FEATURES

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to Chinese Utility Model Application No. 201921003884.0, filed June 28, 2019 and Indian Patent Application No. 201941009920, filed March 14, 2019. The contents of these applications are incorporated herein by reference in their entirety.

Technical Field

[0002] The present disclosure relates generally to filters for use with internal combustion engine systems.

Background

[0003] Internal combustion engines generally use various fluids during operation. For example, fuel (e.g., diesel, gasoline, natural gas, etc.) is used to run the engine. Air may be mixed with the fuel to produce an air-fuel mixture, which is then used by the engine to run under stoichiometric or lean conditions. Furthermore, one or more lubricants may be provided to the engine to lubricate various parts of the engine (e.g., piston cylinder, crank shaft, bearings, gears, valves, cams, etc.). These fluids may become contaminated with particulate matter (e.g., carbon, dust, metal particles, etc.) which may damage the various parts of the engine if not removed from the fluid.

[0004] Some filter assemblies comprise a filter element positioned within a filter housing, such as a shell housing. Such filter assemblies generally have multiple parts to secure the filter element within the filter housing including, for example, spring, coupling elements, or other elements which increase the manufacturing complexity and cost of the filter assembly. Summary

[0005] Embodiments described herein relate generally to filter assemblies that include a filter element having a filter media and an end cap coupled to the filter media that includes coupling features for coupling the end cap to a reservoir, and anti-rotation features to rotationally lock the filter element to a filter housing in which the filter element is disposed.

[0006] In one set of embodiments, a filter assembly comprises a filter housing defining an internal volume. A filter element is disposed within the internal volume. The filter element comprises a filter media, a first end cap coupled to a first end of the filter media, and a second end cap coupled to a second end of the filter media opposite the first end. The second end cap comprises a base, the second end of the filter media coupled to the base, a first circumferential wall extending from a radial outer edge of the base towards the first end of the filter media, and a second circumferential wall extending from the radial outer edge of the base away from the first end of the filter media and having second end cap coupling features defined on a radial inner surface thereof. The filter assembly comprises a reservoir having reservoir coupling features defined at an end thereof proximate to the housing. The reservoir coupling features engage the second end cap coupling features so as to couple the reservoir to the second end cap.

[0007] In another set of embodiments, a filter element comprises a filter media, a first end cap coupled to a first end of the filter media, and a second end cap coupled to a second end of the filter media opposite the first end. The second end cap comprises a base, the second end of the filter media coupled to the base, a first circumferential wall extending from a radial outer edge of the base towards the first end of the filter media, and a second circumferential wall extending from the radial outer edge of the base away from the first end of the filter media and having second end cap coupling features defined on a radial inner surface thereof, the second end cap coupling features configured to couple the second end cap to a reservoir.

[0008] 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 in this disclosure are contemplated as being part of the subject matter disclosed herein.

Brief Description of Drawings

[0009] 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.

[0010] FIG. 1 is a side cross-section view of a filter assembly including a filter element disposed in a filter housing, according to an embodiment.

[0011] FIG. 2 is a top perspective view of a second end cap coupled to a filter media of the filter element of FIG. 1.

[0012] FIG. 3 is a bottom perspective view of the second end cap of FIG. 2.

[0013] FIG. 4 is another side perspective view of the filter assembly of FIG. 1 showing a flow path of a fluid through the filter element.

[0014] FIG. 5 is a side cross-section view of a portion of the filter assembly of FIG. 1 indicated by the arrow A in FIG. 4.

[0015] FIG. 6 is a side cross-section view of a portion of the second end cap of FIG. 2 indicated by the arrow B in FIG. 2.

[0016] FIG. 7 is a top perspective view of a lock ring disposed in the filter assembly of FIG.

1, according to an embodiment.

[0017] FIG. 8 is still another side cross-section view of the filter assembly of FIG. 1 showing a hydrophobic screen disposed in a central channel of the filter media of the filter element of FIG. 1, according to an embodiment. [0018] FIG. 9 is a side perspective view of a filter housing that may be used in the filter assembly of FIG. 1, according to another embodiment.

[0019] FIG. 10 is a side cross-section view of a portion of the filter housing of FIG. 9 taken along the line A-A indicated in FIG. 9.

