <NUM> being hardened by a hardening mechanism <NUM>.

Depending on the type of reinforcing agent <NUM>, the hardening mechanism <NUM> may vary. For instance, in some embodiments, the reinforcing agent <NUM> may be ultraviolet curable. As such, the hardening mechanism <NUM> could be an ultraviolet light. The reinforcing agent <NUM> could also be configured to cure based on a different wavelength of light as well, such as a wavelength within the visible light spectrum. Alternatively, the hardening device <NUM> could be a fan for blowing air against the liquid reinforcing agent. Further, the hardening device could be a heater or even an oven for heat hardening the reinforcing agent. Further yet, in other embodiments, the reinforcing agent <NUM> could be in the form of a multi-part material such as a multi-part epoxy where the hardening device <NUM> applies a second component to cause a first component, i.e. the component that would be in bath <NUM>, to cure and harden.

The seal arrangement <NUM> can then be attached to the media pack <NUM>. Preferably, the seal member <NUM> is mounted to the media pack <NUM> proximate the axial location along axis <NUM> of the reinforcing structure <NUM>. In at least some embodiments, such as illustrated in <FIG>, the seal arrangement <NUM> will at least partially axially overlap with the reinforcing structure <NUM>.

The ultimate depth d2 of the reinforcing structure <NUM> is preferably between <NUM> and <NUM> (<NUM>/<NUM> and <NUM>/<NUM> inch). However, other depths d2 are permissible depending on the overall length L of the media pack <NUM>, the width W of the media pack <NUM> and the ultimate pressure drop across the media pack <NUM> (see e.g. <FIG>). For instance, in some embodiments, ultimate depth d2 may be as low as <NUM> (<NUM> inch).

With reference to <FIG>, (not according to this invention), a method of forming the reinforcing structure <NUM> applies the reinforcing agent <NUM> while forming the media pack <NUM>. More particularly, the reinforcing structure <NUM> is applied either during winding or stacking of the layers of media to form the plurality of layers.

In this method, one of the sealant beads, e.g. sealant bead <NUM> (not shown in <FIG>), is already applied between a facer sheet <NUM> and a fluted sheet <NUM> to form a layer of fluted filter media proximate inlet end <NUM>. The layer of fluted filter media is being wound around winding core <NUM>.

During the winding process, the second sealant bead <NUM> is being applied to secure adjacent layers of filter media together. Simultaneously, the reinforcing agent <NUM> is being applied to the filter media in a flowable state. A first reinforcing agent applicator <NUM> applies reinforcing agent <NUM> to the exposed surface of the fluted sheet <NUM>. A second reinforcing agent applicator <NUM> applies the reinforcing agent <NUM> to the exposed surface of the facer sheet <NUM> in line with the first reinforcing agent applicator <NUM>. As the filter media is wound, the two separately deposited portions of reinforcing agent <NUM> will align. By applying the reinforcing agent <NUM> to both sheets <NUM>, <NUM>, it is contemplated that better penetration into both sheets <NUM>, <NUM> of media may be achieved rather than relying on transfer from one sheet to the other if only a single applicator was provided. However, the use of a single applicator is not excluded.

The reinforcing agent <NUM> is applied proximate inlet face <NUM>. However, the reinforcing agent <NUM> could be applied proximate the outlet face <NUM>. Additionally, multiple reinforcing structures could be provided such that the reinforcing agent <NUM> could be applied at multiple separate locations, such as proximate both the inlet and outlet faces <NUM>, <NUM>. Even further, a reinforcing structure could be located at an axial location between the inlet and outlet faces <NUM>, <NUM>, for example, proximate a midpoint between the inlet and outlet faces <NUM>, <NUM>.

In <FIG>, a sealant applicator <NUM> applies sealant bead <NUM> proximate outlet end <NUM> simultaneously as the reinforcing agent applicators <NUM>, <NUM> apply reinforcing agent <NUM> to the media. Sealant applicator <NUM> may also apply an initial sealant bead that seals the media to the winding core <NUM>. This initial sealant bead may include a portion that runs longitudinally parallel to the flutes and winding core <NUM>, i.e. in a direction extending between the inlet and outlet faces <NUM>, <NUM>.

The sealant beads <NUM>, <NUM> (see also <FIG> and <FIG>) are formed from a material having different physical properties than the reinforcing agent <NUM>. The material of the sealant beads <NUM>, <NUM> has a much higher viscosity value than the reinforcing agent <NUM>, in their respective flowable states. This is because the sealant material for sealant bead <NUM>, <NUM> is configured to plug the channels formed between the facer sheet <NUM> and fluted sheet <NUM> to force the air to pass through the porous filter media.

