GB2503270A

GB2503270A - Centrifugal ventilation fan

Info

Publication number: GB2503270A
Application number: GB201211017A
Authority: GB
Inventors: Alan Macklin
Original assignee: Elta Fans Ltd
Current assignee: Elta Fans Ltd
Priority date: 2012-06-21
Filing date: 2012-06-21
Publication date: 2013-12-25
Anticipated expiration: 2032-06-21
Also published as: GB2503270B; GB201211017D0

Abstract

A ventilation fan comprising a cylindrical tubular housing 126 with an axially orientated inlet and outlet, a centrifugal impeller is within the housing with its axis of rotation parallel to the axis housing. A motor is provided for driving the impeller 114 and a baffle 122 directs air flow from the inlet towards a central region of the centrifugal impeller. Preferably the fan unit includes a guard formed of looped cross members and circumferential bars on which the motor is adjustably mounted. Preferably the baffle includes an angled or curved surface.

Description

Ventilation Fan

Field of invention

The present invention relates to a ventilation fan, in particular a ventilation fan for ventilating an indoor environment such as a building.

Background

The quality of air inside a building can often be improved using a ventilation system.

Ventilation systems are used, for example, to control humidity, temperature andJor odours.

Ventilation systems conventionally use an axial flow fan to either supply air to an indoor environment and/or extract air from an indoor environment. An example axial flow ventilation fan of the prior art is shown at 1 in Figures 13 and 14. The axial flow ventilation fan i has blades 2 connected circumferentially around a shaft 3. A motor 4 drives the shaft 3 to rotate the blades 2 and cause air to flow axially through the fan substantially parallcl to the shaft. Thc blades 2, shaft 3 and motor 4 arc positioned within a housing 5, which in this example can be connected to ducting via end flanges 7, 8. The ventilation fan is controlled using contr& box 6 mounted on the outside of the housing 5.

In recent years there has been a demand for more energy efficient ventilation systems, some of this demand is driven by legislation. For example, the Directive 2009/125/EC for the Eco design requirements of Energy Related Products (ErP) which (when in force) will require ventilation fans to meet certain efficiency standards to be marketable in the European Union.

Summary of invention

The present invention seeks to provide a more energy efficient ventilation fan than the

ventilation fans of the prior art.

Accordingly, in an aspect of the invention there is provided a ventilation fan comprising; a cylindrical tubular housing having an inlet for receiving a substantially axial airflow and an outlet through which a substantially axial airflow can exit; the inlet and the outlet being axially aligned; a centrifugal impeller positioned within the cylindrical tubular housing such that a longitudinal axis of the cylindrical tubular housing is substantially parallel to an axis of rotation of the impeller a motor for driving the impeller; and abafflefordirectingairflowfromtheinlettowardsacentralregionofthe centrifugal impeller.

The present inventor has suiprising found that a centrifugal impeller achieves better energy efficiency when used as a ventilation fan with axial direction of airflow than previously expected. It is generally believed in the art that changing the flow direction through the ventilation fan would decrease the fan efficiency. The present inventor has gone against this prejudice to arrive at the present invention.

The provision of a cylindrical tubular casing rather than a square box casing commonly used in centrifugal fans of the prior art, further increases the energy efficiency of the ventilation fan.

The impeller and cylindrical tubular housing may be configured to divert an airflow from the inlet in a direction transverse to the axis of rotation of the impeller and then to a direction substantially parallel to the axis of rotation of the impeller.

The inlet may be positioned at one end of the cylindrical tubular housing and the outlet may be positioned at the opposite end of the cylindrical tubular housing.

The ventilation fan may be for ventilating an indoor environment. For example, the ventilation fan may form part ofabuilding's ventilation system.

The ventilation fan may comprise a guaM positioned near the outlet of the housing.

The motor may be positioned within the cylindncal tubular housing near the outlet.

Positioning the motor within the housing further improves the energy efficiency of the ventilation fan. In some embodiments, the efficiency may be further increased by mounting the motor coaxially with the impeller.

The motor may be mounted on the guard. For example, the motor may be mounted on a side of the guard that is innermost the housing. Mounting the motor on the guard improves the ease of assembly and reduces the number of components required to construct the ventilation fan, which leads to further improved energy efficiency.