[0020] FIG. 11 is side cross-section view of a portion of a filter assembly that includes the filter housing of FIG. 9 with the filter element of FIG. 1 disposed therein, according to a particular embodiment.

[0021] FIG. 12 is a schematic flow diagram of a method for forming a filter element, according to an embodiment.

[0022] FIG. 13 is a schematic flow diagram of a method for forming a filter assembly, according to another embodiment.

[0023] 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. The illustrative implementations described in the detailed description, drawings, and claims are not meant to be limiting. Other implementations may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented here. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the figures, can be arranged, substituted, combined, and designed in a wide variety of different configurations, all of which are explicitly contemplated and made part of this disclosure.

Detailed Description

[0024] Embodiments described herein relate generally to filter assemblies that include a filter element having a filter media and an end cap coupled to the filter media that includes coupling features for coupling the end cap to a reservoir, and anti-rotation features to rotationally lock the filter element to a filter housing in which the filter element is disposed. [0025] Various filter assemblies comprise a filter element positioned within a filter housing, such as a shell housing. Such filter assemblies generally have multiple parts to secure the filter element within the filter housing including, for example, spring, coupling elements, or other elements which increase the manufacturing complexity and cost of the filter assembly.

[0026] Embodiments of the filter elements and filter assemblies including such filter elements described herein provide one or more advantages including, for example: 1) providing coupling features such as threads on an end cap of a filter element, thereby obviating the use of a separate component including coupling threads; 2) providing anti-rotation features in end caps and corresponding features in a housing such that separate anti-rotation components are not used; 3) providing flexibility of over molding a sealing member on the end cap or providing a separate sealing member around the end cap; 4) allowing removal of a biasing member from the filter assembly; 5) providing a hydrophobic screen formed into a tube and coupled to the end cap such that a separate over molded component is not used; and 6) reducing manufacturing complexity and cost via elimination of various components from the filter assembly.

[0027] FIG. 1 is a side cross-section of a filter assembly 100 according to an embodiment.

The filter assembly 100 may be used to filter a liquid (e.g., lubricant, fuel, etc.) or another fluid provided to an engine. The filter assembly 100 comprises a filter housing 102, a filter element 110 comprising a filter media 120, a first end cap 114, a second end cap 130, and a reservoir 105.

[0028] The filter housing 102 defines a filter housing internal volume within which the filter element 110 is positioned. The filter housing 102 may be formed from a strong and rigid material, for example plastics (e.g., polypropylene, high density polyethylene, polyvinyl chloride, etc.), metals (e.g., aluminum, stainless steel, etc.), polymers (e.g., reinforced rubber, silicone) or any other suitable material. In particular embodiments, the filter housing 102 may comprise a cylindrical housing having generally a circular cross-section. In other embodiments, the filter housing 102 may have any suitable cross-sectional shape, for example racetrack, oval, rectangular, polygonal, etc. In particular embodiments, the filter housing 102 may comprise a shell housing. [0029] A reservoir 105 is coupled to the filter element 110 as described herein. The reservoir 105 has a bowl shape, for example, to collect any water separated from the fluid being filtered through the filter assembly 100. For example, FIG. 4 shows a flow path of fluid through the filter element 110 and collection of water in the reservoir 105 that is separated from the fluid by hydrophobic screen 118 included in the filter assembly 100. A drain port 128 may be provided in the reservoir 105. A drain plug 121 may be coupled to the drain port 128. The drain plug 121 may be selectively removed from the drain port 128 so as to allow accumulated water to be drained from the reservoir 105. In some embodiments, the reservoir 105 may be formed from a transparent or translucent material (e.g., transparent or translucent plastic) such that a level of water collected in the reservoir 105 may be observable by a user from outside of the reservoir 105.

[0030] In some embodiments, a water-in-filter (WIF) sensor 126 may be positioned in the reservoir 105 and connected to a controller (e.g., WIF monitor an engine control unit) via an electrical connector. The WIF sensor 126 may be configured to sense a level of water accumulated in the reservoir. In some embodiments, the WIF sensor 126 may communicate a water level signal to a controller. The controller may inform a user that a water level in the reservoir 105 is above a predetermined threshold, so that the user may remove the drain plug 121 and drain the water from the reservoir 105 via the drain port 128. In other embodiments, a valve 129 may be positioned in the drain port 128. The WIF sensor 126 may be configured to communicate a valve signal to the valve 129, causing the valve 129 to move into an open position in response to a level of water accumulated in the reservoir 105 exceeding a predetermined threshold.

