AU4387001A - Fire resistant diffuser - Google Patents

Description

Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

(ORIGINAL)

Name of Applicant: Actual Inventor: Address for Service: Invention Title: Westaflex (Australia) Pty. Ltd.

of 140 Bamfield Road, West Heidelberg 3081 Victoria, Australia STERLING, Michael William DAVIES COLLISON CAVE, Patent Attorneys, 1 Little Collins Street, Melbourne 3000, Victoria, Australia Fire Resistant Diffuser Details of Associated Provisional Application No.: PQ7595/00 The following statement is a full description of this invention, including the best method of performing it known to us: Q:\OPER\GCP\pq7595cap c.doc 14/5/01 P:\OPER\GCPp7595 cp.do-14/05/01 -2- FIRE RESISTANT DIFFUSER This invention relates to a fire resistant diffuser and a method of moulding a fire resistant diffuser.

Diffusers which are used for ventilation and air conditioning ducts in locations which are required to meet certain fire ratings are normally made from metal. Typically, the diffusers include a square aluminium frame and a grid which is made from aluminium and commonly referred to as an egg crate grid. These diffusers are relatively expensive "but more importantly are often difficult and time consuming to mount. In practice, S 15 considerable care needs to be taken to cut a square opening for the diffuser and then properly align the diffuser frame with the walls of the room in order to have a neat appearance for the diffuser.

An object of the invention is to provide a fire rated diffuser which can be moulded from plastic material and which meets fire ratings.

Another object of the invention is to provide a method of moulding a fire rated diffuser.

According to the present invention there is provided a fire resistant diffuser for ventilation or air conditioning, the diffuser comprising a moulded body which is injection moulded from fire resistant plastics material, the body having a hub, a plurality of arms extending radially therefrom, and a plurality of circumferentially extending ribs which extend between adjacent arms so as to define a plurality of openings, and wherein the thickness of the ribs, as measured in radial cross-section, is greater than about 1.3mm, and P:\OPER\GCFpq7595 eap.dc-I14105/1 -3wherein the minimum dimension of said arms is greater than said thickness, as measured in planes which are transverse to said arms.

Preferably further, the diffuser includes a screw which extends from the hub.

Preferably further, one end of the screw is moulded into the hub.

The invention also provides a diffuser frame in combination with the diffuser defined above.

Preferably further, the diffuser frame includes a cylindrical body integrally S moulded with a flange, the arrangement being such that in use the cylindrical portion extends through a circular hole made in the surface where the diffuser frame is to be used and wherein the flange overlies the surface adjacent to the opening. The cylindrical portion of the diffuser frame includes a spider which has a hub which includes a socket in which the screw of the diffuser can be engaged for mounting the diffuser therein.

Preferably the ends of the radial arms are moulded so as to have a shape which is complementary to that of the cylindrical portion.

20 The invention also provides a method of moulding a fire resistant diffuser as defined above, the method including the steps of providing a die with a hub cavity, radial arm cavities, and rib cavities which define the hub, arms and ribs of the diffuser, and ~.:o!injecting flowable plastics material into the hub cavity.

Preferably the method includes the step of locating a screw in the die prior to injecting the flowable plastics material so that the screw is moulded into the diffuser.

The invention will now be further described with reference to the accompanying drawings, in which: Figure 1 is a cross-sectional view through a diffuser assembly constructed in accordance with the invention; P:\OPER\GCP\pq7595 cap.do-14/05/01 -4- Figure 2 is a plan view of the diffuser frame; Figure 3 is an underside view of the diffuser; Figure 4 is a side view of the diffuser; Figure 5 is a cross-sectional view along the line 5-5; and Figure 6 is a cross-sectional view along the line 6-6.

Figure 1 shows a diffuser 2 which includes a diffuser body 4 and diffuser grid 6.

Both the diffuser body 4 and diffuser grid 6 are injection moulded from fire rated plastics material. One suitable material is fire rated ABS known as ABS 650 WT 100 supplied by Martogg Company.

The diffuser body 4 includes a cylindrical portion 8, a curved flange 10 which is joined to the cylindrical portion 8 by means of a frustoconical transition portion 12.

Figure 1 shows a ceiling 14 which has been cut with a circular hole 16 which is big ooo enough for allowing the cylindrical portion 8 to be passed therethrough. The body 4 is provided with three mounting clips 18 which, when the diffuser is mounted, clamp against 0. the ceiling between the flange 10 and fingers 20 of the clips. The clips 18 are of known type and therefore need not be described in detail.

The body 4 includes a spider 22 which includes a central hub 24, as best seen in o Figure 2. The hub includes a bore 26 which can be used for mounting the diffuser grid, as •oooo explained below.

Figures 3 to 6 illustrate in more detail the diffuser grid 6. It includes an injection moulded body 28 and a mounting screw 30 which projects upwardly from the centre of the body. The body includes a plurality of radial arms 32 which are integrally formed with a hub 34. In the illustrated arrangement, there are sixteen of the radial arms 32. The body 28 also includes a plurality of circumferentially extending rib elements which, together, define five rings 36, 38, 40, 42 and 44. It will be seen that the ends of the arms 32 project beyond the outermost ring 44. It will also be seen that the end faces 46 of the arms 32 are PAOPER1GPq7595 MPAW d-14/05fflI inclined at angles which are complementary to the angle which the frustoconical transition portion 12 makes relative to the cylindrical portion 8.