The motor is adjustably mounted on the guard. An adjustable mounting provides flexibility and permits a standard manufactunng process to be used to produce a guard that maybe used with a variety of motors and/or impellers.

The motor may have an axial length approximately one sixth to one half the length of the impeller. Preferably the axial length of the motor is less than a third of the axial length of the impefler or less than one quarter of the axial length of the impeller.

Providing such a motor improves efficiency, particularly when mounted to the guard coaxially with the impeller, because disruption to the airflow through the ventilation fan is reduced. Further, providing such a motor means that the length of the ventilation fan can be significantly reduced. This reduction in length provides a more compact and versatile ventilation fan.

The motor may have a diameter such that the amount the motor impinges on air flow through the ventilation fan is reduced. For example, the motor may have a diameter approximately one quarter to one half the diameter of the housing. Preferably, the motor has a diameter less than one third of the diameter of the housing.

The motor may be an electrically commutated brush motor. Such a motor further improves the energy efficiency of the ventilation fan.

The impeller may be mounted to the guard via a stationary plate. In such embodiments, the mounting to the guard may be adjustable. In alternative embodiments the impeller may comprise a nng at an inlet end of the impeller which may be fixed to the housing.

The guard may be configured to permit mounting of one or more supplementary components of the ventilation fan.

The guard may comprise circumferential supports and cross members positioned transverse to the circumferential supports. For example, the guard may comprise eight cross members and three circumferential supports. One or more of the cross members, in some embodiments four of the cross members, may be configured to permit the motor and/or the impeller to be mounted to the guard. For example. one or more of the cross members may be formed by a looped bar. In such embodiments, the looped bar may extend past an outer circumferential support and be bent for receiving a fastener for attachment of the guard to the housing.

The baffle may comprise an angled or curved suiface. The baffle may be spaced from the inlet of the housing, or the baffle may be flush with the ifflet of the housing.

The ventilation fan may comprise a cowl near the outlet of the housing. The ventilation fan may comprise a wall or a roof mount.

The housing may have a flange at the inlet and the outlet for attachment of the ventilation fan to a duct. The provision of a cylindrical tubular housing and a circular flange at each end thereof alleviates the need for conversion from square ducting to circular ducting (as required by ventilation fans of the prior art) when the ventilation fan is used for induct supply or extract ventilation.

According to a further aspect of the present invention there is provided a use of the ventilation fan according to the previous aspect for in-duct supply ventilation, in-duct extract ventilation, fitting to a roof, ceiling or wall for ducted supply ventilation, or fitting to a roof, ceiling or wall for ducted extract ventilation.

Description of the drawings

Embodiments of the present invention will now be described with reference to the following drawings in which: Figure 1 shows a perspective view from an inlet of an embodiment of a ventilation fan used for in-duct supply or extraction ventilation; Figure 2 shows a perspective view from an outlet of the ventilation fan shown in Figure 1; Figure 3 shows an end view at the outlet of the ventilation fan shown in Figure 1; Figure 4 shows a side view of the ventilation fan shown in Figure 1; Figure 5 shows a view at the inlet of the ventilation fan shown in Figure 1; and Figure 6 shows a side view of the ventilation fan shown in Figure 1 including hidden detail; Figure 7 shows a perspective view of an embodiment of a ventilation fan used for extract ventilation; Figure 8 shows a side view of the ventilation fan shown in Figure 7; Figure 9 shows a section view through A-A of the ventflation fan shown in Figure 8; Figure 10 shows a perspective view of an embodiment of a ventilation fan used for supply ventilation; Figure 11 shows a side view of the ventilation fan shown in Figure 10; Figure 12 shows a section view through B-B of the ventilation fan shown in Figure 211 11'

J

Figure 13 shows an end view of an axial flow ventilation fan of the prior art; and Figure 14 shows a side view, showing hidden detail, of the axial flow ventilation fan shown in Figure 13.

Detailed description

Referring to Figures 1 to 6 a ventilation fan is indicated generally at 110. The intended use of the ventilation fan 110 is for an in-duct supply or extraction, particularly in buildings, the arrangement of which is well understood in the art so will not be described further here.

The ventilation fan 110 has a housing 112 within which an impeller 114 is positioned.

The impeller and housing are coaxially aligned about an axis 116 that is coincident with a longitudinal axis of the housing and an axis of rotation of the impeller.

