AU2014256416A1 - Return air vent improvements - Google Patents

Abstract

The present invention relates to a return air vent assembly for an HVAC system, and to components of, and a filter for, a return air vent assembly. The return air vent assembly according to the present invention is light weight, adapted for ease of assembly and installation, incorporates a filter requiring less frequent cleaning and replacement, and reduces the tendency for return air to bypass the filter.

Description

1 RETURN AIR VENT IMPROVEMENTS PRIORITY DOCUMENTS [00011 The present application claims priority from Australian Provisional Patent Application No, 2013904317 titled "RETURUN AIR VENT IMPROVEMENTS" and filed on 7 November 2013, the content of which is hereby incorporated by reference in its entirety. TECHNICAL FIELD 100021 The present invention relates to heating, ventilating and air conditioning (HVAC). In a particular form the present invention relates to a return air vent assembly for an HVAC system, and to components of, and a filter for, a return air vent assembly. BACKGROUND 100031 An HVAC system typical comprises an air handling unit (AHU) connected to a ductwork ventilation system that distributes conditioned air (conditioned by the AHU) and returns it to the AHlT. A return air vent is a component of an HVAC system which returns air via ductwork to the AIHJ. [00041 As an AIU forces air (be it hot or cold) into a room it must displace air already in the room or the room will become uncomfortably over-pressurised. The displaced air is accepted by a return air vent and ducted back to the AHU for heating or cooling as required. Thus, return air vents are necessary to prevent build-up of pressure in the structure that may lead to various health problems, as well as preventing mould and mildew, and deterioration of the structure due to moisture build-up. [0005] The size, location, and length of heating, ventilating, and air conditioning (H~VAC) registers and ductwork are determined by measurement of air movement in cubic feet per minute (CFM). Whatever the CFM output of the AHUi the return air vent(s) must be able to match. [0006] Behind each of these vents is typically located a filter which requires periodic cleaning and changing, as even a partially blocked filter will reduce the air flow rate through a return air vent thereby adversely affecting performance of the HVAC system. Moreover, a clogged filter will force return air flow to find pathways of less resistance, such as through gaps in the return air vent assembly, which can cause the return air vent assembly to make whistling (and other) sounds. [0007] It is against this background and the problems and difficulties associated therewith at least, that the present invention has been developed.

2 [00081 Certain objects and advantages of the present invention will become apparent from the following description, taken in connection with the accompanying drawings, wherein, by way of illustration and example, an embodiment of the present invention is disclosed. SUMMARY [00091 According to a first aspect, there is provided a return air vent assembly for an HVAC system, the return air vent assembly comprising a ceiling frame for fitment in an opening in a ceiling, the ceiling frame defining an assembly air inlet, a grille for the assembly air inlet, and an air box extending from and behind the ceiling frame, wherein each of the ceiling frame, grille and air box are made of a plastic material. [0010] For the purpose of this specification, the term plastic material refers to any of a wide range of synthetic or semi-synthetic organic solids that are nouldable. This includes thermoplastics and thermosetting polymers. [0011] in one form, each of the frame, grille, air box and filter are rectilinear in planforn. In an alternative, each may have the planform shape of any convex polygon, but circular is the most likely alternative to rectilinear shapes. [0012] In one form, the frame comprises a body framing the assembly inlet, the body comprising integral means for engaging the air box. That is to say, the engagement (i.e. interlocking) means are included as part of a whole of the body rather than supplied separately. [00131 In one form, the air box comprises integral means for engaging the frame. 100141 In one form, the integral engagement means comrprises features of a snap-fit mechanical joint system. [0015] A snap-fit is a mechanical joint system where part-to-part attachment is accomplished with locating and locking features (constraint features) that are homogenous with one or the other of the components being joined, Joining requires the (flexible) locking features to move aside for engagement with the mating part, followed by return of the locking feature toward its original position to accomplish the interference required to latch the components together. Locator features, the second type of constraint feature, are inflexible, providing strength and stability in the attachment.

