Abstract: An air cleaner device includes a filter element for filtering air and being disposed in a housing. The device comprises a hollow housing having an inlet portion, an outlet portion, and a flow passage therein which is communicated with the inlet portion and the outlet portion. The housing also has an opening which is disposed between the inlet portion and the outlet portion, and communicates the flow passage with the exterior of the housing. A filter element is inserted through the opening into the flow passage, disposed between the inlet portion and the outlet portion, so as to filter the air flowing through the flow passage. A lid is mounted on the housing for covering the opening. A resilient urging member allows the lid to be urged toward the housing so as to close the opening, and the resilient urging member allows the lid to be moved away from the opening when this urging is released.

Abstract: An exhaust gas cleaning device for a motor vehicle is constructed of a honeycomb core body formed by superposing a planar band made of a metal sheet and a corrugated band made from another metal sheet one over the other in a contiguous relationship and then rolling the thus-superposed bands into a multi-layered spiral form with at least one outermost layer thereof being formed of the planar band. The honeycomb core body defines a number of network-patterned axial gas flow passages and is adapted to carry an exhaust gas cleaning catalyst. At least one fin is fixed on an outer peripheral wall of the honeycomb core body.

Abstract: A high efficiency air filter is described which comprises a depth filter sheet that has been formed with micropleats stabilized by application of a strip of a thermoplastic adhesive across the peaks of the micropleats and then formed into a macropleated structure with the axes of the micropleats and the macropleats being essentially parallel. The micropleats preferably have a bending radius of less than about 0.01 inch.

Abstract: An air filter element incudes a plurality of filter paper units each composed of a sheet of filter paper corrugated into a number of folds extending from one side to the other of the sheet, the filter paper units being arranged such that ridges of the folds extend on or parallel to radial lines extending radially outwardly from a center of the air cleaner element, and at least one connector interconnecting side edges of the filter paper units. With the air cleaner element incorporated in an air cleaner, air drawn into the air cleaner from an air inlet flows into a space above the air cleaner element, and then flows through the air cleaner element at a uniform speed over the entire area of the air cleaner element. Therefore, the air can uniformly be filtered, and the resistance to the air flow of the air cleaner element is reduced. The area of the air cleaner element which is open to the air flow is several times greater than the cross-sectional area of the air inlet.

Abstract: The end caps of a filter element are formed on the element by dispensing a photo-initiated polymer in a transparent mold, setting the end of the filter media array in the mold, exposing the mold to ultraviolet light for a time sufficient to cure the polymer, and then stripping the mold from the finished end cap. Accordingly, the time of 60-75 seconds required to cure prior art Plastisol end caps is reduced to a few seconds necessary to cure the end caps made from the photo-initiated polymer. The end caps have been designed with reinforcing ribs to minimize the amount of polymer required while still maintaining necessary hoop strength to retain the media in place.

Abstract: A high efficiency filter assembly having a generally rectangular pleated filter element with ends defined by the pleated edges of the element and sides defined by generally planar side edges of the element. The filter element is mounted in a generally rectangular housing formed by two pairs of oppositely disposed frame members that are joined together. Each frame member has a planar base member and a pair of upright side member defining an open ended channel to receive the ends and sides of the filter element. At least one spacing member extends along the base portion to space the ends and sides of the filter element from the surface of the planar member. A dam member is provided at each end of one of the pairs of planar members to enclose the channel, and a sealant is disposed in the channel and the ends of the filter element are embedded in the sealant.

Abstract: A filter element comprises at least two pleated filtering mediums and at least one roughly flat filtering medium interposed between the pleated filtering mediums. Each pleated filtering medium has an end constituted by edges of triangular bottom sections and the other end constituted by edges of triangular top sections. The triangular bottom sections of one pleated filtering medium is bonded to the flat filtering medium only at and near the edges of the bottom sections. The triangular top sections of the other pleated filtering medium is bonded to the roughly flat filtering medium only at and near the edges of the top sections. Spacers are provided between the top sections and the flat filtering medium and between the bottom sections and the roughly flat filtering medium. Such spacers may be constituted by alternate small ridges and grooves formed in the roughly flat filtering medium.

