Patent Description:
During operation of an internal combustion engine, a fraction of combustion gases can flow out of the combustion cylinder and into the crankcase of the engine. These gases are often called "blowby" gases. The blowby gases include a mixture of aerosols, oils, and air. If vented directly to the ambient, the aerosols contained in the blowby gases can harm the environment. Accordingly, the blowby gases are often routed out of the crankcase via a crankcase ventilation system. The crankcase ventilation system may pass the blowby gases through a coalescer (i.e., a coalescing filter element) to remove a majority of the aerosols and oils contained in the blowby gases. The filtered blowby gases ("clean" gases) are then either vented to the ambient (in open crankcase ventilation systems) or routed back to the air intake for the internal combustion engine for further combustion (in closed crankcase ventilation systems).

Some crankcase ventilation systems utilize rotating crankcase ventilation filter elements, for example, rotating coalescer elements that increase the filter efficiency of crankcase ventilation systems by rotating the coalescer element during filtering. In rotating coalescer elements, the contaminants (e.g., oil droplets suspended and transported by blowby gases) are separated at least in part by centrifugal separation techniques. Additionally, the rotation of the coalescer element can create a pumping effect, which reduces the pressure drop through the crankcase ventilation system.

In various rotating crankcase ventilation filters, multiple parts are generally used for enabling filter element service operation. For example, metallic bushings, inserts and other components may be used to transmit rotational torque from a motor to the filter element for rotating the filter element and withstand vibrations. Such additional components may have tighter tolerances and may have to be heat treated to prevent premature wear. Moreover, a motor shaft, bushings, inserts, and other parts used to transfer the torque to the filter element may have to be hardened to withstand vibration loads through the life of the crankcase ventilation systems.

<CIT> discloses rotating coalescer elements that maximize the radial-projected separation surface area in a given (rotating) cylindrical volume, where flow to be cleaned is passing axially upward or downward through a separating media of the rotating coalescer element. Various example package assemblies are provided with various types of rotating configurations including cylindrical coiled media packs, frustum coiled media packs, concentric cylinders, coiled metal or polymer films with and without perforations, and/or alternating layers of different materials. The described rotating coalescers may be driven by hydraulic turbine, electric motor, belt, gear or by mounting on rotating machine components, such as rotating engine shafts or connected components.

Embodiments described herein relate generally to rotating crankcase ventilation filter assemblies that include an axial flow filter media disposed around a hub coupled to a central shaft that is coupled to a motor. The filter media and the hub are secured between end caps that define an inner volume within which the filter media and the hub are secured.

In a set of embodiments, a rotating crankcase ventilation filter element comprises a motor comprising a stator and a rotor, and a shaft. A first end of the shaft is coupled to the rotor and configured to rotate in response to rotation of the rotor. A hub is disposed circumferentially around the shaft and coupled to the shaft such that the hub is rotationally locked with respect to the shaft. Filter media is disposed around the hub and secured to the hub such that the filter media is rotationally locked with respect to the hub. The filter media is structured for axial flow of a gas through the filter media. A first end cap is disposed on a filter media first end, and a second end cap is disposed on a filter media second end of the filter media. The second end cap is coupled to the first end cap such that the filter media and the hub is secured between the first end cap and the second end cap.

In another set of embodiments, a rotating crankcase ventilation filter assembly comprises a housing, comprising: a housing main body, and a base coupled to a first end of the housing main body. The assembly also comprises a rotating crankcase ventilation filter element disposed at least partially within the housing. The rotating crankcase ventilation filter element comprises a motor comprising a stator and a rotor, and a shaft. A first end of the shaft is coupled to the rotor and configured to rotate in response to rotation of the rotor. A hub is disposed circumferentially around the shaft and coupled to the shaft such that the hub is rotationally locked with respect to the shaft. A filter media is disposed around the hub and secured to the hub such that the filter media is rotationally locked with respect to the hub, the filter media structured for axial flow of a gas through the filter media. A first end cap is disposed on a filter media first end. A second end cap is disposed on a filter media second end of the filter media, the second end cap coupled to the first end cap such that the filter media and the hub is secured between the first end cap and the second end cap.

