GB2291134A

GB2291134A - Fan assembly

Info

Publication number: GB2291134A
Application number: GB9413339A
Authority: GB
Inventors: Colin Biggs
Original assignee: Nuaire Ltd
Current assignee: Nuaire Ltd
Priority date: 1994-07-02
Filing date: 1994-07-02
Publication date: 1996-01-17
Anticipated expiration: 2014-07-02
Also published as: GB2291134B; GB9413339D0

Abstract

A fan assembly comprises a plurality of impeller blades (20) mounted to a rotatable hub (10). The hub (10) has a part-spherical surface (12) which is a solid of rotation about the rotational axis A - A of the hub. Each impeller blade (20) has a concave inner end which seats on the part-spherical surface (12) of the hub (10), such that the blades project radially therefrom. The tips of the blades (20) seat against a part-spherical surface (30) of a duct. The position of each blade (20) can be adjusted to alter the angle of its axis B - B relative to the axis A - A and/or by rotation about its axis B - B to vary the operating characteristics of the fan assembly. <IMAGE>

Description

Fan Assembly This invention relates to a fan assembly, particularly for ventilation systems.

Two basic types of fan assembly are known, the first type being an axial flow arrangement and having the characteristic of displacing large volumes of air or other fluid, and the second type being centrifugal flow arrangement and having the characteristic of generating high pressures.

Mixed arrangements are also known, in which the impeller blades are in an intermediate orientation, providing a characteristic of high volume displacement than the corresponding centrifugal fan and generating higher pressures than the corresponding axial fan.

We have now devised a fan assembly in which the impeller blades can be adjusted, in order to alter the operating characteristics of the assembly.

In accordance with this invention, there is provided a fan assembly having a plurality of impeller blades mounted to a hub which is rotatable around an axis of the fan assembly, the hub having a peripheral surface which lies on an imaginary sphere the centre of which lies on the fan axis, each impeller blade having its own axis lying substantially radially of said sphere and its inner end surface complementary to and seated on said surface of the hub, and each impeller blade being either adjustable in position to alter the angle of its own axis relative to the fan axis and/or adjustable by rotation around its own axis.

Either or both of these adjustments of each blade may be made whilst maintaining the inner end of the blade seated on the surface of the hub, because of the part-spherical shape of the hub surface.

Preferably each impeller blade has a pin projecting from its inner end and along its axis, the blade being mounted to the hub by insertion of this pin into a socket or hole in the hub surface, enabliny adjustment of the impeller blade by rotation around its axis. Preferably, for each impeller blade, the hub is formed with a series of such sockets or apertures, for mounting the blade to the hub in different positions, for different angles of its axis to the fan axis.

Preferably the through-duct of the fan assembly includes a peripheral portion which lies on an imaginary sphere concentric with the part-spherical surface of the hub, the tips of the impeller blades co-operating with this surface of the through-duct. Accordingly, the gaps between the tips of the impeller blades and the corresponding surface of the throughduct are not altered as the impeller blades are adjusted.

An embodiment of this invention will now be described by way of example only and with reference to the accompanying drawing, the single figure of which is a schematic sectional view through a fan assembly in accordance with this invention.

Referring to the drawing, a fan assembly in accordance with this invention comprises an impeller hub 10 mounted for rotation about a longitudinal axis A-A of a duct through the assembly. The hub 10 is driven by an electric motor (not shown) which is mounted in a fixed position on the axis A-A.

The hub 10 has a peripheral outer surface 12 which lies on an imaginary sphere, having its centre at a point 0 on the axis A-A. The assembly further comprises a plurality of impeller blades e.g. 20, the inner end of each blade being formed with a surface complementary to the surface 12 of the hub. Each impeller blade 20 has its inner end seated on the surface 12 and is mounted to the hub 10 with the longitudinal axis B-B of the blade coincident with a radius of the imaginary sphere (i.e. the axis B-B intersects the point 0). Each blade 20 is mounted to the hub 10 by means of a pin projecting from the inner end of the blade, along its axis B-B, and into a socket formed in the hub surface 12.Typically, the hub periphery comprises a piece of sheet metal formed to appropriate shape to provide the spherical surface 12, and a threaded pin of the blade passes through a hole in this sheet metal member and is held in place by a nut threaded onto the bolt from the inner side of the surface 12.

It will be appreciated that each impeller blade 20 may be adjusted by turning it about its axis B-B relative to the hub 10, and then re-fixiny it in its new position. Further, preferably the mounting position of each blade 20 on the hub 10 can be altered, to alter the angle 0 between its axis B-B and the fan axis A-A: for example, a number of different holes can be provided in the hub at different angular positions, for receiving the fixing pin of the blade. It will be appreciated that either or both of these adjustments can be made to each impeller blade, because of the co-operation between the end surface of the blade and the spherical surface 12 of the hub 10.

The through-duct of the fan assembly includes a peripheral portion 30 with which the tips of the impeller blades co-operate. This portion 30 lies on the surface of an imaginary sphere also centred on point 0, and the outer end of each blade is of complementary shape. This enables either of the above-described adjustments of each blade 20 to be made, whilst maintaining only a small gap between the outer end of each blade and the surface 30 of the through duct.

It will be appreciated that, in the fan assembly which has been described, the fan impeller blades may be adjusted in order to alter the operating characteristics of the fan assembly to suit different application of use.

Claims

1) A fan assembly having a plurality of impeller blades mounted to a hub which is rotatable around an axis of the fan assembly, the hub having a peripheral surface which lies on an imaginary sphere the centre of which lies on the fan axis, each impeller blade having its own axis lying substantially radially of the sphere and its inner end surface complementary to and seated on said surface of the hub, and each impeller blade being either adjustable in position to alter the angle of its own axis relative to the fan axis and/or adjustable by rotation around its own axis.

2) A fan assembly as claimed in claim 1, in which each impeller blade comprises a pin projecting from its inner end and along its axis, the blade being mounted to the hub by insertion of the pin into a socket or aperture in the hub surface.

3) A fan assembly as claimed in claim 2, comprising a series of sockets or apertures for selectively receiving each impeller blade.

4) A fan assembly as claimed in any preceding claim, comprising a through-duct having a peripheral portion which lies on an imaginary sphere concentric with the part-spherical surface of the hub, the tips of the impeller blades cooperating with the surface of peripheral portion of the through-duct.

5) A fan assembly substantially as herein described with reference to the accompanying drawing.