However, the reinforcing agent <NUM> is selected to specifically prevent or inhibit plugging the open channels formed between the facer sheet <NUM> and fluted sheet <NUM> and to be substantially completely absorbed into the media or to more closely conform to the shape of the media in a rather uniform thickness. The low viscosity of the reinforcing agent allows it to closely conform to the surfaces of the media. As such, excess reinforcing agent will drip from the filter media when using the bath style application or will closely conform to the shape of the sheets of media (e.g. facer sheet <NUM> and fluted sheet <NUM>) when using other types of applicators such as a spray application, wiping application, etc. Due to the low viscosity relative to the sealant material, a globule of the reinforcing agent <NUM> should not remain within one of the grooves of the valleys or grooves of the fluted media such that the flute formed by that groove would be plugged, unlike for sealant beads <NUM>, <NUM>. In some embodiments, where a more viscous material is used, as noted above, air may be blown through the media pack prior to hardening of the reinforcing agent <NUM> to help blow excess material out of the open ends of the flutes to prevent undesired plugging.

Ideally, only a very small outer layer of the reinforcing agent <NUM> extends outward from the surfaces of the filter media such that only a minimum amount of the flute openings would be closed or otherwise blocked due to the reinforcing agent <NUM> when it hardens. In some embodiments, the reinforcing agent <NUM> blocks less than <NUM>% of the cross-sectional area of an open flute and even more preferably less than <NUM>%. Again, the drawings have the thickness of the reinforcing agent <NUM> exaggerated for illustrative purposes.

When the reinforcing agent <NUM> is applied while forming the media pack <NUM> (which does not form part of the claimed invention), the seal arrangement <NUM> will be attached to the media pack after the step of applying the reinforcing agent. Typically, the seal arrangement <NUM> would be attached after the sealing agent <NUM> has been, at least partially, hardened. However, this order is not required.

While the prior embodiments disclose a reinforcing structure <NUM> that would be applied to substantially the entire cross-sectional area (perpendicular to the longitudinal axis <NUM>, e.g. flow axis) of the filter media of the media pack <NUM>, other embodiments could apply the reinforcing agent <NUM> to only a portion of the media pack. For example, if the media pack is a wound media pack having twenty (<NUM>) wound layers, the reinforcing agent <NUM> may only be applied to the first ten (<NUM>) inner layers or the outer ten (<NUM>) layers but not to all twenty (<NUM>) layers.

If the reinforcing agent <NUM> is applied as illustrated in <FIG> during the winding process, the application of the reinforcing agent <NUM> could be started or stopped to apply the reinforcing agent <NUM> at the desired location of the cross-section. Further, multiple locations of the cross-section could have reinforcing agent <NUM>. This is illustrated in <FIG> by regions <NUM>, <NUM>. In this embodiment, only the portion of the inlet end face <NUM> in regions <NUM>, <NUM> has a reinforcing structure present. While this embodiment shows an inner reinforcing structure (region <NUM>) and an outer reinforcing structure (region <NUM>), other embodiments could have more or less regions than that are illustrated. Further, while the regions are illustrated at the inlet face <NUM>, the different regions could be at the outlet face <NUM> or at an axial location between the inlet and outlet faces <NUM>, <NUM>.

Individual regions would typically apply the reinforcing agent to multiple adjacent layers of media. The reinforcing agent could be applied to as little as one specific layer; however, it would typically be applied to at least two adjacent layers of the media.

If the reinforcing agent <NUM> is applied after the media pack <NUM> is formed, as in the claimed invention, the applicator for applying the reinforcing agent <NUM> could be a sprayer or brush or a sponge like applicator that applies the reinforcing agent <NUM> to the desired regions of the cross-section of the media pack <NUM>. The brush or sponge could perform a wiping type application. Such a wiping type application could also be used during the application such as in <FIG>, rather than spraying.

With reference to <FIG>, it is contemplated to be beneficial to offset the sealant bead, e.g. sealant bead <NUM>, from the inlet face <NUM> or outlet face <NUM> if the reinforcing structure <NUM> is going to be adjacent thereto. With reference to the inlet face <NUM>, but with equal applicability to the outlet face <NUM>, this allows the portion of the filter media <NUM> between the inlet face <NUM> and the sealant bead <NUM> to absorb the reinforcing agent <NUM> and form a strong adhesion between the plurality of layers of filter media without interference from the sealant bead <NUM>. However, this is not necessary.

The Applicants have tested the concept of including such a reinforcing structure and have had very successful results relating to structural integrity (e.g. telescoping or failure).