It should be appreciated that all combinations of the foregoing concepts and additional concepts discussed in greater detail below (provided such concepts are not mutually inconsistent) are contemplated as being part of the subject matter disclosed herein. In particular, all combinations of claimed subject matter appearing at the end of this disclosure are contemplated as being part of the subject matter disclosed herein.

The foregoing and other features of the present disclosure will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only several implementations in accordance with the disclosure and are therefore, not to be considered limiting of its scope, the disclosure will be described with additional specificity and detail through use of the accompanying drawings.

Reference is made to the accompanying drawings throughout the following detailed description. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise.

Various embodiments of the rotating crankcase ventilation filter assemblies and filter elements described herein may provide one or more benefits including, for example: <NUM>) providing axial flow through a rotating crankcase ventilation filter element; <NUM>) providing direct coupling of a shaft of the rotating crankcase ventilation filter element to a rotor of a motor, thereby allowing removal of extra coupling components that reduces manufacturing complexity and maintenance cost; <NUM>) allowing a larger number of axial flow filter media layers to be included in the filter element, thereby reducing wobbling and imbalance of the filter element and reducing vibrations; <NUM>) allowing lubrication of a housing bearing included in the filter assembly by aerosols or oils that are separated from the blowby gas reducing maintenance cost.

Referring to <FIG>, a rotating crankcase ventilation filter assembly <NUM> (hereafter the "filter assembly <NUM>") is shown, according to an embodiment. The filter assembly <NUM> generally processes blowby gases received from an internal combustion engine crankcase to remove aerosols, oils, and other particulate contained in the crankcase blowby gases.

The housing <NUM> includes a housing main body <NUM> and a base <NUM> coupled to a first end of the housing main body <NUM>. In some embodiments, the base <NUM> may be monolithically formed with the housing main body <NUM>. A mounting flange <NUM> extends from the base <NUM> and is configured to be coupled to a support structure, for example, to an engine crankcase sump (not shown). A groove <NUM> is defined on a mounting surface of the mounting flange <NUM> and within which a mounting flange sealing member (e.g., a gasket) may be disposed to fluidly seal the mounting flange <NUM> with the support structure. A drain <NUM> (<FIG>) is defined through the mounting flange <NUM>. Contaminants such as aerosols or oils that are separated from the blowby gases by the filter element <NUM> may be drained back to the crankcase sump via the drain <NUM>.

As shown in <FIG>, the base <NUM> includes a bearing mount flange <NUM> extending axially from an inner rim of the base <NUM> into the internal volume defined by the housing main body <NUM>. The bearing mount flange <NUM> is configured to mount a housing bearing <NUM> therein. Thus, a separate bearing mount plate is not used. The housing bearing <NUM> may be pre-loaded with a biasing member (e.g., a wave washer). The housing bearing <NUM> may be lubricated with aerosols or oil included in the incoming blow by gases flowing into the housing <NUM> via an inlet <NUM>. The positioning of the housing bearing <NUM> is configured to align an inflow of the blowby gases into the housing <NUM> such that the blowby gases flow axially into the filter element <NUM> and flow axially through the filter element <NUM>.

The inlet <NUM> includes a conduit configured to deliver crankcase blowby gases to be filtered (e.g., from a crankcase of an internal combustion engine) into the housing main body <NUM>. The base <NUM> also includes an inlet flange <NUM> extending axially from the inner rim of the base <NUM> away from the housing main body <NUM>. The inlet flange <NUM> is configured to receive an inlet mounting end <NUM> of the inlet <NUM> and be coupled thereto. An inlet sealing member <NUM> (e.g., an O-ring or gasket) is disposed circumferentially between the inlet flange <NUM> and the inlet mounting end <NUM> to form a radial seal and prevent leakage of blowby gases or the coalesced contaminants. An outlet <NUM> is defined in a wall of the housing main body <NUM> and is configured to communicate filtered blowby gases out of the housing <NUM> and to the internal combustion engine (in a closed crankcase ventilation system) or to the ambient (e.g., in an open crankcase ventilation system).

