Background

Windows are available in a wide variety of sizes and can include e.g. one or more movable sashes that can be slidably opened to allow airflow into the interior of a building. However, in many locations, the outside air may contain undesirable pollution or contaminants. It may thus be desirable to filter air that passes into a building through a window opening.

Summary

In broad summary, herein is disclosed an unpowered window air filter apparatus that comprises a first, base unit and a second, movable unit. These and other aspects will be apparent from the detailed description below. In no event, however, should this broad summary be construed to limit the claimable subject matter, whether such subject matter is presented in claims in the application as initially filed or in claims that are amended or otherwise presented in prosecution.

Brief Description of the Drawings

Fig. 1 is a perspective interior view of an exemplary unpowered window air filter apparatus, in a first, unexpanded configuration.

Fig. 2 is a perspective exterior view of an exemplary unpowered window air filter apparatus, in a first, unexpanded configuration.

Fig. 3 is a perspective interior view of an exemplary unpowered window air filter apparatus, in a second, expanded configuration.

Fig. 4 is a perspective exterior view of an exemplary unpowered window air filter apparatus, in a second, expanded configuration.

Fig. 5 is a perspective interior view of an exemplary unpowered window air filter apparatus with an interior cover of the apparatus removed from an exterior shell of the apparatus.

Fig. 6 is a perspective, interior view of an exemplary exterior shell of an unpowered window air filter apparatus, with an interior cover and air filter assembly omitted.

Fig. 7 is a perspective, partially exploded interior view of an exemplary exterior shell of an unpowered window air filter apparatus, with an interior cover and air filter assembly removed and with the shell exploded into an inner chassis and an outer shroud.

Fig. 8 is a perspective, exploded interior view of an exemplary interior cover of an unpowered window filter apparatus .

Fig. 9 is a bottom view of an exemplary unpowered window air filter apparatus.

Fig. 10 is an interior perspective view of an exemplary air filter assembly, in a second, expanded configuration.

Fig. 11 is an interior perspective view of the exemplary air filter assembly of Fig. 10, in a first, unexpanded configuration.

Fig. 12 is an interior perspective view of an exemplary one-way brake. Fig. 13 is another interior perspective view of the exemplary one-way brake of Fig. 12.

Fig. 14 is an interior perspective view of an exemplary unpowered window air filter apparatus installed in a horizontal sash window.

Like reference numbers in the various figures indicate like elements. Some elements may be present in identical or equivalent multiples; in such cases only one or more representative elements may be designated by a reference number but it will be understood that such reference numbers apply to all such identical elements. Unless otherwise indicated, all figures and drawings in this document are not to scale and are chosen for the purpose of illustrating different embodiments of the invention. In particular the dimensions of the various components are depicted in illustrative terms only, and no relationship between the dimensions of the various components should be inferred from the drawings, unless so indicated.

As used herein as a modifier to a property or attribute, the term "generally", unless otherwise specifically defined, means that the property or attribute would be readily recognizable by a person of ordinary skill but without requiring a high degree of approximation (e.g., within +/- 20 % for quantifiable properties). The term "substantially", unless otherwise specifically defined, means to a high degree of approximation (e.g., within +/- 10% for quantifiable properties). The term "essentially" means to a very high degree of approximation (e.g., within plus or minus 2 % for quantifiable properties). It will be understood that the phrase "at least essentially" subsumes the specific case of an "exact" match. However, even an "exact" match, or any other characterization using terms such as e.g. same, equal, identical, uniform, constant, and the like, will be understood to be within the usual tolerances or measuring error applicable to the particular circumstance rather than requiring absolute precision or a perfect match. All references herein to numerical parameters (dimensions, ratios, and so on) are understood to be calculable (unless otherwise noted) by the use of average values derived from a number of measurements of the parameter.

Detailed Description

Glossary

The following terminology is used in describing a window air filter apparatus that can be installed in a sash window of a building:

Terms such as interior and exterior and the like are defined with respect to the window and building; interior means toward a room in which window the air filter apparatus is installed; exterior means away from the room. By way of specific example, an interior side of the window air filter apparatus faces toward a room of the building; an exterior side of the window air filter apparatus faces away from the room and is in contact with environmental air that is desired to be filtered as it passes into the room.

Terms such as inside, outside, inward, outward, and the like, are defined with respect to the air filter apparatus; terms such as inward, inside, and the like denote a direction toward the geometric center of the air filter apparatus. Terms such as outward, outside and the like denote a direction away from the geometric center of the air filter apparatus.

The term longitudinal denotes a direction (L) along the long axis of an air filter apparatus. As installed in a sash window, the longitudinal axis of the air filter apparatus will be orthogonal to the direction of slidable movement of a movable sash of the sash window. In the case of a horizontal sash window (in which case the movable sash is movable back and forth in a horizontal direction with respect to the Earth), the longitudinal direction of the apparatus will be at least generally aligned with the vertical direction with respect to the Earth. The transverse direction (T) of an air filter apparatus is orthogonal to the longitudinal direction of the apparatus and is at least generally aligned with the direction of slidable movement of a movable sash in a window in which the apparatus is installed. The transverse direction can be considered to be the "width" direction of the apparatus as installed. The thickness direction (Th) of an air filter apparatus is orthogonal to the longitudinal direction of the apparatus and is orthogonal to the transverse direction of the apparatus. As installed in a sash window, the thickness direction of the apparatus is at least generally aligned with an interior-exterior axis of the window. The longitudinal direction (L), the transverse direction (T), and the thickness direction (Th) are shown for an exemplary air filter apparatus installed in a horizontal sash window in Fig. 14.

Terms such as upper, lower, upward, downward, above, below and the like are applied to an air filter apparatus installed in a horizontal sash window with the longitudinal axis of the apparatus being at least generally vertically aligned relative to the Earth, and have their customary meaning.

Disclosed herein is an unpowered window air filter apparatus 10, comprising a first, base unit 20 and a second, movable unit 60. The second, movable unit 60 is reversibly slidably movable back and forth relative to the first, base unit 20 between at least a first, unexpanded configuration and a second, expanded configuration. Apparatus 10 is configured to be self-retaining in the second, expanded configuration (including any partially expanded configuration) as discussed in detail later herein. The apparatus includes an air filter media assembly 250 that comprises an air filter media that includes at least one reversibly expandable and contractible section 256 that allows second, movable unit 60 to be reversibly moved back and forth relative to first, base unit 20 between at least the first, unexpanded configuration and a second, expanded configuration.

An exemplary apparatus 10 is shown in a first, unexpanded configuration in interior view (i.e., a view from within a room in a window of which the apparatus is installed) in Fig. 1 and in exterior view (i.e., a view from outside a room in a window of which the apparatus is installed) in Fig. 2. Apparatus 10 is shown in a second, expanded configuration in interior view in Fig. 3 and in exterior view in Fig. 4.

Apparatus 10 is an unpowered air filter apparatus. By unpowered is meant that apparatus 10 does not include any kind of powered fan, blower, or the like, that can cause air to be drawn against and/or pulled through the air filter media 250. In particular embodiments, apparatus 10 does not include any kind of component (whether a sensor, indicator, light, and so on) that is powered by any external or internal electric power source.

