AU2014246650B2 - A wind induction roof ventilator - Google Patents

Abstract

The present invention relates to a roof ventilation apparatus which uses the energy of the wind to induce exhaust air from the roof void. In one aspect, the apparatus comprises a substantially upright and circular ventilation duct for the communication of air between an interior and an exterior of the enclosed space, the assembly further comprising a circular body supported above the duct, and a shroud surrounding and spaced apart from the body at least, so as to define a body encircling gap between the body and the shroud.

Description

A WIND INDUCTION ROOF VENTILATOR

PRIORITY DOCUMENTS

[0001 ] The present application claims priority from:

Australian Provisional Patent Application No 2013901116 titled “A WIND INDUCTION ROOF VENTILATOR” and fded on 2 April 2013; and

Australian Provisional Patent Application No 2013903428 titled “A WIND INDUCTION ROOF VENTILATOR” and fded on 6 September 2013. The content of each of these applications is hereby incorporated by reference in their entirety.

TECHNICAL FIELD

[0002] The present invention relates to a roof ventilation device which uses the energy of the wind to induce exhaust air from a roof void.

BACKGROUND

[0003] Integrated building ventilation devices are well known, and were normally of the static type such as the ridge vent and the China Hat. The performance of a ridge vent is highly dependent on wind direction. China hats are susceptible to dust, birds and vermin infestation. Another example of a static ventilation device is the wind tower or wind catcher which was conceived in the Middle East. They have proved very effective in dry, arid climates. These rather bulky constructions were normally integrated into the building structure. Whilst there is newfound interest in this design heritage, purely traditional solutions seem rather hard to apply and to be accepted by contemporary Architects. In several designs they utilize the low pressure wake zone manifesting in the leeward side of the tower to induce exhaust air out of the building. Some are constructed to be independent of the wind direction, but because of their typically square shape, this is not entirely possible. These days there has been a proliferation of the wind driven rotary ventilator. The wind causes the device to rotate, which supposedly in turn creates an impellor like impetus to expel exhaust air via centrifugal force. Sadly this is a misnomer, and the actual performance falls short of expectations. The ventilation functioning is more attributed to induction effects rather than the rotational effects. Therefore the cost of providing the rotational movement, as well as the maintenance thereof is disproportionate to the derived benefits therefrom.

[0004] Accordingly, up until now previous static or rotary wind driven ventilators have had limited ventilation effectiveness, are difficult to integrate into the building design, or are dependent on wind direction.

[0005] It is against this background and the problems and difficulties associated therewith that the present invention has been developed.

[0006] Certain objects and advantages of the present invention will become apparent from the following description, taken in connection with the accompanying drawings, wherein, by way of illustration and example, an embodiment of the present invention is disclosed.

SUMMARY

[0007] According to a first aspect, there is provided a ventilator assembly for an enclosed space, the assembly comprising a substantially upright ventilation duct for the communication of air between an interior and an exterior of the enclosed space, the assembly further comprising a body supported above the duct, wherein the body comprises a pair of parallel and spaced apart plates extending transversely relative to the duct, and a shroud surrounding and spaced apart from the pair of parallel and spaced apart plates of the body at least, so as to define a body encircling (surrounding) gap between the body and the shroud.

[0008] In one form, the shroud encircles the body and a portion of a terminal end of the duct.

[0009] In one form, the body and the shroud are circular, and so the gap is an annulus.

[0010] In the case that the body and the shroud are circular, so too are the plates.

[0011] In one form, the body comprises a side wall extending between the plates.

[0012] In one form, in an alternative, the body is cylindrical. In this case, that the body and the shroud are circular.

[0013] In one form, the body has a diameter which is equal to or greater than a diameter of the duct. This helps prevent the ingress of rain.

[0014] In one form, the body is supported on one or more supports which depend from the ventilation duct.

[0015] In one form, the shroud is supported by the one or more supports which depend from the ventilation duct.

[0016] In one form, the shroud encircles the one or more supports from which it depends. Accordingly, the encircling gap represents a significant clearance between the body and the shroud, through which vertical air flow can occur.

