Year: 1887

page_text: Date of Application, 22nd Mar., 1887
Complete Left, 22nd Dec., 1887
Complete Accepted, 10th Feb., 1888
SAMUEL SEALY ALLIN 52 Woodstock Road, Bedford Park County of Middlesex,
Gentleman do hereby declare the nature of this invention to be as follows:-
The object of this Invention is to increase the efficiency of fans by diminishing the
resistance due to sudden changes of direction of the air put in motion, to reduce
the loss due to air friction in the casing, and to reduce also the loss due to the
elasticity of the air when being acted on by the fan blades.
The construction of the fan varies according to whatever it is to be used for,
blast or for exhaust purposes, or more correctly according as to whether it can
discharge its air freely into the open all round its periphery or has to discharge
into a casing with one or more outlets or in the usual snail shell case. The fan
consists of a pair of annular discs carried as usual by arms on a spindle. Between
these discs are the blades, the formation of which is the essential feature of the
Invention. They are made with a curve starting from a straight line at the inner
circle to which they are nearly tangential and continually quickening outwards, with
this difference that in exhaust fans the curvature is backwards so that the blade is
convex to the direction of motion in order to attain the highest expelling power with
the minimum of resistance, and in blast fans the curvature is forward, and the blade
concave in the direction of motion, in order that the air may not be expelled radially
against the casing, but may receive a tangential motion in the direction of the outlet.
Inasmuch as in these fans I employ a greater number of blades than usual, I do
not carry in the smaller sizes all the blades to the inner circle but prefer to stop each
alternate blade about half-way.
This arrangement facilitates the entrance of the air and reduces the loss due to its
elastic resistance.
THOMAS WRIGLEY,
36, High Holborn, W.C.,
Agent to Applicant.

page_text: J, SAMUEL SEALY ALLIN of 52 Woodstock Road, Bedford Park, in the county of
Middlesex, Gentleman, 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:—
The object of my invention is to increase the efficiency of centrifugal fans employed
for delivering or exhausting air, by diminishing the resistance due to sudden changes
of direction of the air put in motion, by reducing the loss due to air friction in the
casing, and by reducing also the loss due to the elasticity of the air when being acted
on by the fan blades.
The construction of my improved fan is varied according to whether it is to be used
for blast or for exhaust purposes, or more strictly speaking, according to whether it
has to discharge air against pressure, as into a casing with one or more outlets, as for
instance the usual snail-shell case, or whether it can discharge air freely against
atmospheric resistance, or little more.
In the accompanying 3 sheets of drawings, Figure 1 represents a side elevation,
Figure 2 a sectional side elevation and Figure 3 a cross sectional elevation through
the line a a in Figure 1 of a centrifugal fan constructed according to my invention,
for delivering air for blowing purposes. Figure 4 is a sectional side elevation and
Figure 5 a cross sectional elevation through the line 66 in Figure 4 of a centrifugal
fan, constructed according to my invention, for exhausting air, Figure 6 is a sectional
side elevation of an exhausting fan of somewhat modified arrangement, and Figure 7
is a sectional side elevation of a fan shewing a modified arrangement of blades.
Similar letters of reference denote similar parts throughout the drawings.
Referring to Figures 1 2 and 3 A is the shaft or spindle supported in suitable
bearings B, B. is a sleeve keyed upon the spindle A and formed with a central
disc D, turned to a feather edge upon its periphery and so shaped as to lead the air
in by an easy curve, the blades E are let into the disc D, and the two annular
discs F, F, which form the sides of the fan, are affixed to the blades E, which act as
arms to connect them with the centre.
One of the most essential features of my invention consists in the form which is
given to the said blades. It will be seen on reference to Figure 2, that starting from
the inner end they commence as a straight, or nearly straight line, which if carried
inwards would be tangential to an imaginary circle represented by the dotted line H,
and are then curved with continually increasing curvature to the outer end. The
concave side forms the front of the blade, as shewn by the arrow indicating the
direction of rotation, and the improved result attained by this peculiar form of blade
is that the air is not thrown off as in a blade of the usual shape, but is so to say held
by the blade and receives almost concentric motion round the fan, and is not expelled
radially or forced against the outer part of the casing K. This casing simply forms
an external tube just embracing the edges of the annular discs F, F', instead of

page_text: enclosing the whole of the said discs as is the usual practice, the friction due to the
pressure against the outer surfaces of the discs of the more or less compressed air in
the casing in ordinary fans being thus avoided.
In Figures 4 and 5, which represent an exhausting fan the casing K is not usually
required and the curve given to the blades E is in the opposite direction to that in the
blast fan, so that the convex side forms the front of the blade and with this form of
blade the air is expelled almost radially from the fan with the least possible resistance.
In other respects the construction is similar to that shewn in Figures 1, 2 and 3.
In Figure 6, which shews a modified form of exhaust fan, the blades instead of
starting as tangents from the imaginary circle H, are curved somewhat forward, so
that the blades are of a serpentine form in section.
The size of the circle H is governed by the speed at which the fan is intended to be
driven, thus for high speeds the circle is increased, and for slow. speeds, reduced in
diameter.
In fans running at high speed and where the distance between the blades is con-
siderable, I employ between each pair of blades E, one or more secondary short
blades L Figure 7, which have the effect of diminishing the loss due to the
compression of the air in front of the outer ends of the long blades, as these short
blades act directly upon that part of the body of the air which would otherwise
receive an impulse from the blade behind only through the medium of an elastic
cushion of air.
I wish it to be understood that I do not confine myself to the precise proportions
shewn in the drawings herewith, as these are merely given to illustrate the essential
features of my invention, but having now particularly described and ascertained the
nature of my said invention and in what manner the same is to be performed,
I declare that what I claim is :
(1.) In centrifugal blast fans the use of blades commencing at their inner ends
with a short straight line about one fifth of their length and running into a con-
tinually quickening curve forwards in the direction of motion, substantially as herein
described and shewn with reference to Figs. 1. 2. & 3 of the accompanying drawings.
(2.) In centrifugal exhaust fans the use of similar curved blades formed with a
continually quickening curve backwards to the direction of motion and with the
tips inclined backwards of a radial line substantially as herein described and shewn
with reference to Figs. 4 & 5 of the accompanying drawings.
(3.) In exhaust fans the use of blades serpentine in section and curved at the
top behind the radial line substantially as herein described & shewn with reference
to Fig. 6 of the accompanying drawings.
(4.) In centrifugal fans the use of secondary blades L substantially as and for the
purposes herein set forth with reference to Fig. 7 of the accompanying drawings.
(5.) In centrifugal fans the use of a casing merely embracing the outer edges of
the fan substantially as herein described and shewn with reference to Figs. 1 2 & 3
of the accompanying drawings.
Dated this 20th day of December 1887.