AU769953B2

AU769953B2 - Fittings for use with ducting

Info

Publication number: AU769953B2
Application number: AU35334/00A
Authority: AU
Inventors: Roger Laurence Cooke
Original assignee: Duo Plastics Pty Ltd
Current assignee: Duo Plastics Pty Ltd
Priority date: 1999-07-05
Filing date: 2000-05-16
Publication date: 2004-02-12
Anticipated expiration: 2020-05-16
Also published as: AU3533400A

Description

-A

Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

(ORIGINAL)

Name of Applicant: Actual Inventor(s): Address for Service: Invention Title: DUO PLASTICS PTY LTD DAVIES COLLISON CAVE, Patent Attorneys, 1 Little Collins Street, Melbourne, Victoria 3000.

"Fittings for use with ducting" Details of Associated Provisional Application No. PQ1420/99 filed 5 July, 1999 The following statement is a full description of this invention, including the best method of performing it known to us: -1- Q:\OPER\RSH\pq1420-99 136.doc. 1515/00 PAOPER\RSH\PQ1420-9. 132- 16/5/00 -2- FITTINGS FOR USE WITH DUCTING The present invention relates to fittings for ducting of the type used in ducted air heating or cooling systems. More particularly the invention relates to connectors for use with such ducting.

Ducting for use in ducted air heating or cooling systems is conventionally of circular or square cross-section with the main body of the ducting being defined by a spiral winding carrying a foil covering whereby the ducting has substantial flexibility so that it can be laid 10 to a desired path within relatively confined spaces. Traditionally, an installer of a ducted air heating or cooling system will require a range of duct connectors for installation of the o...system. For example, connectors may be required to connect two lengths of ducting in endto-end relation possibly with a step down in diameter from one length to the next, to take one S or more branch ducts from a main duct, or to form a main duct into two or more ducts.

Conventionally, a connector for such ducting will comprise a tubular inlet and one or more tubular outlets depending on the function of the particular connector. Ducting of appropriate size is simply pushed over the inlet or outlet and is retained thereon by engagement of projections with the coils of the spiral winding forming the main body of the ducting. To permit versatility in usage the inlet and/or outlet(s) may be stepped in order to co-operate with S* 20 a number of different diameters of ducting.

Such connectors have commonly been formed as a one-piece plastics moulding using a rotary moulding process. Although such duct connectors can be produced relatively inexpensively using rotational moulding techniques, nevertheless a one-piece connector is relatively bulky bearing in mind that its inlet and outlet(s) may be sized to receive ducting of up to about 60 centimetres in diameter and as a result, transportation costs tend to be disproportionately high in relation to the cost of producing the connector.

With a view to reducing transportation costs it has been proposed to fabricate the connectors in the form of two half-shells which can readily be transported in a stack with one half-shell nested within an adjacent half-shell. When required for use, two half-shells are P:'OPER\RS H1\229450- I spa.do-2 1/10/03 -3assembled together and ducting is placed over the inlet and outlet(s) to hold the half-shells in assembled relation. To facilitate moulding of the half-shells in previously proposed constructions, the two half-shells abut at planar faces of the half-shells so that in the assembled connector there is a planar connecting face between the two half-shells. This does tend to lead to difficulties in locating the half-shells when assembling the connector particularly prior to application of the first length of ducting which initially holds the two half-shells together. However even when the two half-shells are assembled together and the ducting is in place, the abutting faces of the two half-shells in the main body of the connector beyond the zones of connection of the ducting do not provide a seal and, as a result, leakage of air from the body of the connector can occur. Although it is possible to prevent air leakage at the abutting faces of the two half-shells by applying a silicon bead, this requires an extra operation on the part of the installer. Accordingly, although the construction of connectors from half-shells leads to significantly reduced transportation costs, particularly if interstate transportation is involved, nevertheless the difficulties which have arisen in prior connectors formed from half-shells in the assembly of those half-shells on site and their subsequent sealing has resulted in a reluctance for installers to use such connectors.

According to one aspect of the present invention, there is provided in combination a 20 connector for ducting for use in ducted air heating or cooling systems, said connector having an inlet and at least one outlet, said connector being formed from two half-shells in mating engagement along two opposed joining lines by a joint structure consisting of interengaging male and female joint parts, and ducting mounted over the external surface of the inlet and outlet, said interengaging joint parts serving to locate the two half-shells 25 one relative to the other and providing a substantial seal against leakage of air across the junction between the two half-shells, and said interengaging joint parts being displaced ••go inwardly from the external surface of the connector so as not to impede mounting of the ducting onto the external surfaces of the inlet and outlet.

