CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63/112,696, filed November 12, 2020, and claims the benefit of U.S. Provisional Patent Application No. 63/136,416, filed January 12, 2021 , the disclosures of which are incorporated herein by reference.

TECHNICAL FIELD

[0002] This disclosure pertains to ducts and duct-connecting fittings, and apparatus and methods of making ducts. The ducts may be used as conduits or passages in heating, ventilation, and air conditioning of building spaces. The ducts may deliver air to and remove air from the spaces. The airflows may include supply air, return air, and exhaust air.

BACKGROUND

[0003] In the construction of buildings, such as homes, office buildings, factories, schools, etc., ducting is fabricated, installed, and connected to heating, ventilating, and air conditioning (HVAC) apparatus, such as furnaces, air conditioners, chillers, heat exchangers, and the like. During construction, after the exterior and interior walls, floors, and ceilings are in place, the utilities are installed, including piping, electrical wiring and fixtures, and HVAC. The ducting may be the last portion of the utilities to be installed. Although building construction is typically based on detailed design drawings, the installers of the utilities may deviate from the design for various reasons. If the ducting is installed last, design deviations in piping and electrical (and also design deviations in the walls, floors, and ceilings) may necessitate deviations from the original ducting design. There may be a need to make measurements on site (also referred to as “in the field”), and revise the plans for making and installing the ducting.

SUMMARY

[0004] It is beneficial to be able to fabricate required ducting at a construction site, instead of having to communicate revised ducting requirements back to a shop or factory, and then transport the fabricated ducting to the construction site. Even if no ducting design changes are needed, it is beneficial to be able to fabricate the required ducting on site and to connect the ducts together in an HVAC system. The ducts and fittings of the present disclosure, and the methods and apparatus for making ducts, provide high quality ducting that can be quickly and cost effectively fabricated and assembled at a construction site.

[0005] In one aspect of the present disclosure, a duct is provided comprising an inner sleeve, and outer sleeve, and a layer of insulative material. The inner sleeve may be comprised of a band of inner sheet material having a first lateral edge and a second lateral edge parallel to the first lateral edge, the band of inner sheet material wound in a spiral, wherein the first lateral edge thereof is joined to the second lateral edge thereof. The outer sleeve may be comprised of a band of outer sheet material having a first lateral edge and a second lateral edge parallel to the first lateral edge, the band of outer sheet material wound in a spiral wherein the first lateral edge thereof is joined to the second lateral edge thereof, the outer sleeve surrounding the inner sleeve and defining a gap therebetween. The layer of insulative material is contained in the gap between the inner sleeve and the outer sleeve.

[0006] The insulative material may be a polymer foam. The polymer foam may be provided in a liquid state and cured to a solid state. In some cases, the polymer foam may be cured from the liquid to the solid state in a time between about 2 seconds and about 20 seconds. The polymer foam may be adhered to the inner sleeve and to the outer sleeve.

[0007] The band of inner sheet material may be a first polymer film material, and the band of outer sheet material may be a second polymer film material. Alternatively, the inner sheet material and outer sheet material may be the same material. One of the band of inner sheet material and the band of outer sheet material may be wound with a first pitch relative to a central axis of the duct, and the other of the band of inner sheet material and the band of outer sheet material may be wound with a second pitch relative to the central axis of the duct and in an opposite direction of the first outer sleeves may be cylindrical sleeves, with the gap between the sleeves being an annular gap. The duct may be further comprised of a corrugated sleeve disposed outer sleeves may be oblong in a cross-section perpendicular to a longitudinal central axis of the duct.

[0008] In another aspect of the present disclosure, a method of making a duct is provided. The method comprises dispensing a band of inner sheet material having a first lateral edge and a second lateral edge parallel to the first lateral edge in a spiral around a surface of a mandrel to form an inner sleeve of the duct; dispensing a layer of thermally insulative material onto an outer surface of the inner sleeve; dispensing a band of outer sheet material having a first lateral edge and a second lateral edge parallel to the first lateral edge in a spiral to form an outer sleeve of the duct, wherein an inner surface of the outer sleeve is contiguous with an outer surface of the layer of. In some cases, the thermally insulative material may be a liquid polymer foam. In such cases, the method may further comprise curing the liquid polymer foam into a solid thermally insulative polymer foam wall disposed in a gap between the inner sleeve and the outer sleeve of the duct. When wound in a spiral, the first lateral edge of the band of inner sheet material may be substantially contiguous with the second lateral edge of the band of inner sheet material. In such cases, the method may further comprise joining the first lateral edge of the band of inner sheet material to the second lateral edge of the band of inner sheet material to form the inner sleeve of the duct. In like manner, when wound in a spiral, the first lateral edge of the band of outer sheet material may be substantially contiguous with the second lateral edge of the band of outer sheet material. In such cases, the method further comprises joining the first lateral edge of the band of outer sheet material to the second lateral edge of the band of outer sheet material to form the outer sleeve of the duct.

[0009] The method may further comprise causing the inner sleeve, thermally insulative material, and outer sleeve to move outwardly along a central axis of the mandrel. The inner sleeve, thermally insulative material, and outer sleeve may form an assembled duct. The method may further comprise cutting the assembled duct into discrete lengths of duct.

[0010] The mandrel may be comprised of an elongated cylindrical member, in which case, the first and second sleeves are formed as cylindrical sleeves, the layer of thermally insulative material is an annular layer, and the gap between the sleeves is an annular gap. A linear rate of forming the inner sleeve along a central axis of the duct may be substantially equal to a linear rate of dispensing the annular layer of thermally insulative material along a central axis of the duct. A linear rate of forming the outer sleeve along a central axis of the duct may be substantially equal to a linear rate of dispending the annular layer of thermally insulative material along a central axis of the duct. In cases where the thermally insulative material is a polymer foam, the polymer foam may be cured from a liquid to a solid state in a time between about 2 seconds and about 20 seconds.

[0011] The method may further comprise dispensing the band of inner sheet material from a spool of inner sheet material, and dispensing the band of outer sheet material from a spool of outer sheet material. The method may further comprise winding the band of inner sheet material and the band of outer sheet material both in spiral having a first pitch relative to a central axis of the duct, Alternatively, the method may further comprise winding one of the band of inner sheet material and the band of outer sheet material in a spiral having a first pitch relative to a central axis of the duct, and winding the other of the band of inner sheet material and the band of outer sheet material in a spiral having a second pitch relative to the central axis of the duct and in an opposite direction of the first pitch.

[0012] The method may further comprise forming a corrugated sleeve between the outer sleeve and the layer of insulative material.

[0013] In another aspect of the present disclosure, an apparatus for making a duct is provided. The apparatus may be comprised of a mandrel including an elongated member having an outer surface and a central axis; a source of a band of inner sheet material having a first lateral edge and a second lateral edge parallel to the first lateral edge thereof; a fluid delivery system comprising a fluid nozzle proximate to the outer surface of the elongated member of the mandrel; and a source of a band of outer sheet material having a first lateral edge and a second lateral edge parallel to the first lateral edge thereof. The elongated member of the mandrel may be rotatable around the central axis of the elongated member. In some cases, the elongated member of the mandrel may be a cylindrical member. In other cases, the elongated member of the mandrel may be oblong in cross-section.

[0014] When the apparatus is operating, the source of the band of inner sheet material is operable to dispense a portion of the band of the inner sheet material in a spiral on the outer surface of the elongated member around the central axis of the elongated member, and the source of the band of outer sheet material is operable to dispense a portion of the band of the outer sheet material in a spiral onto a fluid layer dispensed from the fluid nozzle onto the spiral of the band of inner sheet material.

[0015] The source of the band of inner sheet material may dispense the portion of the band of the inner sheet material in the spiral such that a first lateral edge of the band of the inner sheet material is contiguous with a second lateral edge of the band of the inner sheet material. The source of the band of outer sheet material may dispense the portion of the band of the outer sheet material in the spiral such that a first lateral edge of the band of the outer sheet material is contiguous with a second lateral edge of the band of the outer sheet material.

[0016] The apparatus may be further comprised of a fuser in communication with first lateral edge of the band of the inner sheet material and the second lateral edge of the band of the inner sheet material. Alternatively or additionally, the fuser may be in communication with first lateral edge of the band of the outer sheet material and the second lateral edge of the band of the outer sheet material. The fuser is operable to join the first lateral edge of the band of the inner sheet material to the second lateral edge of the band of the inner sheet material, and/or join the first lateral edge of the band of the outer sheet material to the second lateral edge of the band of the outer sheet material.

[0017] The source of the band of inner sheet material may be a first rotatable spool, and the source of the band of outer sheet material may be a second rotatable spool. The angles of the respective axes of rotation of the first spool and second spool may be adjustable with respect to the central axis of the elongated member of the mandrel. The spools are operable to dispense the respective portions of the band of the inner sheet material and the band of outer sheet material in the spirals around the central axis of the elongated member of the mandrel. The spirals of the band of the inner sheet material and the band of outer sheet material may have the same handedness, or opposed handedness.

[0018] The fluid nozzle may be movable along the central axis of the elongated member of the mandrel. In some cases, the fluid nozzle may be slot-shaped. The fluid delivery system may be further comprised of a source of polymer foam in fluid communication with the fluid nozzle.

[0019] The source of the band of inner sheet material is movable along the central axis of the elongated member of the mandrel, and the source of the band of outer sheet material is movable along the central axis of the elongated member of the mandrel.

[0020] The apparatus may be further comprised of a first engagement arm opposed to a second engagement arm. The first and second engagement arms may be movable to respective positions proximate to the outer surface of the elongated member of the mandrel.

[0021] The apparatus may be further comprised of a cutting tool proximate to an outer end of the elongated member of the mandrel and operable to cut in a plane substantially perpendicular to the central axis of the elongated member of the mandrel.

[0022] The apparatus may be further comprised of a worm gear and a source of a formable intermediate sheet material. The worm gear may be rotatable and comprised of one or more spiral teeth. The worm gear is operable to form the intermediate sheet material and the fluid layer into a corrugated structure, including a layer of insulative material and a corrugated sleeve.

[0023] The mandrel of the apparatus may be further comprised of a first magnet disposed in the elongated member proximate to the outer surface and proximate to a distal end of the elongated member, a leading edge of the band of inner sheet material may be comprised of a first magnetic strip removably joinable to the first magnet. In like manner, the mandrel may be further comprised of a second magnet disposed in the elongated member proximate to the outer surface and proximate to the distal end of the elongated member, and a leading edge of the band of outer sheet material may be comprised of a second magnetic strip removably joinable to the second magnet.

[0024] In additional aspects of the present disclosure, fittings for connecting lengths of duct together are provided.

[0025] In one additional aspect, a duct connector fitting is provided comprising a cylindrical tubular body and a flange. The flange extends laterally from a proximal end of the cylindrical tubular body and is comprised of first and second barbs located substantially 180 degrees opposite of each other, and first and second cavities located on the flange substantially 180 degrees opposite of each other and on the flange substantially 90 degrees from the first and second barbs. The flange may extend radially outwardly from the tubular body. The connector fitting may include a circumferential groove in an outer surface of the tubular body, and an O-ring disposed in the circumferential groove.

