Improvements in the Construction of Rotary Fans for Producing or Inducing Currents of Air for Blowing, Ventilating, and other Analogous Purposes.
Year: 1889

page_text: Date of Application, 7th Dec., 1889
Complete Specification Left, 4th Mar., 1890-Accepted, 5th Apr., 1890
PROVISIONAL SPECIFICATION.
Improvements in the Construction of Rotary Fans for Producing or
Inducing Currents of Air for Blowing, Ventilating, and other
Analogous Purposes.
I HENRY ALAND of 73 Roupel Street, Lambeth, in the County of Surrey,
Engineer do hereby declare the nature of my said invention to be as follows:-
The object of my invention is to effect further improvements in the construction
of the class of rotary fans described in the Specification of Letters Patent granted to
me dated 15th April 1885, No. 4660.
In my said Specification, and in the drawings accompanying the same I have
shown a method of mounting fan blades upon a boss or bosses of special construc-
tion, each pair of arms supporting a blade being fitted, one on each side of the.
axle, so that the blade crosses the axle at an angle, according to the required
pitch.
In carrying out my present invention, I form the boss or bosses in such a manner
that when using a pair of arms for supporting each blade, they are both situate on one
and the same side of the axle, the socket of the forward arm being nearer to the axle
than that of the after arm. The blade is thus set so as to be parallel or nearly parallel
to but on one side of a radial line. This position of the blades may be secured in
various ways, by means of various forms of bosses and single arms to the blades.
The blades are preferably bent to what is known as an increasing pitch that is to say,
the forward part of the blade is set at a finer pitch than the after part, whereby the
whole surface of the blade is rendered efficient, by driving the air with a gradually
increasing speed.
I sometimes form the boss with flat radial socket plates, and fit the arms in sockets
at right angles to such plates.
In other cases I make the boss so that it may approximate to a suitable form for
reducing resistance to the current of air, the sockets consisting of provisions cast
with or attached to the boss.
I form such parts of the framework as are subject to air currents with knife edges,
to reduce resistance and increase the efficiency, and in some cases the blades are also
formed with knife edges for the same purpose.
I do not confine myself to any particular number of blades, or to any particular
pitch; as the same may be varied to suit the requirements.
In most cases I prefer the extremities of the blades to be unconfined, so as to
secure the advantages derivable from the induced currents from the surrounding air
beyond the periphery in addition to the parallel draught, but, when required for any
particular purpose, the outer edges of the blades may be enclosed in cylinders, or
fitted with rings or other supports.
In some cases I find it advantageous to fit baffle plates near the axle, to direct and
control the currents of air and prevent return currents into or towards the
central portion of the propeller, when the propeller is required to overcome great
resistance, such baffle plates being made either convex, conical, or flat, according to
circumstances.
DD-1000

page_text: COMPLETE SPECIFICATION.
Improvements in the Construction of Rotary Fans for Producing or
Inducing Currents of Air for Blowing, Ventilating, and other
Analogous Purposes.
I HENRY ALAND, of 73 Roupel Street, Lambeth, in the County of Surrey,
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:
The object of my invention is to effect further improvements in the construction of
the class of rotary fans described in the Specification of Letters Patent granted to me
dated 15th April 1885 No. 4660.
In my said Specification, and in the Drawings accompanying the same I have'
shown a method of mounting fan blades upon a boss or hosses of special construc
tion, each pair of arms supporting a blade being fitted, one on each side of the
axle, so that the blade crosses the axle at an angle, according to the required
pitch.
In carrying out my present invention I form the boss or bosses in such a manner
that when using a pair of arms for supporting each blade, they are both situate on'
one and the same side of the axle, the socket of the forward arm being nearer to
the axle than that of the after arm. The blade is thus set so as to be parallel, or
approximately parallel to, but on one side of, a radial line.
This position of the blades may however be secured by means of various forms of
bosses, and one, two, or more arm or arms bolted or rivetted thereto; or the bosses'
may be cast to receive a prolongation or prolongations of the blade itself, attached
thereto in a like manner.
The blades are preferably bent to what is known as an increasing pitch, that is to
say, the forward part of the blade is set at a finer pitch than the after part, whereby.
the whole surface of the blade is rendered efficient, by driving the air with a gradually'
increasing impulse.
I sometimes form the boss with flat radial socket plates, and fit the arms in sockets,
at right angles to such plates.
In other cases I make the boss so, that it may approximate to a suitable form for
reducing resistance to the current of air, the sockets consisting of provisions cast with
or attached to the boss.
I form such parts of the framework as are subject to air currents, with knife
edges to reduce resistance and increase the efficiency and in some cases the blades are
also formed with knife edges for the same purpose.
I do not confine myself to any particular number of blades, or to any particular
pitch, as the same may be varied to suit the requirements.
In most cases I prefer the extremities of the blades to be unconfined, so as to
secure the advantages derivable from the induced currents from the surrounding air
beyond the periphery, in addition to the parallel draught but when required for any
particular purpose, the outer edges of the blades may be enclosed in cylinders or fitted
with rings or other supports.
In some cases I find it advantageous to fit baffle plates near the axle, to direct
and control the currents of air and prevent return currents into or towards the
central portion of the propeller, when the propeller is required to overcome great
resistance, such baffle plates being made either convex, conical or flat, according to
circumstances.
And in order that my said invention may be particularly described and ascertained,
reference is hereby made to the accompanying drawings in which similar letters of
reference indicate corresponding parts.
Fig. 1 is an elevation of one of my improved air propellers, showing the concave
driving faces of the blades.
Fig. 2 is an elevation showing the back convex faces.