In this embodiment the housing 112 has a cylindrical tubular section 126 extending the ength of the housing. At one axial end of the tubular section 126 is an inlet 118 through which an air flow can enter the housing and at the other axial end of the tubular section 126 is an outlet 120 through which an air flow can exit the housing. In this embodiment the diameter of the housing is in the range of approximately 315 to 630 mm to fit standard ducting, but in alternative embodiments the diameter can be scaled up or down as required. Typically, the housing manufactured from mild steel sheet.

A baffle 122 is spaced from the inlet and positioned to direct air flow towards the centre of the impeller 114. Tn this embodiment the baffle comprises a flat planar surface substantially perpendicular to the axis of rotation of the impellor positioned at a radially outer area, and at a radially inner area the baffle comprises a surface that curves from the planar surface towards the impellor. However, in alternative embodiments the baffle may comprise any arrangement of curved and/or angled surface(s) that direct air flow from the inlet of the housing towards the centre of the impellor. In further alternative embodiments the baffle 122 may be positioned at the inlet 118, such that there is no spacing between the inlet and the baffle. For example, the baffle 122 may be positioned to be flush with the inlet 118.

A flange 128, 130 is positioned at each axial end of the housing 112. Holes 132 (only one labelled for clarity) are positioned circumferentially around each flange for receiving a fastener to fasten the ventilation fan to a duct (not shown but having a corresponding flange). The fastener may be, for example, a bolt or a rivet.

The impeller 114 is a centrifugal impeller, for example a backward curved motorized impeller with integral AC or DC external rotor motor. A suitable impeller is a RH45V-Zl K V pro backward curved motorized impeller supplied by Ziehl-Abegg AG, Heinz-Ziehl-StraBe, 74653 KUnzelsau. Briefly described, the impeller 114 has a central shaft 134 connected to a flat circular end plate 136. The central shaft 134 has a hemispherical shape at an end innermost the impeller. Blades 138 are positioned circumferentially around the edge of the fiat circular end plate and project axially.

The blades 138 are angled radially inwards. In this embodiment the blades form an arc in a direction from the edge of the flat circular end plate 136 towards the centre of the flat circular end plate.

A guard 140 is positioned towards the outlet 120 of the housing 112. at an opposite end of the impeller to the inlet 118 of the housing 112. The guard 140 has three circumferential supports 142, 144, 146 of different diameters so as to be radially spaced. Eight cross members 148, 150 extend from a centre of the guard to an outer circumference of the guard. In this embodiment each cross member is positioned perpendicularly to a tangent of each circumferential support.

Four of the cross members 148 are bars and the other four cross members 150 are looped bars, such that the bar extends from near the centre of the guard to a position outside the outer circumferential support and loops back towards the centre of the guard. The looped end of the circumferential support is bent approximately perpendicularly to the rest of the cross member and is connected to the housing using a fastener 141. In alternative embodiments, the guard may comprise a different number of circurnferentia supports and/or cross members, or may have a different configuration, for example the guard may comprise a square or rectangular grid made from multiple cross bars.

Further fasteners 145 extend through each looped cross member and into a motor 152 that drives the impeller 114, so as to mount the motor 152 to the guard 140, on a side of the guard 140 nearest the impeller 114. The looped cross members 150 enable the motor to be adjustably fastened to the guard. The looped cross members also enable any supplementary elements to be mounted to the guard as required. A plate having one or more radially extending arms, for example four arms, may be positioned between the motor and the guard and the motor may be attached to the guard via the plate. The end of each arm of the plate may be fastened to the guard to improve the stability of the mounting between the motor and the guard.

In this embodiment, the impeller is mounted directly to the motor. However, in alternative embodiment, the impeller may additionally be provided with a stationary nng that can be fastened to the looped bars of the guard. Further alternatively, the impeller may comprise a stationary ring near the inlet end of the centrifugal fan which can attach to the housing, for example to the baffle.

The motor 152 in this embodiment is an electrically commutated brush motor, but any motor having a suitable configuration may be used. hi this embodiment, the motor 152 has a cylindrical casing and has an axial length 156 that is close to one sixth of the axial length of the impeller 114. The diameter 154 of the motor is approximately one quarter to one third of the diameter of the impeller 114.