[0026] The duct connector fitting may be joined to a duct to form a duct assembly. The duct is comprised of a tubular side wall having an inner surface. In such cases, the cylindrical tubular body of the connector fitting extends inwardly within the tubular side wall and is contiguous with the inner surface of the duct. The duct assembly may include an outer compression ring engaged in an interference fit with an outer surface of the tubular side wall of the duct. The duct assembly may include an O-ring disposed between the outer surface of the tubular body of the connector fitting and the inner surface of the tubular side wall of the duct.

[0027] Pairs of duct connector fittings as described above may be joined to each other to form duct assemblies suitable for constructing HVAC systems. Such a duct assembly may be comprised of a first connector fitting and a second connector fitting, each comprised of a cylindrical tubular body and a flange as described above. To connect the first connector fitting to the second connector fitting, the first and second barbs of the first connector fitting are engaged with the first and second cavities of the second connector fitting, and the first and second barbs of the second connector fitting are engaged with the first and second cavities of the first connector fitting. The duct assembly may further include a gasket disposed between the flange of the first connector fitting and the flange of the second connector fitting. The duct assembly may further include a first duct joined to the first connector fitting and a second duct connected to the second connector fitting as described above.

[0028] In another additional aspect, an alternative duct connector fitting is provided, referred to herein as a “slide-in” connector fitting. The connector fitting may be used in a duct assembly to connect a round duct to a round duct, or an oblongshaped duct to an oblong-shaped duct. The duct connector fitting is comprised of a tubular body and a flange extending laterally from a proximal end of the tubular body. The flange is comprised of a first half extending around the tubular body and terminating at a first end wall and a second end wall; a first male tab protruding from the first end wall and a second male tab protruding from the second end wall; a first female cavity extending inwardly from the first end wall into the first half of the flange, and a second female cavity extending inwardly from the second end wall into the first half of the flange; and a second half extending around the tubular body and terminating at the first end wall and the second end wall.

[0029] The flange may extend radially outwardly from the tubular body. In some cases, the tubular body may be cylindrical in cross-section. In some cases, the tubular body may be oblong in cross-section. The duct connector fitting may include a circumferential groove in an outer surface of the tubular body, and an O-ring disposed in the circumferential groove. A duct assembly may be made comprising the duct connector fitting, and a duct comprising a tubular side wall having an inner surface. In such cases, the tubular body of the connector fitting extends inwardly within the tubular side wall and contiguous with the inner surface of the duct. Such a duct assembly may include an outer compression ring and/or an O-ring as described above.

[0030] Pairs of alternative duct connector fittings as described above may be joined to each other to form duct assemblies suitable for constructing HVAC systems. Such a duct assembly may be comprised of a first connector fitting and a second connector fitting, each comprised of a tubular body and a flange as described above. To connect the first connector fitting to the second connector fitting, the first and second male tabs of the first connector fitting are engaged with the first and second female cavities of the second connector fitting, and the first and second male tabs of the second connector fitting are engaged with the first and second female cavities of the first connector fitting.

[0031] In such an arrangement, the first half of the flange of the first connector fitting may be opposed to the second half of the flange of the second connector fitting, and the second half of the flange of the first connector fitting may be opposed to the first half of the flange of the second connector fitting. The duct assembly may be further comprised of a first gasket disposed between the first half of the flange of the first connector fitting and the second half of the flange of the second connector fitting, and a second gasket disposed between the second half of the flange of the first connector fitting and the first half of the flange of the second connector fitting. The duct assembly may further include a first duct joined to the first connector fitting and a second duct connected to the second connector fitting as described above. In some cases, the tubular bodies of the connector fittings and the ducts may be cylindrical in cross-section. In some cases, the tubular bodies of the connector fittings and the ducts may be oblong in cross-section.

[0032] In another additional aspect of the present disclosure, a connector fitting is provided, which may be used to connect a round duct to an oblong-shaped duct. The connector fitting is comprised of a semicircular body comprising a planar semicircular annular flange portion extending from a first end wall around to a second end wall; a semicircular annular extension protruding upwardly from the planar semicircular annular flange and terminating a portion of the first end wall and a portion of the second end wall; a first barb extending laterally outwardly from the first end wall; a first cavity extending laterally inwardly from the second end wall into the semicircular annular extension; a second barb extending upwardly from the semicircular annular extension; a second cavity extending radially inwardly into a side wall of the semicircular annular extension; and an arcuate member extending downwardly from the planar semicircular annular flange portion and comprising an arcuate rim forming an arcuate gap with the planar semicircular annular flange portion. In some cases, the arcuate member may extend less than 180 degrees circumferentially around the planar semicircular annular flange. In some cases, the second barb and the second cavity may be spaced from each other at 90 degrees circumferentially around the semicircular annular extension.

[0033] In another additional aspect of the present disclosure, the connector fitting may be used in a duct assembly to connect a round duct to an oblong-shaped duct. The duct assembly is comprised of first and second connector fittings as described above. When the two connector fittings are joined to each other in an assembled state, the first barb of the first connector fitting is engaged with the first cavity of the second connector fitting, and the first barb of the second connector fitting is engaged with the first cavity of the first connector fitting.

[0034] In one case, the duct assembly may be further comprised of an oblong duct including a flat side wall having a port hole therethrough. In such cases, an edge of the port hole may be disposed in the arcuate gap of the arcuate rim of the first connector fitting and the arcuate gap of the arcuate rim of the second connector fitting.

[0035] Alternatively or additionally, the duct assembly may be further comprised of a third connector fitting comprised of a cylindrical tubular body; and a flange extending laterally from a proximal end of the cylindrical tubular body and comprising third and fourth barbs located substantially 180 degrees opposite of each other, and third and fourth cavities located on the flange substantially 180 degrees opposite of each other and on the flange substantially 90 degrees from the third and fourth barbs. In such cases, the third barb of the third connector fitting is engaged with the first cavity of the first connector fitting, the fourth barb of the third connector fitting is engaged with the first cavity of the second connector fitting, the first barb of the first connector fitting is engaged with the third cavity of the third connector fitting, and the first barb of the second connector fitting is engaged with the fourth cavity of the third connector fitting. The duct assembly may be further comprised of a duct including a tubular side wall having an inner surface. In such a case, the cylindrical tubular body of the third connector fitting may extend inwardly within the tubular side wall and contiguous with the inner surface of the duct.

[0036] In another additional aspect of the present disclosure, an alternative connector fitting is provided, which may be used in a duct assembly to connect a round duct to an oblong-shaped duct. The connector fitting includes “slide-in” type connecting features, and is comprised of a tubular cylindrical body comprising an outer wall including threads formed thereupon, a ring comprising an inner wall including threads formed therein and engageable with the threads of the tubular cylindrical body, and a flange extending laterally from a proximal end of the tubular body. The flange is a “slide-in” type flange, and is comprised of a first half extending around the tubular body and terminating at a first end wall and a second end wall; a first male tab protruding from the first end wall and a second male tab protruding from the second end wall; a first female cavity extending inwardly from the first end wall into the first half of the flange, and a second female cavity extending inwardly from the second end wall into the first half of the flange; and a second half extending around the tubular body and terminating at the first end wall and the second end wall. A distal end of the tubular cylindrical body may include a plurality of notches interspersed with end tabs. Distal ends of the end tabs may include pawls that protrude radially outwardly.

[0037] The connector fitting may be joined to an oblong-shaped duct comprised of a flat wall portion to form a duct assembly. The ring is threaded onto the threads of the tubular cylindrical body and rotated, advancing the ring to an upper position. A hole is formed in the flat wall portion of the duct, and the distal end of the tubular cylindrical body of the fitting is inserted into the hole. The pawls of the end tabs initially extend below the inside surface of the flat wall portion of the duct at the edge of the hole. The rotation of the ring is reversed, causing the ring to move downwardly by the engagement of the threads. The pawls at the distal ends of the end tabs engage against the inside surface of the flat wall portion of the duct at the edge of the hole in the duct, and in combination with the ring being seated against the flat wall portion thereby join the connector fitting to the oblong-shaped duct.

[0038] A duct assembly comprised of a round duct subassembly joined to the oblong-shaped duct may then be formed. The round duct subassembly is comprised of a round duct joined to a slide-in duct connector fitting. The slide-in connector fitting to the oblong-shaped duct is further joined to the slide-in connector fitting of the round duct subassembly to form the round duct to oblong-shaped duct assembly.

[0039] In another additional aspect of the present disclosure, a reducing connector fitting is provided, which may be used to reduce the size of ducting from a first cross-sectional area to a lesser cross-sectional area. The reducing connector includes “slide-in” type connecting features, and is comprised of a tubular body tapering in cross-section from a large area end to a small area end; a first flange extending laterally from the large area end of the tubular body, and a second flange extending laterally from the small area end of the tubular body. The first and second flanges are formed as slide-in flanges as described previously, comprising respective first halves, first male tabs, first female cavities, and second halves. The reducing connector may be joined at the large area end to a first duct subassembly comprising a duct of relatively large cross-sectional area joined to a first slide-in connector fitting, and joined at the small area end to a second duct subassembly comprising a duct of relatively small cross-sectional area joined to a second slide-in connector fitting.

[0040] In some cases, the tubular body of the reducing connector fitting may be frustoconical, and the first and second flanges may be circular. In other cases, the tubular body of the reducing connector fitting may have an oblong-shaped crosssection, and the first and second flanges have corresponding oblong shapes.

[0041] In another additional aspect of the present disclosure, a direction adjustable connector is provided, which may be used to change the direction of ducting to any angle over a substantial range of solid angle. The direction adjustable connector includes “slide-in” type connecting features, and is comprised of a ball tubular body comprising a ball tube section, a ball member joined to a proximal end of the ball tube section, and a first flange extending laterally from a distal end of the ball tube section, and a socket tubular body comprising a socket tube section, a socket member joined to a proximal end of the socket tube section and engaged with the ball member of the ball tubular body, and a second flange extending laterally from a distal end of the socket tube section. The respective first and second flanges may be slide- in type flanges as described previously. Such flanges enable the connection of the respective ends of the direction adjustable connector to duct subassemblies that include corresponding slide-in type flanges to form a direction adjusted duct assembly. In some cases, a slide-in flange of a first direction adjustable connector may be connected to a slide-in flange of a second direction adjustable connector to provide further direction adjustability of a duct assembly.