A motor <NUM> is disposed within the housing main body <NUM>. The motor <NUM> includes a cover <NUM> coupled to a second end of the housing main body <NUM> opposite the first end. The cover <NUM> may be removably coupled to the housing main body <NUM>, for example via securing members (e.g., screws, bolts, nuts, etc.), threads, a snap-fit, or a friction-fit mechanism. In some embodiments, the cover <NUM> may include a cover plate <NUM> disposed radially within an inner rim defined by the cover <NUM>. A cover plate sealing member <NUM> (e.g., an O-ring or gasket) may be disposed between a radially inner sidewall of the cover <NUM> and a radially outer periphery of the cover plate <NUM> to provide a radial seal between the cover plate <NUM> and the cover <NUM>. A motor connector <NUM> (e.g., an electric connector such as a male or female connector) is disposed on the cover plate <NUM> and configured to be coupled to an electrical lead for providing electrical power to the motor <NUM>.

The motor <NUM> is disposed along a longitudinal axis AL of the housing <NUM>. The motor <NUM> includes a stator <NUM> and rotor <NUM> disposed about the longitudinal axis AL. The rotor <NUM> is disposed within a central cavity defined by the stator <NUM> and is configured to be coupled to a shaft <NUM> of the filter element <NUM>, as described in further detail herein. At least a portion of the stator <NUM> is disposed within the cover <NUM>. The stator <NUM> is supported by and coupled to a stator plate <NUM> that is disposed within the internal volume defined by the housing main body <NUM> and is located between the filter element <NUM> and the stator <NUM>.

As shown in <FIG>, the stator plate <NUM> defines a stator plate inner flange <NUM> extending axially from an inner rim of the stator plate <NUM> towards the stator <NUM> such that a radially outer surface of the stator plate inner flange <NUM> is disposed adjacent to a radially inner surface of the stator <NUM>. A stator plate inner sealing member <NUM> (e.g., an O-ring or a gasket) is disposed between the radially outer surface of the stator plate inner flange <NUM> and the radially inner surface of the stator <NUM> so as to form a radial seal therewith.

The stator plate inner flange <NUM> includes a bearing ledge <NUM> extending radially inwards from an end of the stator plate inner flange <NUM> such that a groove is formed for receiving a motor bearing <NUM>. The motor bearing <NUM> may be secured in the groove using a tolerance ring, press-fit, or shrink-fit. In some embodiments, a biasing member <NUM> (e.g., a wave washer) to provide pre-loading to the end of the shaft <NUM> that is disposed in the motor bearing <NUM>. Forming the motor <NUM> static components in two parts with the stator <NUM> and the stator plate <NUM> allows the rotor <NUM> to be installed after the motor bearing <NUM> is fit into the stator plate inner flange <NUM>. The motor bearing <NUM> may be lubricated (e.g., greased) for life. The motor bearing <NUM> fit provides a sufficient air gap between the stator <NUM> and a magnet laminate stack of the rotor <NUM>. In some embodiments, the stator <NUM> may be overmolded and sealed with stator plate <NUM> either directly or with a separate sleeve to prevent ingress of blowby gases into the stator <NUM> or a controller compartment <NUM> of the stator <NUM>.

A radially outer rim of the stator plate <NUM> is disposed against a radially inner surface of the housing main body <NUM>. A stator plate outer sealing member <NUM> (e.g., an O-ring or gasket) between the outer rim of the stator plate <NUM> and the inner surface of the housing main body <NUM> so as to form a radial seal between the stator plate <NUM> and the housing main body <NUM>. A motor controller <NUM> may be disposed in the controller compartment <NUM> formed between the cover <NUM> and the cover plate <NUM>.

Referring to <FIG>, the filter element <NUM> is disposed within the housing main body <NUM> between the base <NUM> and the motor <NUM>. The filter element <NUM> comprises a filter media <NUM>, an end cap assembly <NUM>, a shaft <NUM>, and a hub <NUM>. The shaft <NUM> is disposed about the longitudinal axis AL of the filter assembly <NUM>. The shaft <NUM> may be formed from metals (e.g., stainless steel, cast iron, aluminum, etc.) or any other suitable material. The shaft <NUM> includes a first end <NUM> configured to be coupled to the rotor <NUM> of the motor <NUM>, for example, using a securing member (e.g., screws, nuts, bolts, rivets, etc.) or press-fit thereto, such that the shaft <NUM> is configured to rotate in response to rotation of the rotor <NUM>. A second end <NUM> of the shaft <NUM> opposite the first end <NUM> is configured to slide into the housing bearing <NUM> with a sliding fit to accommodate thermal expansion. The biasing member (e.g., a wave washer or spring) that may be disposed around the housing bearing <NUM> may preload the second end <NUM> of the shaft <NUM>.

The shaft <NUM> includes a shaft main body <NUM>. A first bearing mount surface <NUM> extends axially from the shaft main body <NUM>. The first bearing mount surface <NUM> is defined proximate to the first end <NUM> of the shaft <NUM> and is configured to be mounted within the motor bearing <NUM>. A second bearing mount surface <NUM> extends axially from the shaft main body <NUM> and is defined proximate to the second end <NUM> of the shaft <NUM> and is configured to be positioned within the housing bearing <NUM>. A second bearing mount surface <NUM> may have a smaller diameter than the shaft main body <NUM> such that only the second end <NUM> of the shaft <NUM> is insertable into the housing bearing <NUM> up to the second bearing mount surface <NUM>, and the larger diameter shaft main body <NUM> cannot be inserted into the housing bearing <NUM>. In some embodiments, a length of the shaft <NUM> beyond the second bearing mount surface <NUM> is shorter than a length of the shaft <NUM> beyond the first bearing mount surface <NUM>.

A hub <NUM> is disposed circumferentially around the shaft <NUM> and coupled to the shaft <NUM> such that the hub <NUM> is rotationally locked with respect to the shaft <NUM>. In some embodiments, the hub <NUM> includes a hub inner flange <NUM> disposed circumferentially around the shaft main body <NUM> coaxially around the shaft main body <NUM>. A hub outer flange <NUM> is disposed circumferentially around the hub inner flange <NUM> and radially outwards of the hub inner flange <NUM>. A hub base <NUM> extends radially from the hub inner flange <NUM> to the hub outer flange <NUM>. In some embodiments, the shaft main body <NUM> defines at least one slot <NUM> (e.g., an axial slot). In such embodiments, the hub inner flange <NUM> defines a projection <NUM> that is disposed in the slot <NUM>. In some embodiments, the hub is overmolded around the shaft main body <NUM>.

The filter element <NUM> also comprises a filter media <NUM> disposed around the hub <NUM> and secured to the hub <NUM>. In some embodiments, the filter media <NUM> comprises a wound filter media <NUM> including a corrugated media layer interposed between two flat facing media layers such that axial flow channels are defined between the facing media layers and the corrugated media layer. Referring to <FIG>, the filter media <NUM> may include a first facing media layer 132a, a second facing media layer 132c, and a corrugated media layer 132b interposed between the first facing media layer 132a and the second facing media layer 132c such that adjacent peaks of the corrugated media layer 132b contact either the first facing media layer 132a or the second facing media layer 132c. In this manner, a plurality of axial flow channels are formed between the facing media layers 132a/c and the corrugated media layer 132b. It should be understood that, when the filter media is in a "wound" configuration, the first facing media layer 132a and the second facing media layer 132b may be part of the same continuous sheet of material.

<FIG> shows a pair of filter media layers 132a/b of the filter media <NUM> having a length L that are spaced apart from each other by a setting distance S. The (first) radially inner filter media layer 132a of the pair of filter media layers 132a/b is located at a radial distance R from a rotational axis of the filter media <NUM>, which is defined by the longitudinal axis AL. Blowby gases enter axially between the pair of filter media layers 132a/b. Rotation of the shaft <NUM> at a rotational velocity ω causes the rotationally locked hub <NUM> and the filter media <NUM> to rotate with the shaft <NUM>. The aerosol or oil experience G forces and get separated from blowby flow. Separated aerosol and liquid coalesce in the axial flow channel between the pair of filter media layers 132a/b and forms a film of oil which travels up towards the outlet of the channel as shown in <FIG>. The film then gets shed towards an inner wall of a second (top) end cap <NUM> (depicted in <FIG>). The oil then drains into a gap between the inner wall of the second end cap <NUM> and the filter media <NUM>. Oil drains towards the openings at the bottom of the filter element <NUM> at the outer diameter of the filter media <NUM> due to G forces created by the conical shape of the second end cap <NUM>. The separated oil gets drained from the filter element <NUM> into a collection chamber defined in the base <NUM>, for example, via drain openings created between a second end cap sidewall <NUM> of the second end cap <NUM> and a first end cap <NUM>. The collected oil aerosol or oils can then be drained back to the engine.

The filter media <NUM> and the hub <NUM> are disposed inside an end cap assembly <NUM>. Various embodiments of the end cap assembly <NUM> are described in detail in PCT Application No. <CIT>, entitled "Anti-Rotation Features for Crankcase Ventilation Filters" and the entire disclosure of which is incorporated herein by reference.

Referring to <FIG>, in some embodiments, the end cap assembly <NUM> comprises the first end cap <NUM> disposed on a filter media first end that is proximate to the base <NUM>. The second end cap <NUM> is disposed on a filter media second end that is opposite the filter media first end. The second end cap <NUM> includes the second end cap sidewall <NUM> extending axially from a radially outer rim of second end cap <NUM> towards the first end cap <NUM> and is coupled to a radially outer rim of the first end cap <NUM> (e.g., welded or bonded via an adhesive). The filter media <NUM> and the hub <NUM> is secured between the first end cap <NUM> and the second end cap <NUM>, and are disposed within the end cap assembly <NUM>. A plurality of first end cap apertures <NUM> are defined in the first end cap <NUM> and configured to allow blowby gases to enter the end cap assembly <NUM> and flow axially through the filter media <NUM>. A plurality of second end cap openings <NUM> are defined in the second end cap <NUM> and are configured to allow filtered blowby gases to exit the filter element <NUM> therethrough.

In some embodiments, the hub base <NUM> defines a plurality of openings <NUM> therethrough. The first end cap <NUM> includes a plurality of first pillars <NUM> extending from a base of the first end cap <NUM> towards the second end cap <NUM>. The second end cap <NUM> also includes a plurality of second pillars <NUM> extending from a base of the second end cap <NUM> towards the first end cap <NUM>. Each of the plurality of first pillars <NUM> are coupled to a corresponding second pillar <NUM> of the plurality of second pillars <NUM> through the openings <NUM>. For example, a protrusion <NUM> may extend from a tip of each of the plurality of second pillars <NUM> through corresponding openings <NUM> and inserted into an aperture defined in a corresponding first pillar <NUM> of the plurality of first pillars <NUM>. In some embodiments, the plurality of first pillars <NUM> and the plurality of second pillars <NUM> may be hollow. Securing members <NUM> (e.g., screws, bolts, etc.) may be inserted through the plurality of second pillars <NUM> into corresponding first pillar <NUM> of the plurality of first pillars <NUM> and coupled thereto to secure the first end cap <NUM> to the second end cap <NUM>.

A first central pillar <NUM> defining a first central channel extends axially from the first end cap <NUM> towards the second end cap <NUM> and is disposed around a portion of the hub inner flange <NUM> located below the hub base <NUM>. Moreover, a second central pillar <NUM> defining a second central channel extends axially from the second end cap <NUM> towards the first end cap <NUM> and is disposed around a portion of the hub inner flange <NUM> located above the hub base <NUM>. In this manner, the hub <NUM> is snugly fit between the first end cap <NUM> and the second end cap <NUM>.

To assemble the filter assembly <NUM>, the first end <NUM> of the shaft <NUM> of the filter element <NUM> is coupled to the rotor <NUM> (e.g., shrink-fit or press-fit thereto) such that the filter element <NUM> and the motor <NUM> to form a sub-assembly. The housing bearing <NUM> may be press-fit or shrink-fit to the second bearing mount surface <NUM>. The housing bearing <NUM> may be in a sliding fit with the bearing mount flange <NUM>. In this manner, the filter element <NUM> is aligned with the inlet <NUM> creating a flow path for blowby gases to enter into the filter element <NUM> and flow axially through the filter media <NUM>.

<FIG> and <FIG> show a rotating crankcase ventilation filter assembly <NUM>, according to another embodiment. The filter assembly <NUM> includes a housing <NUM> within which the filter element <NUM> and the motor <NUM> is disposed. The housing <NUM> includes a housing main body <NUM> and a base <NUM>. The housing <NUM> is similar to the housing <NUM> with the following differences. The housing <NUM> includes a mounting flange <NUM> extending from the base <NUM> and is configured to be coupled to a support structure, for example, to an engine crankcase sump (not shown). An outlet <NUM> is defined through a wall of the housing main body <NUM>.