Apparatus 10 comprises a housing that defines an interior space therein, which interior space contains a filter assembly 250. The housing of apparatus 10 is collectively provided by a first, base unit 20 and a second, movable unit 60 that is movable with respect to first, base unit 20 as noted above. In some embodiments, first base unit 20 is collectively provided by a chassis 19 (most easily seen in Fig. 7) in combination with an interior cover 18 (most easily seen in Fig. 8). Interior cover 18 may be removably attachable to chassis 19 by way of at least one latch 35. In some embodiments, second, movable unit 60 is collectively provided by a shroud 59 (most easily seen in Fig. 7) in combination with an interior cover 58 (most easily seen in Fig. 8). Interior cover 58 may be removably attachable to shroud 59 by way of at least one latch 77. Shroud 59 is mated (e.g., snap-fitted) to chassis 19 so that shroud 59 is reversibly, slidably movable back and forth (up and down, in the view of Fig. 7) relative to chassis 19. Interior cover 58 of movable unit 60 is likewise mated (e.g., snap-fitted) to interior cover 18 of base unit 20 so that cover 58 is reversibly, slidably movable back and forth (up and down, in the view of Fig. 8) relative to cover 18. Chassis 19 and shroud 59 combine to provide an exterior shell 17 of apparatus 10 as seen e.g. in Fig. 6 (which shell may also provide transverse sidewalls that provide transverse sides of apparatus 10); interior covers 18 and 58 of units 20 and 60 combine to collectively provide an interior cover 16 of apparatus 10 as seen e.g. in Fig. 5.

In summary, chassis 19 and interior cover 18 may collectively provide first, base unit 20; shroud 59 and interior cover 58 may collectively provide second, movable unit 60, with these components combining to provide the housing of apparatus 10. Interior cover 58 is mated to interior cover 18 so as to be slidably movable relative thereto and shroud 59 is mated to chassis 19 so as to be slidably movable relative thereto. Unit 60 is thus reversibly, slidably movable relative to unit 20. In the illustrated embodiment, interior cover 58 of movable unit 60 comprises a lower (downward-extending) portion 76 that comprises rails 79 as visible in Fig. 8. Rails 79 of interior cover 58 of movable unit 60 may be e.g. slidably mated to rails 31 of base unit 20. This can mate interior cover 58 of movable unit 60 to interior cover 18 of base unit 20 (to provide interior cover 16 of apparatus 10) in a manner that allows cover 58 to be reversibly, slidably movable back and forth (up and down, in the view of Fig. 8) relative to cover 18.

As noted, in some embodiments a chassis 19 and a shroud 59 may combine to provide an exterior shell 17 of apparatus 10. In the illustrated embodiment of Fig. 7, shroud 59 is mated to chassis 19 so that an exterior-facing side 82 of shroud 59 is positioned exteriorly of a substantial portion of the exterior- facing side of chassis 19 (excepting e.g. a small, lowermost portion 24 of the exterior-facing side of chassis 19 that is located vertically below shroud 59). Shroud 59 may be mated to chassis 19 to additionally provide that transverse sides 66 of shroud 59 are positioned transversely outwardly of transverse sides 26 of chassis 19. Chassis 19 may comprise a lower portion and an upper portion as can be seen in the interior view of Fig. 7. In some embodiments, such portions of chassis 19 may be integral with each other, meaning that they are of the same composition and were made together as a single piece, at the same time in the same operation (e.g., an injection molding operation). In other embodiments, such portions may be made separately and then attached together in the manufacturing of apparatus 10. Shroud 59 of movable unit 60 may similarly comprise an upper portion 75 and a lower portion 65 as can be seen in Fig. 7. Portions 75 and 65 may be integral with each other, or may be separately made and attached together.

The exterior-facing side of chassis 19 may comprise openings 41 to admit exterior air therethrough; such openings may be protected e.g. by louvers 42. Openings 41 may be provided along at least about 70, 80, 85, 90, or 95 % of the elongate (vertical) length of chassis 19. Similar openings 70, similarly protected by louvers 71, may be provided e.g. in upper portion 75 of shroud 59. However, if desired, a smaller number (e.g., one) of larger openings 72 may be provided in lower portion 65 of shroud 59. Such an opening or openings may not need to necessarily be protected by louvers of shroud 59, since louvers 42 of chassis 19 may inwardly underlie opening(s) 72 of shroud 59. It will be appreciated that when apparatus 10 is in e.g. an unextended configuration, the louvered windows 70 of shroud 59 and the louvered windows 41 of chassis 19 may overlap each other e.g. in upper portion 25 of chassis 19. In such a case, louvers 42 of chassis 19 may be inwardly-protruding louvers (as in the exemplary embodiment of Fig. 7). Louvers 71 of shroud 59 may then be outwardly-protruding louvers, which may allow the exterior wall of shroud 59 to be positioned very close to the exterior-facing wall of chassis 19 e.g. if it is desired to save space. (In embodiments in which space is not a particular consideration, louvers 71 of shroud 59 may be inwardly-protruding louvers.)

Chassis 19 and shroud 59 may each comprise a main body made e.g. of molded plastic. Interior covers 18 and 58 may likewise be made e.g. of molded plastic. Various additional components (e.g. one or more handles, resilient layers, fittings, brakes, speed limiters, and so on, as disclosed later herein) may be attached to any one of these items, or may be molded integrally therewith as in the case of e.g. handles.

Base unit 20 and movable unit 60 may each exhibit a longitudinal axis and a transverse axis, the longitudinal axis of the base unit and the longitudinal axis of the movable unit being aligned with each other so as to define a longitudinal axis (L) of the unpowered window air filter apparatus 10, as shown in Fig. 14. In many embodiments, the direction along which movable unit 60 is reversibly slidably movable relative to base unit 20 is at least substantially aligned with the longitudinal axis (L) of the unpowered window air filter apparatus, as will be evident from e.g. Figs 1 and 3. In various embodiments, apparatus 10 may exhibit an expansion ratio (defined as the total length (along the longitudinal axis of apparatus 10) of apparatus 10 when fully expanded, divided by the total length of apparatus 10 when fully unexpanded) of at least about 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, or 1.8.

When apparatus 10 is in an unexpanded configuration, the interior (i.e., room-facing) side of apparatus 10 may be provided by interior cover 18 of base unit 20 and by interior cover 58 of movable unit 60, as shown e.g. in Fig. 1. When apparatus 10 is in an expanded configuration, the interior side of apparatus 10 may be provided by these covers as well as by a lower portion 76 of interior cover 58 of movable unit 60 that becomes exposed upon unit 60 being moved upward relative to interior cover 18 of base unit 20.

When apparatus 10 is in an unexpanded configuration, the exterior side (that faces e.g. outside into the environment) of apparatus 10 may be provided by upper portion 64 of exterior side 82 of movable unit 60, by the smaller, lowermost portion 24 of the exterior side 44 of base unit 20, and by a lower portion 36 of the exterior side 44 of base unit 20 that may be exposed e.g. through window 72 of movable unit 60 (all as seen in Fig. 2). When movable unit 60 is moved upward to place apparatus 10 into an expanded configuration, the portion 36 of the exterior side of base unit 20 that is exposed through window 72 of the movable unit will shift upwards, and the lowermost portion 24 of base unit 20 that is exteriorly exposed will increase in vertical size (all as seen in Fig. 4).

The exterior side of apparatus 10 may be exposed to environmental conditions such as rain, snow, hail, windblown debris, and so on. Accordingly, it will be appreciated that the design of apparatus 10, in which the exteriorly-exposed walls of apparatus 10 are protected by e.g. louvers regardless of the amount to which the units are expanded, can help to minimize or prevent the entry of e.g. rain or snow into apparatus 10. In some embodiments, the louvers 71 of shroud 59 and/or the louvers 42 of chassis 19 may be adjustable e.g. so that they can be fully opened in fair weather and may be partly or even completely closed e.g. during foul weather.

The arrangements disclosed herein can allow apparatus 10 to have a very small thickness dimension (that is, the dimension (Th) that extends interiorly-exteriorly, as shown in Fig. 14). It will be appreciated that this can advantageously provide that apparatus 10, when installed in an opening of a window, does not protrude very far out the window and thus will not interfere with e.g. a window screen, shutter, or the like, that might be present exteriorly of the window.