Abstract: A cartridge-type liquid-gas separator having particular use for separating oil from air. The separator includes an outer casing containing an annular pleated first stage filter element and an annular second stage element located concentrically of the first stage element. The first stage filter element is composed of a coalescer section formed of unwoven fibrous material and a disloader section disposed downstream of the coalescer section and composed of multiple layers of fibrous material impregnated with a resin having low surface energy. The first stage element can also include a pair of screens, one located upstream of the coalescer section and a second located downstream of the disloader section. The second stage which is spaced downstream from the first stage is composed of a fibrous stripper layer followed by a screen.

Abstract: An interlocking wedge for pleated paper filter elements of the type having a plurality of pleated paper filter panels secured in a frame in a zig-zag configuration with plural apexes adjacent both the upstream and downstream ends of the frame forming plural wedge shaped air inlet and outlet spaces and a plurality of elongated V-shaped spacing wedges disposed in the downstream wedge shaped air outlet spaces adjacent the panels wherein the downstream end of each of the wedges extends transversely through one of the outlet openings in the downstream end of the frame and define recessed areas so as to provide an interference fit between said portions of the wedges in the downstream end of the frame to interlock the wedges with the frame and thereby prevent lateral separation of the wedges with respect to the frame upon the element being subject to uneven loading.

Abstract: An air sterilization filter for the containment of leakage prevention of biologically contaminated air in space for a biotechnological performance, such as a genetic engineering work. The filter comprises a heat durable sheet filter for collecting microorganisms suspended in air and a heater for heating the sheet filter and sterilizing the collected microorganisms. The filter of the invention is also useful for providing a clean room.

Abstract: An air cleaner assembly includes a pair of molded housing members, each of which include four side walls and an open end. The opposite end of one of the members carries an outlet tube for connection to the air intake system of the vehicle, and the opposite end of the other member includes a lattice-work structure defining openings to admit air into the air cleaner assembly. The two housings snap together by receiving the side walls of the one member into the open end of the other member, and the members defining the lattice-work structure engage a panel cartridge filter assembly to force the latter into an adhesive carried in a groove extending around a flange defined on the one member.

Abstract: A cartridge filter comprises a pleat-type porous membrane having a longer length than an effective filtering surface thereof; upper and lower end plates; a plurality of segmented cylindrical core members disposed between the upper and lower end plates; and protective caps for fastening and sealing an upper and lower reminder of the pleat-type porous membrane other than the effective filtering surface thereof. Each of said end plates is provided with a plurality of fins, each of which is covered by the pleat-type porous membrane. The pleat-type porous membrane is folded at each corner of respective end plates and fastened firmly between the end plate and the protective cap by melting means, adhesion or sealing means.

Abstract: A filter apparatus includes a filter element. The filter element is formed of a sheet of gas-porous filter material which has been folded into accordian pleats. Alternate pleat-folds are of tight, near knife-edge definition, and arcuate form definition. Hence, all folds on one side of the accordian-folded material are of the knife-edge form, and all folds on the other side are of the arcuate. The pleated material is turned into a cylindrical conformation, with the arcuate folds confronting the central axis of the cylinder, and the tight, knife-edge folds outwardly directed. An adhesive-backed band circumscribes the cylinder to hold the accordian-folded material in such form. Ends caps, one with a central aperture formed therein, are fixed to the ends of the cylinder. The latter is then positioned and secured under a venturi section or pipe. The venturi section or pipe, in any cross-section thereof, is of rectilinear shape.

Abstract: An air filter for a motor vehicle includes a filter body (1) closed by a cover (10). Extending from the bottom of the body are rods (8) for supporting a filtering cartridge (9) made from a flexible material, such as plastics foam. These rods are moulded in one piece with the filter body and they are arranged around the outlet opening (4) of the filter. The filter body is easily stripped from the mould and the supporting rods for the cartridge cannot be lost.

Abstract: A high efficiency particulate air filter is disclosed which comprises a frame surrounding and sealably supporting the filter pack, with the frame composed of four separate side panels which are rigidly interconnected at their abutting ends by means of corner plates. The corner plates are in the form of two flanges disposed at right angles to each other, and the flanges are closely received within slots formed on the outer face of the side panels. The corner plates preferably extend across the entire width of the side panels of the frame to impart substantial rigidity to the frame, and a sealing material is disposed in a recess which extends along the bight of the corner plates to provide a continuous seal along the abutting ends of the side panels.