3 [00161 In one form, adhesives may bie used to secure parts of the return air vent assembly together. Adhesives may be used with, or as an alternative to, the integral engagement means. In yet a further possible alternative, fasteners may be used to secure parts of the return air vent assembly together. [0017] In one for, the return air vent assembly further comprises a corrugated filter element located behind (i.e. in a downstream direction of) the grille. [0018] For the purpose of this specification, the word corrugation means to comprise alternating ridges and grooves. [0019] In one form, the filter element depends from the grille, which in turn depends from the frame. 10020] In one form, the grille is pivotable between open and closed positions with respect to the ceiling frame. [0021] In one forn. the open grille is adapted to slidably receive the filter element. [0022] In one forn, the filter element comprises a filter media of corrugated mesh moulded into a filter frame of a plastic material, [00231 In one form, the ceiling frame comprises a pair of inwardly directed locating channels extending around a lip of the filter frame to create a tortuous path of high resistance to air-flow there through. [0024] In one form, the return air vent assembly further comprises a connection element for connecting an end of a duct to the air box, the connection element comprising a body framing a through opening, the body comprising means for engaging the air box. [0025] In one form, the air box comprises integral means for engaging the connection element. [0026] In one form, the integral engagement means again comprises features of a snap-fit mechanical joint system. [0027] In one farn, the return air vent assembly further comprising retaining clips for securing the assembly in the opening in the ceiling. [0028] In one form, the retaining clips are made of a plastic material. [0029] In one form, each of the retaining clips is inserted through an aperture through the body of the ceiling frame from the inside out.

4 [0030] In one forn, each of the apertures in the ceiling frame provided for the retaining clips comprises a flexible cover therefor, where each flexible cover allows the clip to pass therethrough, and then substantially seals around the retaining clip to prevent air bypass via the aperture. [0031] In one form, each clip is generally C-shaped, and comprises a pair or arms which must be forced together for insertion through the aperture. [0032] In one form, each arn comprises outwardly directed locking ribs which will engage an edge of the aperture when the arns are released and allowed to spread as far as they permitted to do so by the aperture, this engagement of the locking ribs with the edge of the aperture preventing any unintended withdrawal of the clip through the aperture. [0033] According to a second aspect, there is provided a frame for a return air vent of an HVAC system, the frame comprising a body framing the assembly inlet, the body comprising integral means for engaging an air box for the assembly. [0034] In one form, the body of the frame is a homogenous body of plastic material. [0035] According to a third aspect, there is provided a filter element for a return air vent of an HVAC system, the filter element comprising a filter media of corrugated mesh moulded into a filter frame of a plastic material. [0036] According to a fourth aspect, there is provided a grille for a return air vent of an HVAC system, the grille comprising a homogenous body of plastic material. [0037) According to a fifth aspect, there is provided an air box for a return air vent of an HVAC system, the air box comprising a body comprising integral means for engaging a frame for the assembly. [0038] In one form, the body of the air box is a homogenous body of plastic material. [0039] In one form, the body of the air box further comprises means for engaging a connection element for connecting an end of a duct to the air box. [0040] According to a sixth aspect, there is a provided a connection element for connecting an end of a duct to an air box for an return air vent of an HVAC system, the connection element comprising a body framing a through opening, the body comprising integral means for engaging the air box. [00411 In one form, in each case, the above described connection means comprises a feature of a snap-fit mechanical joint system.

