AU703448B2 - Duct fitting arrangement and method of making the same - Google Patents

Description

This invention relates to a fitting for an air conditioning duct. The present invention has particular application for the invention disclosed in Australian Patent Number 664353.

Air conditioning ducting is used in the distribution of conditioned air throughout buildings.

In domestic dwellings generally one conditioning unit supplies conditioned air which is then directed through a primary duct into subsidiary ducts by the use of branch fittings, and perhaps into further subsidiary ducts after passage through further branch fittings.

The branch fittings may take on a variety of configurations and may be generally Y shaped, or may be more complex such as a tree shaped branch with three, four or five outlets. These branch fittings are presently generally blow moulded in plastics and may have an inlet and outlets stepped in diameter to provide for connection with any one of a few ducts having differing diameters.

15 Generally in fitting together the branches the ducting is laid out perhaps on the floor of the building to which it is to be fitted, and the ducting being cut to size, and the branch fittings :".selected and laid out. The layout is then carried, usually through a man-hole into a ceiling space, and then assembled. Some of the branch fittings are quite bulky and at times there is some difficulty in carrying such items especially through the tight constraints imposed by a 20 man-hole.

Assembly in the ceiling space can also be awkward in that larger lengths of ducting need oo.SS.

initially to be positioned in contact with the branches. There is a difficulty in that the initial connection is often tenuous, and accurate positioning of the fittings in the ducts is difficult to S 25 maintain whilst placing fasteners to more permanently connect branches to the ducts.

Accordingly it is desired to provide for a firmer fit of duct to duct fittings including the branches.

Australian Patent Application 67316/94 discloses the use of a collar for providing a connection between ducting and the branch fitting. The collar is fitted inside of each of the outlets at a first end of the collar, and barbs on a second end secure the duct over the second end of the collar. The collar in this earlier document is shown to fit to the inside of each of the integrally formed outlets. A rounded bead shown is said to be a means to snap fit the collar into place, temporarily, before further fastening.

The looseness of fit is exacerbated where not only the branch fitting is split as in 67316/94 but especially where the fitting is split as for the fitting described in 664353. In the former 41_7_ case the branch fitting surrounding the collars is complete whereas in the latter case the branch fitting has a split in the housing around the apertures. An inside fit is entirely impractical for keeping a housing split around an aperture together, and would tend to force the halves of the branch fitting apart. Furthermore the branch fitting halves must be assembled fully before an inside collar has any prospect of staying in place, and therefore the collar cannot play a role in keeping the halves of the branch fitting together before the halves are fastened together.

One drawback of providing a collar is that more parts are required and there is a greater attendant cost; manufacture is relatively time consuming and generally each pressing of a mould requires some time, perhaps of the order of a minute or two. Thus where two different moulds and two separate items are to be made the time requirement and costs are higher notwithstanding that there is greater convenience of use.

It is an object of the present invention to provide a duct fitting arrangement, and a method S 15 of making the same that obviates or minimises any one of the above problems or at least provides the public with a useful choice.

p In a broad form and not necessarily the broadest or only form the invention could be said to reside in a duct joining arrangement comprising 20 a plastics fitting housing including at least two open ends for passage of air therethrough, the fitting housing being split into at least two fitting parts such that at least one open end of the fitting is split, the fitting housing including at least at said split open end a first retaining means, 25 the arrangement also including a collar, said collar including, at a second end, a second retaining means, so configured that the collar can fit over a respective split open end of the fitting housing, so that the first retaining means engages the second retaining means to connect the collar to the fitting housing to hold adjacent fitting parts together.

In one form the first retaining means is an outwardly extending first ridge, the second retaining means being a second ridge complementary in shape to the first ridge, so configured that the collar can fit over a respective open end of the fitting, and the second ridge can snap fit with the first ridge.

Preferably the fitting housing is split such that the open ends of the fitting housing are split in two halves, and so that the fittings housing halves are capable of being nested one within ,the other to minimise space required for storage. Australian Patent 664353. gives an indication of the types of split fitting which might be envisaged by the present invention, 4 and is incorporated herein in its entirety by reference. It is also to be understood that fittings where by two conduits are simply joined together, or fittings used to reduce or increase the diameter of the tubing used may also be contemplated by this invention.