S Advantageously, the seal is a labyrinth-type seal.

Advantageously, the female joint part comprises a longitudinally-extending channel and P:OPER\RSH12945O Ispa.doc.2I/I0/03 -4the male joint part comprises a longitudinally-directed projection which is received within the channel, the projection and the channel both lying within the interior of the respective half-shell.

Advantageously, an inner wall of the channel forming the female joint part is extended outwardly to form a projecting lip leading into the channel to guide into the channel the projection of the male joint part so as to facilitate relative location of the two half-shells during assembly.

Particularly, advantageously, each half-shell and its associated joint parts are integrally formed by a rotary moulding process.

According to another aspect of the invention, there is provided a method of manufacturing a connector as defined above, said method comprising moulding each half-shell by rotary moulding in a mould having inserts projecting into the interior of the mould to produce the joint parts on that half-shell.

Advantageously, the two half-shells for assembly into a said connector are formed :9 simultaneously in a single mould in the same rotary moulding operation. Preferably such a 20 mould comprises two mould halves with inserts for forming the joint structure between the mould halves.

According to yet another aspect of the invention, there is provided a connector for ducting for use in ducted air heating or cooling systems, said connector having an inlet and at least 25 one outlet which, in use of the connector, lie within the ducting, said connector being formed from a plurality of shell-like segments in engagement along joining lines by interengaging joint parts carried by the adjacent segments, said interengaging joint parts serving to locate the segments circumferentially one relative to another and providing a .0°O9o seal to substantially prevent leakage of air across the junctions between the segments, and said interengaging joint parts lying within the interior of the connector so as not to impede mounting of the ducting onto the external surfaces of the inlet and outlet.

P:OPER\RSH\2294500- Isp.doc-21/10/03 -4A- An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:- Figure 1 is a transverse cross-section through two half-shells which can be assembled to form a connector in accordance with the preferred embodiment of the invention; Figure 2 is a fragmentary transverse section to a larger scale and showing a joint *o P:\OPER\RSH\PQ1420-9. 132 16/5/00 between the two half-shells in their assembled condition; and Figure 3 is a transverse section through a rotary mould for producing the two halfshells shown in Figures 1 and 2 and showing inserts for producing male and female joint parts of the half-shells.

As shown in the accompanying drawings, a connector in accordance with the preferred embodiment of the invention consists of two half-shells 2,4 which mate along a median plane of the connector in such a manner as to provide a positive location of the two half-shells one relative to the other and also to provide a seal between the two half-shells. The two half- 10 shells 2,4 are substantially identical and differ only in the construction of joint formations at the abutting faces of the two half-shells to provide the locating and sealing joint structure just mentioned. However the design of the joint structure is such that not only does it fulfill the functional requirements of facilitating assembly of the half-shells and providing a seal, but S.also it can be produced by rotational moulding integrally with the remainder of the half-shells.

15 The design of the joint structure will first be described and the design of mould inserts for producing the joint structure will then be described.

As just mentioned the connector in accordance with the preferred embodiment of the invention is assembled from two half-shells which are joined along a median longitudinal S• 20 plane of the connector. The connector itself can take any suitable form such as a straight or angled connector for connecting two lengths of ducting in end-to-end relation, a branch connector of Y or T form, or any other type of connector having an inlet and one, two, or more outlets, with the inlet and/or outlet(s) possibly being of stepped diameter to receive two or more different diameters of ducting and also carrying projections which engage with the coils of the ducting to prevent accidental removal. Each of the two opposite edges of the halfshell consists of a male or female joint part which mates with a corresponding female or male joint part at the adjacent edge of the other half shell. In the embodiment shown one of the two half-shells has a female joint part along both of its opposed edges to mate with male joint part along both of the opposed edges of the other half-shell. However, it would alternatively be feasible for each half-shell to have male joint part along one of its edges and a female joint part along the other of its edges.