page_text: Fig. 3 is an enlarged plan of the boss, with the arms and blades removed.
Fig. 4 is a section on the line a b of Fig. 1 drawn to the same scale as Fig. 3.
Figs. 5 and 6 are elevations, showing another method of forming the boss and
mounting the blades of the propeller and Fig. 7 is a plan of the boss on the line a b
of Fig. 5.
Fig. 8 is a horizontal view of the propeller shown in Figs. 1 and 2, and also
showing only one of the blades in position, for the sake of clearness.
Fig. 9 is an elevation, Fig. 10 a horizontal section and Fig. 11 a plan, showing
another method of forming the boss.
Figs. 12 and 13 show a method of mounting the propeller blades with their outer
ends inclined towards the vacuum side of the propeller.
Referring to Figs. 1 to 8, c is the axle, d is the boss, fast on the axle. e e are
the sockets for receiving the arms ff. 9 g are the propeller blades, g¹ g₁ being the
forward or leading edges of the blades and 92 9³ the back or following edges. h is
the frame in which the propeller is mounted, and which frame may be formed in any
other suitable manner as found most convenient.
.
The boss d may be formed in one casting, with webs d' as shown in Figs. 1. 2. 3. 4.
and 8 or without webs, as shewn in Figs. 5 6 and 7; or it may be made in two
separate parts with or without webs. When made in two parts the pitch of the
propeller blades can be adjusted by the position of the two bosses; the pitch being
reduced by placing them near together, and vice versa.
In Figs. 9 to 13 another construction of boss is shown in the form of a hexagonal
frustrum of a cone, to which single arms are bolted to support the blades. In this
arrangement the angle of the blades may be regulated by the angle of the conical
boss and the curve of the blade; the angle may however be adjusted by hoisting the
arms to the desired pitch.
The arms carrying the blades are sometimes bent towards the incoming current of
air, as shown in Figs. 12 and 13, in which the bars ff are shown to be bent at or
near their junction with the boss.
I do not confine myself to any particular number of blades, or to any particular
curvature, as the same may be varied as required, and the blades may be made flat
and varied in width and superficial area.
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 :-
1. The manufacture and use of air propellers having the blades fitted in such a
manner that their centre of effort is tangential to a circumferential line formed by the
rotation of such centre of effort, substantially as hereinbefore described and illustrated
by the drawings.
'
2. The manufacture and use of air propellers as aforesaid provided with bosses
so constructed as to support the arms and blades, or the blades only, on one side or
mainly on one side of the axle, and tangential to the centre of rotation of the blades,
substantially as hereinbefore described and illustrated by the drawings.
3. The manufacture and use of air propellers as aforesaid, having blades inclined
at an angle to the axle, substantially as hereinbefore described and illustrated by
Figs. 12 and 13 of the drawings.
4. The general arrangement, construction and combination of the several and
respective parts together forming my invention of Improvements in the construction
of rotary fans for producing or inducing currents of air for blowing, ventilating, and
other analogous purposes, substantially as herein before described and illustrated by
the Drawings.
D. 111
.
GEO. DOWNING,
8, Quality Court, London, W.C., Agent for Applicant.