[0042] In another additional aspect of the present disclosure, a connector fitting is provided, which may be used for placing sensors within a duct. The connector fitting includes “slide-in” type connecting features, and is comprised of an annular disc surrounding an open center region and including first and second opposed slide-in faces, and at least one port extending from an outer wall of the annular disc to an inner wall of the annular disc. The first face is comprised of a first half portion extending around the annular disc and terminating at a first end wall and a second end wall, a first male tab protruding from the first end wall of the first face and a second male tab protruding from the second end wall of the first face, a first female cavity extending inwardly from the first end wall of the first face into the first half portion of the first face, and a second female cavity extending inwardly from the second end wall of the first face into the first half portion of the first face, and a second half portion extending around the annular disc and terminating at the first end wall and the second end wall of the first face. The second face is comprised of a first half portion extending around the annular disc, terminating at a first end wall and a second end wall, and opposed to the second half portion of the first face, a first male tab protruding from the first end wall of the second face and a second male tab protruding from the second end wall of the second face, a first female cavity extending inwardly from the first end wall of the second face into the first half portion of the second face, and a second female cavity extending inwardly from the second end wall of the second face into the first half portion of the second face; and a second half portion extending around the annular disc and terminating at the first end wall and the second end wall of the second face.

[0043] The first and second slide-in faces enable the connection of the connector fitting to duct subassemblies that include corresponding slide-in type flanges to form a duct assembly that can include sensors, which may be placed in the ports that extend from the outer wall of the annular disc to the inner wall of the annular disc.

[0044] In another additional aspect of the present disclosure, an elbow connector fitting is provided, which may be used for changing the direction of a duct assembly. The connector fitting includes “slide-in” type connecting features, and is comprised of a tubular body, a first flange, and a second flange. The tubular body terminates at a first end defining a first end plane, and terminates at a second end defining a second end plane non-parallel to the first end plane. The first and second flanges are formed as slide-in flanges as described previously, comprising respective first halves, first male tabs, first female cavities, and second halves.

[0045] The elbow connector fitting may be joined at the first end to a first duct subassembly comprising a first duct joined to a first slide-in connector fitting, and joined at the second end to a second duct subassembly comprising a second duct joined to a second slide-in connector fitting. Because the first and second end planes are non-parallel, the direction of the first duct is different from the direction of the second duct. In one case, the first and second end planes are perpendicular to each other, in which case the elbow connector fitting is a 90 degree elbow.

[0046] In summary, various duct connector fittings are provided for connecting sections of ducting to form duct assemblies for HVAC systems. In various cases described herein, a duct connector fitting is comprised of a first tubular section, a first slide-in flange joined to a proximal end of the tubular section, and a second slide in flange joined to a distal end of the tubular section. The tubular sections may be configured as elbow sections, reducer sections, adjustable direction sections, and/or sensor housing sections. The various duct connector fittings enable rapid low cost modular assembly of ducting for HVAC systems. Each of the foregoing ducts and duct adapter and/or connection fittings, and apparatus and methods for making ducts, can be employed individually or in conjunction. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The present disclosure will be provided with reference to the following drawings, in which like numerals refer to like elements, and in which:

[0048] FIG. 1A is a perspective view of a portion of a first round duct in accordance with the present disclosure;

[0049] FIG. 1 B is a perspective exploded view of the duct of FIG. 1 A;

[0050] FIG. 1 C is a cross section of the duct of FIG. 1 A, taken along linel C-1 C of FIG. 1A;

[0051] FIG. 2A is a perspective exploded view of a second round duct in accordance with the present disclosure;

[0052] FIG. 2B is a cross section of the duct of FIG. 2A, taken in a plane similar to the cross-sectional plane of FIG. 1 C;

[0053] FIG. 3A is a perspective view of a portion of an oblong duct in accordance with the present disclosure;

[0054] FIG. 3B is a perspective exploded view of the duct of FIG. 3A;

[0055] FIGS. 4A-4C are schematic illustrations of an apparatus for making the ducts of FIGS. 1A-3B;

[0056] FIGS. 5-15 depict a sequence of steps of a method for making a duct of the present disclosure;

[0057] FIG. 16A is a side elevation view of a pair of duct fittings of the present disclosure, in position to be joined together;

[0058] FIG. 16B is a perspective view of the duct fittings of FIG. 16A;

[0059] FIG. 16C is an exploded perspective view of a duct assembly that includes the fittings of FIG. 16A;

[0060] FIG. 16D is a perspective view of a pair of duct subassemblies in position to be joined together;

[0061] FIG. 16E is a perspective view of the duct subassemblies of FIG. 16D joined together;

[0062] FIG. 17A is a side elevation view of an alternative duct fitting of the present disclosure;

[0063] FIG. 17B is a side elevation view of the pair of the duct fittings of FIG. 17A in position to be joined together;

[0064] FIG. 17C is a perspective view of the pair of the duct fittings of FIG. 17A in position to be joined together; [0065] FIG. 17D is an exploded perspective view of a duct assembly that includes the fittings of FIG. 17B;

[0066] FIG. 17E is a perspective view of a duct assembly that includes the fitting of FIG. 17A;

[0067] FIG. 17F is a side elevation view of a pair of the duct assemblies of FIG. 17E joined together;

[0068] FIG. 18A is an exploded perspective view of a duct assembly that includes a first round-to oval duct adapter fitting of the present disclosure;

[0069] FIG. 18B is a perspective view of the duct assembly of FIG. 18A in an assembled state;

[0070] FIG. 18C is a cross-sectional view of the duct assembly of FIG. 18B, taken along line 18C - 18C of FIG. 18B;

[0071] FIG. 18D is a cross-sectional view of a portion of the duct assembly of FIG. 18B, taken along line 18D - 18D of FIG. 18B;

[0072] FIG. 18E is an upward-looking cutaway view of the duct assembly of FIG.18B showing a portion of the assembly within the duct;

[0073] FIG. 18F is a cross-sectional view of a lower portion of the duct assembly of FIG. 18B, taken along line 18F - 18F of FIG. 18E;

[0074] FIG. 18G is a detailed cross-sectional view of a duct and fitting connection of the duct assembly of FIG. 18B, taken along line 18G - 18G of FIG. 18F;

[0075] FIG. 19A is a perspective view of a second round-to oval duct adapter fitting of the present disclosure;

[0076] FIG. 19B is an exploded perspective view of a duct assembly that includes the adapter fitting of FIG. 19A;

[0077] FIG. 19C is a perspective view of the duct assembly that includes the adapter fitting of FIG. 19A;

[0078] FIG. 19D is a cross-sectional view of the duct assembly of FIG. 19C taken along line 19D - 19D of FIG. 19C;

[0079] FIG. 19E is a detailed cross-sectional view of a portion of the duct assembly of FIG. 19C, marked “FIG. 19E” in FIG. 19D;

[0080] FIG. 20A is a perspective view of a pair of alternative duct fittings of the present disclosure, in position to be joined together;

[0081] FIG. 20B is an exploded perspective view of a duct assembly that includes the fittings of FIG. 20A; [0082] FIG. 21 A is a side elevation view of a first reducer fitting of the present disclosure;

[0083] FIG. 21 B is a perspective view of the first reducer fitting of FIG 21 A;

[0084] FIG. 21 C is an exploded perspective view of a duct assembly that includes the reducer fitting of FIG. 21 A;

[0085] FIG. 21 D is a side elevation view of a second reducer fitting of the present disclosure;

[0086] FIG. 21 E is a perspective view of the second reducer fitting of FIG 21 D;

[0087] FIG. 22A is a perspective view of a direction-adjustable coupler fitting of the present disclosure;

[0088] FIG. 22B is a cross-sectional view of the coupler fitting of FIG. 22A;

[0089] FIG. 22C is a perspective view of a duct assembly that includes the coupler fitting of FIG. 22A;

[0090] FIG. 22D is a side elevation view of a duct assembly that includes two of the coupler fitting of FIG. 22A;

[0091] FIG. 23A is a side elevation view of a sensor fitting of the present disclosure;

[0092] FIG. 23B is a perspective view of the sensor fitting of FIG 23A;

[0093] FIG. 23C is an exploded perspective view of a duct assembly that includes the sensor fitting of FIG. 23A;

[0094] FIG. 24A is a perspective view of a first elbow fitting of the present disclosure;

[0095] FIG. 24B is a perspective view of a second elbow fitting of the present disclosure;

[0096] FIG. 25A is a perspective view of an HVAC system including ducts and fittings of the present disclosure; and

[0097] FIG. 25B is a perspective view of the HVAC system of FIG. 24A installed under a floor of a residence or other building.

[0098] The present invention will be described in connection with certain preferred embodiments. However, it is to be understood that there is no intent to limit the invention to the embodiments described. On the contrary, the intent is to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims. DETAILED DESCRIPTION

[0099] For a general understanding of the present disclosure, reference is made to the drawings. In the drawings, like reference numerals have been used throughout to designate identical elements. The drawings are to be considered exemplary, and are for purposes of illustration only. The dimensions, positions, order and relative sizes reflected in the drawings attached hereto may vary.

[00100]lt is also to be understood that any connection references used herein (e.g., attached, coupled, connected, and joined) are to be construed broadly and may include intermediate members between a collection of elements and relative movement between elements unless otherwise indicated. As such, connection references do not necessarily imply that two elements are directly connected and in fixed relation to each other.

[00101] The terms "preferred" and "preferably" refer to embodiments of the invention that may afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the present disclosure.

[00102] The term "providing", such as "providing a spool of material" and the like, when recited in the claims, is not intended to require any particular delivery or receipt of the provided item. Rather, the term "providing" is merely used to recite items that will be referred to in subsequent elements of the claim(s), for purposes of clarity and ease of readability.

[00103] The terms "about" and "substantially" are used herein with respect to measurable values and ranges due to expected variations known to those skilled in the art (e.g., limitations and variabilities in measurements).

[00104] Referring to FIGS. 1A-1 C, a first duct of the present disclosure is depicted. The duct 10 is comprised of an inner sleeve 20, and outer sleeve 40, and a layer 60 of insulative material. The inner sleeve 20 may be comprised of a band 22 of inner sheet material having a first lateral edge 24 and a second lateral edge 26 parallel to the first lateral edge 24. The band 22 of inner sheet material may be wound in a spiral. The first lateral edge 24 may be joined to the second lateral edge 26. In joining the first lateral edge 24 to the second lateral edge 26, the edges 24 and 26 may be abutted against each other as shown in FIGS. 1A-1 C, or the edges 24 and 26 may be overlapped. [00105] The outer sleeve 40 may be comprised of a band 42 of outer sheet material having a first lateral edge 44 and a second lateral edge 46 parallel to the first lateral edge 44. The band 42 of outer sheet material may be wound in a spiral. The first lateral edge 42 may be joined to the second lateral edge 44. In joining the first lateral edge 44 to the second lateral edge 46, the edges 44 and 46 may be abutted against each other as shown as shown in FIGS. 1A-1 C, or the edges 44 and 46 may be overlapped.

[00106] The outer sleeve 40 surrounds the inner sleeve 20, and thus the outer and inner sleeves 40 and 20 form a gap therebetween. The layer 60 of insulative material is contained in the gap between the inner sleeve 20 and the outer sleeve 40. The insulative material may be a thermally insulative material, which reduces the rate of heat transfer into or out of the duct when there is a temperature gradient across the wall of the duct, which is formed by the inner and outer sleeves 20 and 40 and layer 60 of insulative material.