Different from the housing <NUM>, the housing <NUM> includes an inlet <NUM> integrally defined through the mounting flange <NUM>. An inlet flange <NUM> extends axially from an end of the inlet <NUM> that is located proximate to the base <NUM> into the internal volume defined by the housing main body <NUM>. The housing bearing <NUM> is mounted within the inlet flange <NUM> such that a separate bearing mounting plate is not used. A drain <NUM> is also defined in the mounting flange <NUM> above the inlet <NUM> and configured to drain aerosols or oils collected in a collection chamber <NUM> defined in the base <NUM> around the inlet flange <NUM>. Moreover, a flange sealing member <NUM> is disposed in a groove defined in a sealing surface of the mounting flange <NUM> and configured to form a seal at an interface of the mounting flange <NUM> and the support structure around the inlet <NUM> and the drain <NUM>.

<FIG> and <FIG> shows a rotating crankcase ventilation filter assembly <NUM>, according to still another embodiment. The filter assembly <NUM> includes a housing <NUM> within which the filter element <NUM> and the motor <NUM> is disposed. The housing <NUM> includes a housing main body <NUM> and a base <NUM>. A mounting flange <NUM> extends from the base <NUM> and is configured to be coupled to a support structure. The mounting flange <NUM> defines a drain <NUM> configured to drain aerosols or oils collected in a collection chamber <NUM> defined in the base <NUM>. A mounting flange <NUM> also defines an inlet <NUM> that is fluidly coupled to an inlet chamber <NUM> defined in the base <NUM>. An outlet <NUM> is defined on a wall of the housing main body <NUM>.

The collection chamber <NUM> defines an axial wall <NUM> extending axially from an inner rim of the collection chamber <NUM> into the housing main body <NUM>. The collection chamber <NUM> is fluidly isolated from the inlet chamber <NUM> and located radially outwards of the inlet chamber <NUM>. A mounting plate <NUM> is positioned radially inward of the axial wall <NUM> and is coupled to a radially inner surface of the axial wall <NUM>, for example, via securing members, a friction fit, or a snap fit. An axial wall sealing member <NUM> is disposed between a radially outer rim of the axial wall <NUM> and the radially inner surface of the axial wall <NUM>. The mounting plate <NUM> also includes a sealing flange <NUM> extending from an inner rim of the mounting plate <NUM> into the housing main body <NUM> and coupled to the first end cap <NUM> of the filter element <NUM> so as to prevent the incoming blowby gases to leak into the collection chamber <NUM> and bypass the filter element <NUM>.

A bearing mounting plate <NUM> is mounted on an axial end of a mounting pillar <NUM> extending from a base of the inlet chamber <NUM> towards the mounting plate <NUM>. The bearing mounting plate <NUM> is configured to house the housing bearing <NUM>. A bearing mounting plate <NUM> is positioned within the inner rim of the mounting plate <NUM> such that a gap is defined between the sealing flange <NUM> and the bearing mounting plate <NUM>, which allows incoming blowby gases to flow through the gap into the filter element <NUM>.

It should be noted that the term "example" as used herein to describe various embodiments is intended to indicate that such embodiments are possible examples, representations, and/or illustrations of possible embodiments (and such term is not intended to connote that such embodiments are necessarily extraordinary or superlative examples).

Claim 1:
A rotating crankcase ventilation filter element (<NUM>), comprising:
a motor (<NUM>) comprising a stator (<NUM>) and a rotor (<NUM>);
a shaft (<NUM>), a first end (<NUM>) of the shaft configured to be coupled to the rotor and configured to rotate in response to rotation of the rotor, a shaft main body (<NUM>) of the shaft defining at least one slot (<NUM>);
a hub (<NUM>) comprising a hub inner flange (<NUM>) disposed circumferentially and coaxially around the shaft, the hub inner flange defining a projection (<NUM>) that is disposed in the slot, the hub coupled to the shaft such that the hub is rotationally locked with respect to the shaft;
a filter media (<NUM>) disposed around the hub and secured to the hub such that the filter media is rotationally locked with respect to the hub, the filter media structured for axial flow of a gas through the filter media;
a first end cap (<NUM>) disposed on a filter media first end; and
a second end cap disposed on a filter media second end of the filter media opposite the filter media first end, the second end cap coupled to the first end cap such that the filter media and the hub is secured between the first end cap and the second end cap.