AU712893B2 - Roof ventilator - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT Name of Applicant: EDMONDS PRODUCTS AUSTRALIA PTY LIMITED Actual Inventor: Address for Service: Chrysiliou Moore Martin CMC Centre 143 Sydney Road Fairlight Sydney NSW 2094 Invention Title: Roof Ventilator The following statement is a full description of this invention, including the best method of performing it known to me/us: e:\karen\work\1611 .doc \\server\e\patentscomp\1499.doc ROOF VENTILATOR This invention relates to ventilators.

Current roof ventilators available for domestic and light industrial use generally comprise a housing which attaches into or onto an aperture in the roof. Mounted on this housing is a stationery shaft upon which are mounted a top and a bottom bearing. The rotor unit of the ventilator is comprised of a number of thin metal strips which extend from the top bearing to the bottom bearing. Because the metal strips are flexible, the outer housings of the top and bottom bearings may move out of alignment and rotate about non parallel axes. This causes noise and eventually bearing failure.

S: Furthermore, in conventional ventilators the top and bottom bearings are encapsulated in a housing to which the metal vanes are riveted. Replacement of •:•the bearing requires all vanes to be removed from the housing to disassemble the housing. This means that, in effect, the bearings are non-replaceable. It is cost 15 effective to replace the entire ventilator rather to repair it on-site. A typical existing roof ventilator is shown in Fig. 1.

In an attempt to overcome at least some of the disadvantages of the prior art, the invention, in one broad form, provides a roof ventilator including: a base for mounting on a roof; at least one bearing mounted on or in the base; an elongate shaft mounted on the at least one bearing for rotation about the axis of the shaft relative to the base; and, a rotor unit mounted on the shaft for rotation therewith relative to the base; wherein the rotor unit includes a lower mounting press fit to a lower portion of the shaft and wherein the lower mounting under normal conditions the lower mounting cannot move axially along the shaft but may move along the shaft under loads caused by excessive wind speeds.

Preferably there are two, spaced apart, bearings in the base and preferably the two bearings are located at each end of a tubular passageway in the base.

\\server\e\patents\comp\1499.doc The shaft preferably extends downwards through the bearings and preferably has a smaller diameter portion extending through the bearings compared to the major portion of the shaft. Preferably the lower free end of the shaft is threaded and is secured in the bearings by sandwiching the bearings between the flange in the shaft and nut on the free end. A spacer unit may be placed between the two bearings.

O

0* a \\search\e\patents\comp\1 499.doc The rotor unit preferably comprises an upper and a lower disc with a multitude of vanes extending between the discs. The discs mount on the shaft for rotation with the shaft relative to the base. Preferably the lower disc is a press-fit on the shaft whilst the upper disc is secured in place by a nut on the upper free end portion of the shaft. Use of a press-fit allows the lower disc to ride up the shaft if the unit is subjected to excessive windspeeds.

With this arrangement, the rotor unit and shaft may be removed from the base unit and the bearing or bearings merely by undoing a single nut.

The invention shall be better understood from the following description of a nonlimiting embodiment and the drawings, in which: Fig 1 is a schematic cross-sectional side view of a prior art roof ventilator and; V906- Fig 2 is a cross-sectional side view of an embodiment of the present invention.

Referring to Fig 2 the ventilator 10 comprises a base unit 12 and a rotor unit 14.

The base unit 12 comprises a circular roof mounting 16, a cylindrical wall 18 15 extending upward from the roof mounting 16 and a bearing housing 20. The 0 cylindrical wall 18 may be secured to the roof mounting by way of rivets, screws or nuts and bolts. Further the base unit 12 may be other than circular, such as square or rectangular.

The bearing housing 20 comprises three identical legs 22 which extend radially at 0 °00 20 120 degrees to each other. The free ends of each leg end at the inner diameter of the wall 18 except for a small flange 24 which extends to at least and preferably beyond the outer diameter of the wall 18. Thus the housing 20 may be positioned on the wall with the flange 24 resting on the upper end of the wall 18 and the legs 22 snugly abutting the inner surface of the wall. A nut and bolt combination or self tapping screw or rivet may then be used to secure each leg 22 to the wall 18 via securing hole 26. More than three legs 22 may be utilised.

Located centrally in the bearing housing 20 is a cylindrical passageway 28 in which two bearings 30, 32 are mounted. Preferably the passageway has end portions of greater diameter than the central portion so as to provide flanges against which the bearings seat.

Mounted on the bearings 30, 32 is an elongate shaft 34 which extends through the bearings and is secured in place by a nut 36. The shaft is a press fit in the \\search\e\patents\comp\1 499.doc bearings so rotates with them relative to the housing 20. Preferably the portion 38 of the shaft which extends through the bearings is of lesser diameter than the remaining portion. Thus the nut 36 may be tightened to draw the shaft axially against the bearings. Obviously, there should be minimal tension in the shaft to avoid damaging the bearings. In addition a spacer 40 is positioned between the two bearings to prevent damage if overtightening of the nut occurs. The change in diameter of the shaft may be by way of a taper rather than a discrete change in diameter.