[00107] The insulative material may be a polymer foam. The polymer foam may be provided in a liquid state and cured to a solid state. The polymer foam may be cured from the liquid to the solid state in a time between about 2 seconds and about 20 seconds. Upon curing, the layer 60 of polymer foam may adhere to the inner sleeve 20 and to the outer sleeve 40. In one exemplary fabricated prototype duct, the polymer foam material was polyurethane.

[00108] The band 22 of inner sheet material may be a first polymer film material. The band 42 of outer sheet material may be a second polymer film material. Alternatively, the inner sheet material and outer sheet material may be made of the same material. In one exemplary fabricated prototype duct, the polymer film material was metalized polyethylene terephthalate. One of the band 22 of inner sheet material and the band 42 of outer sheet material may be wound with a first pitch relative to a central axis 99 of the duct, and the other of the band 22 of inner sheet material and the band 42 of outer sheet material may be wound with a second pitch relative to the central axis 99 of the duct and in an opposite direction of the first pitch, i.e. , the spirals may have opposed “handedness.” For example, referring again to FIGS. 1A-1 C, the band 22 of inner sheet material is wound in a right-handed spiral, and the band 42 of outer sheet material is wound in a left-handed spiral. When the duct 10 is made in such a configuration having opposed spirals, the duct 10 may be provided with additional structural strength. In other cases, the band 22 of inner sheet material and the band 42 of outer sheet material may be wound with the same pitch relative to a central axis 99 of the duct, i.e. , the spirals may have the same “handedness.”

[00109] FIG. 2A is a perspective exploded view of a second round duct in accordance with the present disclosure, and FIG. 2B is a cross section of the duct of FIG. 2A, taken in a plane similar to the cross-sectional plane of FIG. 1 C. In aspects similar to the duct 10 of FIGS. 1A-1 C, the duct 11 is comprised of an inner sleeve 20 and an outer sleeve 40. The duct 11 is further comprised of a layer 61 of insulative material, and a corrugated sleeve 80 disposed between the outer sleeve 60 and the layer 61 of insulative material. In fabrication of the duct 11 , the corrugated sleeve 80 may act as a mold that forms layer 61 of insulative material in a corresponding corrugated shape, as shown particularly in FIG. 2B. In some cases, after the layer 61 of the insulative material is dispensed, the sleeve 80 may be laid in a flat state on the layer 61 of insulative material in the same manner as the inner sleeve 20 and outer sleeve 40. Subsequently, a worm gear or other tool with an exterior surface having an approximately sinusoidal shape may be used to press onto the sleeve 80 and cause the corrugation of the sleeve 80. The peaks of the corrugation may be applied with adhesive by a roller dipped in a liquid adhesive bath so that the outer sleeve 60 will adhere to the corrugated sleeve 80.

[00110] FIG. 3A is a perspective view of an oblong duct in accordance with the present disclosure, and FIG. 3B is a perspective exploded view of the duct of FIG. 3A. In general, an oblong duct as disclosed herein is a duct having a cross-section with a ratio of width to height not equal to one. In other words, an oblong duct has a width greater than its height. An oblong duct may be elliptical in cross section, rectangular in cross-section, or a having a combination of outer opposed semicircular sections joined to a rectangular central section, such as duct 13 of FIG. 3A. In aspects similar to the duct 10 of FIGS. 1A-1 C, the duct 13 is comprised of an inner sleeve 23, an outer sleeve 43, and a layer 63 of insulative material. The inner and outer sleeves 23 and 43 may be oblong with respect to a cross-section viewed perpendicular to a longitudinal central axis 98 of the duct.

[00111] The inner sleeve 23 may be comprised of a band 25 of inner sheet material having a first lateral edge 27 and a second lateral edge 29 parallel to the first lateral edge 27. The band 25 of inner sheet material may be wound in a spiral, such that the first lateral edge 27 is joined to the second lateral edge 29. In joining the first lateral edge 27 to the second lateral edge 29, the edges 27 and 29 may be abutted against each other as shown, or the edges 27 and 29 may be overlapped. [00112] The outer sleeve 43 may be comprised of a band 45 of outer sheet material having a first lateral edge 47 and a second lateral edge 49 parallel to the first lateral edge 47. The band 45 of outer sheet material may be wound in a spiral, such that the first lateral edge 47 is joined to the second lateral edge 49. In joining the first lateral edge 47 to the second lateral edge 49, the edges 47 and 49 may be abutted against each other, or the edges 47 and 49 may be overlapped.

[00113] The outer sleeve 43 surrounds the inner sleeve 23, and thus the outer and inner sleeves 43 and 23 form an oblong-shaped gap therebetween. The layer 63 of insulative material is contained in the gap between the inner sleeve 23 and the outer sleeve 43. The insulative material may be a thermally insulative material, such as a polymer foam, as described previously for duct 10 of FIGS. 1A-1 C. The band 25 of inner sheet material may be a first polymer film material, and the band 45 of outer sheet material may be a second polymer film material, or the bands 25 and 45 may be of the same material, as described previously for duct 10 of FIGS. 1A-1 C.

[00114] In some cases, the oblong duct 13 may be formed having two opposed parallel planar walls 15 and 17 located between two opposed cylindrical sections 14 and 16, as shown in FIG. 3A. In other cases (not shown), the oblong duct may have an elliptical cross section. By making a duct with an oblong shape, the duct is provided with a high flow capacity, while having a low profile. This may be beneficial in instances where there is limited space in which to install the duct. Additionally, an oblong duct having planar walls may be beneficial in that joining such a duct to other ducts perpendicular to it is simplified.

[00115] FIGS. 4A-4C are schematic illustrations of an apparatus 100 for making the ducts of FIGS. 1A-3B. FIGS. 5-15 show the apparatus 100 in operation, executing a sequence of steps of a method for making a duct of the present disclosure.

[00116] The apparatus 100 may be comprised of a mounting base or table 102, a mandrel 110, a source 120 of a band 22 of inner sheet material, a fluid delivery system 160, and a source 140 of a band 42 of outer sheet material. The mandrel 110 may be comprised of an elongated member 112 having an outer surface 113 and a central axis 199. The elongated member 112 of the mandrel 110 may be rotatable around the central axis 199 of the elongated member 112 as indicated by arrow 198. A motor 115 may be provided to rotate the elongated member 112. In some cases, the elongated member 112 may be a cylindrical member as shown in FIGS. 4A and 4C. In other cases (not shown), the elongated member 112 may be oblong in cross-section. [00117] As described previously, the band 22 of inner sheet material has a first lateral edge 24 and a second lateral edge 26 parallel to the first lateral edge 24, and the band 42 of inner sheet material has a first lateral edge 44 and a second lateral edge 46 parallel to the first lateral edge 44. When the apparatus 100 is operating, the source 120 of the band 42 of inner sheet material is operable to dispense a portion of the band 42 of the inner sheet material in a spiral on the outer surface 113 of the elongated member 112 around the central axis 199 of the elongated member 112. In like manner, the source 140 of the band 42 of outer sheet material is operable to dispense a portion of the band of the outer sheet material in a spiral onto a fluid layer 65 (FIG. 6) dispensed from the fluid nozzle 162 onto the spiral of the band 22 of inner sheet material.

[00118] The source 120 of the band 22 of inner sheet material may dispense the portion of the band 22 of the inner sheet material in the spiral such that the first lateral edge 24 of the band 22 of the inner sheet material is contiguous with the second lateral edge 26 of the band 22 of the inner sheet material. In like manner, the source 140 of the band 42 of outer sheet material may dispense the portion of the band 42 of the outer sheet material in the spiral such that a first lateral edge 44 of the band 42 of the outer sheet material is contiguous with a second lateral edge 46 of the band 42 of the outer sheet material. As used in this context, the term “contiguous” means that the first lateral edge 24 of the band 22 of the inner sheet material may be abutted against the second lateral edge 26 of the band 22 of the inner sheet material, or the first lateral edge 24 of the band 22 of the inner sheet material may have a small overlap (about 1/8 to 1/4 of an inch in some cases) with the second lateral edge 26 of the band 22 of the inner sheet material.

[00119] In some cases, the source 120 of the band 22 of inner sheet material may be a first rotatable spool 121 , and the source 140 of the band 42 of outer sheet material may be a second rotatable spool 141. Referring in particular to FIG. 5, the angles of the respective axis of rotation 197 of the first spool 121 and axis of rotation 196 of the second spool 141 may be adjustable with respect to the central axis 198 of the elongated member 112 of the mandrel 110, as indicated by respective arcuate arrows 195 and 194. In some cases, this adjustability may be provided by mounting the spools 121 and 141 on respective turntables 123 and 143, which may be rotated by drive motors 125 and 145. The spools 121 and 141 are operable to dispense the respective portions of the band 22 of the inner sheet material and the band 42 of outer sheet material in the spirals around the central axis 199 of the elongated member 112 of the mandrel 110, which is coaxial with the central axis of the duct being fabricated. The spirals of the band 22 of the inner sheet material and the band 42 of outer sheet material may have the same handedness, i.e. , they may both have a left handed spiral, or they may both have a right handed spiral. Alternatively, the spirals of the band 22 of the inner sheet material and the band 42 of outer sheet material may have opposed handedness, i.e., one band may have a left handed spiral, and the other band may have a right handed spiral.

[00120] The source 120 of the band 22 of inner sheet material may be movable along the central axis 199 of the elongated member 112 of the mandrel 110. In like manner, the source 140 of the band 42 of outer sheet material may be movable along the central axis 199 of the elongated member 112. In the exemplary apparatus 100 of FIGS. 4A-12, the respective sources 120 and 140 are mounted on a support plate 131 , which in turn may be mounted on a linear slide 133. The support plate 131 may be moved on the linear slide 133 by suitable means (not shown) such as a drive motor, a pneumatic cylinder, or a hydraulic cylinder, as indicated by arrow 193.

[00121] Referring in particular to FIG. 7, the apparatus 100 may be further comprised of a fuser 150 in communication with first lateral edge 24 of the band 22 of the inner sheet material and the second lateral edge 26 of the band 22 of the inner sheet material where the bands intersect in the spiral wrap. Alternatively or additionally, the fuser 150 may be in communication with first lateral edge 44 of the band 42 of the outer sheet material and the second lateral edge 46 of the band 42 of the outer sheet material. The fuser 150 is operable to join the first lateral edge 24 of the band 22 of the inner sheet material to the second lateral edge 44 of the band 22 in the spiral wrappings of the band 22, and/or join the first lateral edge 44 of the band 42 of the outer sheet material to the second lateral edge 46 in the spiral wrappings of the band 42 of the outer sheet material. The fuser 150 may be mounted on a support plate 135, which in turn may be mounted on a linear slide 137. The support plate 135 may be moved on the linear slide 137 by suitable means (not shown) such as a drive motor, a pneumatic cylinder, or a hydraulic cylinder, as indicated by arrow 192. Suitable fusers include, but are not limited to, adhesive dispensers, ultrasonic welding horns, lasers, and heating elements.