The ventilation fan 110 is controlled using a control box 158 positioned on the outside of the cylindncal tube section 126 of the housing 112. The control box 158 is of the type familiar to a person skilled in the art, so is not explained further.

In use, in both supply and extraction ventilation, the motor 152 and control box 158 are operated to rotate the impeller 114. Air enters the ventilation fan through the inlet 118 of the housing 112. The baffle 122 directs the airflow towards the centre of the impeller 114. The end plate 136 of the impeller prevents the air flow from direct axial flow through the ventilation fan 110. The blades 138 of the impeller 114 direct the air flow radially towards the outer circumference of the impeller. The cylindrical tube portion 126 of the housing 112 then directs the air flow to again flow axially and exit the housing 112 through the outlet 120.

The inventor of the present invention has surprisingly found that by using a centrifugal fan, which deflects and then re-deflects the airflow through the ventilation fan has improved efficiency over the ventilation fans of the prior art.

Centrifugal impellers of the type described above when used in fans of the prior art are housed within a square casing. The motor is mounted outside the housing and has a diameter much greater than the diameter of the motor of the present invention. The axial length of the motor of the prior art is generally at least twice the axial length of the impeller.

The present inventor has found that replacing the square housing with a cylindrical tubular housing can significantly improve the efficiency of the fan. Further, reducing the length of the motor permits the ventilation fan to be more compact than the ventilation fans of the prior art, which means the fan is more versatile. I.e. referring to Figure 6, the overall axial length C and the overall radius D of the ventilation fan can be reduced compared to the ventilation fans of the prior art. The reduced length of the motor means that the motor can be mounted to the guard and within the housing. this mounting arrangement further improves the efficiency of the ventilation fan. The circular cross section of the ventilation fan means that there is no need to convert from square ducting to circular ducting, as is required with centrifugal ventilation fans of the prior art. Accordingly, the space requirements for installing the ventilation fan are further reduced.

Further, reducing the diameter of the motor reduces the obstructions in the flow path of the air flow, which further improves the efficiency of the ventilation fan. The efficiency savings achieved with this arrangement can produce a ventilation fan that meets at least stage I of the ErP regulation.

The efficiency of the ventilation fan is further improved by the use of an electrically commutated brush motor. Using such a motor may improve the efficiency of the ventilation fan to a level that meets stage 2 of the ErP regulation.

Referring now to Figures 7 to 9 a ventilation fan for mounting to a roof/ceiling or wall for extraction ventilation is indicated generally at 210, and refelTing to Figures 10 to 12 a ventilation fan for mounting to a roof/ceiling or wall for supply ventilation is indicated generally at 310.

Many of the features of the ventilation fan 2i0, 310 shown in Figures 7 to 12 are similar to those described previously. Similar features are not described again here, but are given similar reference numerals as in Figures 1 to 6, but with a prefix "2" or "3" instead of "I".

In these embodiments, the ventilation fan 210, 310 has a mount 260 for mounting the ventilation fan to a wall or roof. A cowl 262, 362 is provided for positioning on the opposite side of a wall or roof to the impeller 214, 314 and housing 212, 312. A connector 264, 364 connects between the cowl and the housing and mount 260.

Although the invention has been described above with reference to one or more preferred embodiments, it will be appreciated that various changes or modifications may be made without departing from the scope of the invention as defined in the appended claims.