[0042] A detailed description of one or more embodiments of the invention is provided below along with accompanying figures that illustrate by way of example the principles of the invention. While the invention is described in connection with such embodiments, it should be understood that the invention is not limited to any embodiment. On the contrary, the scope of the invention is limited only by the appended claims and the invention encompasses numerous alternatives, modifications and equivalents. For the purpose of example, numerous specific details are set forth in the following description in order to provide a thorough understanding of the present invention. f0043] The present invention may be practiced according to the claims without some or all of these specific details. For the purpose of clarity, technical material that is known in the technical fields related to the invention has not been described in detail so that the present invention is not unnecessarily obscured. BRIEF DESCRIPTION OF DRAWINGS 100441 Embodiments of the present invention will be discussed with reference to the accompanying drawings wherein: [00451 Figure 1 is a perspective underside view of an return air vent assembly for an HVAC system; [0046] Figure 2 is a perspective upperside view of the return air vent assembly of Figure 1; [0047] Figure 3 is a perspective underside view of a ceiling frame from the return air vent assembly of Figure 1; [0048] Figure 4 is a perspective upperside view of the ceiling frame of Figure 3; [0049] Figure 5 is a perspective underside view of a grille from the return air vent assembly of Figure 1; [0050] Figure 6 is a perspective upperside view of the grille of Figure 5; 10051] Figure 7 is a perspective upperside view of a filter element from the return air vent assembly of Figure 1; [0052] Figure 8 is a perspective upperside view of an assembly of the filter element and the grille of Figure 1; [0053] Figure 9 is a partial cross-sectional view of the assembly of Figure 8; 6 100541 Figure 10 is a perspective upperside view of an air box from the return air vent assembly of Figure 1; 10055] Figure 11 is a perspective underside view of the air box of Figure 10; [0056] Figure 12 is a perspective upperside view of a duct connection element from the return air vent assembly of Figure 1; [0057] Figure 13 is a perspective underside view of the duct connection element of Figure 12; [0058] Figure 14 is a cross-sectional view taken through return air vent assembly of Figure 1, taken along line A-A thereof; [0059] Figure 15 is a detail view of a clip and a cover illustrating their relationship with each other and the ceiling frame; [0060] Figure 16 is a detail view of the clip and cover of Figure 15; [0061] Figure 17 is a detail view of the clip of Figure 15; and [00621 Figure 18 is a detail view of the cover of Figure 15. [0063] In the following description, like reference characters designate like or corresponding parts throughout the figures. DESCRIPTION OF EMBODIMENTS [0064] Referring now to Figure 1, where there is shown an return air vent assembly I for an HVAC system, the return air vent assembly 1 comprising a ceiling frame 2 for fitment in and extending about a perimeter of an opening in a ceiling, and a retaining flange 9 for aiding securement of the frame 2 in the opening. 100651 With reference to Figures 3 and 4, it can be seen that the ceiling frame 2 comprises (defines) an assembly inlet 2A, a frame outlet 2B for airflow, and a reinforcing cross member 7 which extends up above (i.e. out of plane with) the sides of the ceiling frame 2 before it bridges these to reinforce the ceiling frame 2 (which would be unworkably flexible without cross member 7). The reason for shaping the cross member 7 in this way will be explained below.