P:\OPER\RSH\PQ1420.9.132 16/5/00 -6- In the embodiment shown, the upper half-shell 2 is formed with the male joint parts 6 each which consists of a transverse projection 8 having an outer face 8a lying on the median plane of the assembled connector. The projection 8 is directed laterally inwardly and has at its inner end a longitudinal projection 10 which extends outwardly of the half-shell 2 beyond the face 8a. The lower half-shell 4 includes the corresponding female joint parts 12 each consisting of a transverse projection 14 extending laterally inwardly and having an outer face 14a with an outer surface lying on the median plane of the connector and which, in the assembled connector, abuts against the face 8a of the associated male joint part 6. At its inner end the projection 14 carries a first longitudinal projection 16 which extends inwardly of the 10 half-shell from the projection 14. That first projection 16 carries at its inner end a second longitudinal projection 18 spaced laterally inwardly of the first projection 16 to define between the two projections 16,18 a channel which is closed at its inner end by a base Preferably the second or inner projection 18 extends outwardly of the half-shell 4 beyond the face of the transverse projection 14.

e When the two half-shells 2,4 are assembled to form the connector the longitudinal projection 10 of the male joint part is received within the channel of the female joint part.

This provides positive lateral or circumferential location between the two half-shells 2,4 and also provides a labyrinth-type seal between the two half-shells 2,4. It is to be noted in this respect that although the male projection 10 may be a relatively tight fit within the channel or one of its faces may be in engagement with the corresponding side of the channel, even if there is not a sealing engagement between the projection and channel, nevertheless a substantial seal will still be formed by the mating male and female joint parts as the air flow path defined between these mating components will be labyrinthine or tortuous thereby providing a substantial barrier to leakage of air from the interior of the connector within the normal range of operating pressures of a ducted air heating system or cooling system. The extension of the inner longitudinal projection 18 of the female joint part outwardly of the halfshell 4 beyond the planar face 14a is particularly advantageous as it provides along the edge of the half-shell a projecting lip which acts as a lead-in lip which facilitates insertion of the male projection 10 into the channel. Accordingly, this lip provides a significant aid to assembly of the two half-shells.

P:\OPER\RSH\PQ1420-9. 132- 16/5/00 -7- Accordingly, by means of the joint construction just described the two half-shells 2,4 can readily be assembled to form the connector by mating of the male and female joint parts and once assembled, a substantial seal is formed between the two half-shells without the need to apply any additional sealing means such as silicon.

As shown in Figure 3 a rotary mould for forming simultaneously both half-shells and the associated male and female joint parts comprises two half moulds 30,32 shaped to form the structure of the two half-shells 2,4. In conventional manner the two mould halves 30,32 have external flanges 30a, 32a for receiving bolts whereby the two half-shells can be clamped 10 together during moulding and opened for removal of the moulded product after completion of moulding.

Each pair of mating male and female joint parts along each of the two opposite edges S of the completed connector is formed by a set of inserts 36 positioned between the external 15 flanges of the half moulds 30,32 at each side of the assembled mould. Each set of inserts 36 consists of a first insert 38 which projects into the interior of the mould by a limited distance to form the male joint part 6, a second insert 40 which extends into the interior of the mould by a greater distance to define the female joint part 12 and, between the first and second inserts 38,40 a third insert 42 which projects into the interior of the mould by a greater 20 distance than the first and second inserts 38,40. The third insert 42 is constructed of, or coated with, a material which is resistant to settling of the molten plastics material during the rotary moulding process. By way of example only, the third insert 42 may be composed of P.T.F.E. such as that sold under the trade mark "TEFLON".

The first insert 38 projects into the interior of the mould to define a right angled edge against which is formed the male joint part 6 during rotation of the mould. Figure 3 illustrates how the molten plastics will flow over that right angled edge during mould rotation to form the male joint part. The outer edge of the longitudinal projection 10 of the male joint part is defined at the adjacent face of the intermediate third insert 42. The second insert is shaped with a projecting lip 40a which is spaced inwardly from the mould surface of the adjacent mould half 32 so as to shape the female joint part 12 in the manner illustrated during

K

P:\OPER\RSH\PQ1420-9.132- 16/5/00 -8rotation of the mould. The outer edge of the inner longitudinal projection 18 of the female joint part 12 is defined at the adjacent face of the intermediate third insert 42.