[0031] The reservoir 105 includes reservoir coupling features 127 defined at an end thereof proximate to the filter housing 102 and configured to be coupled to the second end cap 130 of the filter element 110, as described in further detail herein. The reservoir coupling features 127 may include threads defined an outer surface of the walls of the reservoir 105 that project towards the filter housing 102. In other embodiments, the reservoir coupling features 127 may include a snap-fit mechanism, slots, protrusions, indents, detents or any other suitable coupling features. [0032] In some embodiments, the filter housing 102 also includes a housing ledge 103 (e.g., a circumferential ledge) extending radially inwards from a filter housing second end 108 proximate to the reservoir 105. Furthermore, the reservoir 105 comprises a reservoir ledge 106 (e.g., a circumferential ledge) protruding radially outwards from an outer surface of the reservoir 105 such that when the reservoir 105 is coupled to the second end cap 130, the reservoir ledge 106 is disposed axially adjacent to the housing ledge 103, for example, abuts the housing ledge 103.

[0033] In some embodiments, a third sealing member 107 (e.g., an O-ring or gasket) is disposed between the reservoir ledge 106 and the housing ledge 103 and forms an axial seal therebetween. For example, a circumferential groove may be defined in the reservoir ledge 106 and a portion of the third sealing member 107 disposed therein.

[0034] The filter element 110 is positioned along a longitudinal axis AL of the filter assembly 100 within the filter housing internal volume. The filter element 110 comprises the filter media 120. The filter media 120 includes a porous material having a predetermined pore size and is configured to filter particulate matter from the fluid flowing therethrough. The filter media 120 or any other filter media described herein may include pleated media, tetrahedral media, fluted filter media, corrugated filter media or variations thereof. U.S. Patent No. 8,397,920, entitled “PLEATED FILTER ELEMENT WITH TAPERING BEND LINES,” by Moy et al., filed on October 14, 2011, and issued on March 19, 2013, assigned to Cummins Filtration IP Inc., describes various embodiments of such tetrahedral filter media. Some configurations of tetrahedral filter media include a plurality of inlet tetrahedron flow channels and a plurality of outlet tetrahedron flow channels. The inlet tetrahedron merge in a central portion of the filter material thereby allowing axial cross-flow of fluid between the inlet tetrahedron channels prior to the fluid passing through the filter media. Such an arrangement provides for additional particulate loading on the upstream side of the media, which increases filter capacity.

[0035] In some embodiments, the filter media 120 may be caged. For example, the filter element 110 may also comprise a porous rigid structure (e.g., a wire mesh) positioned around the filter media 120, which is structured to prevent damage to the filter media 120 during insertion of the filter element 110 into the filter housing internal volume. [0036] A center tube 116 may be positioned axially within a central channel defined by the filter media 120, for example, the filter media 120 may be positioned around a center tube 116. In particular embodiments, the center tube 116 may be included in the filter element 110, for example, the filter media 120 may be wound around or otherwise coupled to the center tube 116. The center tube 116 defines a center tube channel in fluid communication with a fluid outlet 125 through which filtered fluid is delivered out of the filter housing 102. The center tube 116 may define a plurality of openings 117 structured to allow the filtered fluid to flow through the filter media 120 into the center tube 116 and therefrom to the fluid outlet 125.

[0037] A first end cap 114 is coupled to a filter media first end of the filter media 120 distal from the reservoir 105, for example, bonded thereto via an adhesive. In some embodiments, a nut plate 170 is positioned in the filter housing internal volume proximate to a filter housing first end 104. The nut plate 170 comprises a generally circular member positioned radially around the longitudinal axis AL and having a diameter or cross-section corresponding to diameter or cross-section of the filter housing 102. The nut plate 170 comprises a nut plate outer portion 171 positioned proximate to a sidewall of the filter housing 102. In some embodiments, threads may be defined on an edge of the nut plate outer portion 171 of the nut plate 170. The threads may be configured to mate with mating threads defined on an inner surface of the sidewall of the filter housing 102 proximate to the filter housing first end 104. In other embodiments, the edge of the nut plate outer portion 171 may be welded to the inner surface of the filter housing 102.