[00122] The fluid delivery system 160 may be comprised of a fluid nozzle 162 proximate to the outer surface 113 of the elongated member 112 of the mandrel 110, and thus proximate to the spiral wrap of the band 22 of the inner sheet material around the elongated member 112. The fluid nozzle 162 may be movable along the central axis 199 of the elongated member 112 of the mandrel 110 as indicated by arrow 191. The fluid nozzle 162 may be mounted on a support plate 139, which in turn may be mounted on the linear slide 137, or a separate linear slide (not shown). The support plate 139 may be moved on the linear slide 137 by suitable means (not shown) such as a drive motor, a pneumatic cylinder, or a hydraulic cylinder. In that manner, the fluid nozzle 162 may be moved synchronously with the wrapping of the spiral of the band 22 of the inner sheet material around the elongated member 112. Referring to FIGS. 4C and 6, in some cases, the fluid nozzle 162 may be a slot-shaped nozzle 162A. The width of the slot-shaped nozzle 162A may be selected such that the liquid bead 65 that is dispensed onto the band 22 of inner sheet material that is wound in the spiral is about the same width as the band 22 of inner sheet material.

[00123] The fluid delivery system 160 may be further comprised of a source 164 of polymer foam in fluid communication with the fluid nozzle 162/162A. In the apparatus 100 shown in FIG. 6, the source 164 may be a pressure vessel 165 containing a polymer fluid that expands into a foam when discharged. The fluid delivery system 160 may further include various fluid conduits (e.g., conduits 161 and 163), and instrumentation, valves, and a fluid pump (all not shown).

[00124] The apparatus 100 may be further comprised of a first engagement arm 171 opposed to a second engagement arm 176. The first and second engagement arms 171 and 176 may be movable radially inwardly, such as by robotic arms (not shown) to respective opposed positions proximate to the outer surface 113 of the elongated member 112 of the mandrel 110, and thus to respective opposed positions proximate to the outer sleeve 40 of a portion of fabricated duct 10. The engagement arms 171 and 176 include engagement tips 172 and 177 at the respective distal ends thereof. In the exemplary apparatus 100, the engagement tips 172 and 177 may be suction cups that are in communication with a vacuum source (not shown). In operation of the apparatus 100, the engagement arms 171 and 176 may be deployed with the engagement tips 172 and 177 temporarily engaged with the outer sleeve 40 of a portion of fabricated duct 10 as indicated by respective arrows 190 and 189, so that the portion of fabricated duct can be moved laterally along the elongated member 112 of the mandrel 110, as will be described subsequently in further detail.

[00125] Referring to FIG. 14, the apparatus 100 may be further comprised of a cutting tool 180 proximate to an outer end 111 of the elongated member 112 of the mandrel 110. The cutter 180 may be positioned to cut in a plane substantially perpendicular to the central axis 199 of the elongated member 112 of the mandrel 110. In one case, the cutter 180 may be a saw including a saw blade 182. The cutter 180 is operable to cut the assembled duct 10 into discrete lengths of duct, which lengths may be predetermined in advance as required by an overall HVAC ducting design for which ducts 10 are being made.

[00126] Referring to FIG. 4C, the mandrel 110 of the apparatus 100 may be further comprised of a first magnet 114 disposed in the elongated member 112 proximate to the outer surface 113 and proximate to the distal end 111 of the elongated member 112. Additionally, a leading edge 21 of the band of inner sheet material may be comprised of a first magnetic strip 28 removably joinable to the first magnet 114. Prior to beginning the spiral wrapping of the band 22 of inner sheet material around the outer surface 113 of the elongated member 112, the leading edge 21 of the band 22 of inner sheet material including the first magnetic strip 28 may be placed on the outer surface 113 in close proximity to the first magnet 114. This has the effect of removably joining the first magnetic strip 28 to the first magnet 114, and thus removably joining the leading edge 21 of the band 22 of inner sheet material to the outer surface 113 of the elongated member 112. This arrangement enables the spiral wrapping of the band 22 of inner sheet material around the outer surface 113 of the elongated member 112 to begin. In some cases, the strength of the magnetic strip 28 and the first magnet 114 may be chosen so that the beginning of the spiral wrapping is enabled, but weak enough so that subsequently the first and second engagement arms 171 and 176 engaged with the duct can overcome the magnetic attraction force and move the assembled duct 10 laterally on the elongated member 112 of the mandrel 113 as will be described subsequently. In other cases, the first magnet 114 may be provided as an electromagnet, which includes a voltage source and electrical conductors to a coil (all not shown). Accordingly, the first magnet 114 may be energized to provide an attractive magnetic force on the magnetic strip 28 at the leading edge 21 of the band 22 of inner sheet material in order to start the spiral wrapping of the band 22 of inner sheet material around the elongated member 112, and de-energized to release the magnetic strip 28 and enable movement of the assembled duct 10 laterally on the elongated member 112 of the mandrel 113.

[00127] In like manner, the mandrel 110 may be further comprised of a second magnet 116 disposed in the elongated member 112 proximate to the outer surface 113 and proximate to the distal end 111 of the elongated member 112. The leading edge 41 of the band 42 of outer sheet material may be comprised of a second magnetic strip 48 removably joinable to the second magnet 116. The operation and possible additional features of the second magnet 116 and the second magnetic strip 48 to enable the spiral wrapping of the band 42 of outer sheet material around the fluid layer 65 on the inner sleeve 20 of the duct 10 are as described above for the first magnet 114 and the first magnetic strip 28.

[00128] Referring to FIG. 8, the apparatus 100 may be comprised of a worm gear 105 or other tool with an exterior surface having an approximately sinusoidal shape, and a source (not shown) of a formable intermediate sheet material 62. The source of formable intermediate sheet material may be a spool of a band of material as described previously for inner sleeve 20 and outer sleeve 40. The worm gear 105 may be mounted on an arm 107, which may be joined to the support plate 131. In operation of the apparatus 100, the worm gear 105, which may be rotatable and may be comprised of one or more spiral teeth (not shown), is pressed against the formable intermediate sheet material 62, which is wrapped around the fluid layer 65. The worm gear 105 forms the intermediate sheet material 62 and the fluid layer 65 (which may be a polymer foam layer) into a corrugated structure, including a layer 61 of insulative material and a corrugated sleeve 80 as shown in FIGS. 2A and 2B and described previously.

[00129] FIGS. 5-15 show the apparatus 100 in operation, executing a sequence of steps of a method for making a duct of the present disclosure. The method is described with reference below to FIGS. 5-15 in sequence. However, it is to be understood that the sequence of steps may vary from the order set forth below, and/or certain steps may be excluded, or additional steps may be included.

[00130] FIG. 5: With the leading edge 21 of the band 22 of inner sheet material removably joined to the outer surface 113 of the elongated member 112 as described previously with reference to FIG. 4C, rotation of the elongated member 112 is begun, causing the band 22 of inner sheet material to form a spiral wrap around the elongated member 112. (It is noted that although the leading edge 41 of the band 42 of outer sheet material is shown in position for removably joining to the outer surface 113 of the elongated member 112 in FIG. 5, the band 42 is not yet joined to the elongated member 112.) Traversal of the support plate 131 and the spool 121 of inner sheet material along the elongated member 112 is begun as indicated by arrow 193L. The initial spiral wrapping of the band 22 of inner sheet material begins the formation of the inner sleeve 20 of the duct 10. (See also FIGS. 1A-1 C.)

[00131] FIG. 6: Dispensing of a layer 65 of liquid polymer foam from the nozzle 162 or 162A onto an outer surface of the inner sleeve 20, with traversal of the support plate 139 and nozzle 162/162A is begun as indicated by arrow 191 L. Additionally, the leading edge 41 of the band 42 of outer sheet material may be removably joined to the outer surface 113 of the elongated member 112 at this time, as described previously with reference to FIG. 4C. Traversal of the support plate 131 and the spool 121 of inner sheet material along the elongated member 112 continues.

[00132] FIG. 7: With the leading edge 41 of the band 42 of outer sheet material removably joined to the outer surface 113 of the elongated member 112 as described previously with reference to FIG. 4C, rotation of the elongated member 112 continues, causing the band 42 of outer sheet material to form a spiral wrap around the outer surface of the layer 65 of liquid polymer foam. The initial spiral wrapping of the band 42 of outer sheet material begins the formation of the outer sleeve 40 of the duct 10. (See also FIGS. 1A-1C.) The liquid polymer foam between the inner sleeve 20 and the outer sleeve 40 of the duct 10 begins to cure into a solid foam. Traversal of the support plate 131 and the spools 121 and 141 of inner sheet material and outer sheet material along the elongated member 112 continues. Traversal of the support plate 139 and nozzle 162/162A along the elongated member 112 continues. A first portion 12 of the duct 10 is formed. In forming the first portion 12 of the duct 10, and subsequent portions, a linear rate of forming the inner sleeve 20 along a central axis of the duct 10 may be substantially equal to a linear rate of dispensing the annular layer 65 of liquid polymer foam along a central axis of the duct 10. A linear rate of forming the outer sleeve 20 along a central axis of the duct may be substantially equal to a linear rate of dispensing the annular layer of liquid polymer foam 65 along a central axis of the duct 10. In some cases, the polymer foam may be cured from a liquid to a solid state in a time between about 2 seconds and about 20 seconds.

[00133] If a fuser 150 is provided (shown only in FIG. 7, but may be present in FIGS. 4A-15), traversal of the fuser 150 and support plate 135 occurs, thereby keeping the fuser 150 in communication with the contiguous edges 24 and 26 of the spiral wrapped band 22 of inner sheet material, thereby joining them together. (It is noted that the use of the fuser 150 is optional. In some cases, the liquid polymer foam may wet the contiguous edges 24 and 26 of the spiral wrapped band 22, and the subsequent curing of the liquid foam into solid foam may adhere to the inner sleeve 20 and cause the edges 24 and 26 to be joined to each other.) The fuser 150 may be positioned and traversed to be in communication with the contiguous edges 44 and 46 of the spiral wrapped band 42 of outer sheet material, thereby joining them together to form the outer sleeve 40 of the duct 10. Alternatively, a separate fuser (not shown) may be provided for this purpose.

[00134] FIG. 8: If a worm gear 105 and source (not shown) of a formable intermediate sheet material 62 are provided (shown only in FIG. 8, but may be present in FIGS. 4A-15), these components may be operated concurrently with other duct fabrication steps to form a corrugated sleeve 80 as shown in FIGS. 2A and 2B.

[00135] The motion (leftward in FIG. 7) of the spools 121 and 141 of inner sheet material and outer sheet material along the elongated member 112 and the motion of the fluid nozzle 162/162A are stopped. Delivery of the polymer foam layer 65 may also be stopped. The rotation of the portion 12 of duct 10 may also be stopped, but the elongated member 112 of the mandrel 110 may continue to rotate by slipping within the first portion 12 of duct 10.