It is to be understood that the first ridge may be formed as part of a groove proximal to a respective open end of the fitting, or alternatively the first ridge may be formed as part of a protrusion extending outwardly from the housing of the fitting. Alternatively the first or second ridge may be part of a barb, and may be extended circumferentially to form an annular barb or a part-annular barb. The purpose of the first ridge is to engage with the second ridge so as to provide engagement of the two parts.

The first ridge preferably extends circumferentially around the housing proximal to a respective open end of the housing, however it is to be understood that there may be several such ridges spaced apart to provide a means for engaging correspondingly positioned second ridges.

In one form the first retaining means comprises a plurality of outwardly extending part .ridge protrusions spaced apart circumferentially, and the second retaining means comprises a plurality of outwardly extending circumferentially spaced apart second ridge parts and 20 spaces therebetween wherein ridges of the collar can be aligned with spaced on the open end of the fitting, pushed forward and twisted behind the ridges of the collar, limit means are provided to prevent the collar from being pushed beyond a predetermined distance over the open end of the fitting.

In an alternative form the collar and a free end of the branch fitting are formed for screw on connection.

It is to be understood that the collar may include a change in diameter along its length to act as a reducing collar or an expansion collar so that the diameter of duct that can be fitted to a 30 particular fitting can be determined by the collar rather than the fitting. Providing the capacity to choose the size of ducting that is to fit over free ends of the branch fitting by selecting an appropriate collar has the advantage of minimising the size of the fitting, rather than following current practice of providing for a stepped outlet on the fitting, which can be cut off to provide for the desired outlet diameter.

Preferably the fitting housing and the collar are formed within the same mould, so that the first and second ridge can be made to fit accurately and provide an accurate snap fit. The latter referred to preferred form is still more preferably used with a split fitting housing all moulded from the same mould. In preference the moulding is by blow moulding, however, it is to be understood that the invention may also encompass other forms of moulding of the halves and the collar and such moulding may include moulding the parts separately.

Each fitting part may include two longitudinal edges and each part having bearing means adjacent to or on each edge to bear against an adjacent bearing means or edge of an adjacent fitting part. In one form adjacent longitudinal edges of adjacent fitting parts bear against one another. In an alternate form adjacent longitudinal edges of adjacent fitting parts overlap and a stop on or close to a first one of said adjacent edges engages a second stop or a second of said edges of the adjacent fitting parts.

It is to be understood that the invention encompasses a method of making a duct fitting arrangement, said duct fitting arrangement comprising a duct fitting housing including at least two tubular outlets and a collar with a free end configured to fit over the tubular outlets and engaging therewith and with a duct to thereby join the duct with the fitting housing, said method comprising the step of integrally forming the fitting with a collar extending from the ends of each of the outlets followed by the step of severing the collars.

Preferably a radially extending wall is formed at an interface between the collar or collars :20 and a respective open end of the formed branch fitting, said radially extending wall being S"removed during the step of severing.

Preferably the branch fitting and the tubular outlets are each split longitudinally in the direction of airflow, said method including the step of splitting the fitting longitudinally in the direction of airflow once the collars are severed.

It is also to be understood that the invention encompasses a method of installing an air conditioning duct fitting arrangement, said duct fitting arrangement comprising a duct fitting housing including at least two tubular outlets and a collar with a free end configured •30 to fit over the tubular outlets and engaging therewith and with a duct to thereby join the duct with the duct fitting, the branch fitting and the tubular outlets are split longitudinally in the direction of airflow, the method including the steps of joining two halves together, the step of fitting a collar to an open end of duct tubing, the step of joining the collar to the fitting housing around the outside of said at least tubular outlets of the joined halves of the duct fitting.

The method may be further characterised by the step of applying at least one fastener to the join between the collar and the fitting.

To assist with the understanding of the invention one embodiment is illustrated. It is to be understood from the foregoing that the illustrated embodiment of the invention is merely illustrative and in no way restricts the scope of the invention.

In the illustrations: a a a.r a *p e .c Figure. 1 is a partial cross sectional view of the illustrated embodiment showing a branch fitting integrally moulded with a collar, Figure 2 is a partial cross sectional view of the illustrated embodiment showing a half of the fitting engaged with the collar, the collar being connected with an air conditioning duct, Figure 3 is a close up partial view of the manner in which the collar is snap fitted over the branch fitting, a different configuration for retaining the duct is provided compared with that shown in Figures 1 and 2, Figure 4 is a partial cutaway view of part of the branch fitting integrally moulded 20 with the collar, Figure 5 is a perspective view showing an outside of the branch fitting with the duct fitted over one free end of the duct, Figure 6 is a cross sectional view showing a second embodiment of the collar, where the collar acts as a reducer, Figure 7 is a perspective view of a collar and branch fitting of a further embodiment having a screw threaded connection, and Figure 8 embodiment.

is a perspective view of a collar and branch fitting of a still further Similar reference characters indicate corresponding parts throughout the several views of 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.