Claims

Claims I. A ventilation fan comprising; a cylindrical tubular housing having an inlet for receiving a substantially axial airflow and an outlet through which a substantially axial airflow can exit, the inlet and the outlet being axially aligned; a centrifugal impeller positioned within the cylindrical tubular housing such that a longitudinal axis of the cylindrical tubular housing is substantially parallel to an axis of rotation of the impeller; a motor for dnving the impeller; and a baffle for directing air flow from the inlet towards a central region of the centrifugal impeller.
2. The ventilation fan according to claim 1 comprising a guard positioned near the outlet of the housing.
3. The ventilation fan according to claim I or 2, wherein the motor is positioned within the cylindrical tubular housing near the outlet and the motor is mounted coaxially with the impeller.
4. The ventilation fan according to claim 3 as dependent on claim 2, wherein the motor is mounted on the guard.
5. The ventilation fan according to claim 4, wherein the motor is adjustably mounted on the guard.
6. The ventflation fan according to claim 4, wherein the motor is mounted on a side of the guard that is innermost the housing.
7. The ventilation fan according to any one of the previous claims, wherein the motor has an axial length approximately one sixth to one half the length of the impeller, preferably the axial length of the motor is less than a thith or less than a quarter of the axial length of the impeller.
8. The ventilation fan according to any one of the previous claims, wherein the motor has a diameter approximately one quarter to one half, preferably less than one third, of the diameter of the housing.
9. The ventilation fan according to any one of the previous claims, wherein the motor is an electrically commutated brush motor.
10. The ventilation fan according to any one of daims 2 to 9, wherein the guard comprises circumferential supports and cross members positioned transverse to the circumferential supports.
11. The ventilation fan according to claim 10, wherein one or more of the cross members are configured for receiving a fastener for attaching the guard to the housing and/or for receiving a fastener for mounting motor to the guard.
12. The ventilation fan according to claim 11. wherein the one or more of the cross members is a looped bar.
13. The ventilation fan according to any one of the previous claims, wherein the baffle comprises an angled or curved surface.
14. The ventilation fan according to any one of the previous claims, comprising a cowl near the outlet of the housing.
15. The ventilation fan according to any one of the previous claims comprising a wall or a roof mount.
16. The ventilation fan according to any one claims I to 16, wherein the housing has a flange at the inlet and the outlet for attachment of the ventilation fan to a duct.
17. The use of the ventilation fan according to any one of the previous claims for in-duct supply ventilation, in-duct extract ventilation, fitting to a roof, ceiling or wall cowl for ducted supply ventilation, or fitting to a roof, ceiling or wall for ducted extract ventilation.
18. A ventilation fan substantially as hereinbefore described with reference to andlor as shown in the accompanying drawings.Amendments to the claims have been filed as follows: Claims I. A ventilation fan comprising; a cylindrical tubular housing having an inlet for receiving a substantially axial airflow and an outlet through which a substantially axial airflow can exit, the inlet and the outlet being axially aligned; a centrifugal impeller positioned within the cylindrical tubular housing such that a longitudinal axis of the cylindrical tubular housing is substantially parallel to an axis of rotation of the impeller; a motor for dnving the impeller; a baffle for directing air flow from the inlet towards a central region of the centrifugal impeller; and a guard positioned towards the outlet of the housing at an opposite end of the C') 15 impellor to the inlet of the housing; wherein the motor is positioned within the cylindrical tubular housing and is mounted coaxially with the impeller, and wherein the motor is mounted on the guard; and wherein the axial length of the motor is one sixth to one half of the axial ength of the impeller. r2. The ventilation fan according to claim I, wherein the motor is adjustably mounted on the guard.3. The ventilation fan according to claim 1 or 2, wherein the motor is mounted on a side of the guard that is innermost the housing.4. The ventilation fan according to any one of the previous claims, wherein the motor has an axial length less than a third or tess than a quarter of the axial length of the impeller.5. The ventilation fan according to any one of the previous claims, wherein the motor has a diameter approximately one quarter to one half, preferably less than one third, of the diameter of the housing.6. The ventilation fan according to any one of the previous claims, wherein the motor is an electrically commutated brush motor.7. The ventilation fan according to any one of claims 1 to 6, wherein the guard comprises circumferential supports and cross members positioned transverse to the circumferential supports.8. The ventilation fan according to claim 7, wherein one or more of the cross members are configured for receiving a fastener for attaching the guard to the housing andlor for receiving a fastener for mounting motor to the guard.9. The ventilation fan according to claim 8, wherein the one or more of the cross members is a looped bar.C1) 15 10. The ventilation fan according to any one of the previous claims, wherein the baffle o compnses an angled or curved surface.r II. The ventilation fan according to any one of the previous claims, comprising a cowl near the outlet of the housing.12. The ventilation fan according to any one of the previous claims comprising a wall or a roof mount.13. The ventilation fan according to any one claims I to i2, wherein the housing has a flange at the inlet and the outlet for attachment of the ventilation fan to a duct.14. The use of the ventilation fan according to any one of the previous claims for in-duct supply ventilation, in-duct extract ventilation, fitting to a roof, ceiling or wall cowl for ducted supply ventilation, or fitting to a roof, ceiling or wall for ducted extract ventilation.15. A ventilation fan substantially as hereinbefore described with reference to andlor as shown in the accompanying drawings. C') r