[00136] FIG. 9: The opposed first and second engagement arms 171 and 176 are moved radially inward as indicated by respective arrows 190IN and 189IN so that the engagement tips 172 and 177 are engaged with the outer surface of the outer sleeve 40 of the portion 12 of duct 10. In one case in which the engagement tips 172 and 177 are suction cups, a vacuum may be applied to the suction cups to engage them with the outer sleeve 40. The respective mounting base 131 and engagement arm 171 and support plate 139 and engagement arm 172 are then moved outwardly along the central axis 199 as indicated by arrows 193R and 191 R, thereby moving the portion 12 of duct 10 outwardly along the central axis 199 as indicated by arrow 188. In the apparatus 100 of FIGS 5-15, the spools 121 and 141 are mounted on mounting plate 131 and the fluid nozzle 162/162A is mounted on mounting plate 139, so the spools 121 and 141 and fluid nozzle 162/162A also move outwardly.

[00137] In an alternative cases (not shown), the spools 121 and 141 and fluid nozzle 162/162A may be mounted on separate mounting plates and be moved by separate drive motors. In such cases, the rotation of the elongated member 112, spiral winding of the bands 22 and 42 of inner and outer sheet materials, and delivery of liquid polymer foam from the nozzle 162/162A may continue while the engagement arms 172 and 177 and the portion 12 of duct 10 are moved outwardly along the central axis 199.

[00138] FIG. 10: Outward motion of the mounting plates 131 and 139, spools 121 and 141 , and fluid nozzle 162/162A along the central axis 199 is stopped. The first and second engagement arms 171 and 176 and engagement tips 172 and 177 are moved radially outwardly as indicated by respective arrows 190OLIT and 189OLIT. [00139] FIG. 11 : The cycle of steps for spiral wrapping the bands 22 and 42 of inner and outer sheet materials and dispensing liquid polymer foam to form the inner sleeve 20, layer 60 of insulative material, and outer sleeve 40 of the duct 10 as shown in FIGS. 6-8 and described previously is repeated, thereby forming of an additional portion 12 of the duct 10.

[00140] FIG. 12: The cycle of steps for deploying the engagement arms 171 and 176, and moving the portion 12 of duct 10 outwardly along the central axis 199 as shown in FIGS. 9-10 are repeated.

[00141] FIG. 13: The cycle of steps as shown in FIGS. 6-10 have been repeated, thereby forming of an additional portion 12 of the duct. Multiple cycles to form additional portions 12 of the duct may be repeated. When the desired total length of duct 10 has been fabricated, the spiral wrapping of the band 22 of inner sheet material may be stopped. The spool 121 of inner sheet material may be removed as shown. The spiral wrapping of the band 42 of outer sheet material may be continued until the entire layer 65 of dispensed polymer foam has been covered.

[00142] FIG. 14: The spiral wrapping of the band 42 of outer sheet material has been stopped. The spool 141 of outer sheet material may be removed as shown. The engagement arms 171 and 172 are deployed to engage with the portion 12 of the duct. The cutter 180 may be actuated to cut away a piece of the portion 12 of the duct, providing a finished piece of duct 10. As additional portions 12 of duct are formed, the cutter 180 may be used repeatedly to cut off finished pieces of duct 10.

[00143] FIG. 15: The engagement arms 171 and 172 are moved outwardly as indicated by arrows 193R and 191 R, thereby separating a finished duct 10 from the apparatus 100. The engagement tips 176 and 177 may release the duct 10 as indicated by arrow 187.

[00144] In additional aspects of the present disclosure, fittings for connecting lengths of duct together are provided. Such fittings are shown in FIGS. 16A-24B.

[00145] Referring first to FIGS. 16A-16E, a pair of duct fittings 200L and 200R is shown. Fitting 200L and 200R may be identical, and are referred to as “hermaphroditic” fittings. Fitting 200L includes a pair of male features that are engageable with female features of fitting 200R, and fitting 200L includes a pair of female features that are engageable with male features of fitting 200R.

[00146] More specifically, fittings 200L and 200R are each comprised of a cylindrical tubular body 210 and a flange 220. The flange 220 extends laterally from a proximal end 211 of the cylindrical tubular body 210. The flange 220 is comprised of first and second barbs 222 and 224 (male features) located substantially 180 degrees opposite of each other, and first and second cavities 223 and 225 (female features) located on the flange 210 substantially 180 degrees opposite of each other. The cavities 223 and 225 are also located on the flange substantially 90 degrees from the first and second barbs 222 and 224. The flange 220 may extend radially outwardly from the tubular body 210. The connector fitting 200L/200R may include a circumferential groove in an outer surface of the tubular body 210.

[00147] Referring to FIG. 16C, a duct connector fitting 220L/220R may be joined to a duct to form a duct assembly 200LA/200RA. The duct 10 is comprised of a tubular side wall 18 having an inner surface 19 and an outer surface 31. In such cases, the cylindrical tubular body 210 of the connector fitting 200L/200R extends inwardly within the tubular side wall 18 and is contiguous with the inner surface 19 of the duct 10. The duct assembly 200LA/200RA may include an outer compression ring 230 engaged in an interference fit with the outer surface 31 of the tubular side wall 18 of the duct 10. The duct assembly 200LA/200RA may include an O-ring 240 disposed between the outer surface of the tubular body 210 of the connector fitting and the inner surface 19 of the tubular side wall 18 of the duct 10. The O-ring 240 may be disposed in the circumferential groove of the tubular body 210. The duct 10 may be a duct as shown in FIGS. 1A-1 C or a duct 11 as shown in FIGS. 2A-2B and described previously herein.

[00148] Referring to FIGS. 16C-16E, pairs of duct connector fittings 200L and 200R as described above may be joined to each other to form a duct assembly 200A suitable for constructing HVAC systems. Such a duct assembly 200A may be comprised of a first connector fitting 200L and a second connector fitting 200R, each comprised of a cylindrical tubular body 210 and a flange 220 as described above. To connect the first connector fitting 200L to the second connector fitting 200R, the fittings 200L and 200R and ducts 10 joined thereto are rotated from positions of misalignment (e.g., as shown in FIG. 16C) to desired aligned positions as shown in FIG. 16D. The fittings 200L and 200R and ducts 10 are then moved toward each other as indicated by arrows 97. Referring to FIG. 16E, the first and second barbs 222 and 224 of the first connector fitting 200L are engaged with the first and second cavities 223 and 225 of the second connector fitting 200R, and the first and second barbs 222 and 224 of the second connector fitting 200R are engaged with the first and second cavities 223 and 225 of the first connector fitting 200L. The duct assembly 200A may further include a flat gasket 250 disposed between the flange 220 of the first connector fitting 200L and the flange 220 of the second connector fitting 200R. The duct assembly 200A may further include a first duct 10 joined to the first connector fitting 200L and a second duct 10 connected to the second connector fitting 200R as described above.

[00149] Alternative duct connector fittings, referred to herein as a “slide-in” connector fittings, are shown in FIGS. 17A-17F, and FIGS. 20A and 20B. The connector fittings of FIGS. 17A-17F may be used in a duct assembly to connect a round duct to a round duct, and the connector fittings of FIGS. 20A-20B may be used in a duct assembly to connect an oblong-shaped duct to an oblong-shaped duct.

[00150] Referring first to FIGS. 17A-17C, a slide-in duct connector fitting 300L or 300R for joining round ducts is comprised of a tubular body 310 and a flange 320 extending laterally from a proximal end 311 of the tubular body 310. The flange 320 is comprised of a first half 321 and a second half 331 . The first half 321 extends around the tubular body 310 and terminates at a first end wall 322 and a second end wall 327. A first male tab 323 protrudes from the first end wall and a second male tab 328 protrudes from the second end wall 327. A first female cavity 324 extends inwardly from the first end wall 322 into the first half 321 of the flange 320, and a second female cavity 329 extends inwardly from the second end wall 327 into the first half 321 of the flange 320. The second half 331 of the flange 320 extends around the tubular body 310 and terminates at the first end wall 322 and the second end wall 327. The flange 320 may extend radially outwardly from the tubular body 310. The duct connector fitting 300L/300R may include a circumferential groove 312 in an outer surface of the tubular body 310, and an O-ring 340 disposed in the circumferential groove 312. The tubular body 310 of the fitting 300L/300R may include notches 315 interspersed with end tabs 317 formed in the distal end 313 of the tubular body 310. Pawls 318 may be provided, which protrude radially outwardly from the distal ends 319 of the end tabs 317. Such notches 315, end tabs 317, and pawls 319 may facilitate the fitting and securing of the tubular body 310 of the fitting 300L/300R in a duct 10 as will be described subsequently. In some cases, the tubular body 310 may be cylindrical in cross-section.

[00151] In other cases, the tubular body may be oblong in cross-section. Oblong connector fittings, such as connector fittings 400B and 400T of FIGS. 20A and 20B may be used in a duct assembly to connect an oblong-shaped duct to an oblongshaped duct. It can be seen that fittings 400B and 400T are similar to the fittings 300L and 300R, and are comprised of a tubular body 410 and a flange 420 extending laterally from a proximal end 411 of the tubular body 410. The flange 420 is comprised of a first half 421 and a second half 431. The first half 421 extends around the tubular body 410 and terminates at a first end wall 422 and a second end wall 427. A first male tab 423 protrudes from the first end wall 422 and a second male tab 428 protrudes from the second end wall 427. A first female cavity 424 extends inwardly from the first end wall 422 into the first half 421 of the flange 420, and a second female cavity 429 extends inwardly from the second end wall 427 into the first half 421 of the flange 420. The second half 431 extends around the tubular body 410 and terminates at the first end wall 422 and the second end wall 427. The flange 420 may extend radially outwardly from the tubular body 410. The duct connector fitting 400B/400T may include a circumferential groove 412 in an outer surface of the tubular body 410, and an O-ring 440 disposed in the circumferential groove 412. The tubular body 410 of the fitting 400B/400T may include notches 415 formed in the distal end 413 of the tubular body 410 and interspersed with end tabs 417.

[00152] Referring to FIGS. 17D-17F, a duct assembly 300LA or 300RA may be made comprising the duct connector fitting 300L/300R, and a duct 10 comprising a tubular side wall 18 having an inner surface 19. In such cases, the cylindrical tubular body 310 of the connector fitting 300L/300R extends inwardly within the tubular side wall 18 and is contiguous with the inner surface 19 of the duct. Such a duct assembly may include an inner compression ring 330. The compression ring 330 may be fitted within the tubular cylindrical body 310 at the distal end 313 thereof, causing the end tabs 317 at the end 313 of the tubular body 310 expand outwardly against the inner surface 19 of the tubular side wall 18 of the duct 10, thereby joining the duct connector fitting 300L/300R to the duct 10. In cases where the duct 10 is made of a conformable material, the pawls 318 may protrude into the inner surface 19 of the side wall 18 of the duct 10.

[00153] Referring also to FIG. 20B, an oblong-shaped duct assembly 400BA or 400TA may be made comprising the duct connector fitting 400B/400T, and an oblongshaped duct 13 comprising a tubular side wall 18 having an inner surface 19. In such cases, the tubular body 410 of the connector fitting 400B/400T extends inwardly within the tubular side wall 18 and contiguous with the inner surface 31 of the duct. Such a duct assembly may include an outer compression ring 430 and/or an O-ring 440 as described above.

