Arrangement for radial fans

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION On the drawing, 1 generally designates a fan housing which can be shaped out of plate or cast material into a spiral, viewed in a plane perpendicular to the axial line 2 of the fan.
The spiral is defined internally by a spirally-shaped side wall 3, a base wall 4 and an end wall 5 located opposite the latter.
These internal wall surfaces of the fan housing have a geometry which is a characteristic of the invention, while the external shape of the fan housing is not important and has therefore been shown schematically without the necessary joints and other details.
On the base wall 4 there is a guide edge 6 which is concentric with the axial line and is suitable for fixing in an electric motor 7 which can be of a conventional kind, expediently with a rotary speed of 2,800 r.
p.
m.
at 50 Hz; only the drive shaft 8 and the fixing flange of this have been shown (partially in section).
The fan wheel 9 is attached to the drive shaft so that its end plate 10 located nearest to the motor is on a level with the base wall 4.
The fan wheel is of the wheel-drum type and, in a known way, has a plurality of blades 11 arranged in a ring; these are curved forwards in the direction of rotation, shown with the arrow 12, and extend axially from the end plate 10 to the outer end 13 of the wheel where the blades are joined to an annular plate 14.
This is concentric with the axial line and defines the circular in-flow opening 15 in the wheel.
The fan intake, designated 16, is disposed in the housing wall 5.
The air which is to be conveyed by the fan is sucked in from here and reaches the inside 17 of the ring of blades via an open part of the wheel opening 15, after which the air is flung out by the blades at a high peripheral speed, into the fan housing duct 18, according to the operating principle of radial fans, and whilst flowing in the latter undergoes an increase in pressure before the air leaves through the outlet pipe 19 connected to the duct