This property can be characterized by means of an aspect ratio, which is defined as the ratio of the longitudinal length of the unpowered window air filter apparatus to the interior-exterior thickness of the unpowered window air filter apparatus. In various embodiments, when the movable unit is in the first, unexpanded configuration, the aspect ratio of the unpowered window air filter apparatus (measured at the point of maximum thickness of the apparatus) may be at least about 6: 1, 8: 1, 10: 1, or 12: 1.

In many embodiments, apparatus 10 may exhibit a tapered shape when viewed along the longitudinal axis of apparatus 10 (as is evident in the bottom view of Fig. 9). This may be provided by way of base unit 20 comprising first and second transverse sides 26 (provided e.g. by first and second sidewalls 38 of chassis 19) that are tapered inwardly toward each other so that they are spaced further apart from each other at a position proximate interior side 21 of the base unit, and are spaced closer to each other at a position proximate exterior side 44 of the base unit, as shown in exemplary embodiment in Fig. 7. Movable unit 60 may similarly comprise first and second transverse sides 66 (provided e.g. by first and second sidewalls 78 of shroud 59) that are tapered inwardly toward each other so that they are spaced further apart from each other at a position proximate interior side 61 of the movable unit, and are spaced closer to each other at a position proximate exterior side 82 of the movable unit. It will be appreciated that such a tapered shape of apparatus 10 can provide that when air filter apparatus 10 is installed in an opening of a sash window with the narrower end facing exteriorly and the wider end facing interiorly (as in Fig. 14), one transverse wall of apparatus 10 will abut a stationary jamb of the window, and the other transverse wall of apparatus 10 will abut an edge of the movable sash of the window, with the wide end of the tapered apparatus being on the interior side of the window opening. This arrangement can provide that apparatus 10 is less likely to be dislodged from the opening so as to fall outside of the window.

If desired, apparatus 10 may comprise one or more edge flanges that extend in a generally transverse direction, beyond the transverse edges of the main body of apparatus 10, so as to be positioned interiorly of an interior surface of e.g. the window jamb or an edge of the movable sash. Such features can additionally minimize the likelihood of apparatus 10 being dislodged so as to fall outside of the window. Thus in some embodiments, base unit 20 (e.g., an interior cover thereof) may comprise first and second flanges 33 that respectively extend at least generally transversely beyond the first and second transverse sidewalls 38 of the base unit, at a location proximate an interior side 21 of the base unit. Movable unit 60 (e.g., an interior cover thereof) may similarly comprise first and second flanges 63 that respectively extend at least generally transversely beyond the first and second transverse sidewalls 78 of the movable unit, at a location proximate interior side 61 of the movable unit. Such flanges may be e.g. made separately and attached respectively to the main bodies of the base unit and the movable unit; or, they may be integrally molded therewith. If desired, in some embodiments apparatus 10 may include one or more retaining straps with a first end that is attached to apparatus 10 and with a second end that can be attached to a retaining device (e.g., a hook) that can be mounted e.g. on an interior wall of a room, to a portion of the window frame, or the like.

Unpowered air filter apparatus 10 can be installed into an opening of a sash window, e.g. a horizontal sash window (meaning a window in which a movable sash thereof is slidably movable in a horizontal direction, e.g. as in the exemplary window 300 of Fig. 14). With reference to Fig. 14, this can be done by moving movable sash 301 (to the left, in the view of Fig. 14) to create an opening 305 in the window that is transversely wide enough to receive apparatus 10. Apparatus 10 can then be positioned in the opening, with a lowermost surface of lower end 28 of base unit 20 resting on the upward-facing surface 313 of a bottom sill 315 of the window frame 31 1, and with a first transverse side of apparatus 10 abutted against an inward-facing surface 312 of side jamb 317 of window frame 31 1. Movable unit 60 of apparatus 10 can then be moved slidably upward (along the long axis L of apparatus 10) until an uppermost surface of upper end 68 of movable unit 60 is abutted against a downward-facing surface 314 of an upper lintel 316 of window frame 31 1. (Apparatus 10 is self-retaining in this configuration, e.g. by the use of a one-way brake as discussed later herein.) Movable sash 301 can then be slidably moved (to the right, in the view of Fig. 14) toward air filter apparatus 10 until an inward-facing face 303 of leading edge 302 of movable sash 301 is abutted against a second transverse side of air filter apparatus 10. In this manner apparatus 10 is transversely pinned in between leading edge 302 of movable sash 301 and side jamb 317; and, apparatus 10 is longitudinally pinned in between bottom sill 315 and upper lintel 316 of the window frame. Apparatus 10 can thus be securely held in place in the opening of the window.

To aid in the secure holding of apparatus 10 in place in a window opening 305, and/or to minimize any air leaks around apparatus 10, apparatus 10 can comprise resilient layers (comprised e.g. of foam rubber, or of any suitable resiliently compressible material) on various surfaces thereof. For example, a resilient layer 29 may be provided on the lower end 28 of base unit 20 e.g. so that a major surface of resilient layer 29 provides the aforementioned lowermost surface of base unit 20 that rests against the lower sill of the window frame. Similarly, a resilient layer 69 may be provided on the upper end 68 of movable unit 60 e.g. so that a major surface of resilient layer 69 provides the aforementioned uppermost surface of movable unit 60 that abuts the upper lintel of the window frame.

Resilient layers can similarly be provided on the first and second transverse sides of apparatus 10. As seen most easily e.g. in Figs. 2-4, this may be achieved by way of first and second resilient layers 67 that are provided on at least portions of the first and second transverse sides 66 of movable unit 60, in combination with first and second resilient layers 27 that are provided on at least portions of the first and second transverse sides 26 of base unit 20. Such resilient layers may extend along at least a portion of the longitudinal length of the various transverse sides. In some embodiments, resilient layers 67 of movable unit 60 may each extend at least substantially along the entire longitudinal length of movable unit 60, including a portion 74 of resilient layer 67 that extends downward along lower portion 65 of movable unit 60, as seen in Figs. 3 and 4.

In some embodiments, resilient layers 27 of base unit 20 may each include a lowermost portion located proximate the lower end 28 of base unit 20, and also a portion 37 that extends upward along an exteriormost part of transverse side 26 of base unit 20, as seen in Figs. 2-4. Such arrangements can provide that when movable unit 60 is in the first, unexpanded configuration, portion 37 of resilient layer 27 of a first transverse side 26 of base unit 20 exteriorly abuts lower portion 74 of resilient layer 67 of a first transverse side 66 of movable unit 60. Similar considerations hold for the second transverse walls of base unit 20 and movable unit 60. Such arrangements can also provide that when apparatus 10 is in an expanded configuration (whether partially or fully expanded), a resilient layer may be provided at every point along the entire longitudinal length of the first and second transverse sides of apparatus 10, as is evident from Figs. 3 and 4. This can help ensure that a sufficiently air-tight seal is provided between the entire length of the first and second transverse sides of apparatus 10, and the window jamb and the leading edge of the window sash against which the first and second transverse sides are abutted, regardless of the extent to which unit 60 is expanded relative to unit 20.

Apparatus 10 may use any suitable air filter assembly 250 comprising any suitable air filter media

255. In order to install an air filter assembly 250 in apparatus 10, interior cover 18 of base unit 20 and interior cover 58 of movable unit 60 may be removable (from chassis 19 and shroud 59), e.g. by unlatching latches 35 and 77. In a convenient embodiment, covers 18 and 58 can remain attached to each other during this operation so that they may be removed from chassis 19/shroud 59 as a single unit as depicted e.g. in Fig. 5. A filter media assembly 250 can then be installed within apparatus 10, after which covers 18 and 58 can be reattached to chassis 19 and shroud 59. (In alternative embodiments interior covers 18 and/or 58 may be respectively hingedly connected to base unit 20 and movable unit 60 rather than being completely separable from these units.)