[0038] A plurality of through holes 172 are defined in the nut plate outer portion 171. The plurality of through holes 172 may be configured to allow the fluid to be communicated therethrough into the filter housing internal volume around the filter media 120. As shown in FIG. 4, the fluid flows radially through the filter media 120 into the central channel defined by the filter media 120, and is thereby filtered. The nut plate 170 also comprises a nut plate inner portion 174. The nut plate inner portion 174 is positioned on the filter element 110 and may be configured to secure the filter element 110 in the filter housing 102.

[0039] Expanding further, an interfacial sealing member 122 may be positioned on or coupled to the first end cap 114. The interfacial sealing member 122 may be formed from a soft polymeric material, for example, rubber or polymers. In particular embodiments, the interfacial sealing member 122 may be monolithically formed with the first end cap 114 (e.g., molded therewith).

[0040] As shown in FIG.1, the nut plate inner portion 174 is structured to contact the interfacial sealing member 122. The filter element 110 is locked in place via locking features defined in the second end cap 130, as described in further detail herein. Thus, the interfacial sealing member 122 is pressed against the nut plate inner portion 174 so as to form a fluid tight seal therewith and prevent unfiltered fluid from entering the central channel defined by the filter media 120.

[0041] A nut plate conduit 176 extends axially from an inner rim of the nut plate inner portion 174 away from the filter element 110. The nut plate conduit 176 is configured to receive an outlet conduit 162 of a filter head 160 to which the filter assembly 100 may be removably coupled, and configured to allow filtered fluid to be communicated from the fluid outlet 125 out of the filter assembly 100 into the outlet conduit 162. The filter head 160 may include, for example, a receiving structure of a system (e.g., an engine or a vehicle) structured to allow mounting of the filter assembly 100 thereto. The filter head 160 also includes one or more inlet conduits 164 configured to communicate unfiltered fluid to the filter assembly 100 and receive filtered fluid therefrom (e.g., via the outlet conduit 162). A plurality of threads may be defined on an inner surface of the nut plate conduit 176 and configured to mate with mating threads defined on an outer surface of the outlet conduit 162 of the filter head 160. This may allow coupling of the filter assembly 100 to the filter head 160.

[0042] The second end cap 130 is coupled to a filter media second end of the filter media 120 opposite the filter media first end proximate to the reservoir 105. Referring to FIGS. 2-7, the second end cap 130 comprises a base 132 disposed radially about the longitudinal axis AL. The second end of the filter media 120 is coupled to the base 132, for example, bonded thereto via an adhesive or fusion bonded thereto.

[0043] The second end cap 130 comprises a first circumferential wall 134 extending from a radial outer edge of the base 132 towards the filter media first end, i.e., towards the first end cap 114. A second circumferential wall 136 extends from the radial outer edge of the base 132 away from the filter media 120. Second end cap coupling features 137 are defined on a radial inner surface thereof and engage the reservoir coupling features 127 so as to couple the reservoir to the second end cap 130. As shown in FIGS. 1 and 3, the second end cap coupling features 137 include threads, and the reservoir coupling features 127 include mating threads. In other embodiments, the second end cap coupling features 137 and the corresponding reservoir coupling features 127 include snap-fit features, protrusions, indents, detents, slots, or any other suitable coupling features.

[0044] In some embodiment, the second end cap 130 further comprises a first sealing member 133 disposed circumferentially around an outer surface of the first circumferential wall 134 as shown in FIGS. 2-3. In other embodiments, the first sealing member 133 may be disposed around an outer surface of the second circumferential wall 136 or at an interface of the first circumferential wall 134 and the second circumferential wall 136. The first sealing member 133 forms a radial seal with an inner surface of the filter housing 102 to prevent unfiltered fluid to flow around the filter element 110. In some embodiments, the first sealing member 133 comprises a lip seal over molded onto the second end cap 130. In other embodiments, the first sealing member 133 comprises an O-ring disposed around the outer surface.