7 [00661 The return air vent assembly 1 further comprises a grille 4 adapted to nest in the assembly inlet 2A defined by the ceiling frame 2, and hinge down from this nested position as required by pivoting on pins 11. [0067] With reference to Figures 5 and 6, it can be seen that the grille 4 comprises an edge trim 6 extending about the perimeter thereof, which seats against the ceiling frame 2 to prevent airflow between these, and an array of parallel slats 8 bridged by an array of parallel ribs 10 extending normal to the slats 8. Depending from the edge trim 6 and extending behind (or in a downstream direction of) this is an inwardly directed locating channel 14 for a filter element 20. [0068] To this end, the return air vent assembly I further comprises a filter element 20 slidably received in locating channel 14 behind (or in an airflow downstream direction of) the slats 8 and ribs 10 of the grille 4 so as to substantially infill the assembly inlet 2A. Both the ceiling frame 2 and the grille 4 are of a rectilinear shape (although they are not limited to this shape - they could be any shape, but circular is the most likely alternative), and they are moulded from an engineering plastic material. [0069] With reference to Figure 7, it can be seen that the filter element 20 comprises a filter media 22 of fine polypropylene or similar mesh, injection moulded into a plastic filter frame 24. The filter media 22 is corrugated by way of being pleated so as to significantly increase the cross sectional area of the filter media 22 without increasing the overall size of the filter element 20. The pleats 26 are arranged at approximately 30 degrees, and the resultant cross sectional area of the filter media 22 is around 300% larger than a conventional filter, This dramatically reduces the air noise as it passes through the filter element 20. [00701 The polypropylene material is very robust, thus enabling the filter element 20 to be washed many times without damaging the filter media 22. Moreover, the cleaning frequency is significantly reduced due to the increased area of the filter media 22. 100711 The filter frame 24 comprises an outwardly directed lip 25 extending about the perimeter of the filter frame 24. In use, this lip 25 locates in the locating channel 14 provided by the grille 4, as illustrated in Figure 8. Referring now to Figure 9, where it can be seen that this locating channel 14 comprises a floor 15 upon which the lip 25 of filter frame rests, a wall 16 extending up beside the lip 25 of the filter frame 24, and a retaining flange extending behind lip 25 of the filter frame 24. The way in which the locating channel 14 extends about the lip 25 of the filter frame 24 creates a tortuous path of high resistance to air-flow, which as a result, means air bypass of the filter element 20 via this route is substantially reduced. A tortuous path of this type cannot be integrated in a metal grille of the type commonly found in known HVAC vents.

8 [0072] The grille 4 incorporates flush mounted latches which release this so that the grille 4 can be swung about pins II and down from the ceiling frame 2. In this way, the filter element 20 can be removed from locating channel 14 by sliding, for removal for cleaning, or replacement as required, It is for this reason that cross member 7 is shaped as described above and depicted in Figure 4, if it extended directly from one side of the ceiling frame 2 to the other it would obstruct channel 14 and prevent the filter element 20 from sliding into and out of channel 14 in this fashion. [0073] Secured to a rear or downstream side of the ceiling frame 20 is a retum air box 30. Referring now to Figures 10 and 1, it can be seen that the air box 30 comprises an in air box inlet 30A and at least one air box outlet 30B for airflow. The air box inlet 30A is sized and shaped to match the ceiling frame outlet 2B. Unlike known air boxes, which are typically fabricated from sheet metal, air box 30 is manufactured by way of being moulded from an engineering plastic material. [0074] Both the frame outlet 2B and the air box inlet 30A comprise complimentary connecting portions adapted to mechanically connect these together with a snap-fit. The ceiling frame 2 comprises a mounting flange 5 for the air box 30, where this mounting flange 5 comprises an array of apertures 34 for receiving an array of cantilever snap-fits 36 depending from the air box 30, and wherein in use, the mounting flange 5 is captured between the cantilever snap-fits 36 and the mounting skirt 32 with a snap-fit. [0075] In this way, the air box 30 clips on to the ceiling frarne 2 without the need for screws or rivets. [0076] Unlike known air boxes, air box 30 is manufactured without spigots for flexible duct attachment. Instead, for each air box outlet 30B (of which there may be more than one) there is a connection elenient 40 for connecting an end of a flexible duct to the air box 30, the connection element 40 comprising a body 42 framing a through opening, the body 42 comprising means for engaging the air box 30. Both the connection element 40 and the air box 30 comprise complimentary connecting portions adapted to mechanically connect these together with a snap-fit. The air box 30 comprises these connecting portions about the or each outlet 30B thereof. [0077] More specifically, the air box 30 comprises a mounting flange 38 for the connection element 40, where this mounting flange 38 comprises an array of apertures 39 for receiving an array of cantilever snap-fits 43 depending -from the connection element 40, and wherein in use, the mounting flange 38 is captured between the cantilever snap-fits 43 and a mounting skirt 45 depending from the connection element 40, with a snap-fit. [0078] The body 42 of each connection element 40 comprises a spigot 44 on which the end of the flexible duct will be disposed. In this way, the installer is able to tape the flexible duct on to the spigot 44 9 and then clip the connection element 40 on to the air box 30. This is particularly beneficial in cases where the air box 30 requires 2 spigots in close proximity to each other, as this is otherwise difficult to tape. [00791 Advantageously, because spigots 44 are supplied with the connection element 40 as a separate clip-on part, one air box 30 can be configured in a number of different ways by the use of a variety of connection elements 40 which are configured for different duct sizes and shapes. [00801 Due to its dramatically reduced weight when compared with known return air vent assemblies (which generally comprise metal components) return air vent assembly I can be secured in the opening in the ceiling 3 using plastic retaining clips 50. [00811 Each of these clips 50 is inserted through an aperture 56 in the ceiling frame 2 from the inside out prior to installation of the filter element 20 and grille 4. Each clip 50 curves downwardly so as to sandwich the ceiling between itself 50 and the retaining flange 9, which extends from the ceiling frame 2. [0082] Each clip 50 is a generally C-shaped, homogenous plastic part comprising a pair or arms 52 and 54 which must be forced together for insertion through the aperture 56. Each arm 52 and 54 comprises outwardly directed locking ribs 58 which will engage an edge of the aperture 56 when the arms 52 and 54 are released and allowed to spread as far as they permitted to do so by the aperture 56, this engagement of the locking ribs 58 with the edge of the aperture 56 preventing any unintended withdrawal of the clip 50 through the aperture 56. [0083] Each of the apertures 56 in ceiling frame 2 for the clips 50, comprises a flexible cover 60 therefor. Each cover 60 allows the clip 50 to pass through, and then substantially seals around the clip 50 to prevent air bypass via the aperture 56. If the installer opts use an alternative fixing method to the clips 50, then the apertures 56 for the clips 50 remain sealed by their respective flexible covers 60. 100841 Referring now to Figure 18, where it can be seen that each flexible cover 60 comprises a series of slits which define a pair of horizontal flaps 62 and a pair of vertically separated doors 64 bridging the horizontal flaps 62. In use, when the clip 50 is forced through the aperture 56 the horizontal flaps 62 provide openings for the ans 52 and 54 of the clip 50, and the doors 64 close the space defined between the arns 52 and 54, [00851 in contrast to the present invention, return air vent assemblies of the prior art typically comprise a frame and grille of aluminium, and an air box and duct connector (or spigot) of sheet metal, all of which are secured together using fasteners. The resultant air vent assembly is quite heavy, so roof mounting needs to be by way of timber or steel supports attached to the ceiling joints or trusses. Attachment of the flexible duct is carried out in the roof.

10 [0086] The aluminium grilles of return air vent assemblies of the prior art are typically painted or powder coated, so they are very susceptible to scratching or chipping, and require careful handling by the installer. [0087] In addition to all of the above, return air vent assemblies of the prior art typically comprise a filter element of polyester fibres mounted into a frame of extruded aluminium, similar to a flyscreen for windows. This filter media is not robust, and requires regular replacement. It can be cleaned initially by vacuuming and light washing with a garden hose, but it delaminates and stretches. Failure to replace the filter media leads to dust settling on the coil of the air handler, resulting in expensive repairs or replacement. [0088] Moreover, as the filter accumulates dust, the airflow is diminished, and the performance of the air-conditioning unit is reduced. What is more, return air will seek to bypass a blocked filter via gaps between the filter, grille and frame, resulting in noise, including whistling. [0089] Advantageously then, it will be apparent from the description above, that the return air vent assembly according to the present invention is light weight, provides snap-together construction for ease of assembly and installation, it incorporates a filter requiring less frequent cleaning and replacement, and it reduces the tendency for return air to bypass the filter. [00901 Throughout the specification and the claims that follow, unless the context requires otherwise, the words "comprise" and "include" and variations such as "comprising" and "including" will be understood to imply the inclusion of a stated integer or group of integers, but not the exclusion of any other integer or group of integers. [0091] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement of any forn of suggestion that such prior art forns part of the common general knowledge. [0092] It will be appreciated by those skilled in the art that the invention is not restricted in its use to the particular application described. Neither is the present invention restricted in its preferred embodiment with regard to the particular elements and/or features described or depicted herein. It will be appreciated that the invention is not limited to the embodiment or embodiments disclosed, but is capable of numerous rearrangements, modifications and substitutions without departing from the scope of the invention as set forth and defined by the following claims. [00931 Please note that the following claims are provisional claims only, and are provided as examples of possible claims and are not intended to limit the scope of what may be claimed in any future patent applications based on the present application. Integers may be added to or omitted from the example claims at a later date so as to further define or re-define the invention.