Abstract: The method for spacing the folds of a folded filter media assembly includes the steps of separating the folds of the filter media by the use of the tapered assembly comb having uniformly spaced teeth and subsequently inserting a rigid divider into the separated and spaced media folds to produce a uniformly spaced filter media. The comb can be discarded after the divider is inserted, and, accordingly, the comb is made of an inexpensive material having a desired degree of rigidity for handling, e.g., cardboard. The uniformly spaced filter media assembly is inserted into an operative position for filtering, e.g., as an air filter.

Abstract: A cartridge fluid filter includes a housing within which are positioned annular, concentrically mounted filter elements that are held together in relative position by first and second end caps to define a gap between the filter elements. A filter core is positioned within the gap that communicates with an outlet defined in the first end cap. An annular reinforcing disc is mounted in the first end cap to support the end cap around the outlet.

Abstract: A diesel exhaust particulate trap is provided with a heat resistant particulate filter which includes a perforated and pleated metal substrate member coated with a ceramic fiber filter material on its interior surface so as to define a filter chamber for the inside-out flow of exhaust gases through the filter. In a preferred embodiment, an electrical particulate filter igniter is associated with the filter. The igniter includes a trap door pivotably secured to the substrate member, which is normally biased to a closed position by a spring but which can be opened by exhaust flow prior to an accumulation of particulates on the filter. Opening and closing of the trap door is used to effect deenergization and energization, respectively, of an electrical heating element used to initiate combustion of particulates.

Abstract: A filter assembly comprising a filter retainer apparatus, an air filter frame and having a removable pleated filter media. The pleated filter element is secured within the frame by the retainer apparatus which comprises an expandible retainer having elongated flanges disposed on opposite ends. One flange is secured to a rod which slidably fits within a sleeve to which the other flange is attached. Resilient apparatus, preferably an elongated helical spring positioned between the sleeve and the rod, keeps the flanges in spaced relationship. One of the flanges engages one end fold in the filter element and forces it into contact with the frame. The rod is then forced into the sleeve compressing the spring and the other flange engages the other end fold of the filter element, forcing the other end fold into contact with the frame. The spring forces the rod and the sleeve apart so that the flanges securely hold the filter element in the frame.

Abstract: An air cleaner comprises at least two pleated paper filter elements each having the configuration of a frustrum of a cone and mounted in side-by-side relation in a casing with their relatively wide diameter ends in sealing relation to a common, impermeable baseplate means dividing said casing into two discrete portions, said baseplate means having openings defined therein to provide direct communication between one of said portions and the insides of said elements, impermeable means for closing the relatively narrow diameter ends of the elements, together with an aperture in the casing in each of said portions, whereby in use, air entering one of said apertures can pass to the other aperture only through said filter elements. The impermeable means for closing the narrow ends of the elements is preferably a blanking plate integral with each of said ends.

Abstract: A filter device used to filter medical anesthesia gases and other inhalable respiratory gases. The filter device has a ported housing, and a filter member within the housing. The filter member is a porous sheet that is transversely pleated and draped to define a peripheral foot of such porous sheet. The peripheral foot is sealed along its entire periphery to the housing. Two sets of intermeshing hangers are provided with both sets of the hangers being anchored to the housing and distortingly maintaining the porous sheet in such a pleated condition.

Abstract: The invention relates to a portable air cleaner unit which includes a casing having an air inlet and an outlet and defining an air cleaning path between the inlet and outlet. A prefilter is disposed downstream of the air inlet and a main filter is disposed downstream of the prefilter. An air mover such as a fan is disposed downstream of the main filter, and an exposed negative ion source is disposed downstream of the fan on the external surface of the air outlet. In accordance with the invention, the main filter consists of fibers shredded from a non-carcinogenic plastic membrane which has been permanently electrostatically charged. The negative ion source ionizes the cleaned air as it leaves the cabinet.

Abstract: A filter assembly in an air cleaner includes a lower wire-form adapted to receive two opposite ends of a pliable filter material. Spaced wires on the lower wire-form enable manual forming of pleats in the filter material and define the tops of such pleats. A complementary upper wire-form is engageable with the lower wire-form and attached filter to define the bottoms of such pleats.

Abstract: A filter element has a filter medium positioned between concentrically spaced cylindrical walls. A semiflexible, urethane ledge gasket has an annular seal portion that sealingly engages one end of the walls and filter medium and an edge of a generally circular retainer plate that closes one end of the filter element. An annular gripper surface extends inwardly from the seal portion and is spaced axially from the outer surface of the retainer plate so as to provide a finger gripping surface so that the filter element can be removed from its housing. An annular lip extends outwardly from the seal portion to engage an end of the housing.

