Improvements in Fans or Blowers and Centrifugal Pumps.
Year: 1890

page_text: te of Application, 4th Oct., 1890-Accented, 17th Jan., 1891
COMPLETE SPECIFICATION.
Improvements in Fans or Blowers and Centrifugal Pumps.
I, CAMILLE EDMOND AUGUSTE RATEAU, of Saint Etienne, in the Republic of
France, Engineer, do hereby declare the nature of this invention and in what manner
the same is to be performed to be particularly described and ascertained in and by the
following statement :-
This invention relates to improvements in fans or blowers and centrifugal pumps.
In my improved fans or blowers and centrifugal pumps all the parts are arranged
so as to allow fluid, air or water great speed of circulation, and so as to avoid, as much
as possible, non-delivery of any part of the charge by dead fluid or shocks. Very
powerful apparatuses are thus provided of exceptionally small dimensions and giving
high pressures and good mechanical results.
The principal parts of a fan or blower or of a centrifugal pump are :—
1. The vanes or blades, the function of which is to communicate speed to the fluid
by forcing it in a predetermined direction.
2. The diffuser serving to transform the active force of the current into useful
statical pressure.
And my invention has mainly for object improvements in the said parts.
In the accompanying drawing I have given by way of example views of a fan or
blower and of a centrifugal pump illustrating my improvements
Figures 1 and 2 are a transverse section and a longitudinal section respectively of a
fan or blower constructed according to my invention.
Figures 3 and 4 are diagrammatic views illustrating the principle on which my
vanes are constructed.
Figures 5, 6, 7 and 8 are similar views to Figures 1, 2, 3 and 4 illustrating my
invention applied to a centrifugal pump.
Similar letters in all the figures indicate similar parts.
The fan-wheel or turbine wheel is constructed of a hody A of the shape shewn in
Figures 2 and 6, the surface of which forms the arc of a circle a b, provided with a
boss B whereby it is mounted upon the shaft C by which it is rotated. On the
body A are fixed vanes I), D of special form as hereinafter described to the number
of about 30 for fans and about 2. for pumps. Each vane D has four edges: one of
these edges a, b is fixed upon the body A of the wheel; another b, c is a generatrix of
an imaginary cylinder or periphery of the wheel; a third c d in the rotary movement
moves in close proximity to a part E of the casing forming a continuation of the bell
or trumpet mouth i, j hereinafter described; finally the fourth edge d a is situated in
the inlet opening F.
The fluid enters at the edge d a of each vane D and is ejected at the edge b c.
Between the two edges the fluid is guided between the body A of the wheel and the
part E of the casing, the meridian curve of which is calculated so that the relative
speed of the fluid between the vanes D remains nearly constant.
The surface of the vane is formed in the following manner :-
An arc of a circle ce drawn in a plane perpendicular to the axis of the apparatus
has a double movement, that is to say, it slides along the axis and turns around it in
such a manner that its plane is always normal to the axis, the point x, which is
invariably connected thereto, remains on the axis and, finally, the point c describes an
arc of directrix curve b', c', f' upon the peripheral cylinder of the wheel. This curve
is a circumference, the centre of which is in the middle plane Q of the top of the fan
or pump.
From the side of the wheel body A this directrix is very slightly inclined
on the generatrices of the cylinder; but from the side of the inlet opening F it cuts
them at an angle of about 45 degrees calculated so that the fluid enters without
shock.