[0045] A plurality of slots 135 are defined at predetermined locations on an outer surface of the second circumferential wall 136 and configured to receive corresponding protrusions defined on an inner surface of the filter housing 102 or in a lock ring disposed in the filter housing 102. For example, referring to FIGS. 5-7, in some embodiments, a lock ring 140 may be disposed circumferentially within the filter housing 102 and couple to a filter housing second end 108 (e g., welded, bolted, threaded, or snap-fit thereto) proximate to the second end cap 130. The lock ring 140 includes a plurality of protrusions 145 extending from the lock ring 140 towards second end cap 130. For example, the lock ring 140 may be stamped or molded to form the protrusions 145 thereon.

[0046] As shown in FIGS. 2-7, the plurality of slots 135 are defined on the outer surface of the second circumferential wall 136, and the plurality of protrusions 145 are disposed in corresponding slots 135 of the plurality of slots 135 and configured to prevent rotation of the filter housing 102 relative to the filter element 110. Furthermore, each protrusion 145 may also limit axial displacement of the filter element 110 away from the filter head 160. Each slot 135 may include a flared inlet 139 having inclined sidewalls that flare out from an end of the slot towards an axial edge of the second circumferential wall 136 such that a first end of the flared inlet 139 axially distal from the corresponding slot 135 has a larger width than a second end of the flared inlet 139 proximate to the corresponding slot 135. The flared inlet 139 guides a corresponding protrusion 145 into a corresponding slot 135 so as to facilitate insertion of the filter element 110 into the filter housing 102.

[0047] A plurality of protrusions may be defined on an inner surface of a filter housing such that the lock ring 140 may be excluded. For example, referring to FIGS. 9-11, a filter housing 202 according to another embodiment is shown. The filter housing 202 includes a housing ledge 203 extending radially inwards therefrom from an end thereof located proximate to the reservoir 105. A plurality of housing protrusions 245 extend from an inner surface of the filter housing 202 towards the second circumferential wall 136 are inserted into corresponding slots 135 to prevent rotation of the filter housing 202 relative to the filter element 110. Thus, the lock ring 140 is excluded from a filter assembly including the filter housing 202.

[0048] Furthermore, in some embodiments, the first sealing member 133 disposed on the outer surface of the second end cap 130 may be excluded. Instead, a second sealing member 246 is disposed between the filter housing 202 and the second circumferential wall 136 proximate to the reservoir 105. The second sealing member 246 forms a radial seal between an inner surface of the filter housing 202 and an outer surface of the second circumferential wall 136. In some embodiments, the second sealing member 246 comprises a rectangular gasket. In other embodiments, the second sealing member 246 may comprise an O-ring.

[0049] In some embodiments, the filter assembly 100 may include a hydrophobic screen (e.g., a porous mesh formed from a hydrophobic material or having a hydrophobic coating disposed thereon) disposed within the center tube 116 and configured to separate water from the fluid flowing therethrough. The separated water is collected in the reservoir 105 and can be removed through the drain port 128 by the user by removing the drain plug 121 from the drain port 128.

In some embodiments, as shown in FIG. 4 a porous tube, for example, a screen mounting tube 180 (e.g., plastic molded tube) is disposed axially within the center tube 116 and a hydrophobic screen 118 disposed therearound. The screen mounting tube 180 adds an extra component to the fdter assembly 100 and increases manufacturing complexity and cost thereof.

[0050] Referring now to FIG. 8, in other embodiments, the hydrophobic screen 118 is disposed radially within the center tube 116 and extends axially from the first end cap 114 to the second end cap 130 such that the screen mounting tube 180 is excluded from the filter assembly 100. For example, the hydrophobic screen 118 may be rolled into a tube. A first screen mounting wall 123 (e g., a circumferential wall) may extend from an inner rim of the first end cap or from the interfacial sealing member 122 towards the second end cap 130, and a first end of the hydrophobic screen 118 disposed circumferentially around the first screen mounting wall 123 (e.g., wrapped therearound). In some embodiments, the first end of the hydrophobic screen 118 may be coupled to (e.g., adhered to or potted in) the first end cap 114.