Abstract: A gas dust-removing or dedusting filter of the kind incorporating a filter casing, filter tubes or bags having a flattened oval cross-section, and internal spacing elements. The casing includes a vertical partition having perforations and dividing the casing into a pure or clean gas chamber and a gas dust-removing chamber. The tubes or bags are horizontally insertable into the dust-removing chamber through the perforations of the partition and are sealed at their open ends to the clean gas side of the partition while their closed ends are supported on the rear wall of the casing.In accordance with the invention, parallel vertical guide members, each having a surface which slopes with respect to a rear wall of the casing, are secured to the inner side of the rear wall of the casing. One guide member is disposed between two adjacent filter tubes or bags. The filter tubes or bags rest on support bars adjacent the rear wall of the casing, which engage said guide members.

Abstract: A pocket filter cartridge having a plurality of side-by-side filter bags secured to a filter header assembly adapted to be secured across a dirty gas stream in a gas duct. The header assembly includes a generally rectangular frame in which the filter bags are secured by collars mounted in the mouths of each of the bags which are held together by clip members to clamp the bags between the collars and the frame to secure the bags to the header assembly.

Abstract: An air filter, particularly adapted for use in internal combustion engines, eliminates the necessity of discarding the entire air filter when the filter element becomes clogged to the extent that its efficiency is reduced below acceptable levels. The air filter of the invention incorporates a readily removable and replaceable filter element disclosed in a preferred embodiment as an inexpensive length of paper, accordion pleated in a manner to permit it to be folded into a highly compact product until ready for use. In use, the element is extended to partially open the pleats or folds, providing maximum filter area. The element in use is confined in a hollow annular assembly composed of confronting rings preferably of neoprene rubber or its equivalent, and further composed of foraminous retaining elements extending between the rings. Replacement of a filter element is readily achieved by removal of one of the rings, providing access to the filter element chamber.

Abstract: An air filter assembly for a fuel-injected engine of the rectangular air inlet type typical of some imported automobiles is secured directly to the filter seat flange of the air intake opening of the engine, without a separate housing or canister. The filtering element is of a soft, porous foam material backed by a wire mesh of relatively large mesh size, and a collar at the base of the filter assembly is secured to both the filtering element and the backing mesh to hold the assembly together and in the proper configuration. Backing may be included on both the inner and the outer sides of the filtering element, sandwiched between inner and outer bands or flanges of the collar, with fasteners extending between the bands to pull them together and hold the filtering element and backing in the collar. The filtering element and backing are formed into an outwardly bulging, generally arcuate configuration for optimizing filtering area.

Abstract: An internal loading cylindrical air filter apparatus having a circular tubular knit pile fabric filter element extending unsupported between end plates to provide an essentially full length unobstructed filter area, and having a rotating internal suction cleaning nozzle therefor. The tubular filter element is supported at its entry end by a detachable angle ring having a cylindrical ring flange extending through an opening in the entry end plate of the apparatus to permit endwise assembly and disassembly of the fabric filter element into the apparatus. Annular or helical strands may extend in circumferential engagement with the filter element for restraining it from ballooning out of effective cleaning distance with respect to the rotating suction nozzle under heavy filtering conditions, and a crank may be provided for adjusting the extending length of a helically extending restraining strand for controlling the degree of restaint imposed on the filter element.

Abstract: A reusable filter to remove contaminants from high temperature gases, in excess of 4500.degree. F., developed by burning propellants and used to do work such as actuation of piston-powered devices in aircraft store ejector racks. Contaminants are removed to prevent fouling of the device being acted upon. The filter has a metal strip wound in the form of a helix, the turns of the helix being spaced from one another to permit side entry of the gas between the turns. Protuberances spaced along one side of the strip establish filter gaps between the turns. A closed, convoluted structural support runs through the center of the helix from one end to the other of the filter in order to support the shape of the helix. The convoluted structural support also defines a plurality of axial flow passages between its closed surface and the helix, the passages communicating with the filter gaps to allow axial gas flow along the inside of the filter for end exit.