Claims (21)

1. A return air vent assembly for an HIVAC system, the return air vent assembly comprising a ceiling frame for fitment in an opening in a ceiling, the ceiling frame defining an assembly air inlet, a grille for the assembly air inlet, and an air box extending from and behind the ceiling frame, wherein each of the ceiling frame, grille and air box are made of a plastic material.

2. The return air vent assembly of claim 1, wherein the ceiling frame comprises a body framing the assembly inlet, the body comprising integral means for engaging the air box.

3. The return air vent assembly as in either of the preceding claims, wherein the air box comprises integral means for engaging the ceiling frame.

4. The return air vent assembly as in either of claims 2 or 3, wherein the integral engagement means comprises features of a snap-fit mechanical joint system.

5. The return air vent assembly as in any one of the preceding claims, further comprising a filter element located behind the grille.

6. The return air vent assembly of claim 5, wherein the grille is pivotable between open and closed positions with respect to the ceiling frame.

7. The return air vent assembly of claim 6, wherein the open grille is adapted to slidably receive the filter element.

8. The return air vent assembly as in any one of claims 5 through 7, wherein the filter element comprises a filter media of corrugated mesh moulded into a filter frame of a plastic material.

9. The return air vent assembly of claim 8, wherein the ceiling frame comprises a pair of inwardly directed locating channels extending around a lip of the filter frame to create a tortuous path of high resistance to air-flow there through.

10. The return air vent assembly as in any one of the preceding claims, further comprising a connection element for connecting an end of a duct to the air box, the connection element comprising a body framing a through opening, the body comprising integral means for engaging the air box.

11. The return air vent assembly of claim 10, wherein the connection element is made of a plastic material. 13

12. The return air vent assembly as in either of claims 10 or 11, wherein the air box comprises integral means for engaging the connection element.

13. The return air vent assembly as in any one of claims 10 through 12, wherein the integral engagement means comprise features of a snap-fit mechanical joint system.

14. The return air vent assembly as in any one of claims 10 through 13, wherein the connection element comprises a spigot on which the end of the duct is disposed.

15. The return air vent assembly as in any one of the preceding claims, further comprising retaining clips for securing the assembly in the opening in the ceiling.

16. The return air vent assembly of claim 15, wherein the retaining clips are made of a plastic material.

17. The return air vent assembly as in either of claims 15 or 16, wherein each of the retaining clips is inserted through an aperture through the body of the ceiling frame from the inside out.

18. The return air vent assembly of claim 17, wherein each of the apertures in the ceiling frame provided for the retaining clips comprises a flexible cover therefor, where each flexible cover allows the clip to pass therethrough, and then substantially seals around the retaining clip to prevent air bypass via the aperture.

19. The return air vent assembly as in any one of claims 15 through 18, wherein each clip is generally C-shaped, and comprises a pair or arms which must be forced together for insertion through the aperture.

20. The return air vent assembly of claim 19, wherein each ann comprises outwardly directed locking ribs which will engage an edge of the aperture when the arms are released and allowed to spread as far as they permitted to do so by the aperture, this engagement of the locking ribs with the edge of the aperture preventing any unintended withdrawal of the clip through the aperture.

21. A filter element for a return air vent of an HVAC system, the filter element comprising a filter media of corrugated mesh moulded into a filter frame of a plastic material.