[00154] Pairs of alternative duct connector fittings as described above may be joined to each other to form duct assemblies suitable for constructing HVAC systems. Referring to FIGS. 17D-17F, a cylindrical duct assembly 300A may be comprised of a first connector fitting 300L and a second connector fitting 300R, each comprised of a tubular body 310 and a flange 320, and each joined to ducts 10, as described above. Referring to FIG. 17D in particular, to connect the first connector fitting 300L to the second connector fitting 300R, the second connector fitting 300R is moved axially and laterally relative to the first connector fitting 300L, as indicated by arrow 96. The first and second male tabs 323 and 328 of the first connector fitting 300L are engaged with the first and second female cavities 324 and 329 of the second connector fitting 300R, and the first and second male tabs 323 and 328 of the second connector fitting 300R are engaged with the first and second female cavities 324 and 329 of the first connector fitting 300L. It is noted that the fittings 300L and 300R may be identical in all features, and in opposed positions are joinable by a “slide-in” motion.

[00155] In such a joined arrangement, the first half 321 of the flange 320 of the first connector fitting 300L is opposed to the second half 331 of the flange 320 of the second connector fitting 300R, and the second half 331 of the flange 320 of the first connector fitting 300L is opposed to the first half 321 of the flange 320 of the second connector fitting 300R. The duct assembly 300A of FIG. 17F may be further comprised of a first gasket 350A disposed between the first half 321 of the flange 320 of the first connector fitting 300L and the second half 331 of the flange 320 of the second connector fitting 300R, and a second gasket 350B disposed between the second half 331 of the flange 320 of the first connector fitting 300L and the first half 321 of the flange 320 of the second connector fitting 300R. The gaskets 350A and 350B may be formed as a single gasket, with a central section having through holes to accommodate the male tabs 323 and 328 of the connector fittings 300L and 300R. The duct assembly 300A may further include a first duct 10 joined to the first connector fitting 300L and a second duct 10 connected to the second connector fitting 300R as described above.

[00156] Referring to FIG. 20B, an oblong duct assembly 400A may be comprised of a first connector fitting 400B and a second connector fitting 400T, each comprised of a tubular body 410 and a flange 420, and each joined to ducts 13, as described above. To connect the first connector fitting 400B to the second connector fitting 400T, the second connector fitting 400T is moved axially and laterally relative to the first connector fitting 400B, as indicated by arrow 95. The first and second male tabs 423 and 428 of the first connector fitting 400B are engaged with the first and second female cavities 424 and 429 of the second connector fitting 400T, and the first and second male tabs 423 and 428 of the second connector fitting 400T are engaged with the first and second female cavities 424 and 429 of the first connector fitting 400B. It is noted that the fittings 400B and 400T may be identical in all features, and in opposed positions are joinable by a “slide-in” motion.

[00157] Another type of connector fitting is provided, which may be used to connect a round duct to an oblong-shaped duct. Referring to FIGS. 18A-18G, the connector fitting 500A or 500B is comprised of a semicircular body 505 comprising a planar semicircular annular flange portion 510 and a semicircular annular extension 520 protruding upwardly from the planar semicircular annular flange portion 510. The planar semicircular annular flange portion 510 extends from a first end wall 512 around to a second end wall 514. The semicircular annular extension 520 protrudes upwardly from the planar semicircular annular flange portion 510 and terminates a portion of the first end wall 512 and a portion of the second end wall 514. A first barb 516 extends laterally outwardly from the first end wall 512. A first cavity 518 extends laterally inwardly from the second end wall 514 into the semicircular annular extension 520. A second barb 522 extends upwardly from the semicircular annular extension 520. A second cavity 523 extends radially inwardly into a side wall 524 of the semicircular annular extension 520. An arcuate member 540 extends downwardly from the planar semicircular annular flange portion 510 and comprises an arcuate rim 542 forming an arcuate gap 541 with the planar semicircular annular flange portion 510. In some cases, the arcuate member 540 may extend less than 180 degrees circumferentially around the planar semicircular annular flange portion 510. In some cases, the second barb 522 and the second cavity 523 may be spaced from each other at 90 degrees circumferentially around the semicircular annular extension 520.

[00158] The connector fitting 500A/500B of FIGS. 18A-18G may be used in a duct assembly to connect a round duct to an oblong-shaped duct. The duct assembly 500A is comprised of first and second connector fittings 500A and 500B as described above. The fittings 500A and 500B may be identical, and may be considered as “hermaphroditic,” being comprised of a male engagement feature and a female engagement feature, similar to the fittings 200L and 200R of FIGS. 16A and 16B. When the two connector fittings 500A and 500B are joined to each other in an assembled state, the first barb 516 (male engagement feature) of the first connector fitting 500A is engaged with the first cavity 518 (female engagement feature) of the second connector fitting 500B, and the first barb 516 of the second connector fitting 500B is engaged with the first cavity 518 of the first connector fitting 500A. [00159] In one case, the duct assembly 500A may be further comprised of an oblong duct 13 including a flat side wall 37 having a hole 33 therethrough. In such cases, an edge 35 of the hole may be disposed in the arcuate gap 541 of the arcuate rims 542 of the first and second connector fittings 500A and 500B.

[00160] Alternatively or additionally, the duct assembly 500A may be further comprised of an additional duct subassembly 200RA as shown in FIGS. 16C-16E and FIG. 18A and described previously. The duct subassembly 200RA may be comprised of a connector fitting 200R and a cylindrical duct 10. The connector fitting 200R is connectable as a third connector fitting to the connector fittings 500A and 500B when they are joined to each other as shown in FIGS. 18B-18F to form the duct assembly 500A. When such a connection is made, the barb 222 of the third connector fitting 200R is engaged with the cavity 523 of the first connector fitting 500A, the barb 224 of the third connector fitting 200R is engaged with the cavity 523 of the second connector fitting 500B, the first barb 522 of the first connector fitting 500A is engaged with the cavity 223 of the third connector fitting 200R, and the barb 522 of the second connector fitting 500B is engaged with the cavity 225 of the third connector fitting 200R. The duct assembly 500A of may be further comprised of a duct 10 including a tubular side wall 18 as described previously.

[00161] In another additional aspect of the present disclosure, an alternative connector fitting is provided, which may be used in a duct assembly to connect a round duct to an oblong-shaped duct. The connector fitting includes “slide-in” type connecting features as described previously with reference to FIGS. 17A-17F. Referring to FIGS. 19A and 19B, the connector fitting 600 is comprised of a tubular cylindrical body 610, a ring 630, and a flange 620. The tubular body 610 is comprised of an outer wall 612 including threads 614 formed thereupon. The ring 630 is comprised of an inner wall 632 including threads 634 formed therein and engageable with the threads 614 of the tubular cylindrical body 610. The flange 620 extends laterally from a proximal end 611 of the tubular body 610. The flange 620 is a “slide-in” type flange, and is comprised of a first half 621 extending around the tubular body 610 and terminating at a first end wall 622 and a second end wall 627. A first male tab 623 protrudes from the first end wall 622 and a second male tab 628 protrudes from the second end wall 627. A first female cavity 624 extends inwardly from the first end wall 622 into the first half 621 of the flange 620, and a second female cavity 629 extends inwardly from the second end wall 627 into the first half 621 of the flange 620. A second half 631 of the flange 620 extends around the tubular body 610 and terminates at the first end wall 622 and the second end wall 627. A distal end 613 of the tubular cylindrical body 610 may include a plurality of notches 615 interspersed with end tabs 617. Pawls 618 may be provided, which protrude radially outwardly from the distal ends 619 of the end tabs 617.

[00162] Referring to FIGS. 19B-19E, the connector fitting 600 may be joined to an oblong-shaped duct 13 comprised of a flat wall portion 37 to form a duct assembly 600A. The ring 630 is threaded onto the threads 614 of the tubular cylindrical body 610 and rotated, advancing the ring 630 to an upper position on the tubular cylindrical body 610. A hole 33 is formed in the flat wall portion 37, and the distal end 613 of the tubular cylindrical body 610 of the fitting 600 is inserted into the hole 33. Referring in particular to FIG. 19E, when the insertion is performed, the fit of the tubular cylindrical body 610 of the fitting 600 in the hole 33 may be sufficiently tight such that the pawls 618 contact the edge 35 of the hole 33, causing the end tabs 617 to flex radially inwardly. When the pawls 618 pass the inside surface 36 of the duct 13, the end tabs 618 snap back radially outwardly. The rotation of the ring 630 is reversed, causing the ring 630 to move downwardly by the engagement of the threads 614 with the threads 634. The pawls 618 engage against the inside surface 36 of the duct 13 at the edge 35 of the hole 33 in the duct, and in combination with the ring 630 being seated against the flat wall portion 37 of the duct 13, thereby join the connector fitting 600 to the duct 13. In some cases, an inner compression ring 660 may be fitted within the tubular cylindrical body 610. The inner compression ring 660 may further press the end tabs 617 against the edge 35 of the hole 33.

[00163] The duct assembly 600A may be further comprised of a round duct subassembly joined to the connector fitting 600 and the oblong-shaped duct 13. The round duct subassembly may be a slide-in type round duct subassembly 300RA comprised of a round duct 10 joined to a slide-in duct connector fitting 300R as shown in FIGS. 17D-17F and described previously herein. The slide-in connector fitting 600 connected to the oblong-shaped duct 13 is further joined to the slide-in connector fitting 300R of the round duct subassembly 300RA to form the round duct-to-oblong- shaped duct assembly 600A. Referring to FIGS. 19B and 19D, inner compression ring 360 may be fitted within the connector fitting 300R.

[00164] In a system of ducts and fittings in an HVAC system, there is sometimes a need to reduce the size of a duct at some point along its length. To meet this need, a reducing connector fitting is provided, which reduces the size of ducting from a first cross-sectional area to a lesser cross-sectional area. [00165] FIGS. 21A-21 C depict a duct reducing connector 700 for use with cylindrical ducts, and a duct assembly 700A that includes a cylindrical duct reducing connector 700. The reducing connector 700 is comprised of a tubular body 710, a first flange 720, and a second flange 770. The tubular body 710 tapers in cross-section from a large area end 712 to a small area end 714. The first flange 720 extends laterally from the large area end 712 of the tubular body 710. The second flange 770 extends laterally from the small area end 714 of the tubular body 710. The first and second flanges 720 and 770 may be formed as slide-in flanges as described previously, comprising respective first halves 721 and 771 , male tabs 723, 728, 773, and 778, first female cavities 724, 729, 774, and 779, and second halves 731 and 781. The reducing connector 700 may be joined at the large area end 712 to a first duct subassembly 300T comprising a duct 10L of relatively large cross-sectional area joined to a first slide-in connector fitting 300LG, and joined at the small area end 714 to a second duct subassembly 300B comprising a duct 10S of relatively small cross- sectional area joined to a second slide-in connector fitting 300SM.