page_text: The arc c, e which is a generatrix of the surface of the vane has a radius of 0.54 m.
for a fan or blower having a wheel of 2 m. in diameter and 5 cm. 6 for a pump having
a wheel of 18 c/m. in diameter.
For apparatuses of different size these radii remain proportional to the diameter
of the wheel.
The arc ce has its centre at CO (Figures 3 and 7) and if continued would not
pass through the centre æ; it is connected to this centre by the right line e, x.
The arc of directrix circle of the surface of the vane (the centre of which is in the
middle plane of the crown Q) is struck from the peripheral cylinder of the wheel. The
drawings (Figures 4 and 8) shew its development on a diametrical plane.
The radins of this arc is varied according to the purpose for which the blower or
the pump is intended. For apparatus of great discharge or outflow and low pressure
like those illustrated it is 0.76 m. for a blower of 2 m. and 6 c/m. 4 for a pump of 18 c/m.
For apparatuses of small outflow under great pressure the radii would be respectively
0.62 m. and c/m.
In ventilators and pumps of different sizes these radii are proportional to the diameter
of the wheel.
The vane thus obtained possesses the following properties :-It extends over the
body A of the wheel almost normally everywhere and with its longest edge. It is very
rigid by reason of the curve that it presents in all directions. The Huid is caught
without shock in the inlet opening F and is ejected at the periphery with the greatest
possible speed, as the vane D is curved in front at an angle of about 45 degrees more
or less according to circumstances. Between their entry and exit the different
particles of fluid are pushed progressively by the pallets. The trajectories that they
describe have almost constant and, in all cases, gradually variable radial curves.
The wheel of the fan or blower is, as shewn in Figure 2, fixed at the end of the
shaft C by means of a conical socket G.
A conical cap k (Figures 2 and 6) covers the end of the shaft C of both the fan and
the pump and guides the fluid before its passage into the inlet opening F. The fluid
is also guided by the bell or trumpet-mouth i j which precedes the inlet opening F.
The diffuser is composed of three distinct parts as shewn in the accompanying
drawings-Firstly, of a flat spiral diffuser H H (Figures 1, 2, 5 and 6) formed of two
parallel plates limited to the peripheral circumference of the wheel and to an Archi-
medean screw or spiral, the height of which consequently increases progressively from the
outset or inlet mouth of the diffuser to the base of the fluid-pipe or conduit: secondly
of a diffusing collector II (Figures 1, 2, 5 and 6) or volute having circular or square
sections increasing in diameter in proportion as the spiral increases in height: thirdly
of a conical or pyramidal pipe JJ (Figures 1, 2, 5 and 6) or conduit which forms a
continuation of the diffusing collector and effects the diffusion of the fluid.
The principal feature of my diffuser is this combination of the flat spiral portion
with the enlarged part. It has for object to allow an almost complete transforina-
tion of the active force of the fluid into pressure before it enters the pipe or conduit,
at the same time preventing the shock of the current which is leaving the wheel with
that which is already diffused.
The height of the spiral part increasing proportionately to the winding are it is just
the same with the outlet which it offers to the current. On the contrary, the sections
of the diffusing collector increase according to a parabolic law, so that at the terminal
portion, the section shall be nearly triple that which it would be if there were no
interposed flat part.
The apparatuses represented in the accompanying drawings are especially adapted
for giving large results at ordinary pressures. If a fan is required giving a high
degree of pressure, or a pump which will raise fluid to a great height, it will of course
be necessary to rotate the wheel very quickly, as the pressure obtained is proportionate
to the square of the number of revolutions. And then, in order not to have to transmit
to the shaft a too large amount of mechanical work, it is advisable to reduce the out-
flow by diminishing the size of the passage through which the fluid flows through the
apparatus. This is effected by lessening the distance between the edges a b and c d

page_text: which correspond with the circular body A of the wheel and the fixed part E against
which the vanes D rotate. The height of the vanes will therefore also be reduced as
well as all the surfaces over which the fluid flows.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is
The general arrangement of the fan and centrifugal pump hereinbefore described
and illustrated in the accompanying drawings and particularly-1. The form of the
vanes hereinbefore described produced by the conoidal displacement of an arc of
a circle, the plane of which is normal to the axis. 2. The diffuser constructed of a
flat spiral portion and a spiral volute of which the conical outlet pipe forms a
continuation.
ALL
Natahor 1800
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.