This invention relates to varied rotary apparatus, that is, apparatus which may be used either tc create a rotary vortex in a ducted fluid stream by passage of the stream over an array of stationary vanes, to accelerate a fluid by rotation of ar. array of rotary vanes in the fluid, preferably in a duct, cylinder or other chamber to induce axial movement of the fluid therethrough or to compress the fluid therein downstream of the vanes, or to induce rotational movement in an array of vanes by passage of a fluid under pressure through the array.

Vanes for use in aach type of rotary apparatus are well known and generally comprise pitched blades which extend radially from a central core or hub which, in the case of rotary vanes, is rotatably mounted, generally axially in a chamber through which the fluid, which may be liquid or gaseous, passes. In such known arrangements, the leading edge of the blades is generally linear and is disposed normal to the d rection of fluid flow. In certain applications where the fluid contains suspended solids, especially of a filamentary, fibrous or reticular nature, the solids tend to become trapped on, over or around the blades and this may cause a loss in efficiency or smoothness of operation, or total failure of the machine pending removal of the offending material.

It is an object cf the present invention to provide an arrangement of vanes for use in rotary apparatus of the type described and which are less prone to becoming host to solids entrained in the fluid stream. It is another object to reduce turbulence in fluid passing over the vanes.

According to an aspect of the present invention, vaned rotary apparatus (as hereinbefore defined) comprises an external casing through which, in use, fluid is constrained to pass, mounted to which are a plurality of inwardly-extending vanes, in which the vanes comprise independent pitched elements which are supported only where they are mounted to the casing.

Although there may be separation between adjacent vanes when viewed axially, there is preferably partial overlap between adjacent vanes, such that a leading edge portion of one vane will obscure the trailing edge portion of the next vane with an axial gap therebetween to allow substantially free or unimpeded passage between the vanes of solids entrained in the fluid stream. The leading edges of the vanes are preferably curved to facilitate the movement of especially filamentary or woven materials caught around the leading edges towards the central region of the array and a central gap may be provided between the vanes to facilitate removal of such material from the vanes. 1?he leading edges are also preferably angled in a downstream direction from the wall of the casing towards the centre thereof, again to facilitate removal of materials caught around the leading edge of the vanes.

Conveniently, the vanes comprise generally elliptical plane elements, the maximum width (normal to the major axis) being the radius of the casing or slightly less thereof, the roots of which are set in the wall of the casing at an angle to provide the pitch and also to provide the downstream-sloping direction of the leading edges.

A minimum of two vanes are required in apparatus

according to the invention; the maximum number is _d ependent on opercitional or functional requirements but in most applications four or five vanes would be sufficient, although up to eight vanes may exceptionally be used.

In order further to improve the ability of the apparatus to resist becoming host to materials entrained in the fluid stream, the vanes may be axially spaced apart such that corresponding parts of the vanes are not in the same lateral plane. In such an arrangement, the leading edge of the most upstream vane is thus axially spaced apart from the leading edge of the next downstream vane and, for optimum entrapment-resistance, the vanes may be spaced such that the leading edge of the next downstream vane is axially spaced from the trailing edge of the vane immediately upstream. To maintain the vortex-generation effect of axially-spaced vanes, the pitch angle of the vanes may be reduced; that is, the vanes may have a shallower angle to a lateral plane than is the case with apparatus where the vanes are co-planar.

Apparatus according to the invention may find application in a stationary embodiment in for example suction cleaners which operate by creation of a vortex in dirt- laden air whereby the dirt particulates are subject to centrifugal forces and are precipitated into a collection chamber as they lose energy. Alternatively, in a rotating embodiment the casing may be rotationally mounted and driven to create a moving airflow through the casing. In another rotational embodiment as in the turbine, the casing may be rotationally driven by passing a moving airflow through the casing and over the vanes.

Embodiments of the invention will now be described by way

of example with reference to the accompanying drawings, of which:

Figure 1 is an axial view showing apparatus having three vanes, suitable for use in a suction or vacuum cleaner;

Figure 2 is a perspective view of the apparatus of Figure 1;

Figure 3 is an εtxial view of apparatus having three axially spaced vanes; and

Figure 4 is a side view of the apparatus of Figure 3.

Referring to Figure 1, the apparatus includes an annular housing 11 suitable for incorporation in a vacuum cleaner or other machine which requires the generation of a vortical airflow. Three vanes 12 extend from the wall of the housing into the lumen of the duct thereby defined. Each vane is formed from a planar sheet material and has a generally elliptical or eyelid shape. The vanes are mounted at an angle so that the leading edges 13 partially overlap the trailing edges 14. A small triangular aperture 15 is defined at the centre; none of the vanes makes physical contact with the others.

As more clearly shown in Figure 2, an axial aperture 16 is defined between the leading edge 13 of any one vane and the trailing edge 14 of the adjacent vane. The lines 17 show the angled mounting position of the roots of the vanes in the wall of the housing.

In use in a dirt-laden air stream, dirt particles or fragments either impinge on the sloping upper surface of the vanes 12 and cire deflected through one of the gaps 16

or, typically in ;he case of filamentary material, are urged by the airflow on either side of the leading edge 13 of the vanes and are blown therealong until they pass through the gap 1Ξ, after which they become separated from the trailing edge 14 of the vane.

As shown in Figures 3 and 4, an arrangement of axially spaced apart vanes is viewed respectively axially and from the side. The most upstream vane is labelled 31 with the leading edge root labelled 32; the next downstream is labelled 33 with the leading edge rot thereof labelled 34 and the most downstream vane is labelled 35 with the leading edge root thereof labelled 36. As seen from Figure 3 there is a slight overlapping of the vanes in the central axial region 37 but, as seen from Figure 4, the vanes are axially spaced apart, the spacing between the respective leading edges 34 and 36 and the trailing edges of the vane next upstream being equivalent to the longitudinal pitch of the vanes.

A pitch angle of less than 45° is preferred in most applications; a pitch angle of 30° may for example be used with apparatus having three vanes or 20° with apparatus having four vanes, or with apparatus having axially spaced-apart vanes as shown by way of example in Figures 3 and 4.