As used herein, the term air filter assembly 250 broadly encompasses any piece or pieces of air filter media 255, in any suitable configuration. In some embodiments, such an air filter assembly may be provided by a piece of air filter media 255 alone (that is e.g. respectively attached at first and second ends 252 and 253 (e.g., non-corrugated ends) to first, base unit 20 and to second, movable unit 60). Or, such an assembly may take the form of a piece of air filter media that includes one or more reinforcing layers, fasteners, or the like, e.g. at end 252 and/or end 253, which may render it easier to attach these ends respectively to the first, base unit and the second, movable unit. Such a reinforcing layer 271 may be e.g. attached (e.g., laminated) to an endmost panel of a pleated air filter media as shown in exemplary embodiment in Fig. 10. In still other embodiments, such an assembly may take the form of a piece of air filter media that is mounted to a frame (which frame resides inside the housing of apparatus 10). Such a frame must of course allow the required reversible expansion/contraction of the air filter media.

Exemplary frames which may be suitable are described e.g. in U.S. Provisional Patent Application Serial No. 62/041496, entitled Window Air Filter, which is incorporated by reference in its entirety herein.

Air filter media 255 of air filter assembly 250 includes at least one section 256 (along the long axis of the media) that is e.g. pleated, crinkled, or ruffled to provide for reversible expansion and contraction of the filter media 255 to correspond with the desired length of window air filter apparatus 10 as installed in an opening in a window. In other words, such a section 256 of the filter media exhibits a readily recognizable three-dimensional shape when apparatus 10 is in an unexpanded configuration. Such a section is expandable (when unit 60 is moved toward an expanded configuration relative to unit 20) by way of the three-dimensional structure of the media being flattened toward a more planar configuration (e.g., by the at least partial unfolding of pleats) rather than by any elastomeric stretching of e.g. fibers of a fibrous air filter media. Such a section is thus by definition a non-elastomerically expandable and contractible section. In many embodiments such a non-elastomerically expandable and contractible property may be achieved by including multiple pleats in section 256 of the media, as discussed in detail below. In various embodiments, the non-elastomerically expandable and contractible section 256 of the filter media may, or may not, approach a generally or substantially planar appearance when apparatus 10 is in a maximally expanded configuration. In various embodiments non-elastomerically expandable and contractible section 256 may make up at least about 50, 60, 70, 80, 85, 90, 95, or essentially 100 % of the total length of air filter media 255. By definition, expandable and contractible section 256 of air filter media 255 does not encompass any arrangement in which e.g. a portion of an air filter media is provided along with a roller upon which it can be rolled and unrolled to decrease or increase the effective length of the filter media.

In many embodiments, filter media 255 may exhibit a rectangular shape (particularly when in a maximally-expanded configuration) with major (e.g., corrugated) edges 251 and with minor (e.g., non- corrugated) ends/edges 252 and 253. In some embodiments, a first minor end 252 of air filter assembly 250 may be removably attached (whether directly, or indirectly) to first, base unit 20 of apparatus 10; and, a second minor end 253 of assembly 250 may be likewise attached to second, movable unit 60 of apparatus 10. In particular embodiments, first end 252 of the filter media may be attached to first, base unit 20 at a location proximate the lower end 28 of unit 20, and second end 253 of the filter media may be attached to second, movable unit 60 at a location proximate the upper end 68 of unit 60. In such embodiments, the length of filter media 255 along its long axis (which long axis will be at least generally aligned with the long axis of apparatus 10) may be at least about 60, 70, 80, 85, 90, or 95 % of the total length of apparatus 10 from an upper end to a lower end thereof. In at least some embodiments, this ratio will be achieved when apparatus 10 is in a fully expanded configuration, when it is in a fully unexpanded configuration, and at all intermediate (partially-expanded) configurations in between.

In some embodiments, air filter assembly 250 may include one or more connectors 271 (located e.g. proximate one or both minor ends 252 and 253 of media 255) that facilitate the removable attachment of air filter assembly 250 to apparatus 10. Such a connector may take the form of include teeth, hooks, or any other mechanical fastening mechanism. In some embodiments, such a connector may take the form of one or more patches that are bonded (e.g., laminated) to a portion of air filter media 255 proximate a non- corrugated end thereof, which patch is configured to bond to a complementary patch provided within first, base unit 20 and/or within second, movable unit 60. For example, such a patch could be a hook patch that is bonded to filter media 255 and that can be mated with a complementary loop patch that is bonded to some portion of apparatus 10. Or, such a patch could be a loop patch that is bonded to filter media 255 and that can be mated with a complementary hook patch that is bonded to some portion of apparatus 10. In specific embodiments, a portion of air filter media 255 itself may function as a loop patch, e.g. if filter media 255 comprises a fibrous media with adequate hook-bonding characteristics. In still other embodiments, such a patch might be a pressure-sensitive adhesive patch (using e.g. a repositionable or removable adhesive) that can be adhesively attached to a surface within apparatus 10).

In embodiments of the general type illustrated in Fig. 10, a reinforcing layer 271 that is bonded (e.g., laminated) to an end panel of a pleated air filter media 255, may serve as a connecting/fastening mechanism by which the air filter assembly may be removably installed within apparatus 10. For example, a reinforcing layer 271 may be a layer of relatively stiff chipboard, which layer (along with the end panel of the pleated air filter media to which it is attached) may be inserted into receiving slots or the like that are provided within apparatus 10, so as to secure the air filter assembly in place. If desired, such a reinforcing layer may further comprise e.g. one or more die-cut holes that can receive one or more fastening protrusions of apparatus 10. Regardless of the specific mechanism of attachment, first and second minor ends 252 and 253 of filter media 255 are respectively attached to the first, base unit and the second, movable unit of apparatus 10 in such a manner that at least section 256 of filter media 255 can be reversibly expanded and contracted to facilitate the installation (and removal) of apparatus 10 from a window, without the air filter media being damaged, torn, disattached, or the like.

As noted, at least section 256 of filter media 255 is three-dimensional so that (at least when apparatus 10 is not in a fully expanded configuration) it exhibits a greater surface area than a flat sheet which occupies the same two-dimensional area. For example, the filter media can be pleated, crinkled, or ruffled, or otherwise include a suitable expanding and contracting surface area. In specific embodiments, at least portion of air filter media 255 is pleated so as to contain rows of oppositely -facing pleats. In some embodiments, the overall length of the filter media, along with parameters such as e.g. pleat spacing, pleat height, and so on, can be chosen so that when apparatus 10 is put into a maximally-expanded

configuration, filter media 255 e.g. still exhibits an appreciably pleated appearance (rather than being stretched into an essentially planar configuration).

By way of a specific example, as shown in Figs. 10 and 1 1, at least a section 256 of filter media 255 may be pleated so as to include a plurality of pleats 260 that comprise fold lines 261 and panels 264, which collectively define interior pleat tips 262 and exterior pleat tips 263. The pleating is such that the filter media can, in at least some embodiments, be reversibly and repeatedly transitioned between an expanded configuration as in Fig. 10 and an unexpanded configuration as in Fig. 1 1, with a spacing distance between successive interior pleat tips 262, and with a spacing distance between successive exterior pleat tips 263, being greater in the expanded configuration than in the unexpanded configuration. While the configurations shown in Figs. 10 and 1 1 may correspond respectively to a maximally expanded and a maximally unexpanded configuration, it will be understood that the pleated filter media 255 can be transitioned (e.g., stretched or compacted) to any of a number of different partially-expanded

configurations.