The diffuser grid 6 is mounted in the body portion 4 by rotating the body 28 so that its screw 30 meshes in threads provided in the bore 26. Alternatively, the bore may be shaped so that the threads of the screw 30 tap a thread when the diffuser grid 6 is rotated.

As best seen in Figure 5, the radial armns 32 are tapered in cross-section. This facilitates removal of the moulded body 28 from the die in which the body is moulded. In the preferred form of the invention, the width W 1 is 3mim on the underside of the grill and the width W2 on the top side of the grill is 1.8mm. Similarly, the segments which make up the rings 36, 38, 40, 42 and 44 are also tapered. It is preferred that the width W3 on the underside of the grill is about 1.9mm and the width W4 on the top side of the grill is 1.3mm, as shown in Figure 6.

It has been found that it is possible to achieve reliable moulding of the body 28 if the minimum dimension of any of the parts thereof is equal to or greater than 1.3mm. In the illustrated arrangement, the die (not shown) for forming the body 28 includes a screw which communicates with the hub 34 on the opposite side to the screw 30. The flowable ABS plastics materi al first flows along the cavities which define the radial arms 32 and thereafter in the segments which define the rings 36, 38, 40, 42 and 44. Also, the tapered cross-sectional shapes of the arms and ribs facilitates removal of the body 28 from the die.

It is preferred that the die includes a cavity in which the screw 30 can be placed so that it is integrally moulded with the body 28.

The diffuser assemblies of the invention can be constructed in various sizes for cooperation with ducting of standard sizes, such as 150mm, 200mm. and 250mm. The ducting is normally fitted or connected onto the cylindrical portion 8.

P:\OPER\GCPpq7595 cap.doc-14/05 I -6- Many modifications will be apparent to those skilled in the art without departing from the spirit and scope of the invention.

The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that that prior art forms part of the common general knowledge in Australia.

*o*

Claims (13)

1. A fire resistant diffuser for ventilation or air conditioning, the diffuser having a moulded body which is injection moulded from fire resistant plastics material, the body having a hub, a plurality of arms extending radially therefrom, and a plurality of circumferentially extending ribs which extend between adjacent arms so as to define a plurality of openings, and wherein the thickness of the ribs, as measured in radial cross- section, is greater than about 1.3mm, and wherein the minimum dimension of said arms is greater than said thickness, as measured in planes which are transverse to said arms.

2. A fire resistant diffuser as claimed in claim 1 wherein the diffuser includes a screw which extends from the hub. A fire resistant diffuser as claimed in claim 2 wherein one end of the screw is S 15 moulded into the hub.

4. A fire resistant diffuser as claimed in claim 1, 2 or 3 wherein the plastics material is ABS. 20 5. A fire resistant diffuser as claimed in claim 4 wherein the plastics material is ABS *go• 650 WT 100.

6. A fire resistant diffuser as claimed in claim 1 to 5 wherein the arms are tapered in circumferential cross-section.

7. A fire resistant diffuser as claimed in claim 6 wherein the width of each arm is about 1.8mm on the top side and about 3mm on the underside.

8. A fire resistant diffuser as claimed in claim 1 to 7 wherein the ribs are tapered. P:\OPER\GCpq7595 ap.doc.-410/0I -8-

9. A diffuser frame assembly including a diffuser frame and a diffuser as claimed in any one of claims 1 to 8. An assembly as claimed in claim 9 wherein the diffuser frame includes a cylindrical body integrally moulded with a flange, the arrangement being such that in use the cylindrical portion extends through a circular hole made in the surface where the diffuser frame is to be used and wherein the flange overlies the surface adjacent to the opening.

11. An assembly as claimed in claim 10 wherein the cylindrical portion of the diffuser frame includes a spider which has a hub which includes a socket in which the screw of the diffuser can be engaged for mounting the diffuser therein. An assembly as claimed in claim 11 wherein the ends of the radial arms are S: 15 moulded so as to have a shape which is complementary to that of the cylindrical portion.

13. An assembly as claimed in claim 12 wherein the ends of the radial arms are located •eoon a conical surface. 20 14. A method of moulding a fire resistant diffuser as defined in any one of claims 1 to 8, the method including the steps of providing a die with a hub cavity, radial arm cavities, and rib cavities which define the hub, arms and ribs of the diffuser, and injecting flowable plastics material into the hub cavity.

15. A method of moulding a fire resistant diffuser as claimed in claim 14 wherein the method includes the step of locating a screw in the die prior to injecting the flowable plastics material so that the screw is moulded into the diffuser.

16. A fire resistant diffuser substantially as hereinbefore described with reference to the accompanying drawings. P:\OPER\GCIpq7595 cap.doc-14/05/01 -9-

17. A diffuser frame assembly substantially as hereinbefore described with reference to the accompanying drawings.

18. A method of moulding a fire resistant diffuser substantially as hereinbefore described with reference to the accompanying drawings. DATED this 14th day of May, 2001 WESTAFLEX (AUST.) PTY. LTD. 15 By its Patent Attorneys DAVIES COLLISON CAVE a. Sc 00., 0 Sr