Fluid reaction surfaces (i.e. – impellers) – Specific working member mount – Adjustable
Patent
1995-03-27
1996-08-13
Look, Edward K.
Fluid reaction surfaces (i.e., impellers)
Specific working member mount
Adjustable
416208, 416214R, 416220A, F01D 530
Patent
active
055450113
DESCRIPTION:
BRIEF SUMMARY
FIELD OF INVENTION
The present invention relates to an angle adjustable suspension of vanes in a hub, comprising a seat in the hub and a mounting part on the vane.
PRIOR ART
There is a need for adjusting the angles of vanes on blade wheels in order to adjust the characteristics of the blade wheel to existing conditions and desires. There are solutions which allow adjustment of the angle of the vanes also during operation as well as automatic adjustment of the angle of the vane depending on current load.
U.S. Pat. No. 2,844,207 discloses an adjustable fan blade means, wherein the fan blades can be adjusted individually when the fan wheel rests. The fan blades are axially locked, for uptake of rotational load, by a lock washer which abuts a shoulder in the hub and the adjusted angular position is maintained with the aid of a locking screw which is forced against the blade stud, which extends through a peripheral hole in the hub. With this construction the torsional moment as well as the bending moment will be taken up only by the friction between the abutment surface of the locking screw and the periphery of the blade stud. This solution is not satisfactory for fastening of vanes being exposed to large loads and does not give sufficient safety margins for the uptake of the rotational load and the bending moment.
DESCRIPTION OF THE INVENTION
The main object of the present invention is to provide an adjustable vane suspension in a hub, which gives a safe hold of the vane in the hub and at the same time allows for a quick and exact individual angular adjustment of the vane.
This and other objects of the present invention are achieved by the vane suspension according to the present invention which is characterized in that the mounting part on the vane comprises a stud and a shoulder provided at the end of the stud with a partly spherical contact surface facing the blade of the vane, and in that the seat of the hub has a hub shoulder with a partly cylindrical contact surface radially facing the centre of the hub, which two surfaces are arranged to mutually cooperate by linear abutment, whereby the position of the line (21,21') is constant irrespective of the angular position of the vane in relation to the hub.
Through the cooperating, partly spherical and partly cylindrical contact surfaces, respectively, an effective and secure uptake of the load from the rotational load through shearing is achieved. The design of the respective contact surfaces of the hub shoulder and the vane stud results in a compression load distributed in linear contact, the geometrical position of which is constant at different angular adjustments of the vane. In practice, a compression load deformation takes place so that the contact takes place over a certain area, while at the same time the material is deformation annealed in this area, which is favourable from a resistance point of view. In order to satisfy casting demands the cylindrical contact surface of the hub shoulder can be given a certain inclination.
According to one embodiment of the present invention the vane shoulder further has one at least partly cylindrical peripheral surface with a hole that extends through the shoulder, and the hub seat has a recess situated radially inwards of the hub shoulder for frictional cooperation with the cylindrical peripheral surface of the vane shoulder as well as a hole surrounded by an abutment surface arranged on the outside of the hub, whereby a clamping means is intended to be introduced through said hole in order to, though pre-stressing, generate a frictional force between vane shoulder and hub shoulder, which maintains an adjusted angular vane position.
By designing the seat of the hub with a recess having mutually inclined surfaces the torque can be taken up separately by a counteracting frictional moment between the restriction surfaces of the recess and the vane shoulder. Advantageously, the clamping means can be comprised of a through screw and nut and washer. When the screw is fastened with its prestressing load two react
REFERENCES:
patent: 2246539 (1941-06-01), Ruths et al.
patent: 2844207 (1958-07-01), Curley
patent: 4150921 (1979-04-01), Wennberg et al.
patent: 4715784 (1987-12-01), Mosiewicz
patent: 4877376 (1989-10-01), Sikorski et al.
Granfors Soren
Molin Jan
ABB Flakt AB
Look Edward K.
Sgantzos Mark
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