[0051] The second end cap 130 comprises a second screen mounting wall 138 (e.g., a circumferential wall) located radially inwards of the first circumferential wall 134 and projecting axially from the base 132 towards the first end cap 114. As shown in FIG. 4, a second end of the hydrophobic screen 118 is disposed circumferentially within the second screen mounting wall 138. Moreover, the second end of the hydrophobic screen 118 may be coupled to the base 132 (e.g., via an adhesive or potted therein) or to a radial inner surface of the second screen mounting wall 138. While not shown, openings may be defined into the base 132 to allow water separated from the fluid by the hydrophobic screen to be drained into the reservoir 105.

[0052] FIG. 12 is a schematic flow diagram of a method 300 for forming a filter element (e.g., the filter element 110), according to an embodiment. The method 300 includes providing a filter media, at 302. The filter media may include the filter media 120.

[0053] At 304, a first end cap is coupled to a first end of the filter media. For example, the first end cap 114 is coupled to the first end of the filter media 120. At 306, a second end cap is coupled to the second end of the filter media opposite the first end. The second end cap includes a base to which the second end of the filter media is coupled. A first circumferential wall extends from a radial outer edge of the base towards the first end, and a second

circumferential wall extends from the radial outer edge of the base away from the filter media and includes second end cap coupling features defined on a radial inner surface thereof The second end cap may include, for example, the second end cap 130.

[0054] FIG. 13 is a schematic flow diagram of another method 400 for forming a filter assembly (e.g., the filter assembly 100), according to an embodiment. The method 400 includes providing a filter element, at 402. The filter element includes a filter media (e.g., the filter media 120). A first end cap (e.g., the first end cap 114) is coupled to a first end of the filter media, and a second end cap (e.g., the second end cap 130) is coupled to a second end of the filter media opposite the first end. The second end cap comprises a base and the second end of the filter media is coupled to the base. A first circumferential wall extends from a radial outer edge of the base towards the first end, and a second circumferential wall extends from the radial outer edge of the base away from the filter media and includes second end cap coupling features defined on a radial inner surface thereof. A plurality of slots (e.g., the slots 135) may be defined on an outer surface of the second circumferential wall. The filter element may include, for example, the filter element 110 or any other filter element described herein.

[0055] At 404, the filter element is inserted into a filter housing. The filter housing may include the filter housing 102 having the lock ring 140 defining the protmsions 145, or the filter housing 202 having the plurality of protrusions 245 defined on the inner surface thereof.

Inserting the filter element into the filter housing causes the plurality or protrusions (e.g., the protrusions 145, 245) to slide into corresponding slots (e.g., the slots 135), and rotationally lock the filter element with respect to the filter housing.

[0056] At 406, a reservoir (e.g., the reservoir 105) is coupled to the second circumferential wall of the second end cap. For example, the reservoir includes reservoir coupling features (e.g., the reservoir coupling features 127) defined at an end thereof proximate to the housing, the reservoir coupling features engage the second end cap coupling features (e.g., the second end cap coupling features 137) so as to couple the reservoir to the second end cap. In some embodiments, the second end cap coupling features and the reservoir coupling features include mating threads. [0057] 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).

[0058] The terms“coupled,”“connected,” and the like as used herein mean the joining of two members directly or indirectly to one another. Such joining may be stationary (e.g., permanent) or moveable (e.g., removable or releasable). Such joining may be achieved with the two members or the two members and any additional intermediate members being integrally formed as a single unitary body with one another or with the two members or the two members and any additional intermediate members being attached to one another.

[0059] It is important to note that the construction and arrangement of the various exemplary embodiments are illustrative only. Although only a few embodiments have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter described herein. Other substitutions, modifications, changes and omissions may also be made in the design, operating conditions and arrangement of the various exemplary embodiments without departing from the scope of the embodiments described herein.

[0060] While this specification contains many specific implementation details, these should not be construed as limitations on the scope of any embodiment or of what may be claimed, but rather as descriptions of features specific to particular implementations of particular

embodiments. Certain features described in this specification in the context of separate implementations can also be implemented in combination in a single implementation.

Conversely, various features described in the context of a single implementation can also be implemented in multiple implementations separately or in any suitable subcombination.

Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.