The branch fitting arrangement comprises a fitting housing which housing comprises a central portion and at least two tubular portions extending from the central portion each tubular portion having an open end for passage of air therethrough. A first end of a collar is inserted within the free end of a duct and a free (or second) end of the collar can fit over the open ends of each of the tubular portions of the fitting housing, for connection therewith.

The fitting housing and the collar are formed in a single mould, into a shape as best seen in Figure 1 where the collar portion extends from the open end of the fitting housing.

The fitting housing and collar is made of plastics and preferably a polyethylene, and is preferably by blow moulding. The blow moulded combination of fitting housing and collar is removed from the mould and then cut. Firstly the collars are severed along line from all three open ends of the branch fitting. The cutting may be achieved by use of a band saw. Subsequently the fitting housing is split longitudinally in the direction of the 15 airflow into two halves, as can be seen in co-pending Australian Patent 664353 so as to split all apertures in two.

The fitting housing halves can be nested together for transport or storage, and the collars are separately packaged for transport or storage.

2 Other methods that might be used for forming the combination of the fitting housing and the collar or perhaps separately, include vacuum forming or injection moulding. An alternative method of forming the fitting housing and the collar is by rotor (or spin) moulding.

oo For details of the method of splitting and joining of the two halves of the fitting housing reference is to be made to Australian Patent 664353, although it is to be understood that the preferred form of joining two halves is simply by the use of staples along the seam between the two halves, and also through any tabs or protrusions (50) formed therebetween.

Referring now specifically to the retaining means for retaining the collar on the fitting housing, and referring firstly to Figure 1. The free end of the duct includes a first circumferential groove (10) adjacent a first annular barb a central body proximal face (12) of the first barb extends radially outwardly and provides a first ridge. The barb tapers inwardly from the central body proximal face. An annular step (13) extends between the first annular barb (11) and a second annular barb A central body proximal face (14a) Sof the second barb extends radially outwardly and provides a second ridge. The radially 8 extending wall (30) of the annular step defines an interface between an outer edge of the free end of the duct fitting and the free end of the collar. There is complete removal of the radially extending wall on severing the collar from the fitting. It can be seen that the second annular barb is of a greater diameter than the first annular barb, by an extent equal to that of the step or the width of the radially extending wall. The inner periphery of the second annular barb being of smaller diameter than the outer periphery of the first annular barb. This configuration is to facilitate fitting of the second barb over the first barb so that the first ridge fits over the second ridge, whilst giving a firm snap fit of the collar over the first barb.

The configuration of the collar includes a relatively flat annular surface (15) (when viewed in axial cross section) and at a second end of the collar includes a third annular barb (16).

The collar shown in figures 1 to 5 is such that the diameter of the duct fitted is approximately the same size as the open end of each of the tubular portions of the fitting housing. However as can be seen in Figure 6, the diameter of the collar can be made to I vary so that the collar acts either as a reducing collar (as shown) or as an expansion collar.

This configuration of fitting housing greatly minimises the length of the tubular portions of of the fitting housing as is presently employed. At present the tubular portions are generally S 20 stepped, so that one fitting may be used for any one of a number of combinations of o diameters of ducting connected with a branch fitting. The tubular portions being cut back to the diameter required. Often such steps may be as long as three steps, and where S0 smaller diameter tubes are to be used, the overall size of the branch fitting becomes quite large. This makes the fitting quite difficult to manoeuvre. In the presently illustrated 25 invention, the overall size can be greatly diminished, and the tubular portion may only take up as much length as is required to provide a groove and the first annular barb.