[0017] In one form, the shroud is arranged to prevent the ingress of rainfall from the sides in the event of an ambient wind.

[0018] In one form, the body abuts an uppermost end of the duct. In this case, the duct comprises one or more apertures in a wall thereof for air flow.

[0019] In one form, the duct comprises an uppermost open end. In this case, the body is supported so as to be a distance apart from the open uppermost end of the duct.

[0020] In one form, the body has an upper side and a lower side.

[0021 ] In one form, the underside of the body is flat.

[0022] In one form, the upper side of the body is curved convexly. In one form, by virtue of its convexity, the upper side of the body projects above an uppermost edge of the shroud.

[0023] In one form, the cylindrical body comprises a downward extending and encircling lip. This helps force water runoff, and prevents water adhesion to the underside of the flat surface.

[0024] In one form, the shroud comprises an uppermost edge having an outwardly extending and encircling lip.

[0025] In one form, the enclosed space is a one of a building or ceiling cavity.

[0026] In a further aspect the invention may be said to reside in a ventilator assembly for an enclosed space, the assembly comprising a substantially upright and circular ventilation duct for the communication of air between an interior and an exterior of the enclosed space, the assembly further comprising a circular body supported above the duct, wherein the body comprises a pair of parallel and spaced apart plates extending transversely relative to the duct, and a shroud surrounding and spaced apart from the pair of parallel and spaced apart plates of the body at least, so as to define a body encircling gap between the body and the shroud.

[0027] A detailed description of one or more embodiments of the invention is provided below along with accompanying figures that illustrate by way of example the principles of the invention. While the invention is described in connection with such embodiments, it should be understood that the invention is not limited to any embodiment. On the contrary, the scope of the invention is limited only by the appended claims and the invention encompasses numerous alternatives, modifications and equivalents. For the purpose of example, numerous specific details are set forth in the following description in order to provide a thorough understanding of the present invention.

[0028] The present invention may be practiced according to the claims without some or all of these specific details. For the purpose of clarity, technical material that is known in the technical fields related to the invention has not been described in detail so that the present invention is not unnecessarily obscured.

BRIEF DESCRIPTION OF DRAWINGS

[0029] Embodiments of the present invention will be discussed with reference to the accompanying drawings wherein: [0030] Figure 1 is a schematic isometric view of a ventilator assembly according to a first embodiment; [0031 ] Figure 2 is a schematic side elevation of the ventilator assembly of Figure 1; [0032] Figure 3 is a schematic plan view of the ventilator assembly of Figure 1; [0033] Figure 4 is a schematic section view of the ventilator assembly of Figure 1; [0034] Figure 5 is a schematic isometric view of a ventilator assembly according to a further embodiment; [0035] Figure 6 is a schematic side elevation view of the ventilator assembly of Figure 5; [0036] Figure 7 is a schematic plan view of the ventilator assembly of Figure 5; [0037] Figure 8 is a section view of the ventilator assembly of Figure 5; and [0038] Figure 9 is an isometric view of the ventilator assembly of Figure 5, where the shroud is removed to enable examination of the internal components.

[0039] In the following description, like reference characters designate like or corresponding parts throughout the figures.

DESCRIPTION OF EMBODIMENTS

[0040] Referring now to Figure 1, there is shown a ventilator assembly (1) that would be typically roof mounted and subject to wind pressure. Note that the device is symmetric about a vertical central axis. Figure 2 shows the ventilator assembly in elevation, which is typical throughout an entire revolution.

[0041] The assembly (1) includes a circular ventilation duct (2), which forms the base of the device, and facilitates communication of venting air from the building to the outside air stream. Some distance (d) above the top of the duct (2) and concentric with it, is mounted a cylindrical body (4) with domed surfaces top and bottom surfaces. The distance (d) is a parameter which is determined to ensure adequate airflow transfer area from the duct to the outer shroud. In the illustrated embodiment, the cylindrical body (4) has a diameter substantially greater than the ventilation duct (2) in order to prevent rainfall ingress to the ventilation duct (2) from above. Preferably the depth of the cylindrical body (4) should be of sufficient length to create an annular airflow path (a) between it and an outer shroud (3), for the purpose of constraining any water droplets and preventing water ingress into the ventilation duct (2). The bottom edge (4a) of the cylindrical body (4) protrudes beyond the underside flat surface creating a lip. Said lip is intended to detach any incumbent water streams, and eliminate water adhesion to the under surface of the dome insert and hence reduce water droplets entering the ventilation duct (2).

[0042] The internal zone of the cylindrical body (4) may be hollow or filled with an insulating material. In either case the double skinned domed insert reduces direct solar radiation or heat conduction and/or convection transferring to the ventilation duct (2) and hence into the particular roof void. That said, cylindrical body (4) is supported by several vertical supports in the form of brackets (5) arranged concentrically around the ventilation duct (2). Also supported by the brackets (5) is the encircling shroud (3), which is essentially a duct which encircles the cylindrical body (4). The top edge of the shroud has a sharp lip (6) around the entire perimeter. The outer shroud (3) has two significant purposes. The first purpose is to prevent water ingress into the ventilation duct (2) from an oblique angle in the event of an ambient wind. Hence it projects below the level of the ventilation duct (2) by a small distance (dl) and similarly projects above the dome weather lip (4a) by a distance (d2) as shown in Figure 2, and more specifically in Figure 4.

[0043] The second purpose of the shroud (3) is to facilitate airflow separation at its top and bottom edges, arising from the approach of an ambient wind flow. This airflow separation creates local low pressure wake zones above the cylindrical body (4) and in the vicinity of the top of the ventilation duct (2), which together induce the exhaust air flow through the ventilation duct (2).

[0044] The sharp lip (6) around the top perimeter of the shroud (3) also has two purposes. The main purpose is to reinforce the air flow separation principle at the top edge of the shroud (3). The other purpose is of a practical nature which suffices to instil a degree of rigidity to the construction of the shroud (3).

[0045] The top surface of the cylindrical body (4) is arranged to project marginally above the top lip (6) of the outer shroud (3) as can be seen from Figure 2. This is intentioned to maintain the wind airflow over the device and simultaneously prevent any recirculation flow from the separated air flow downwards which would throttle the upward induced airflow.

[0046] In summary, in the presence of an ambient wind, the entire ventilator assembly (1) creates local low pressure wake zones in the vicinity of the ventilation duct (2) which combined, serve to induce air from the building via the ventilation duct (2). The presence of the cylindrical body (4) maintains airflow over the ventilator assembly (1) to prevent recirculation, and simultaneously prevents rainfall ingress into the ventilation duct (2).

[0047] Referring now to Figures 5 through 9, which illustrate an alternate ventilator assembly (7), wherein the body comprises two parallel circular plates (8) and (9). The two plates (8) and (9) are separated by a distance which is roughly equivalent to the dome thickness of the cylindrical body (4) described in the previous embodiment. The upper plate (8) can be termed the induction plate and in one form is located coincidentally with the level of the top edge (12) of an encircling shroud (11). This upper plate (8) would typically be cross broken during fabrication to provide stiffness, resulting in a shallow dome protruding above the cowl top edge as can be seen in Figure 6. The lower plate (9) can be termed the pressure plate and is also cross broken to form a shallow dome. In addition, this lower plate (9) has a narrow downturn creating a lip (9a) rolled into the perimeter. Said lip (9a) is required to prevent adhesion of incumbent water to the underside of the lower plate (9). Contrary to the previously described embodiment, in this case air flow is permitted between the two plates (8) and (9), and this has been found to improve induction performance when compared with the first embodiment.

[0048] As in the previous embodiment, the two parallel circular plates (8) and (9) are supported by the ventilation duct (10), however in this case ventilation duct (10) extends to and is flush with the underside of the aforementioned pressure plate (9). The ventilation duct (10) has long, narrow, lengthwise extending slots (14) evenly spaced around its circumference, as can be seen in Figure 8 and Figure 9. Said slots (14) are mainly required to permit induction airflow to vent from the ventilation duct (10), but further, serve to smooth or stabilise the flow along a generally axial direction. The combined duct and slot arrangement forms a physical and viscous barrier which assists in guiding the primary stagnation airflow through the annulus which exists between the ventilation duct (10) and the shroud (11), thereby improving the induction effect. A subordinate function of the slots is to prevent the infestation of any vermin or birdlife entering the ventilation duct (10) and hence gaining access to the roof space. Furthermore, this so described extension of the ventilation duct (10) provides additional structural rigidity of the ventilation duct (10) and serves to support the pressure plate (9). One further advantage of the extended ventilation duct (10) is that water ingress can be expected to be reduced by virtue of this perforated exterior. As before the entire device is enclosed by the shroud (11) which exhibits the same functioning and features as described in the previous embodiment.

[0049] It will be apparent then that an advantage of the static ventilator assemblies according to the embodiments of the present invention, is that they have no moving parts and are therefore more reliable than the more common rotary wind driven ventilators. Furthermore, because they are specifically designed to employ wind induction effects, they are capable of having superior ventilation induction flow rates than the common rotary wind ventilators.

[0050] Whilst various other duct cowl devices exist, these are mainly intended to permit buoyant air venting from an exhaust whilst preventing water ingress. None of them are specifically designed to induce airflow through the exhaust duct using the force of the wind in the manner described above and therefore this current invention is unique.

[0051 ] Throughout the specification and the claims that follow, unless the context requires otherwise, the words “comprise” and “include” and variations such as “comprising” and “including” will be understood to imply the inclusion of a stated integer or group of integers, but not the exclusion of any other integer or group of integers.

[0052] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement of any form of suggestion that such prior art forms part of the common general knowledge.

[0053] It will be appreciated by those skilled in the art that the invention is not restricted in its use to the particular application described. Neither is the present invention restricted in its preferred embodiment with regard to the particular elements and/or features described or depicted herein. It will be appreciated that the invention is not limited to the embodiment or embodiments disclosed, but is capable of numerous rearrangements, modifications and substitutions without departing from the scope of the invention as set forth and defined by the following claims.

Claims (12)

1. A ventilator assembly for an enclosed space, the assembly comprising a substantially upright ventilation duct for the communication of air between an interior and an exterior of the enclosed space, the assembly further comprising a body supported above the duct, wherein the body comprises a pair of parallel and spaced apart plates extending transversely relative to the duct, and a shroud surrounding and spaced apart from the pair of parallel and spaced apart plates of the body at least, so as to define a body encircling (surrounding) gap between the body and the shroud.

2. The ventilator assembly of claim 1, wherein the shroud encircles the body and a portion of a terminal end of the duct.

3. The ventilator assembly as in either of the preceding claims, wherein the body and the shroud are circular, and so the gap is an annulus.

4. The ventilator assembly of claim 1, wherein the plates are circular.

5. The ventilator assembly as in any one of the preceding claims, wherein the body comprises a side wall extending between the plates.

6. The ventilator assembly as in any one of claims 3 through 5, wherein the body is cylindrical.

7. The ventilator assembly as in any one of claims 3 through 6, wherein the body has a diameter which is equal to or greater than a diameter of the duct.

8. The ventilator assembly as in any one of the preceding claims, wherein the body is supported on one or more supports which depend from the ventilation duct.

9. The ventilator assembly as in any one of the preceding claims, wherein the shroud is supported by the one or more supports which depend from the ventilation duct.

10. The ventilator assembly as in any one of the preceding claims, wherein the duct comprises an uppermost end, and is open at this end.

11. The ventilator assembly as in any one of claims 1 through 9, wherein the duct comprises a duct wall comprising at least one through aperture at or near an uppermost end thereof.

12. A ventilator assembly for an enclosed space, the assembly comprising a substantially upright and circular ventilation duct for the communication of air between an interior and an exterior of the enclosed space, the assembly further comprising a circular body supported above the duct, wherein the body comprises a pair of parallel and spaced apart plates extending transversely relative to the duct, and a shroud surrounding and spaced apart from the pair of parallel and spaced apart plates of the body at least, so as to define a body encircling gap between the body and the shroud.