AU721569B2 - An air conditioning duct fitting - Google Patents

Description

Regulation 3.2

AUSTRALIA

Patents Act 1952 COMPLETE SPECIFICATION FOR A STANDARD PATENT

(ORIGINAL)

Name of Applicant: Actual Inventors: Westaflex (Australia) Pty. Ltd.

140-152 Bamfield Road, West Heidelberg, Victoria 3081, Australia John GILLARD Michael William STERLING DAVIES COLLISON CAVE, Patent Attorneys, 1 Little Collins Street, Melbourne, 3000.

An Air Conditioning Duct Fitting Address for Service: Invention Title: The following statement is a full description of this invention, including the best method of performing it known to us: P:OPER\GCP\63492-98.SPE 18/4/00 -2- AN AIR CONDITIONING DUCT FITTING This invention relates to ducting for air conditioning, and in particular to branch fittings for such ducting.

Ducting for domestic air conditioning is non-standard because of the diversity of layouts of dwellings that exist. Generally a main duct is divided several times to smaller branch ducts to distribute the conditioned air to individual rooms or parts of rooms. The size of individual branch ducts is determined by the relative volume of air that it is desired to have -•distributed.

~The main duct could be for example 500mm in diameter, and an initial branch duct might vary in increments of 50mm from 450 to 300mm, or even down to about 200 mm where it is necessary to supply conditioned air to a small room close to the air conditioning unit. Where the duct is forked then it can readily be appreciated that the combination of sizes that might be used for two outlets of a fitting can be quite large in number, and it is desirable to provide for standard fittings that might suffice for several combinations of sizes rather than producing an enormous range of individually prepared fittings.

2 Terminal outlets with varying sized inlets have been suggested for air conditioning units such as in US Patent 3866950 and US Patent 5109756 whereby the smaller diameter receiving ends have provision to be cut away, when larger diameter inlet ducts are used. Such fittings however are not adapted to address questions of ease of connection, and the maintenance of maximum air flow where a fitting reduces the diameter of ducting at an outlet of that fitting.

An object of the invention is to provide a fitting for air conditioning ducts which includes a fitting body which can be used in conjunction with a novel collar, the collar serving to interconnect the fitting outlet to the duct.

P:\OPER\GCP\63492-98SPE- 18/4/00 -3- According to the present invention there is provided a fitting for air conditioning ducts said fitting including, in combination, a fitting body and a collar, said fitting body having a generally hollow body with an inlet and at least one outlet, said outlet having at least one coupling formation to which said collars can be coupled, and wherein the collar comprises a hollow, generally cylindrical body having at one end thereof at least one interlocking formation which, in use, interlocks with said at least one coupling formation, said cylindrical body including a plurality of projections which, in use, engage the inner surface of an end of a duct whereby the duct is effectively coupled to said fitting bodies by the collar.

10 In one form of the invention, a plurality of outlets of different sizes are provided and o• these are not concentric.

:i The collar may be provided with interlocking projections which form a snap fit with complementary formations at the outlets of the fitting body.

Whilst it may be desired to have the snap fittings being such that the collar and the outlet frictionally engage sufficiently to provide a relatively permanent attachment, there is sufficient advantage in having the two connect together in a relatively non-permanent arrangement, so that a more permanent fastener can be used once the two have been accurately positioned. Thus where the fitting and the collar are made of relatively thin plastics o material, one of more rivets, or self tapping screws might be fixed through an overlapping portion of the collar and the fitting to make the snap fit more secure.

The stepped sections can be adapted for easy removal of unwanted portions. Thus where the fitting is moulded from plastics, no special provision need really be taken, and the unwanted portions can simply be removed by a saw. Alternatively the plastic could be moulded to provide a weaker line to define a frangible portion than might simply be torn away. It may be desirable to have a pull tab extending from and formed within the plastics, which pull tab may or may not be formed free of the main body of the fitting, and a strip r 7 0 defined within two thinner score lines, and extending from the pull tab and extending substantially around the section to be removed. So that to remove the unwanted sections, the P:\OPER\GCP\63492-98.SPE 18/4/00 -4tab is simply lifted and pulled so that a cut is provided by removal of the strip.

The stepped sections are understood therefore to have generally asymmetric centres, which centres can be arranged to progressively extend in the direction of flow of air through the inlet and downstream of a virtual axis of a respective outlet, and accordingly facilitate flow of air into the branch where a small outlet is provided for. Preferably also the direction of flow through the outlets is obtuse to the direction of air flow through the inlet.

A preferred method of producing the fitting is by blow moulding the fitting from 10 plastics. Preferably the fitting is produced in halves, the two halves being complementary, which halves can be secured together on installation, or at least after transport. This enables o e• *o*o* *.i P:\OPER\GCP\67316.DIV 21/4/98 halves to be nested together for ease of transport. A flange can be formed at the edge of such halves which edges are intended for fitting to a complementary half. This then facilitates the putting together of such halves, so that the flanges provide complementary surfaces that might either be glued together, or a fastener can penetrate the flanges to fix the two halves together.

It may be desired to have the fitting insulated, and therefore a sheet of flexible expanded foam can be fastened to the outside of the fitting to minimise heat loss or gain.

For a better understanding of the invention will now be described with reference to one embodiment of the invention which will now be described with reference to the drawings in which: Figure 1 is a plan view showing the layout of a dwelling being illustrative of the position of a number of fittings typically used; Figure 2 is a plan view of the fitting as might be connected to a number of outlets; Figure 3 is an axial cross section trough the fitting showing the flow of air through the illustrated embodiment of the fitting; Figure 4 shows the nesting of two halves of the fitting; Figure 5 shows the means by which the fitting provides for a snap fit to ducting; Figure 6 shows a plan view of a preferred form of fitting of the invention; Figure 7 shows an outlet face of the fitting; Figure 8 shows the inlet face of the fitting; Figure 9 shows a collar of the invention; and Figure 10 shows the manner in which the collar couples to the fitting and to a duct.

Similar reference characters indicate corresponding parts throughout the several views Sof the drawings.

Dimensions of certain of the parts as shown in the drawings may have been modified and/or exaggerated for the purposes of clarity of illustration.

P:\OPER\GCP\67316.DIV 21/4/98 -6- A dwelling 1 is shown in Figure 1 with a single air conditioning unit 2, from which run three main ducts, 3. Two of the three main ducts are branched by a separate branch fitting 4, which type of branch fitting is the subject of the illustrated embodiment. The branch lines each eventually terminate in terminal outlets 5 which terminal outlets distribute air into rooms 6 of the dwelling.

A closer view of a branch fitting is provided in Figure 2, from which it can be seen that generally a wider duct 7 feeds into an inlet side of the fitting, and the air flow from such wider duct is fed through the fitting into two usually thinner branch ducts 8 and 9 respectively.

The fitting includes an inlet 10 and two outlets 11 and 12. The outlets direct air at an angle obtuse to the direction of air flow through the inlet, and such placement enhances the air flow through the fitting.

The illustrated inlet has two stepped annular sections 13 an upstream one being smaller in diameter than the downstream section. The axial centres of each section is generally in line, and an end view of these two sections would show them to be concentric. Typically the widest of these two sections has a size to fit a duct of 500mm and the narrowest has a size to fit a 450mm duct.