Additionally, similar media packs were tested to determine the effect on overall pack efficiency and capacity. A standard pack (no reinforcement structure) and two media packs including the reinforcement structure <NUM> at the outlet face were tested using an ISO <NUM> test where at a flow rate of <NUM> SCFM using an airborne contaminant of PTI Fine 11968F, was used until a differential pressure of <NUM> inch H<NUM>O was reached. One of the media packs (referred to herein as Test Element A) including the reinforcement structure had a minimum amount of reinforcing agent such that it had an ultimate depth of less than <NUM> (<NUM>/<NUM> inch) from the outlet face. Another one of the media packs (referred to herein as Test Element B) including the reinforcement structure had a larger amount of reinforcing agent such that it had an ultimate depth of on average between <NUM> and <NUM> (<NUM>/<NUM> inch and <NUM>/<NUM> inch) of reinforcing agent extending towards the inlet face.

From this test, the pack with the larger amount of reinforcing agent actually had better accumulated efficiency, larger capacity and a lower amount by weight of bypassed particulate. These results were generally expected as the reinforcing structure was positioned proximate the downstream outlet face adjacent the corresponding sealant bead where little to no fluid filtration occurs due to the sealant beads inhibiting fluid flow through that portion of the filter media.

The following specific test results were captured:.

<FIG> is further filter element <NUM> not according to the invention. This filter element <NUM> included a pleated media pack <NUM> mounted within a frame structure <NUM>. The frame structure may include a seal arrangement for sealing the media pack within filter housing to prevent fluid bypass. The filter media pack <NUM> will be sealed within the frame structure <NUM> with a sealant <NUM> to prevent fluid bypass between the media pack <NUM> and the frame structure <NUM>. The frame structure can take many forms and could be provided by urethane (particularly foamed urethane), plastic frame materials, a combination of the urethane and plastic materials. When a urethane is used, it may take the form of both the frame structure <NUM> and the sealant <NUM>. The sealant <NUM> also seals the open ends of the pleats.

With additional reference to <FIG>, the filter element <NUM> is shown in partial cross-section. As can be seen in <FIG>, the pleated media pack <NUM> is generally a single sheet of media that is folded to form a plurality of adjacent panels <NUM> that form a plurality of peaks <NUM> and valleys <NUM>. The peaks 307A form an inlet side or inlet face of the filter element <NUM> while the peaks 307B form an outlet side or outlet face of the filter element <NUM>. The valleys that open toward the inlet face are referred to as inlet valleys 308A and the valleys that open toward the outlet face are referred to as outlet valleys 308B.

The peaks <NUM> are generally the folds that connect adjacent panels <NUM> of the media.

The peaks <NUM> of the filter element <NUM> are impregnated with a reinforcing agent <NUM> to provide strength to the media pack <NUM>. This arrangement may be referred to as a peak reinforcing structure. The reinforcing agent <NUM> is illustrated as heavy thick lines while filter media without the reinforcing agent <NUM> is shown schematically as thin lines.

Again, like with previous filter elements using fluted media, it is preferred that the reinforcing agent <NUM> extends into the pores of the filter media and through the filter media. However, it is possible that it could be provide more as a coating.

As illustrated in <FIG>, the reinforcing agent could extend between peaks 307A and 307B along a face of the panels as illustrated by reinforcing agent <NUM> to provide additional rigidity and structural support to the pleats. This rigidity can help keep adjacent panels <NUM> of filter media from collapsing on one another and closing the valleys 308A, 308B such that the filtering capacity of the filter element <NUM> is diminished. While only a single strip of reinforcing agent <NUM> is illustrated, multiple strips could be provided between opposed edges of the filter media. Multiple strips are illustrated in <FIG>. Again, preferably, the reinforcing agent <NUM> penetrates through the filter media to form a composite reinforcing structure formed from the reinforcing agent <NUM> and the material of the filter media. It is noted that the portion of reinforcing agent <NUM> on the peaks 307A, 307B can also provide rigidity and help keep the peaks 307A, 307B separated.

Preferably, the width w2 of the strips of reinforcing agent <NUM>, also referred to as intermediate reinforcing structures, is between about <NUM> and <NUM> (<NUM>/<NUM> inch and <NUM>/<NUM> inch) so as to provide sufficient strength or support without unduly limiting the filter capacity of the filter media.