Abstract: A reusable filter to remove contaminants from high temperature gases, in excess of 4500.degree. F., developed by burning propellants and used to do work such as actuation of piston-powered devices in aircraft store ejector racks. Contaminants are removed to prevent fouling of the device being acted upon. The filter has at least one metal strip wound in the form of a flat spiral about a central member, the turns of the flat spiral being spaced from one another to permit axial entry of gas between the turns. A further flat spiral filter may be similarly constructed about the central member and axially displaced from the first filter, and both such filters may have different filtering capacities. On each flat spiral, protuberances are spaced along one side of the metal strip to establish filter gaps between the turns. The one or more flat spirals are restrained at their outer circumference by a cylindrical casing having inlet and outlet ends for the hot gas.

Abstract: A gas filter comprising a square frame and an interchangeable filter package containing a filter web of a folded zig-zag configuration forming a plurality of proximate filter pockets received on a support grid mounted on the frame and having a shape complementary to the folds of the filter web.

Abstract: A two-stage air-oil separator is connected to the air exhaust system of a compressor. The first stage has a pleated extended area agglomerator formed of layers of glass fiber material. The second stage has radially spaced filter elements with high loft filter material layers held between vinyl-coated glass scrims. The layers in the various filter elements are wrapped with different tightness. Fluid inlets and outlets are provided.

Abstract: The size of an air filter is greatly reduced compared to the size of conventional bag house type filters by the use of pleated paper filter elements grossly derated to withstand the sudden pulsating forces inherent in reverse jet cleaning.

Abstract: A novel arrangement for mounting the filter elements of an air filter in a manner which facilitates their removal and replacement without tools or accessories.

Abstract: A filter for cleaning large quantities of contaminated gas, wherein the gas to be cleaned is passed through a filter medium which is spanned onto a drum. The retained contaminants are removed by a device which wipingly passes over the filter medium. The drum is fixedly connected with a conduit or line through which there is conducted the contaminated gas. The removal device comprises a compressed gas-blast device equipped with at least one jet nozzle and movable over at least part of the outer surface of the drum surrounds the periphery of such drum. The jet nozzle is directed towards the surface of the filter medium. Means serve for the withdrawal of the separated contaminants from the internal hollow space or compartment of the drum.

Abstract: The air filter and vacuum cleaning system includes an air filter unit having partitions and filtering material arranged to define a plurality of air channels between the air entrance and exit ends of the filter. The filter material itself is in the form of a cloth strip of fibrous material such as glass fibers and is wound back and forth about the ends of the partitions adjacent the entrance and exit openings of the filter to provide folds. A vacuum cleaning head is mounted for movement across the entrance end of the filter, the head having a vacuum slot cooperating with the air channels and folds of the filter material to result in high velocity air which will pick up and move slugs of accumulated impurities on the inner folds of the filter material adjacent the air exit end.

Abstract: The present invention refers to the mounting of filter bags and the like of the kind comprising the mounting of such filter bags in a frame which holds them by means of a holding ring and which applies pressure against the outer walls of the frame, securing the lip of the bags between the body of the frame and the holding ring.

Abstract: A plurality of separate V-shaped wire mesh members are arranged and connected in side-by-side relationship to provide a plurality of V-shaped cells across an air stream. A W-shaped retainer or connector formed of perforated sheet metal has outer, downstream facing trackways which receive side edges of the wire mesh members, and a central, upstream facing trackway which receives and retains the free edges of V-shaped filter media bags which are inserted into the V-shaped cells overlying the wire mesh. A stabilizer bar extends across and attaches to the exposed adjoining edges of the V-cells to support the cells in proper relation and retain the filter media in place.

Abstract: A filter including a resilient frame, a hollow body of pleated paper, and end closures, molded together to make a flexible unitary structure which maintains its shape and has the efficiency characteristics of the paper medium.

Abstract: Disclosed herein is an air filter assembly particularly adapted for use in building air conditioning systems. The assembly is comprised of an open ended housing defining an air inlet and an air outlet and having a continuous layer of pleated filtering media extending thereacross and a plurality of pleat support members disposed at the air inlet and outlet ends of the filter housing.