The shaft 34 may be removed from the bearings merely by undoing the nut 36 and drawing the shaft upwards.

The rotor unit 14 includes an upper mounting disc 42, a plurality of vanes 44, a cylindrical hub 46, a plurality of radially extending support legs 48 and a lower :-°°°mounting disc The upper mounting disc 42 has a central aperture through which a threaded end of the shaft 34 passes. Preferably the threaded end is of smaller diameter than the rest of the shaft, so forming an annular surface against which the disc 42 may oooo bear against and be secured to by a nut 52.

The disc 42 has an outer annular flange 54 which preferably extends in a plane perpendicular to the axis of the shaft, although this is not essential.

The vanes 44, which are preferably of thin metal sheet, are secured about the circumference of flange 54 by way of rivets 56 and extend in a curve to the cylindrical hub 46, to which they are attached, also by rivets 58.

The support legs 48 are L-shaped and have a first arm 60 extending axially on the inner surface of the hub 46, to which they are attached and a second arm 62 which expends radially inwardly, generally perpendicular to the first arm 60, to the lower mounting disc. The second arm 62 is secured to the lower mounting disc by rivets 64.

The lower mounting disc 50 also has a central aperture through which the shaft 34 passes. Preferably the aperture is an interference fit with the shaft, although it may be secured by a spot weld or the like. Use of a press-fit allows the lower disc to ride up the shaft if the unit is subjected to excessive windspeeds.

3 i \\search\e\patents\comp\1499.doc When assembled, it will be noted that the support legs 48 clear the bearing housing 22 whilst the hub 46 overlaps the cylindrical wall 18, so as to provide some resistance to rain being blown into the opening in the roof.

From the above, it will be apparent that the rotor unit 14 is quite separate from the bearing housing 20 and associated bearings 30, 32 and may be assembled separately from the remainder of the ventilator. To couple the rotor unit 14 to the bearing housing 20, it is merely necessary to insert the shaft into the bearings and apply the nut 36.

More importantly, it is apparent that the bearings 30, 32 are located in a rigid housing 18 and the outer shell is not subject to twisting forces as is the prior art.

o Thus, in use, the bearings remain aligned and so noise due to the out of alignment bearings is reduced.

Because the rotor may be removed/installed merely by tightening or loosening of r:r; the nut 36, it is easy to remove the rotor if a bearing does need replacing. Since S• 15 the bearings are only a press fit in the housing, it is easy to remove them with a drift and insert a new bearing.

o.o° An added advantage of this configuration is that the bearings are separate from the rotor unit. Thus, for instance, the rotor unit may be completed and painted as required for a customer separate from the bearings. In contrast the prior art requires painting of individual components of the rotor unit prior to assembly, because the bearings will not survive exposure to a baking oven. This means that o standard rotor units may be kept in stock for painting as required.

It will be apparent to those skilled in the art that many modifications and variations may be made to the embodiment described herein without departing from the spirit or scope of the invention.

Claims (8)

1. A roof ventilator including: a base for mounting on a roof; at least one bearing mounted on or in the base; an elongate shaft mounted on the at least one bearing for rotation about the axis of the shaft relative to the base; and, a rotor unit mounted on the shaft for rotation therewith relative to the base; wherein the rotor unit includes a lower mounting press fit to a lower portion 10 of the shaft and wherein the lower mounting under normal conditions the lower mounting cannot move axially along the shaft but may move along the shaft under loads caused by excessive wind speeds.

2. The roof ventilator of claim 1 wherein the rotor unit includes an upper disc mounted on the shaft and a plurality of vanes extending between the upper and lower mountings.

3. The roof ventilator of claim 1 wherein the rotor unit includes an upper mounting secured to an upper portion of the shaft and a lower mounting secured by a press fit to a lower portion of the shaft.

4. The roof ventilator of claim 1 wherein the at least one bearing includes two, spaced apart, bearings. l

5. The roof ventilator of claim 1 wherein the at least one bearing includes two, spaced apart, bearings located at each end of a tubular passageway in the base.

6. The roof ventilator of claim 1 wherein the shaft has a smaller diameter portion extending through the at least one bearing compared to the major portion of the shaft.

7. The roof ventilator of claim 1 wherein the shaft includes a flange and is secured to the at least one bearing by sandwiching the at least one bearing between the flange and a nut on the free end of the shaft. \\server~e~patents\comp\14gg.doc

8. A roof ventilator substantially as herein described with reference to Fig 2. Dated this 21 st day of July, 1999 EDMONDS PRODUCTS AUSTRALIA PTY LIMITED by its Patent Attorneys CHRYSILIOU MOORE MARTIN RU C 77 S 06