Similarly, the depth d3 that the reinforcing agent <NUM> penetrates from a given peak 307A, 307B towards the next peak 307B, 307A (i.e. from the inlet face towards the outlet face or from the outlet face towards the inlet face along a given panel) is preferably between about <NUM> and <NUM> (<NUM>/<NUM> inch and <NUM>/<NUM> inch) so as to provide protection and strength to the corresponding peaks 307A, 307B. <FIG> is an enlarged cross-sectional illustration of one peak 307A illustrating reinforcing agent <NUM> applied to the peak 307A. Preferably, the reinforcing agent <NUM> extends entirely through the filter media. It should be noted that, like before, the thickness of the reinforcing agent <NUM> is exaggerated for illustrative purposes only.

In some cases, the reinforcing agent <NUM> will not fully fill the portion <NUM> of the corresponding valley 308B proximate the peak 307A and will generally form a V-shape. In alternative cases. the reinforcing agent could entirely fill the portion <NUM> (see e.g. <FIG>) to be similar to a triangular shape of reinforcing agent <NUM>.

The application of the reinforcing agent <NUM> to the peaks <NUM> helps prevent cracking or damage to the peaks <NUM> due to impingement of fluid flow and impurities as well as the cyclical pressure loading that can be applied to the filter media during a duty cycle of a filter element.

The reinforcing agent <NUM>, <NUM> could be applied similar to those methods above such as dipping in a bath, spraying, or brushing/wiping.

Typically, the sealant <NUM> will have a different characteristic than the reinforcing agent <NUM>, <NUM> but need not be in the cases. Typically, the reinforcing agent <NUM>, <NUM> will have a lower viscosity than the sealant <NUM>.

When pleated filter media is used, it is desired that the reinforcing agent covers less than <NUM>% of the surface are of the filter media, more preferably, less than <NUM>% of the surface area of the filter media and even more preferably less than <NUM>% of the surface area of the filter media.

<FIG> illustrates a further method of forming a filter media pack (not according to this invention). The resulting filter element is again formed by winding filter media to form a plurality of layers of filter media. During the winding process as well as application of bead <NUM>, a plurality of reinforcing stitch beads <NUM> are being applied by applicators <NUM>. The stitch beads help secure the adjacent layers of the filter media together and prevent telescoping as well as improved rigidity for the resulting filter media pack.

The stitch beads <NUM> are applied between the adjacent layers of media. The stitch beads <NUM> are thin layers of adhesive used to secure the exposed peaks <NUM> of the fluted sheet <NUM> to the exposed surface <NUM> of the facer sheet <NUM>. While a high penetration adhesive may be used other higher viscous adhesive such as a hot melt may also be used.

The thickness of the stitch beads <NUM> is such that the open flutes, i.e. regions formed between peaks <NUM> of the fluted sheet, are not blocked by the adhesive forming the stitch beads <NUM>.

Each of the stitch beads <NUM> is a continuous strip of adhesive applied to surface <NUM> during the winding process. In other cases, the stitch bead <NUM> could be intermittently applied.

<FIG> is a simplified cross-sectional illustration of adjacent layers of filter media after formation using the process illustrated in <FIG>. Here, adhesive stitch beads <NUM> were applied to surface <NUM> of facer sheet <NUM>. In this illustration, the adhesive forming stitch beads <NUM> only slightly penetrates into the fluted sheet <NUM> (e.g. at the peaks <NUM>) and surface <NUM> of the facer sheet <NUM>. As illustrated, the adhesive only slightly interferes with the open flutes <NUM> formed between adjacent peaks <NUM> and surface <NUM> of the facer sheet <NUM>. Preferably, the stitch beads <NUM> fill less than <NUM>% of the cross-sectional area of the open flutes <NUM> and preferably less than <NUM>% of the cross-sectional area of the open flutes <NUM>.

While <FIG> illustrates a plurality of stitch beads, some cases may have only a single stitch bead while others may have more than two stitch beads.

While being applied during the winding process, other cases could incorporate such a stitch between adjacent stacked layers of filter media. Further, while <FIG> only illustrates a stitch bead being formed while winding the layers of fluted filter media, stitch beads could also be formed to hold the fluted sheet <NUM> to the facer sheet <NUM> during the initial formation of the layer of filter media.

Preferably, the adhesive used to form the stitch bead has a quick cure rate (also referred to as quick setting). This type of adhesive is often referred to as having an aggressive green-tack. In one case, the stitch bead could be formed by a visible light cure adhesive where the adhesive is cured proximate the time at which the two layers of media are being brought together.

While the stitch beads <NUM> help the structural integrity of the resulting media pack, the stitch beads <NUM> also help resist synching of the layers of filter media during the winding process, e.g. to inhibit slipping of adjacent layers during winding in a direction perpendicular to axis around which the layers of filter media are wound.