Pleats can be formed in the filter media 255 using various methods and components as are well known in the art, e.g., to form a pleated filter for use in applications such as air filtration., for example those described in U.S. Patent No. 6,740, 137 to Kubokawa et al. and U.S. Patent No. 7,622,063 to Sundet et al., the entire teachings of both of which are incorporated herein by reference. In at least some embodiments, the reversibly expandable and contractible section 256 of air filter media 255 is pleated so as to exhibit a pleat direction (Dp, as shown in Fig. 10) that is at least substantially orthogonal to the longitudinal direction of apparatus 10.

In some embodiments, the transverse width of filter media 255 can be selected to that major side edges (e.g., corrugated edges) 251 of the filter media can be positioned very close to (e.g., within about 2 mm of) the transversely inwardmost surface 43 of a transverse wall of the housing of apparatus 10 (as shown e.g. in Fig. 5), along at least about 80, 85, 90, 95, or essentially 100 % of the entire longitudinal length of the air filter media. In specific embodiments, the transverse width of filter media 255 can be chosen so that the major side edges 251 are in actual contact with a transversely inwardmost surface 43 of a transverse wall of the housing of apparatus 1 1, along at least about 80, 85, 90, 95, or essentially 100 % of the entire longitudinal length of the air filter media. Such an arrangement can minimize any air leaks that might bypass the filter media by passing around side edges 251 thereof, while still providing that the pleated media can be expanded and contracted as desired without snagging on any component of the housing. This may be enhanced by providing that inwardmost surface 43 of a transverse wall of the housing of apparatus 10 (an inwardmost surface 43 of chassis 19, in the particular embodiment of Fig. 7), is continuous, unbroken, and uninterrupted by any inwardly-protruding features (e.g., surface 43 may be essentially planar) along the entire length of surface 43 that can be contacted by a side edge of the filter media. If desired, sheets of e.g. weatherstripping or the like may be provided on the interior of portions of apparatus 10, to further minimize any ability of air to bypass the filter media.

As noted, the air filter assembly 250 can e.g. consist essentially of filter media 255 alone (as in the illustrated embodiment), or can include one or more additional components or structures applied or assembled to the filter media 255 so long as the resultant filter media assembly 250 can be reversibly and repeatedly transitioned between an unexpanded configuration and an expanded configuration. In specific embodiments, an air filter assembly 250 may comprise an air filter media 255 along with one or more support members 270 that are e.g. bonded to the pleat tips of at least one side (e.g., an interior side) of the air filter media, as shown in exemplary embodiment in Fig. 10. If present, all such support members 270 must, individually or collectively, allow the above-described expansion and contraction of filter media 255. Accordingly, in at least some embodiments such support members are elastomeric, defined as meaning that they can exhibit an elastic elongation (meaning a reversible elongation that does not involve any irreversible deformation) of at least about 20 % when apparatus 10 is in a fully expanded

configuration. In particular embodiments, an air filter assembly 250 may comprise a number of support members 270, each with a long axis that is aligned with the long axis of the pleated filter media and with the long axis of apparatus 10, each support member being elastically elongatable along its long axis, to an elongation of at least about 30 %, 40 %, 50 %, 75 %, or 100 % when apparatus 10 is in a fully expanded configuration. In various embodiments, support members 270 can take the form of e.g. strips, filaments, and the like. Such support members may be oriented e.g. parallel to each other, or may be more or less randomly oriented with respect to each other. In at least some embodiments, such support members are bonded to pleat tips but are not bonded to pleat panels within the pleat valleys. Such support members may extend along at least about e.g. 60 %, 70 %, 80 %, 90 %, 95 %, or essentially 100 % of the longitudinal length of the pleated air filter media.

In some embodiments, a pleated filter media can include a support layer that is pleated along with the media and that thus may be in contact with pleat panels within pleat valleys as well as being in contact with pleat tips (such a support layer may be in addition to, or in place of, the above-described support members 270). Such a support layer may take the form of e.g. an open wire mesh, a porous non-woven, and so on, that is e.g. adhesively bonded, thermally bonded, or the like, to the filter media. Any such support members and/or pleated support layers, may be provided e.g. on an interior side of the pleated filter media, on an exterior side of the pleated filter media, or on both sides. Any such member(s) or layer(s)s, whether pleated or unpleated, must not interfere with the ability to expand and contract the pleated media. Such a member or layer is thus distinguished from e.g. materials such as certain wire screens and the like that are used as stiffeners for the specific purpose of stabilizing pleats in a particular configuration.

Filter media 255 may be any suitable filter media, chosen from e.g. fiberglass, fibrous polymeric webs, and so on. In some embodiments, an electrostatic charge is optionally imparted into or on to material(s) of filter media 255. In other words, an electrostatically charged media may be used, of which many grades are available, and many of which offer high efficiency with low pressure drop. Thus, the filter media can be, or include, an electret nonwoven web. Electric charge can be imparted to the filter media in a variety of ways as is well known in the art, for example by hydrocharging, corona charging, etc. In other embodiments, the filter media is not electrostatically charged. Additional multi-functional media grades, which incorporate activated carbon or other materials for purifying gas-phase pollutants, may also be incorporated into a layer of the filter media. The filter media can be constructed, for example, from nonwoven fibrous media formed of thermoplastics or thermosetting materials such as

polypropylene, linear polyethylene and polyvinyl chloride. Other suitable, non-limiting materials for the filter media include porous foams, nonwovens, papers, fiberglass, or the like. In some embodiments, the filter media comprises a filter media that captures dust, allergens such as pollen and mold spores, and fine-particle pollutants, from the outdoor air. The filter media may be a single layer; or it may be a multilayer media comprised of multiple layers that serve various functions (e.g., it may include any or all of a primary particle-filtering layer, a coarse pre-filtering layer, and a gas or vapor absorbing layer).

Regardless of the particular composition of air filter media 255, media 255 by definition does not take the form of a screen that is configured primarily to keep out insects, large debris particles, and the like. (However, apparatus 10 may include one or more such screens as an additional component that is separate from, and is not attached to, the air filter media 255, as long as such a screen does not interfere with the ability to expand and contract the filter media). In some embodiments, media 255 exhibits a filtration Quality Factor of at least about 0.5, 0.8, or 1.2; in other embodiments, media 255 exhibits an average initial submicron (capture) efficiency of at least about 40, 60, 80, 90, 95, or 98 %. Filtration Quality Factor and average initial submicron efficiency can be measured according to the procedures outlined in columns 9 and 10 of US Patent No. 8029723 to Angadjivand, which disclosures therein are incorporated by reference herein for this specific purpose. It will be appreciated that the tolerances with which various components of apparatus 10 are abutted near each other and/or attached to each other may be controlled so as to minimize the number and/or amount of air leaks into apparatus 10. This may advantageously provide that little or no exterior air is able to bypass filter media 255 so as to e.g. allow unfiltered air to enter a building through apparatus 10. It will be appreciated that such tight-fitting of various components to minimize air leaks must nevertheless preserve the ability to move units 60 and 20 back and forth relative to each other as previously described. In particular, the closeness with which the various walls (e.g., transverse walls and exterior walls) of base unit 20 and movable unit 60 approach each other can be controlled to provide a tight fit in at least portions of these units. If desired, resilient layers (e.g., foam weatherstripping) can be provided e.g. between surfaces of base unit 20 and movable unit 60 at locations most advantageous to minimize air leaks.

As noted, in the installation of apparatus 10 into an opening of a window, apparatus 10 is placed into the opening e.g. with the lower end of base unit 20 resting on the window sill, and movable unit 60 is moved slidably upward (toward an expanded configuration) until the upper end of movable unit 60 is abutted against the window lintel. In many embodiments, it may be useful for apparatus 10 to include a one-way brake 150 that allows movable unit 60 to be self-retaining in such a configuration, to render the installation easier for a user. Such a one-way brake may comprise a first, engaged configuration, in which engaged configuration the brake allows movable unit 60 to move away from the first, unexpanded configuration toward the second, expanded configuration. However, in the first, engaged configuration the brake prevents the movable unit from moving away from the second, expanded configuration toward the first, unexpanded configuration. With reference to Figs. 12 and 13, such a one-way brake can allow movable unit 60 to be moved upward as desired; and, unit 60 can then be left at any desired position without it being impelled by gravity to slidably move back downward. In particular embodiments, this engaged configuration is a default configuration of brake 150, meaning that the brake is always in the engaged configuration unless a user acts to remove the brake from the engaged configuration and to actively keep the brake from returning to an engaged configuration. This can provide that a user does not have to perform any action (e.g., pushing a button, turning a lever, etc.) to release the brake in order to slidably move unit 60 upward. Nor does a user have to continuously, or intermittently, perform any such action during the process of slidably moving unit 60 upward.

In at least some embodiments, brake 150 can be actuated (e.g., manually, by a user) into a second, disengaged configuration that allows movable unit 60 to be moved reversibly back and forth (e.g., up and down) in either direction between the first, unexpanded configuration and the second, expanded configuration. Thus, brake 150 can be actuated into the second, disengaged configuration when it is desired to put apparatus 10 into an unexpanded configuration (e.g., so that apparatus 10 can be more easily removed from a window). In embodiments in which the engaged configuration of brake 150 is a default configuration, the actuation must be maintained to keep the brake disengaged in order to keep moving unit 60 toward the first, unexpanded configuration. That is, if the actuation is performed e.g. by pushing a button, the user must keep the button pushed in order to keep moving unit 60 toward an unexpanded configuration.

Brake 150 can take the form of any braking device or mechanism that can perform the above- described one-way braking when engaged, and can allow bidirectional motion when disengaged. In various embodiments, such one-way braking devices may rely on e.g. ratchets, cog wheels, and so on. However, in some embodiments, brake 150 is a non-stepwise brake, meaning that brake 150 is configured so that when the brake is in the engaged configuration the brake allows movable unit 60 to be moved away from the first, unexpanded configuration toward the second, expanded configuration, in a continuous manner (e.g. any desired amount, e.g. a fraction of a millimeter) rather than in stepwise increments. (Such a brake will also, when disengaged, allow continuous rather than stepwise motion, in either direction.)

Any suitable one-way, non-stepwise brake can be used as desired. In some embodiments, such a brake may rely on a braking member (or members) that is slotted to allow a slider bar to pass therethrough and that when in a first, engaged configuration, frictionally impinges on the slider bar so as to allow motion in one direction but not in the opposite direction. The one or more braking members can be moved to a second, disengaged configuration in which each movement in either direction is allowed. One-way, non-stepwise brakes of this general type are described in U.S. Provisional Patent Application No. xx/xxxxxx, attorney docket number 76687US002, entitled Powered Window Air Filter Apparatus, filed evendate herewith, which is incorporated by reference herein in its entirety. Any such brake can be actuated by any suitable actuator, e.g. a push-button, a handle to be turned or pulled, and so on.

In some embodiments, such a one-way, non-stepwise brake 150 is of the general type depicted in Figs. 12 and 13. Brake 150 utilizes an elongate bar 151 that extends along at least a portion of the longitudinal axis of apparatus 10 (the full extent of an exemplary bar 151 is most easily seen in Fig. 8). Bar 151 is fixedly attached to either, but not both, of base unit 20 and movable unit 60. (In the exemplary embodiments of Figs. 12 and 13, bar 151 is fixedly attached to movable unit 60 and is not fixedly attached to base unit 20.) In some embodiments, elongate bar 151 may be an integrally molded portion of movable unit 60, which portion exhibits a long axis that is aligned with the long axis (and direction of reversible expansion and contraction) of apparatus 10. In specific embodiments, a rail 79 of lower portion 76 of interior cover 58 of movable unit 60 may serve as elongate bar 151 of brake 150, as in the exemplary embodiment of Figs. 8 and 12.

Brake 150 comprises a braking cam 152 that is movably connected to the unit to which slider bar is not fixedly attached. In the depicted embodiment of Figs. 12 and 13, braking cam 152 is movably connected to base unit 20 by way of connection 164. Braking cam 152 is biased by a biasing member 159 (in this embodiment, a coil spring operating in compression against tooth 158 of cam 152) into a first, engaged position in which braking cam 152 allows bar 151 to slidably move only in a first direction (upward, in the view of Figs. 12 and 13) that allows movable unit 60 to move away from the first, unexpanded configuration toward the second, expanded configuration. In this engaged position, a contact surface 154 of a protrusion 153 of braking cam 152 impinges on a surface (e.g., a transverse surface) 165 of bar 151 so as to frictionally prevent bar 151 from moving in a second, opposite direction (downward, in the view of Fig. 12) that would allow movable unit 60 to move away from the second, expanded configuration toward the first, expanded configuration. However, the impinging of this contact surface of cam 152 on the surface of bar 151 does not prevent bar 151 from moving in the first direction.

Brake 150 comprises an actuator (a push-button 34, in the depicted embodiment) whereby a user can manually actuate brake 150 so as to move (e.g., to rotatably move) braking cam 152 away from the first, engaged position and into a second, disengaged position which allows bar 151 allowed to move freely in either direction along the longitudinal axis of the apparatus 10. In its simplest form, such movement can involve rotating cam 152 (counterclockwise, in the view of Figs. 12 and 13) so that contact surface 154 of cam protrusion 153 is no longer in contact with the surface of bar 151. Thus, while brake 150 is in a disengaged configuration, movable unit 60 can be moved reversibly back and forth relative to base unit 20, e.g. between the second, expanded configuration and the first, unexpanded configuration.

In some embodiments, contact surface 154 of cam protrusion 153 may take the form of an arcuate, resilient surface. In particular embodiments, such a surface can be a convex surface of a resilient sleeve 156 (made e.g. of rubber, silicone, or the like) that is positioned on a drum 155 that is mounted on cam 152, as shown in exemplary embodiment in Figs. 12 and 13. (Such components may be used for convenience and do not necessarily require that drum 155 is capable of rotating around its axis.) In the illustrated embodiment, button 34 can be pushed to move it slidably inwards (from the position shown in Fig. 1 1, to the position shown in Fig. 12) to actuate brake 150 into the second, disengaged configuration. Button 34 is connected to a ramp 161 that, when moved inwards, impinges on surface 163 of cam 152 so as to rotate cam 152 as described above. In the illustrated embodiment, button 34 is hingedly connected by way of connection 162 to base unit 20 of apparatus 10; however, any suitable connection can be used. As noted, one or more biasing members 159 can provide that braking cam 152 remains in the first, engaged position unless continued inward force is applied to button 34 by a user. Thus, this exemplary design provides a brake 150 in which the default configuration of the brake is an engaged configuration. While biasing member 159 is a coil spring in the depicted embodiment, any type of spring or suitable biasing member may be used.

In the above-described embodiment, bar 151 is fixedly attached to movable unit 60 and is not attached to base unit 20 (rather, brake 150 is attached to base unit 20). In an alternative embodiment, this could be reversed with bar 151 being fixedly attached to base unit 20 and with brake 150 thus being attached to movable unit 60. However, it will be appreciated that the depicted arrangement allows actuator button 34 to be positioned on base unit 20 rather than on movable unit 60, with the advantageous result that button 34 may remain more easily reachable by a user even when movable unit 60 is in its most expanded (e.g., its highest possible) position. In some embodiments, a single braking cam 152 may be used; in other embodiments, two or more braking cams 152 may be used (which may be jointly actuated by the use of e.g. a single actuator such as push-button 34).

As discussed above, in at least some embodiments movable unit 60 of apparatus 10 can be moved toward an expanded configuration, e.g. upward, and a one-way brake 150 can provide that movable unit 60 will not move back downward to any appreciable extent (even if the user lets go of movable unit 60) unless the brake is disengaged. When the brake is disengaged, movable unit 60 can then be moved downward (or allowed to move downward under the influence of gravity). In some embodiments, it may be advantageous for apparatus 10 to comprise a one-way speed limiter 160 that limits the speed at which movable unit 60 can be moved away from the second, expanded configuration toward the first, unexpanded configuration (such movement, in most uses of apparatus 10, will correspond to a downward direction relative to the Earth). However, limiter 160 will not appreciably limit the speed at which movable unit 60 can be moved away from the first, unexpanded configuration toward the second, expanded configuration (such a movement, in most uses of apparatus 10, will correspond to an upward direction).

Limiter 160 can be of any suitable design, operating by any suitable mechanism of action. In some embodiments, limiter 160 can be of the general type described in U.S. Provisional Patent

Application No. xx/xxxxxx, attorney docket number 76687US002, entitled Powered Window Air Filter Apparatus, filed evendate herewith, which is incorporated by reference herein in its entirety. Regardless of the specific configuration and components, such a limiter can provide that when one-way brake 150 is actuated to disengage the brake to allow movable unit 60 to move downward, away toward an unexpanded configuration, the limiter can ensure that the Earth's gravity does not cause unit 60 to move downward too rapidly. It will thus be appreciated that the arrangements disclosed herein can allow a user to grasp base unit 20 (e.g. by grasping either lower handle 22 or upper handle 23), and to push actuator button 34. This can allow movable unit 60 to gently descend, motivated by gravity but with the speed limited by limiter 160, without the user necessarily having to grasp any portion of movable unit 60 during this process. (To raise unit 60 to an expanded configuration, a user can of course grasp handle 22 or 23 of base unit 20 with one hand, and grasp handle 62 of movable unit 60 with the other hand to raise unit 60, since it is not necessary to push actuator button 34 in order to move unit 60 in this direction.)

If desired, a piece (e.g., an elongate length) of resilient material (e.g. foam rubber,

weatherstripping, or the like) can be inserted in between the glass of the movable sash 301, and the glass of the other (e.g., non-movable) sash 304, e.g. at location 318 of Fig. 14, in order to minimize any passage of unfiltered air through the small gap between these glass layers that may result from the window being (partly) open.

Also if desired, a window-stop may be positioned e.g. at location 319 of Fig. 14. Such a window- stop may ensure that movable sash 301 is not inadvertently moved (leftward, in the view of Fig. 14) away from its position of being abutted against a lateral side of apparatus 10. Such a window-stop may be any suitable item, e.g. a rubber wedge whose leading edge may be jammed against the trailing edge of movable sash 301, an elongate rod with one end abutted against the trailing edge of movable sash 301 and the other end abutted against the side jamb of the window frame, and so on. Either or both of such a piece or pieces of e.g. weatherstripping, and a window-stop, may be included in a kit that e.g. comprises an apparatus 10 (which may already have one filter assembly 250 installed therein) and that comprises one or more replacement filter assemblies, instructions for use, and so on.

Although discussions herein have focused on sash windows with e.g. one horizontally movable sash and with one sash that is fixed in place, it will be appreciated that apparatus 10 may easily be installed in a window that comprises two horizontally movable sashes (in such case, either sash may be chosen to be moved so as to provide a window opening in which to install apparatus 10). Moreover, although discussions herein have focused on horizontal sash windows (meaning windows with at least one movable sash that is movable in a direction that is at least generally horizontal with respect to the Earth), it will be appreciated that apparatus 10 may be easily installed in a vertical sash window (meaning a window with at least one movable sash that is movable in a direction that is at least generally vertical with respect to the Earth). In such a case, the movable sash may be moved e.g. upward to provide an opening with a vertical span sufficient to accommodate the transverse direction (the width) of apparatus 10. Apparatus 10 may then be positioned so that the "lower" end 28 of apparatus 10 abuts a first jamb of the window, and so that the "upper" end 68 of apparatus 10 abuts a second jamb of the window, and with one transverse side of apparatus 10 resting on the window sill. After this, the vertically-movable sash can then be moved downward so that its leading edge is abutted against the other transverse side of apparatus 10. (Apparatus 10 could also be installed in an opening in the upper part of a vertical sash window, rather than in an opening in the lower part.)

It will thus be appreciated that installation and use of apparatus 10 in a vertical sash window can be performed in the same manner as described herein with regard to a horizontal sash window, with apparatus 10 merely being rotated e.g. 90 degrees with respect to the Earth. It will thus be understood that the use herein of terms such as upper, lower, above, below, uppermost, lowermost, and so on, are used for convenience of description in the exemplary embodiment of installation of apparatus 10 in a horizontal sash window; it is emphasized that such language does not limit the use of apparatus 10 to horizontal sash windows.

In some embodiments, apparatus 10 may be provided with one or more magnetic attachment elements, which can be magnetically attached to one or more complementary magnetic attachment elements that are positioned at a suitable location or locations on the window frame. Such arrangements and methods are described in detail in U.S. Provisional Patent Application No. xx/xxxxxx, attorney docket number 76686US002, entitled Magnetically Attachable Window Air Filter, filed evendate herewith, the entirety of which is incorporated by reference herein. List of Exemplary Embodiments

Embodiment 1 is an unpowered window air filter apparatus, comprising: a housing comprising a first, base unit and a second, movable unit; wherein the second, movable unit is reversibly slidably movable back and forth relative to the first, base unit along a longitudinal direction of the apparatus, between at least a first, unexpanded configuration and a second, expanded configuration; and wherein the apparatus includes an air filter assembly that has a first end that is attached to the first, base unit at a location proximate a lower end of the first, base unit, and that has a second end that is attached to the second, movable unit at a location proximate an upper end of the second, movable unit, wherein the air filter assembly comprises an air filter media that includes at least one reversibly expandable and contractible section that is reversibly, non-elastomerically expandable and contractible along a direction that is aligned with the longitudinal direction of the apparatus, and wherein a longitudinal length of the air filter media is at least about 70 % of a total longitudinal length of the apparatus, whether the second, movable unit is in the first, unexpanded configuration or the second, expanded configuration.

Embodiment 2 is the unpowered window air filter apparatus of embodiment 1, wherein the base unit and the movable unit of the housing each exhibit a longitudinal axis and a transverse axis, wherein the longitudinal axis of the base unit and the longitudinal axis of the movable unit are aligned with each other so as to define the longitudinal direction of the apparatus. Embodiment 3 is the unpowered window air filter apparatus of any of embodiments 1-2 wherein the reversibly expandable and contractible section of the air filter media is a pleated section of the air filter media that exhibits a pleat direction that is orthogonal to the longitudinal direction of the apparatus. Embodiment 4 is the unpowered window air filter apparatus of embodiment 3 wherein at least about 80 % of the longitudinal length of the air filter media is pleated and wherein the longitudinal length of the air filter media is at least about 80 % of the total longitudinal length of the apparatus. Embodiment 5 is the unpowered window air filter apparatus of embodiment 4 wherein the air filter assembly comprises a pleated air filter media with at least one support member that is bonded to at least some pleat tips of the pleated air filter media and that extends along at least about 80 % of the longitudinal length of the pleated air filter media. Embodiment 6 is the unpowered window air filter apparatus of embodiment 4 wherein the air filter assembly comprises a pleated air filter media with at least one reinforcing layer bonded to at least a portion of an upper-end panel of the pleated air filter media and with at least one reinforcing layer bonded to at least a portion of a lower-end panel of the pleated air filter media.

Embodiment 7 is the unpowered window air filter apparatus of any of embodiments 1-6 wherein the air filter media exhibits first and second transverse edges that each are positioned within about 2 mm of a transversely inwardmost surface of a housing of the apparatus, along the entire longitudinal length of the air filter media. Embodiment 8 is the unpowered window air filter apparatus of any of embodiments 1- 7 wherein the air filter media is a pleated air filter media and wherein the first and second transverse edges of the air filter media are corrugated edges and wherein each corrugated edge of the air filter media is in contact with a transversely inwardmost surface of a transverse sidewall of the housing of the apparatus, along at least about 90 % of the longitudinal length of the air filter media.

Embodiment 9 is the unpowered window air filter apparatus of any of embodiments 1-8 wherein the base unit and the movable unit each comprise first and second transverse walls that are tapered inwardly toward each other so that they are spaced further apart from each other at a position proximate an interior side of the unit, and are spaced closer to each other at a position proximate an exterior side of the unit. Embodiment 10 is the unpowered window air filter apparatus of embodiment 9 wherein the base unit and the movable unit each comprise first and second flanges that respectively extend at least generally transversely beyond the first and second transverse walls of the unit, at a location proximate the interior side of the unit.

Embodiment 11 is the unpowered window air filter apparatus of embodiment 9 wherein the first and second transverse walls of the base unit each comprise a generally transversely-outwardly -facing resilient layer along at least a portion of a longitudinal length of the transverse wall, and wherein the first and second transverse walls of the movable unit each comprise a generally transversely -outwardly-facing resilient layer along at least a portion of a longitudinal length of the transverse wall; and, wherein when the movable unit is in the first, unexpanded configuration, at least a portion of the resilient layer of the first transverse wall of the base unit exteriorly abuts a lower portion of the resilient layer of the first transverse wall of the movable unit, and at least a portion of the resilient layer of the second transverse wall of the base unit exteriorly abuts a lowermost portion of the resilient layer of the second transverse wall of the movable unit. Embodiment 12 is the unpowered window air filter apparatus of any of embodiments 1-11 wherein a lowermost surface of the base unit is provided by a downwardly -facing resilient layer, and wherein an uppermost surface of the movable unit is provided by an upwardly-facing resilient layer.

Embodiment 13 is the unpowered window air filter apparatus of any of embodiments 1-12 wherein the apparatus comprises a one-way brake with a default configuration that is a first, engaged configuration, in which engaged configuration the brake allows the movable unit to move away from the first, unexpanded configuration toward the second, expanded configuration but prevents the movable unit from moving away from the second, expanded configuration toward the first, unexpanded configuration; and, wherein the brake can be actuated into a second, disengaged configuration that allows the movable unit to move reversibly back and forth in either direction between the first, unexpanded configuration and the second, expanded configuration.

Embodiment 14 is the unpowered window air filter apparatus of embodiment 13 wherein the oneway brake is a non-stepwise brake that is configured so that when the brake is in the first, engaged configuration the brake allows the movable unit to move away from the first, unexpanded configuration toward the second expanded configuration in a continuous manner rather than in stepwise increments; and, wherein the brake is configured so that when the brake is in the second, disengaged configuration, the brake allows the movable unit to move reversibly back and forth in either direction between the first, unexpanded configuration and the second, expanded configuration in a continuous manner rather than in stepwise increments.

Embodiment 15 is the unpowered window air filter apparatus of embodiment 14 wherein the one- way, non-stepwise brake comprises: an elongate bar that is attached to the upper, movable unit of the apparatus and that exhibits a long axis that is aligned with the longitudinal direction of the apparatus; and, a braking cam with a protrusion that is rotatably movable toward, and away from, a surface of the elongate bar, wherein the cam protrusion comprises a contact surface; wherein when the contact surface of the cam protrusion is in contact with the surface of the elongate bar the upper, movable unit of the apparatus is able to move in a first direction that is toward the second, expanded configuration but is not able to move in a second, opposite direction that is toward the first, unexpanded configuration; and, wherein when the contact surface of the cam protrusion is not in contact with the surface of the elongate bar the upper, movable unit of the apparatus is able to move in a first direction that is toward the second, expanded configuration and is also able to move in a second, opposite direction that is toward the first, unexpanded configuration.

Embodiment 16 is the unpowered window air filter apparatus of claim 15 wherein the braking cam is actuatable by way of a push-button actuator that is located on an interior cover of the apparatus and that is operative ly connected to the braking cam. Embodiment 17 is the unpowered window air filter apparatus of any of embodiments 15-16 wherein the contact surface of the cam protrusion is provided by a surface of a resilient layer, which surface exhibits a convex shape.

Embodiment 18 is the unpowered window air filter apparatus of any of embodiments 1-17 wherein the apparatus further comprises a one-way speed limiter that limits the speed at which the movable unit can be moved away from the second, expanded configuration toward the first, unexpanded configuration but does not limit the speed at which the movable unit can be moved away from the first, unexpanded configuration toward the second, expanded configuration.

Embodiment 19 is a replacement air filter assembly that is configured to be removably installable into a housing of an unpowered window air filter apparatus of any of embodiments 1-18. Embodiment 20 is the replacement air filter assembly of embodiment 19 wherein the replacement air filter assembly comprises a pleated air filter media. Embodiment 21 is a kit comprising the unpowered window air filter apparatus of any of embodiments 1-18 wherein the kit further includes at least one replacement air filter assembly

Embodiment 22 is a method of installing the unpowered air filter apparatus of any of

embodiments 1-18 into an opening in a sash window, the method comprising: sliding a movable sash of the sash window so as to create an opening in the window; positioning the unpowered air filter apparatus in the opening of the window, with a lowermost surface of the base unit of the unpowered air filter apparatus resting on a lower sill of the window and with a first transverse side of the unpowered air filter apparatus abutted against a side jamb of the sash window; slidably moving the movable portion of the unpowered air filter apparatus upward until an uppermost surface of the movable portion is abutted against an upper lintel of the sash window; and, slidably moving the movable sash of the sash window toward the unpowered air filter apparatus until an edge of the movable sash is abutted against a second transverse side of the unpowered air filter apparatus.

It will be apparent to those skilled in the art that the specific exemplary elements, structures, features, details, configurations, etc., that are disclosed herein can be modified and/or combined in numerous embodiments. All such variations and combinations are contemplated by the inventor as being within the bounds of the conceived invention, not merely those representative designs that were chosen to serve as exemplary illustrations. Thus, the scope of the present invention should not be limited to the specific illustrative structures described herein, but rather extends at least to the structures described by the language of the claims, and the equivalents of those structures. Any of the elements that are positively recited in this specification as alternatives may be explicitly included in the claims or excluded from the claims, in any combination as desired. Any of the elements or combinations of elements that are recited in this specification in open-ended language (e.g., comprise and derivatives thereof), are considered to additionally be recited in closed-ended language (e.g., consist and derivatives thereof) and in partially closed-ended language (e.g., consist essentially, and derivatives thereof). To the extent that there is any conflict or discrepancy between this specification as written and the disclosure in any document incorporated by reference herein, this specification as written will control.