In use then as described in Australian Patent 664353, the fitting housing may be transported to a distribution point, and the halves joined. Typically the ducts, and duct fittings are laid out on the floor of the building into which the air conditioning conduits are to be laid. The respective collars are then fitting to respective free ends of the ducts. The ducts generally comprise an inner conduit (20) comprising a helically wound wire (21) supporting a mylar film An insulation layer (23) surrounds the inner conduit, and an outer sheath (24) covers the insulation layer. The duct is fed over the third annular barb, and a strap (25) is tightened over the duct around the relatively fiat annular surface (15) to hold the duct into place on the collar. The third annular barb (16) prevent slippage of the Rduct from the collar. The ducts and the fitting housings are then carried into the ceiling space of the dwelling, and laid out. The collars are then connected with respective tubular portions of the fitting housing, by snap fitting of the second barb over the first barb. It may be desired to further secure the two barbs together and this may be achieved by perhaps stapling the two together, or by applying another form of fastener.

A further embodiment is shown in Figure 7. It can be seen that instead of a having a snap fit retaining means that there is provided a screw on retaining means. Open ends of the branch fittings are each formed with a plurality of spaced apart and angled ridges (32).

Corresponding angled grooves (33) are formed at one end of the collar. The ridges and grooves are lined up and the collar can be screwed onto the open end of the branch fitting.

Whilst ridges have been shown on the branch fitting it will be understood that other protrusions capable of registering within the grooves will also be suitable.

It can also be seen that on the first end of the collar, in place of a single barb, there are a series of complex ridges that assist with retention within a duct to be fitted thereon in a manner similar to that shown in Figure 2.

A still further embodiment is shown in Figure 8. The collar is retained on an open end of S" 20 the branch fitting with the use of a plurality of protrusions (35) on the open end of the branch fitting (two only which are shown), each protrusion having a first ridge For each protrusion the collar has a receiving groove each having a second ridge (38).

The collar is positioned so that the entry (39) for each of the receiving grooves is aligned with a respective protrusion. The collar is slid over the protrusion and then twisted so that the protrusion is captured within the retention portion (40) of the receiving groove. The collar being prevented from withdrawing by reason of the adjacent positioning of the first and second ridges.

It can be seen that in all embodiments the collar is fitted over the two parts of the branch fittings to keep them in place. Longitudinal edges of each of the two halves are straight and can rest against similar edges of the other one of the two halves, so that when the collar is put into place the edges will be held against each other. It will be appreciated that longitudinal edges may overlap and longitudinal edges may rest against appropriately positioned stops rather than against adjacent longitudinal edges.

It will be appreciated that the illustrated embodiment of the invention have advantages over the prior art and presently used systems of using branch ducts, and other duct fittings, at least in terms of manufacture.

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS: 1. A duct joining arrangement comprising a plastics fitting housing including at least two open ends for passage of air therethrough, the fitting housing being split into at least two fitting parts such that at least one open end of the fitting is split, the fitting housing including at least at said split open end a first retaining means, the arrangement also including a collar, said collar including, at a second end, a second retaining means, so configured that the collar can fit over a respective split open end of the fitting housing, so that the first retaining means engages the second retaining means to connect the collar to the fitting housing to hold adjacent fitting parts together.

2. A duct joining arrangement as in claim 1 wherein each fitting part including two longitudinal edges and each part having bearing means adjacent to or on each edge to be held against an adjacent bearing means or edge of an adjacent fitting part.

S 3. A duct joining arrangement as in claim 2 wherein adjacent longitudinal edges of adjacent fitting parts are held against one another.

i20 2 4. A duct joining arrangement as in claim 2 wherein adjacent longitudinal edges of adjacent fitting parts overlap and a stop on or close to a first one of said adjacent edges engages a second stop or a second of said edges of the adjacent fitting parts.

5. A duct joining arrangement as in any one of claims 1 to 4 wherein the first retaining means is an outwardly or inwardly extending first ridge, the second retaining means being a second ridge complementary in shape to the first ridge, so configured that the collar can fit over a respective open end of the fitting, and the second ridge can snap fit Swith the first ridge.

6. A duct joining arrangement as in claim 5 wherein the first ridge is formed as part of a groove proximal to a respective open end of the fitting, 7. A duct joining arrangement as in claim 5 wherein the first ridge may be formed as part of a protrusion extending outwardly from the housing of the fitting.