As illustrated in <FIG>, because the stitch bead is not a seal bead, the stitch bead <NUM> will have less adhesive at a given location than the corresponding seal bead. For instance, the thickness of a stitch bead when measured perpendicular to the layer of media will be less than the thickness of a seal bead as it is being applied during manufacture.

The seal bead <NUM> is being applied during the winding process to close off one end of the flutes that are formed between the adjacent layers of fluted filter media. The other seal bead would be formed during the process of forming the fluted filter media and would be located between the facer sheet <NUM> and the fluted sheet <NUM>. These two seal beads are axially spaced apart and located proximate opposite edges of the layer of fluted filter media. Further, the stitch beads <NUM> are illustrated as being axially spaced from seal bead <NUM> along the axis of the flutes.

<FIG> and <FIG> illustrate a further case (not according to this invention) that is similar to those described with reference to <FIG> and <FIG>. Here, a stitch bead <NUM> is again being applied between adjacent layers of wound filter media. Rather than applying a bead of adhesive to surface <NUM> of the facer sheet <NUM>, the adhesive for the stitch bead <NUM> is applied directly to the peaks <NUM> with applicator <NUM>. The applicator <NUM> may be a pressurized ejector or could operate in other manners such as by a rolling action or a wiping action to apply the adhesive to peaks <NUM>.

As the filter media is being wound, the adhesive forming stitch bead <NUM> is sandwiched between the exposed peaks <NUM> of the fluted sheet <NUM> and surface <NUM> of facer sheet <NUM>.

Each stitch bead is applied as an intermittent bead of adhesive. One benefit of this arrangement is that very limited wasted adhesive is applied between the layers of the filter media. More particularly, adhesive is not unnecessarily applied to surface <NUM> of the facer sheet <NUM> between the peaks where the adhesive does not contact any portion of the fluted sheet <NUM>. This limits wasted material as well as prevents unnecessary blocking of the filter media of the facer sheet <NUM> between the peaks.

As illustrated, the adhesive only slightly interferes with the open flutes <NUM> formed between adjacent peaks <NUM> and surface <NUM> of the facer sheet <NUM> and to a lesser extent than the prior examples. Preferably, the stitch beads <NUM> fill less than <NUM>% of the cross-sectional area of the open flutes <NUM> and preferably less than <NUM>% of the cross-sectional area of the open flutes <NUM>. Again, the stitch beads <NUM> do not block the open flutes formed between the adjacent peaks. The blocking of the open flutes occurs by the application of seal bead <NUM>.

Again, stitch beads can be applied to both sides of the fluted sheet <NUM>. More particularly, stitch beads may be applied between the facer sheet <NUM> and the fluted sheet <NUM> during the formation of the layer of fluted filter media. The stitch bead would assist in maintaining the peaks and valleys of the fluted sheet <NUM> during the formation process. Again, these stitch beads would not block the open flutes formed between adjacent peaks.

Claim 1:
A method of providing reinforcing of a media pack comprising:
forming a media pack (<NUM>) having opposed flow faces forming an inlet face (<NUM>) and an outlet face (<NUM>), the media pack having a plurality of adjacent layers of fluted filter media forming a plurality of inlet and outlet flutes (<NUM>, <NUM>), each layer of fluted filter media including a porous fluted sheet (<NUM>) and a facer sheet (<NUM>) attached to the porous fluted sheet, wherein forming the media pack further comprises:
applying a first seal bead (<NUM>, <NUM>) between the fluted sheet and the facer sheet of each layer of fluted filter media closing off flutes formed between the facer sheet and the fluted sheet forming the plurality of inlet flutes or the plurality of outlet flutes; and
applying a second seal bead (<NUM>, <NUM>) between the fluted sheet and the facer sheet of adjacent layers of the fluted filter media closing off flutes formed between the fluted sheet and the facer sheet of adjacent layers forming the other of the plurality of outlet flutes or the plurality of inlet flutes, the first and second seal beads being axially spaced apart from one another along the flutes;
applying a reinforcing agent (<NUM>) to the media pack after the media pack is formed, the reinforcing agent being applied in a flowable state, the reinforcing agent being different than the first seal bead and the second seal bead, the first seal bead and the second seal bead having a higher viscosity than the reinforcing agent when applied; and
hardening the reinforcing agent to form a reinforcing structure to reinforce the media pack,
wherein the inlet flutes have an open end proximate the inlet end and a closed end proximate the outlet end and the outlet flutes have a closed end proximate the inlet end and an open end proximate the outlet end, and the reinforcing agent does not close the open ends of the flutes.