The two outlets 11 and 12 are preferably made of identical shape however can be cut to different dimensions. The outlets have four stepped annular sections 30, 31, 32 and 33 for fitting to outlet ducts each of progressively reduced diameter. The reduction in diameter might start with a size of 450mm and reduce by 50mm increments to 250mm. For both outlets the S. centres of each of the annular sections is not in line with a virtual axis defining the line of the outlet the axis of the largest section 30), but tend downstream with reference to air flow through the inlet. In this illustrated embodiment downstream edges 34, 35, 36 and 37 of each of the stepped sections is aligned but spaced apart downstream from the axis of the largest section P:\OPER\GCP\67316.DIV 21/4/98 -7- The branch fitting illustrated in Figure 2 shows two different sized ducts 8 and 9 extending from the outlets 11 and 12. The section 33 forms the outlet to the duct 9 whereas the section 31 forms the outlet to the duct 8. Prior to connecting the duct 8 the sections 32 and 33 at the outlet 11 are removed by sawing, cutting or the like.

One major advantage of having stepped sections asymmetrically aligned can perhaps best be seen with reference to Figure 3. It is found in the illustrated embodiment that loss of air pressure is reduced, and air flow shown by arrow 14 has no pockets of dead air which might otherwise build up adjacent to the downstream wall 15 of the fitting and caught by the stepped portions were they to be asymmetrically positioned.

The illustrated embodiment is made in two halves with a flange 16 positioned centrally with respect to the inlet when the two halves are joined together. Such a flange facilitates the joining of the two halves together. The great advantage of such an arrangement is that two or more of such halves can be nested together such as can be seen in Figure 4, where three halves are shown. Such nesting enables compact stacking of the components for more efficient transport. The components typically do not weigh a great deal especially when they are formed of blow moulded plastics and consequently transport costs can be greatly minimised.

Figure 5 illustrates the manner in which the inlet and outlets of the duct can cooperate with a collar 18, the collar 18 being specially adapted to interlock with the ends of ducts. In Figure 5 it will be seen that the collar 18 includes a convex projecting rib 17 which can interlock with an internal groove 19 defined by the inner surface of the section 13. It is Spreferred that the outer diameter of the rib 17 is snugly engagable with the groove 19 so as to enable a snap fit connection. Appropriately dimensioned collars can be used to cooperate with the different diameter sections 31, 32 and 33, as required.

The ducting conduit 20 fits over a free end of the collar, and is secured thereon generally by barbs or projections 21. The snap fit that is provided by the illustrated embodiment is not particularly sturdy, but does have the advantage of providing some P:\OPER\GCP\67316, DIV 21/4198 -8resistance to displacement of the connection made, to last at least until more permanent fixing can be provided such as by a pop-rivet. This facilitates installation.

Figures 2 to 5 illustrate arrangements in which the outer surfaces of the sections 13, 30, 31, 32 and 33 are convex, that is to say these sections can be regarded as a bead or the like. It is quite possible to arrange for the sections 13, 30, 31, 32 and 33 to have outer surfaces which are concave.

Figures 6 to 10 illustrate a preferred embodiment of the invention.

Figures 6 and 7 show a fitting 60 which is preferably blow formed from plastics material. It has an inlet face 62 and outlet faces 64 and 66. The fitting is moulded essentially as a closed hollow body except for a mould opening 67 in the inlet face 62. As best seen in Figure 6, the fitting 60 is generally triangular when viewed in plan. The drawing shows an optional cut line 68 where the fitting can be cut into two pieces for compact transportation and storage. The corners 70 are undercut, as shown in Figure 6, for strengthening the fitting when subjected to positive internal pressure.

9 o As shown in Figure 7, the outlet face 64 is provided with a number of cut lines 71, 72 and 74. The cut lines are preferably moulded into the face but it will be appreciated that they could be applied after moulding by printing or the like. As with the embodiment of Figures 2 and 3, the cut lines 71, 72 and 74 are asymmetrical and each of them touches at a point 76 which is opposite to the inlet face 62. The number of cut lines and their diameters be varied according to requirements. The cut lines are preferably the same on the other outlet face 66.

S

The inlet face 62 also has cut lines 78, 80 and 82 as shown in Figure 8. On the inlet face, the cut lines 78, 80 and 82 are concentric. With this configuration pockets of dead air are avoided as in the case with the fitting of Figure 3.