Abstract: A corrugated tubular filter element is provided, resistant to corrugation collapse under high differential pressure, although formed of filter sheet material susceptible to such collapse, comprising, in combination, filter sheet material enclosed in a dual layer of more open foraminous sheet material and formed in a closed corrugated configuration having axial corrugation folds arranged in groups with adjacent side surfaces in supporting contact with each other; and, interposed between said groups, solid wedge support elements extending axially of the corrugation folds from end to end of the element having side surfaces in supporting contact with external side surfaces of the end folds of each group, substantially filling the spaces between the end folds of adjacent groups, and confining the folds of each group in substantially parallel array against lateral movement; and a foraminous support sheath disposed at least one of externally and internally of the filter sheet material in supporting contact with adja

Abstract: A plurality of laterally spaced parallel tapes extend along each side of a strip of filter material in engagement with it, and the sheets and tapes are in accordion folded form so that there is a stack of integrally connected parallel filter sheets spaced apart by the portions of the tapes between them. Each tape has at its side of the stack exposed portions, along which a line of hardened adhesive extends to connect them and form a stiffening band, whereby there are parallel stiffening bands extending across each side of the stack of filter sheets.

Abstract: Holder for an annular filter includes a support frame or basket with a flared portion at its upper end which cooperates with the inner leg of an inverted U-shaped sealing ring to clamp the upper end of the filter. The sealing ring has its outer leg seated on a sealing gasket positioned on top of a support plate surrounding an aperture through which the filter is lowered during operation of a particle collection apparatus. The holder is replaceably sealed in position by screwing a pair of threaded rings together to force the flared portion downwardly. The diameters of the various parts are larger than the aperture to prevent them from being dropped through the aperture and the overall design is such that the filters can be replaced from the upper clean side of the collection apparatus rather than the lower dirty side.

Abstract: A gas filtering device of the type having a pleated filter media for filtering a gas stream passing through the media from the upstream side to the downstream side of the filter device, a peripheral frame surrounding and attached to the margin of the pleated filter media, a filter media reinforcing device comprised of an elongated rigid beam disposed within a pleat of the pleated filter media and extending the entire length of the pleat, and filter media retaining means attached to the rigid beam and extending across the downstream side of the filter media.

Abstract: An air filter for filtering particulate matter from air flowing therethrough to a point of use requiring clean air, includes an imperforate front wall, a perforate back wall and opposite, imperforate side walls. The front wall is smaller in height than the back wall and a pair of pleated filter elements extend from the top of the front wall to the top of the back wall and from the bottom of the front wall to the bottom of the back wall, respectively, defining a wedge-shaped outlet space between the filter elements extending from the front wall to the back wall and being larger toward the back wall. A plurality of the filters are adapted to be stacked one on top of the other to define a plurality of inlet spaces therebetween and a plurality of outlet spaces. Reinforcing members are interposed between the filter elements in each filter, whereby the filter is enabled to support the weight of a man thereon.

Abstract: An improved filter bag mounting assembly for fabric type dust collectors compositely constituted of a selectively shaped mounting and filter media supporting member adapted for removable insertion in a complementally sized receiving aperture in a tube sheet, a filter media sheathed retainer assembly terminally connected at one end, in releasably latched gas tight relation to the mounting member and a closure plug disposed in the other terminal end of said media sheathed retainer and secured thereto in releasable gas tight latched relation.

Abstract: This invention relates to improvements in an air-cleaner for internal combustion engines, more particularly, to an improved air-cleaner having such sound-silencing construction that an air-cleaner element is removably fixed in a vibration-isolating cover which is provided in the housing of the air-cleaner.

Abstract: A high performance ventilation system with means for recovering a high percentage of sensible and latent thermal energy from the exhausted air for return via the supply air. Two matrices of thermally absorbent, expanded honeycomb material are respectively alternately interconnected with fan-driven supply and exhaust paths via a valve device to store energy in one matrix while retrieving energy from the other. Constant air flow direction is maintained in the ventilated area. The valve may be thermostat controlled. The matrices are preferably formed of a fibrous organic material such as paper, in an expandable honeycomb configuration, and resin impregnated for durability and strength. A degree of residual flexibility is desired whereby the matrices may be adjusted for fitting, air control and cleaning purposes.

Abstract: A high performance ventilation system with .[.means.]. .Iadd.provisions .Iaddend.for recovering a high percentage of sensible and latent thermal energy from the exhausted air for return via the supply air. Two matrices of thermally absorbent, expanded honeycomb material are respectively alternately interconnected with fan-driven supply and exhaust paths via a valve device to store energy in one matrix while retrieving energy from the other. Constant air flow direction is maintained in the ventilated area. The valve may be thermostat controlled. The matrices are preferably formed of a fibrous organic material such as paper, in an expandable honeycomb configuration, and resin impregnated for durability and strength. A degree of residual flexibility is desired whereby the matrices may be adjusted for fitting, air control and cleaning purposes.