[00166] FIGS. 21 D-21 E depict a duct reducing connector 740 for use with oblong ducts, such as a duct 13 shown and described previously. The reducing connector 740 is comprised of an oblong tubular body 750, a first flange 760, and a second flange 790. The oblong tubular body 750 tapers in cross-section from a large area end 752 to a small area end 754. The first flange 760 extends laterally from the large area end 752 of the oblong tubular body 750. The second flange 790 extends laterally from the small area end 754 of the oblong tubular body 750. The first and second flanges 760 and 790 are formed as slide-in flanges as described previously, comprising respective first halves 761 and 791 , male tabs 763, 768, 793, and 798, first female cavities 764, 769, 794, and 799, and second halves 767 and 797. The reducing connector 740 may be joined at the large area end 752 to a first oblong duct subassembly such as subassembly 400TA of FIG. 20B having a corresponding large cross-sectional size and slide-in oblong connector fitting 400T, and joined at the small area end 754 to a second oblong duct subassembly such as subassembly 400TA of FIG. 20B having a corresponding small cross-sectional size and slide-in oblong connector fitting 400T.

[00167] In another additional aspect of the present disclosure, a direction adjustable connector is provided, which may be used to change the direction of ducting at any angle over a substantial range of solid angle. Referring to FIGS. 22A-22C, the direction adjustable connector 800 includes “slide-in” type connecting features, and is comprised of a ball tubular body 810 and a socket tubular body 830. The ball tubular body 810 is comprised of a ball tube section 812, a ball member 814 joined to a proximal end 811 of the ball tube section 812, and a first flange 820 extending laterally from a distal end 813 of the ball tube section 812. The socket tubular body 830 is comprised of a socket tube section 832, a socket member 834 joined to a proximal end 831 of the socket tube section 832 and a second flange 840 extending laterally from a distal end 833 of the socket tube section 832. The ball member 814 of the ball tubular body 810 is engaged with and contained in the socket member 834 of the socket tubular body 830.

[00168] The first and second flanges 820 and 840 may be formed as slide-in flanges as described previously, comprising respective first halves 821 and 841 , male tabs 823, 828, 843, and 848, first female cavities 824, 829, 844, and 849, and second halves 827 and 847. The direction adjustable connector 800 may be joined at the first flange 820 to a first duct subassembly 300LA comprising a duct 10 joined to a first slide-in connector fitting 300L, and joined at the second slide-in flange 840 to a second duct subassembly 300RA comprising a duct 10 joined to a second slide-in connector fitting 300R.

[00169] The ball member 814 of the ball tubular body 810 is movable within the socket member 834. Referring to FIG. 22C, in a duct assembly 800A that includes the direction adjustable connector 800, the direction of a first duct 10L that is joined to a slide in connector 300L and to the first flange 820 is adjustable relative to the direction of a second duct 10R that is joined to a slide in connector 300R and to the second flange 840, as indicated by arrows 94. In some cases, the adjustment may be over a range of about 25 degrees of solid angle. Greater angles may be possible with revisions to the dimensions of the ball member 814 and the socket member 834.

[00170] Referring to FIG. 22D, in some cases, a slide-in flange 840 of a first direction adjustable connector 800L may be connected to a slide-in flange 820 of a second direction adjustable connector 800R to provide further direction adjustability of a duct assembly 800AA. In some cases, the adjustment may provide an increase of adjustability by about a factor of two. In other cases, the combination of connectors 800L and 800R in series may be used to provide a parallel offset of the direction of two ducts as indicated by arrow 93.

[00171] In another additional aspect of the present disclosure, a connector fitting is provided, which may be used for placing sensors within a duct. Referring to FIGS. 23A-23C, the connector fitting 850 includes “slide-in” type connecting features, and is comprised of an annular disc 852 surrounding an open center region 851 and including first and second opposed slide-in faces 860 and 880.

[00172] The first face 860 is comprised of a first half portion 861 extending around the annular disc 852 and terminating at a first end wall 862 and a second end wall 867, a first male tab 863 protruding from the first end wall 862 of the first face 860 and a second male tab 868 protruding from the second end wall 867 of the first face 860, a first female cavity 864 extending inwardly from the first end wall 862 of the first face 860 into the first half portion 861 of the first face 860, and a second female cavity 869 extending inwardly from the second end wall 867 of the first face 860 into the first half portion 861 of the first face 860, and a second half portion 871 extending around the annular disc 852 and terminating at the first end wall 862 and the second end wall 867 of the first face.

[00173] The second face 880 is comprised of a first half portion 881 extending around the annular disc 852 and terminating at a first end wall 882 and a second end wall 887, and opposed to the second half portion 871 of the first face 860, a first male tab 883 protruding from the first end wall 882 of the second face 880 and a second male tab 888 protruding from the second end wall 887 of the second face 880, a first female cavity 884 extending inwardly from the first end wall 882 of the second face 880 into the first half portion 881 of the second face 880, and a second female cavity 889 extending inwardly from the second end wall 887 of the second face 880 into the first half portion 881 of the second face 880; and a second half portion 891 extending around the annular disc 852 and terminating at the first end wall 882 and the second end wall 887 of the second face 880. The connector fitting 850 includes at least one port 853 extending from an outer wall 854 of the annular disc to an inner wall 856 of the annular disc. The connector fitting 850 may include a plurality of ports 853 provided at different radial locations around the annular disc 852.

[00174] Referring to FIG. 23C, the first and second slide-in faces 860 and 880 enable the connection of the connector fitting 850 to duct subassemblies, such as subassemblies 300LA and 300RA that include corresponding slide-in type flanges 300L and 300R, to form a duct assembly 850A. The duct assembly 850A may include sensors, such as sensor 855, which may be placed in the ports 853. Such sensors 855 may sense parameters including but not limited to air flow rate, air velocity, air temperature, air pressure, relative humidity, particle count, and concentration of oxygen or other gas constituent(s). Such sensors 855 may transmit data mechanically, such as the gas pressure conveyed by a pitot tube; electrically, such as by electrical wire; optically such as by optical fiber; or wirelessly such as by a Bluetooth® wireless signal; and by combinations of these signal transmission media. A sensor 855 may include a camera (not shown) adapted to obtain images within the duct assembly. Such sensors may be in communication with a processor (not shown) that controls an HVAC system 1000 (FIGS. 25A - 25B).

[00175] It is further noted that the connector fittings 300L, 300R, 600, 400T, 400B, 700, 740, 800, and 900 described herein and shown in FIGS. 17A-17F, FIG. 19A, FIG. 20A, FIGS. 21A-21 E, 22A-22B, 23A-23B, and 24A-24B may also include ports 853 for the fitting of sensors therein.

[00176] In another additional aspect of the present disclosure, an elbow connector fitting is provided, which may be used for changing the direction of a duct assembly. Referring to FIGS. 24A and 24B, the connector fittings 900 and 950 include “slide-in” type connecting features. Fitting 900 of FIG. 24A is comprised of a cylindrical tubular body 910, a first flange 920, and a second flange 940. The tubular body terminates 910 at a first end 912 defining a first end plane, and terminates at a second end 914 defining a second end plane non-parallel to the first end plane. In other words, the tubular body 910 includes a curvilinear bend or an abrupt angular change in direction, thereby forming an elbow section. The first and second flanges 920 and 940 are formed as slide-in flanges comprising respective first halves, first male tabs, first female cavities, and second halves as described previously.

[00177] Fitting 950 of FIG. 24B is comprised of an oblong-shaped tubular body 960, a first oblong flange 970, and a second oblong flange 990. The first and second flanges 970 and 990 are formed as slide-in flanges comprising respective first halves, first male tabs, first female cavities, and second halves as described previously.

[00178] The elbow connector fittings 900 and 950 may be joined at their respective first ends to first duct subassemblies comprising a first duct joined to a first slide-in connector fitting, and joined at the respective second ends to a second duct subassemblies comprising a second duct joined to a second slide-in connector fitting as shown in FIGS. 25A and 25B. For each of the subassemblies including elbow connector fittings 900 and 950, because the first and second end planes are nonparallel, the direction of the first duct joined to the elbow connector fitting is different from the direction of the second duct joined to the elbow connector fitting. In one case, the first and second end planes are perpendicular to each other, in which case, the elbow connector fitting is a 90 degree elbow. [00179] In summary, various duct connector fittings are provided for connecting sections of ducting to form duct assemblies for HVAC systems. In various cases described herein, a duct connector fitting is comprised of a first tubular section, a first slide-in flange joined to a proximal end of the tubular section, and a second slide in flange joined to a distal end of the tubular section. The tubular sections may be configured as elbow sections, reducer sections, adjustable direction sections, and sensor housing sections. The various duct connector fittings enable rapid low cost modular assembly of ducting for HVAC systems.

[00180] One exemplary HVAC system is shown in an upper perspective view in FIG. 25A, and in a lower perspective view in FIG. 25B. In one case, the HVAC system 1000 may be disposed on a basement floor 2. The ducting of the system 1000 may be located proximate to or within the floor joists 4 of a first floor structure 6. The HVAC system is comprised of a HVAC unit 1010 containing a fan, a heater, and an air conditioning unit (not shown, contained in the housing 1010), and various power supply and control components (not shown). Heated or air conditioned (cooled) air from the HVAC unit 1010 is delivered to the rooms above the first floor 6 through output duct assembly 1020 as indicated by arrows 92. Return air is drawn back to the HVAC unit 1010 through return duct assembly 1070 as indicated by arrow 91. The output duct assembly 1020 may be comprised of ducts and fittings as described herein, such as round ducts 10, oblong ducts 13, connector fittings 300L, 300R, 400B, 400T, and 700, reducer fitting 740, elbows 900, and an oblong duct end plug 1021 similar to the oblong fittings 400T and 400B of FIG. 20A, but with a blank end 1022. (In other cases, the duct plug may be circular for fitting to a cylindrical duct.) The return duct assembly 1070 may be comprised of oblong ducts 13, connector fittings 400B and 400T, and elbows 950. Other arrangements of the ducting assemblies would be suitable. Additionally, the exemplary HVAC system 1000 is shown as including “slide-in type” connector fittings disclosed herein. Alternatively or additionally, the system 1000 may include “hermaphroditic” fittings as disclosed herein.

[00181] The various duct fittings disclosed herein may be made of plastic via injection molding, 3D printing, or other suitable manufacturing processes. Non-plastic materials may also be suitable as materials for the fittings.

[00182] It is therefore apparent that there has been provided, in accordance with the present disclosure, ducts and duct adapter and/or connector fittings for conveying fluids such as air and other gases, apparatus and methods for making ducts. [00183] The present disclosure is not to be limited in terms of the particular embodiments described in this application, which are intended as illustrations of various aspects. Many modifications and variations can be made without departing from its spirit and scope. Functionally equivalent methods and apparatuses within the scope of the disclosure, in addition to those enumerated herein, are possible from the foregoing descriptions. Such modifications and variations are intended to fall within the scope of the appended claims. The present disclosure is to be limited only by the terms of the appended claims, along with the full scope of equivalents to which such claims are entitled.