P:\OPER\GCP\67316.DIV 21/4/98 -9- Figure 9 shows a novel form of collar 84 for use with the fitting 60. The collar essentially comprises a hollow cylindrical moulded body having a plurality of barbs 86 integrally moulded therewith. The barbs 86 are for the purpose of engaging with the inner surface of a duct 94 for fixing the duct thereto, as diagrammatically illustrated in Figure The duct includes a helical metal frame 96 and a flexible covering 98 and the barbs are preferably arranged to engage at least some of the convolutions of the frame 96. The forward end of the collar 84 includes a tapered leading edge 87 which facilitates entry of the collar 84 into the interior of the duct.

The rear end of the collar 84 includes a groove 88 which in use receives a peripheral edge 92 of a hole cut in the inlet or outlet faces of the fitting. This is diagrammatically illustrated in Figure 10. Preferably, the end of the collar 84 includes a tapered trailing edge (or projections) which facilitates penetration of the collar into the opening cut into the fitting. The resilience of the material of the fitting enables the collar to be pressed into the opening so that the peripheral edge 92 at the opening is received within the groove 88, as shown in Figure 10. In the preferred mounting technique, a bead of silicon (not shown) or other sealant is placed in the groove 88 by the installer so as to form a good seal.

Alternatively, adhesive tape can be applied about the joint to prevent air leakage.

,....Appropriately sized collars 84 can be used for forming connections to ducts for the outlet faces 64 and 66 as well as the inlet face 62.

Various features of the invention have been particularly shown and described in connection with the illustrated embodiment of the invention, however, it must be understood .:.ooi :...that these particular arrangements merely illustrate and that the invention is not limited thereto and can include various modifications falling within the spirit and scope of the invention.

Claims (9)

1. A fitting for air conditioning ducts said fitting including, in combination, a fitting body and a collar, said fitting body having a generally hollow body with an inlet and at least one outlet, said outlet having at least one coupling formation to which said collars can be coupled, and wherein the collar comprises a hollow, generally cylindrical body having at one end thereof at least one interlocking formation which, in use, interlocks with said at least one coupling formation, said cylindrical body including a plurality of projections which, in use, engage the inner surface of an end of a duct whereby the duct is effectively coupled to said o. 10 fitting body by the collar.

2. A fitting as claimed in claim 1 wherein there are a plurality of said coupling "".formations which are not concentric.

3. A fitting as claimed in claim 1 or 2 wherein said at least one interlocking formation includes a circumferentially extending rib and wherein said at least one coupling formation includes at least one complementary circumferentially extending groove. *4go

4. A fitting as claimed in claim 1 or 2 wherein said at least one interlocking formation *e 20 includes a circumferentially extending groove and wherein said at least one coupling S"formation includes at least one complementary circumferentially extending edge portion which defines said at least one outlet.

A fitting as claimed in claim 4 wherein a tapered face is provided adjacent to said circumferentially extending groove to facilitate entry of the said one end of the collar in said outlet.

6. A fitting as claimed in any one of claims 1 to 5 wherein said fitting body formed from two components which are joined together. P \OPER\GCP\6349298.SPE 18/4/00 11

7. A fitting as claimed in claim 6 wherein said components have complementary edges parts of which are joined to one another to form said fitting body and wherein said inlet is adjacent to said parts f the edges but said at least one outlet is not adjacent to said parts of the edges.

8. A fitting as claimed in claim 6 or 7 wherein said fitting body is formed by blow moulding.

9. A fitting for air conditioning ducts including in combination a fitting and a collar o 10 substantially as hereinbefore described with reference to the accompanying drawings. t o DATED this 18th day of April, 2000 WESTAFLEX (AUSTRALIA) PTY. LTD. S: by its Patent Attorneys DAVIES COLLISON CAVE 0e%. a. Sea...