By use of the mould with two sets of inserts 36 as described, both half-shells 2,4 with mating joint parts to form a complete connector are formed simultaneously in a single rotary moulding operation. Although it is particularly convenient to use a single mould to form the two mating half shells for each connector it would, alternatively, be feasible to provide one mould with inserts for simultaneously producing a pair of half-shells with male joint parts and a second mould with inserts for producing simultaneously a pair of half-shells with female 10 joint parts.

It is to be noted that an existing rotary mould having mould halves which clamp directly together at their external flanges to produce a complete connector (in other words an ;integral connector, not a split connector assembled from two half-shells) can readily be converted into a mould for producing the two half-shells with male and female joint parts simply by the incorporation of the sets of inserts between the two flanges. The inserts themselves are not of complex shape and can be produced relatively inexpensively.

Although it is envisaged that most practical forms of the invention will utilise two half- 20 shells to form the connector, in principle it would be feasible to assemble the connector from three or more shell-like segments with interengaging joint parts of the form described between adjacent segments.

The embodiment has been described by way of example only and modifications are possible within the scope of the invention.

Throughout this specification and claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers or steps but not the exclusion of any other integer or group of integers.

Claims

1. In combination a connector for ducting for use in ducted air heating or cooling systems, said connector having an inlet and at least one outlet, said connector being formed from two half-shells in mating engagement along two opposed joining lines by a joint structure consisting of interengaging male and female joint parts, and ducting mounted over the external surface of the inlet and outlet, said interengaging joint parts serving to locate the two half-shells one relative to the other and providing a substantial seal against leakage of air across the junction between the two half-shells, and said interengaging joint parts being displaced inwardly from the external surface of the connector so as not to impede mounting of the ducting onto the external surfaces of the inlet and outlet.

2. A combination according to claim 1, wherein the seal is a labyrinth-type seal.

3. A combination according to claim 1 or claim 2, wherein the female joint part comprises a longitudinally-extending channel and the male joint part comprises a longitudinally-directed projection which is received within the channel, the projection and the channel both lying within the interior of the respective half-shell.

4. A combination according to claim 3, wherein an inner wall of the channel forming *.the female joint part is extended outwardly to form a projecting lip leading into the channel to guide into the channel the projection of the male joint part so as to facilitate relative location of the two half-shells during assembly.

5. A combination according to any one of claims 1 to 4, wherein each half-shell and its associated joint parts are integrally formed by a rotary moulding process.

6. A connector for ducting for use in ducted air heating or cooling systems, said 9999 connector having an inlet and at least one outlet which, in use of the connector, lie within 9999 30 the ducting, said connector being formed from a plurality of shell-like segments in engagement along joining lines by interengaging joint parts carried by the adjacent segments, said interengaging joint parts serving to locate the segments circumferentially one relative to another and providing a seal to substantially prevent leakage of air across the junctions between the segments, and said interengaging joint parts lying within the P:\OPER\RS H\229450D- I spa.dm.21/10103 interior of the connector so as not to impede mounting of the ducting onto the external surfaces of the inlet and outlet.

7. A connector according to claim 6, wherein the interengaging joint parts comprise a first joint part having longitudinally-extending channel and a second joint part having a longitudinally-directed projection received within the channel.

8. A connector according to claim 6 or claim 7, wherein the connector is formed from two such segments each in the form of a half-shell.

9. A method of manufacturing a connector according to any one of claims I to 5 or claim 8, said method comprising moulding each half-shell by rotary moulding in a mould having inserts projecting into the interior of the mould to produce the joint parts on that half-shell.

A method according to claim 9, wherein the two half-shells for assembly into the connector are formed simultaneously in a single mould in the same rotary moulding operation.

11. A method according to claim 9 or claim 10, wherein the mould comprises two mould halves with removable inserts between the mould halves for forming the joint structure.

12. A process for manufacturing a connector according to any one of claims I to 5 or claim 8, said method comprising moulding two half-shells by rotary moulding in a mould comprising two mould halves, with inserts between the mould halves for forming the joint parts on the half-shells.

13. A method according to claim 11 or claim 12, wherein the inserts are removably clamped between the mould halves.

14. A connector substantially as hereinbefore described with reference to the accompanying drawings. P:\OPER\RSH\PQ1420-9. 132 16/5100 -11 I- A method for manufacturing a connector substantially as hereinbefore described with reference to the accompanying drawings. DATED this 15th day of May, 2000 DUO PLASTICS PTY.LTD. By its Patent Attorneys: DAVIES COLLISON CAVE too**: