GB2272512A - A guide vane - Google Patents

Abstract

A guide vane 5 in the form of an insert for a duct forming part of a heating, ventilating or air conditioning apparatus comprises a resilient element defining at least two substantially planar surfaces, the element being introduced into the interior of the duct so as to be supported therein by way of the edges of the vane engaging the inner wall of the duct with at least one of the substantially planar surfaces extending axially of the duct so as to restrict flow across the duct and to direct flow axially along the duct, thereby improving the rate of flow through the duct The element may be formed flat and folded to define a V- or concertina shape. Plural vanes 5 may be provided in the duct. The element may be moulded from polypropylene. <IMAGE>

Description

DESCRIPTION OF INVENTION A Guide Vane.

THE PRESENT INVENTION relates to a guide vane and more particularly to a guide vane for use in ducting forming part of a heating, ventilating or air conditioning apparatus, in the broadest sense. Thus, whilst specific reference will be made to using the guide vane in ducting associated with an extractor fan, it should be appreciated that the invention may be used in ducting in other situations.

It is, of course, well known that the rotating impeller of an axial flow fan imparts a rotary movement or swirl to air as it passes through the fan, as well as directing the air generally axially along ducting connected to the fan outlet. This outlet swirl or turbulence reduces the overall efficiency or flow rate which can be achieved by the fan.

It is known to form ducting with integral vanes which extend transversely across the ducting between opposed regions thereof, the vanes assisting in guiding the flowing axially along the ducting and serving to reduce rotary or swirling movement of the air. However, because the vanes are formed integrally with the ducting the benefits provided by the vanes are only obtained if an installation is provided with this particular type of ducting when it is initially assembled. It is therefore not possible to obtain the benefits provided by such vanes in an installation which incorporates conventional ducting unless one is prepared to completely replace the ducting, which an expensive and time consuming operation and which, in some cases, may not be possible or practical.

The present invention seeks to address the problems outlined above.

According to one aspect of this invention provides a guide vane in the form of an insert in a duct, the guide vane comprising an element defining at least two substantially planar regions, the element being supported within the interior of the duct by way of edges of the vane engaging the interior of the duct, the vane being oriented so that at least one of the substantially planar regions extends axially of the duct and faces in a direction transverse to the longitudinal axis of the duct so as to restrict flow across the duct and to direct flow axially along the duct.

Preferably the vane is generally V-shaped in crosssection, the arms of the V-shaped vane being resiliently biased into engagement with the interior of the duct.

The vane may be integrally formed to have a generally V-shaped cross-section, the arms of the V-shaped vane being urged towards each other upon insertion of the vane in the duct, the resilience of the material from which the vane is formed causing the arms to be biased away from each other into engagement with the interior of the duct.

Alternatively the vane may be integrally formed as a substantially planar component, the vane defining a fold line about which the vane may be folded so as to be generally V-shaped in cross-section, the inherent resilience of the material from which the vane is formed causing the vane naturally to tend to the planar or flattened-out condition when it has been folded about the fold line, the resilience of the material causing edges of the vane to be resiliently biased into engagement with the interior of the duct.

According to another aspect the invention provides a blank for forming a guide vane as described above the blank comprising an integrally formed substantially planar component defining a fold line about which the blank may be folded so as to be generally V-shaped in cross-section, the inherent resilience of the material from which the blank is formed causing the blank naturally to tend to the planar or flattened-out condition when it has been folded about the fold line, the resilience of the material causing edges of the blank to be resiliently biased into engagement with the interior of a duct when a vane formed from the blank is located in the duct.

Conveniently the fold line is defined by a channel extending across a surface of the blank between opposed edges thereof.

Advantageously the edges of the blank are formed with indents or recesses at the points where the fold line meets the edges.

Preferably the fold line is approximately centrally located with respect to the blank, enabling the blank to be folded in half so as to define two substantially equal sized portions.

Advantageously the blank is substantially rectangular.

Preferably the blank is integrally moulded from a polypropylene plastics material.

In order that the present invention may be more readily understood and so that further features thereof may be appreciated, the invention will now be described by way of example, with reference to the accompanying drawings in which: FIGURE 1 is a diagrammatic, perspective view of a ventilating installation incorporating a guide vane in accordance with the present invention; FIGURE 2 is a plan view of a guide vane in accordance with this invention; FIGURE 3 is a front elevation of the guide vane of Figure 2; and FIGURE 4 is an enlarged view of that region of the guide vane which is circled in Figure 3.

Referring initially to Figure 1, a conventional extractor fan installation may comprise an axial flow fan 1 mounted within a room or space to be ventilated, ducting 2 which extends from the fan outlet through a wall 3 and a baffle 4 mounted on the exterior of the wall 3 so as to cover the end of the ducting 2. As shown in Figure 1 the wall 3 may be a cavity wall. It will be appreciated that as described so far the extractor fan installation is conventional.

Within the ducting 2 there is provided a guide vane 5 in accordance with this invention.

As can be seen from Figures 2 and 3 of the drawings the guide vane comprises a substantially planar, rectangular component which is moulded from polypropylene plastics material in a flat form. The vane therefore has a pair of opposed longer sides 6 and a pair of opposed shorter sides 7. The corners between the four sides are rounded. At positions centrally along each of the longer sides 6 the edges of the vane are formed with small semi-circular indents or recesses 8. The vane defines a central fold line 9 which is parallel to the shorter sides 7 and extends between the semi-circular recesses 8.

As can best be seen from Figures 3 and 4 of the drawings the central fold line 9 is formed in the upper surface of the guide vane and comprises a semi-circular channel 10 which extends across the upper surface of the vane, the channel having a depth which is approximately equal to half the overall depth of the guide vane.

The upper surface of the guide vane may carry written or pictorial instructions of how the vane is to be fitted into a duct such as the duct 2 shown in Figure 1 of the drawings. The fold line 9 enables the vane to be folded in half so that it adopts a generally V-shape. As a result of the inherent resilience of the plastics material from which the vane is formed the vane naturally attempts to return to the flattened-out condition when it has been folded about the centre line 9. Whilst the vane is held in the folded up condition it is inserted into a duct with the apex of the V-shape disposed uppermost. When the vane is being used in a duct such as the duct 2 of an extractor fan installation it is located approximately centrally along the length of the duct. When it is in approximately the correct position the vane is released and as it attempts to return to the flattened out condition the free edges of the arms of the V-shape are urged against the interior of the duct whilst the apex of the V-shape is similarly pushed upwardly against the interior of the duct.

Thus the vane is automatically held in place as a result of its own resilience. The dimensions of the vane are, of course, selected so that the vane will fit appropriately into the size of ducting for which it is intended. Thus a range of sizes of vane will be provided. When it is in position within the circular ducting the apex of the vane defines an included angle of approximately 300, although the precise angle is not critical. The important point is that when the vane has been folded and inserted into the duct it presents planar surfaces extending axially of the ducting with these planar surfaces extending over a major part of the depth of the ducting.

It will be appreciated that when the vane is located within the ducting the planar surfaces presented by the vane each face in a direction transverse to the longitudinal axis of the duct and the vane therefore serves to prevent movement of air in this direction. Thus the vane effectively reduces or prevents rotary movement or swirl and serves to direct air axially along the duct.

Wind tunnel tests have shown that air flow achieved by a typical extractor fan installation, such as that shown in Figure 1 of the drawings, can be increased significantly when a guide vane in accordance with this invention is located within the ducting in the manner as shown. In wind tunnel tests conducted in accordance with BS 848:Part 1:1980 (fans for general purposes; Part 1 method of testing performance) the fan assembly shown in Figure 1 of the drawings gave an air flow, in free air, of 185m3 per hour. When the guide vane 5 was removed from the duct the air flow achieved was reduced to 100m3 per hour.

Clearly this represents a significant improvement in the efficiency of such an installation and would enable the fan to be run at a slower speed whilst still providing the same flow rate through the installation. The fan is, of course, quieter when running at a lower speed. Alternatively a smaller motor could be used in the fan.

The fact that the guide vane is formed as a component in its own right enables it to be retro-fitted in existing installations. In an extractor fan installation such as that shown in Figure 1 of the drawings it is merely necessary to remove the external baffle or the internal fan, both of which are nowadays designed to be readily removable for cleaning purposes, whereupon the vane can simply be inserted into the duct. The external baffle or the internal fan is then simply replaced in the usual way.

It will be appreciated that fitting the vane into the duct is a very simple operation which does not require the use of any tools and which can be undertaken by unskilled persons.

It is to be appreciated that although one particular design of vane has been shown in the drawings and described above the specific design may be varied.

Whilst reference has been made to providing one vane in a central position within a duct, it is to be appreciated that it may prove desirable to provide a number of vanes at positions spaced axially along the length of a duct or even to provide a vane having much longer sides 7 so that when folded and introduced into a duct, the vane extends over a significant part of the length of the duct.

Alternatively a number of smaller vanes could be inserted in the duct so as to be disposed in juxtaposition, thereby effectively forming a continuous vane running along the length of the duct.

It would, of course, be possible for the fold line to be located such that the vane presents two unequal sized portions when folded. Whilst the vane has been described as having one fold line it could define a plurality of parallel fold lines on its upper and lower surfaces so that it may be folded concertina-fashion to present more than two portions.

Claims (13)

1. A guide vane in the form of an insert in a duct, the guide vane comprising an element defining at least two substantially planar regions, the element being supported within the interior of the duct by way of edges of the vane engaging the interior of the duct, the vane being oriented so that at least one of the substantially planar regions extends axially of the duct and faces in a direction transverse to the longitudinal axis of the duct so as to restrict flow across the duct and to direct flow axially along the duct.

2. A guide vane according to Claim 1 wherein the vane is generally V-shaped in cross-section, the arms of the V-shaped vane being resiliently biased into engagement with the interior of the duct.

3. A guide vane according to Claim 1 or Claim 2 wherein the vane is integrally formed to have a generally V-shaped cross-section, the arms of the V-shaped vane being urged towards each other upon insertion of the vane in the duct, the resilience of the material from which the vane is formed causing the arms to be biased away from each other into engagement with the interior of the duct.

4. A guide vane according to Claim 1 or Claim 2 wherein the vane is integrally formed as a substantially planar component, the vane defining a fold line about which the vane may be folded so as to be generally V-shaped in cross-section, the inherent resilience of the material from which the vane is formed causing the vane naturally to tend to the planar or flattened-out condition when it has been folded about the fold line, the resilience of the material causing edges of the vane to be resiliently biased into engagement with the interior of the duct.

5. A blank for forming a guide vane according to Claim 4, the blank comprising an integrally formed substantially planar component defining a fold line about which the blank may be folded so as to be generally V-shaped in cross-section, the inherent resilience of the material from which the blank is formed causing the blank naturally to tend to the planar or flattened-out condition when it has been folded about the fold line, the resilience of the material causing edges of the blank to be resiliently biased into engagement with the interior of a duct when a vane formed from the blank is located in the duct.

6. A blank according to Claim 5 wherein the fold line is defined by a channel extending across a surface of the blank between opposed edges thereof.

7. A blank according to Claim 6 wherein the edges of the blank are formed with indents or recesses at the points where the fold line meets the edges.

8. A blank according to Claims 5, 6 and 7 wherein the fold line is approximately centrally located with respect to the blank, enabling the blank to be folded in half so as to define two substantially equal sized portions

9. A blank according to any one of Claims 5 to 8 wherein the blank is substantially rectangular.

10. A blank according to any one of Claims 5 to 9 wherein the blank is integrally moulded from a polypropylene plastics material.

11. A guide vane substantially as herein described with reference to and as shown in the accompanying drawings.

12. A blank for forming a guide vane substantially as herein described with reference to and as shown in the accompanying drawings.

13. Any novel feature or combination of features disclosed herein.