Claims (16)

1. 8. A duct joining arrangement as in any one of claims 5 to 7 wherein the first or second ridge at least in part forms a barb so that it is more difficult to reverse the snap fit than to engage the snap fit.
2. 9. A duct joining arrangement as in any one of claims 5 to 7 wherein the first ridge extends circumferentially around the housing proximal to a respective open end of the housing. A duct joining arrangement as in any one of claims 5 to 8 wherein the first ridge comprises several part ridges spaced apart circumferentially to provide a means for snap fitting with correspondingly positioned circumferentially spaced apart second ridge parts.
3. 11. A ductjoining arrangement as in any one of claims 1 to 4 wherein the first retaining means comprises a plurality of outwardly extending part ridge protrusions spaced apart circumferentially, and the second retaining means comprises a plurality of outwardly extending circumferentially spaced apart second ridge parts and spaces therebetween wherein ridges of the collar can be aligned with spaces on the open end of the fitting, pushed forward and twisted behind the ridges of the collar, limit means are provided to prevent the collar from being pushed beyond a predetermined distance over the open end 20 of the fitting. °o
4. 12. A ductjoining arrangement as in any one of claims 5 to 10 wherein the first and second ridges each include at least an radially straight surface transverse to the direction of airflow which co-acts.
5. 13. A duct joining arrangement as in any one of claims 5 to 10 wherein the first and second ridges include co-acting radially curved surfaces.
6. 14. A duct joining arrangement as in any one of claims 1 to 4 wherein the collar and 30 a free end of the branch fitting are formed for screw on connection. A duct joining arrangement as in any one of claim 1 to 14 wherein the fitting housing is split such that the open ends of the fitting housing are split in two halves, and so that the fittings housing halves are capable of being nested one within the other.
7. 16. A duct joining arrangement as in any one of claims 1 to 15 wherein the collar does not include a substantial change in diameter along its length and thus does not act as a reducing or expansion collar.
8. 17. A duct joining arrangement as in any one of claims 1 to 15 wherein the collar includes a change in diameter along its length to act as a reducing collar or an expansion collar.
9. 18. A duct joining arrangement as in any one claims 1 to 10 wherein the fitting housing and the collar are formed within the same mould, so that the first and second ridge can be made to fit accurately and provide an accurate snap fit.
10. 19. A duct joining arrangement as in any one of the preceding claims wherein the fitting housing is adapted to join at least two ducts A duct joining arrangement as in any one of claims 1 to 18 wherein the fitting is adapted to join only one duct
11. 21. A duct joining arrangement as in any one of the preceding claims wherein each of the open ends of the fitting are split. b..e 22 A duct joining arrangement as in any one of the preceding claims wherein a first end of the collar or collars is adapted for connection with a duct.
12. 23. A method of making a duct fitting arrangement of any one of claims 1 to 22 said method comprising the step of integrally forming the fitting with at least one collar extending from the respective end of each of the outlets followed by the step of severing the collar or collars. 24 A method as in claim 23 wherein a radially extending wall is formed at an interface between the collar or collars and a respective open end of the formed branch fitting, said radially extending wall being removed during the step of severing. A method of making a duct fitting arrangement as in claim 23 wherein the branch fitting and the tubular outlets are split longitudinally in the direction of airflow, said method including the step of splitting the fitting longitudinally in the direction of airflow once the collars are severed.
13. 26. A method of making a duct fitting arrangement as in claim 23 wherein the step of forming is by blow moulding, 13
14. 27. A method of installing an air conditioning duct fitting arrangement of any one of claims 1 to 23, the method including the steps of placing the two fitting parts together, the step of fitting a collar to an open end of duct tubing, the step of joining the collar to the fitting housing around the outside of said at least one tubular outlets of the joined halves of the duct fitting, and the step of placing a duct onto the end of the collar.
15. 28. The method of installing an air conditioning duct fitting arrangement as in claim 27 wherein the method is further characterised by the step of applying at least one fastener to the join between the collar and the fitting.
16. 29. A duct joining arrangement as hereinbefore described with reference to the illustrations. Dated this 16th day of August 1996 IorcA 5'\<eeA A Tc"\cAoes POLYAI AETY T D L P T O .A 0 By their Patent Attorneys, A. P. T. Patent and Trade 4 Mark Attorneys :.2 9 S 9 .9.9V7X*' 14 ABSTRACT A duct joining of plastics where the housing includes at least two open ends to allow for passage of air. The fitting housing is split longitudinally in the direction of airflow into at least two fitting parts. One or more of the open ends of the fitting are split. A collar fits over the outside of the split open ends to keep the two parts together. A first part of a retainer mechanism is located at the split open ends, and a second part of the retainer mechanism is located on a first end of the collar. Ducting can be fitted over the second part of the collar. The collar and fitting housing parts may all be integrally formed. 0 0*0 s., .0. so 0* O *Oe* C