Improvements in the Construction of Rotary Fans for Producing or Inducing Currents of Air, for Blowing, Ventilating, and . other Analogous Purposes.
Year: 1885

page_text: 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 Cavendish House Harbut Road New Wandsworth, in the
County of Surrey, Engineer, do hereby declare the nature of my Invention for
"IMPROVEMENTS IN THE CONSTRUCTION OF ROTARY FANS, FOR PRODUCING OR
INDUCING CURRENTS OF AIR, FOR BLOWING, VENTILATING, AND OTHER ANALOGOUS
PURPOSES," to be as follows:-
Whereas it has hitherto been the custom and practice to construct rotary air
propellers, either with the periphery enclosed in a fixed stationary cylinder or
casing, or with part of the periphery enclosed with segmental plates, enclosing
portions thereof, and so fixed as to revolve with the blades, as part of the
revolving propeller. Now the object of my invention is to form revolving
propellers open and free to the suction chamber, and my invention relates to the
construction of that class of rotary fans, which propel air by means of screw blades.
rotating upon a central axle: the air being caused to travel in a line parallel to
that of, the axis, or approximately thereto.
In carrying out my invention, I fit a suitable number of screw blades to the
axle, either at right angles thereto, or at an inclination to the line of axis; and,
when so inclined, the inclination is in the direction towards which the air travels.
The blades of the screw are (preferably) curved so that they may possess the
form known as an "increasing pitch," that is to say, the forward part of the blade
has a comparatively fine pitch, and the after part, or back of the blade, has a much
coarser pitch; whereby the air is gradually increased in speed as it is operated
upon by the screw blades. In some cases however I make use of blades of uniform
pitch.
The supply of air to the screw takes place from an area far exceeding that of
the screw; there being not only a parallel motion of air towards the screw from
the front, equal to the whole of the screw area, but also a supply of air from
beyond the screw area towards the blades, whereby a vortex action is obtained,
and a small diameter of screw produces a partial vacuum over a large cubical area,
and concentrates the induced current thereby acquired: driving the same with
greatly enhanced effect, compared with the action of ordinary screws.

page_text: In order to afford free access of air to every part of the fan, I eliminate, as
much as possible, all framing not absolutely required for strength and safety, and
especially dispense with rings, casings and cylinders surrounding the blades; and,
where such adjuncts are required, I reduce them to the smallest possible dimensions,
in order to remove all obstruction to the accessibility of the air.
I prefer to mount the axles in brasses which are self-adjusting; and for this
purpose I make some portion of the brasses globular, and resting in globular
supports in the plummer blocks, or other bearings.
In some cases I fit additional short blades between the main blades, in order to
increase the efficiency of the fans.
When using my improved fans as exhausters, for ventilation or otherwise, I fit
the casing close to the front edge of the fan, but without actual contact; and so
form the casing that the air entering the fan has free access to the periphery, as
well as to the remainder of the screw area.
In some cases I find it advantageous to fit two screws on one axle, with a suction
chamber between and surrounding such screws the exit holes being of the same
diameter as those of the screws, or thereabouts.

page_text: other Analogous Purposes:
I, HENRY ALAND, late of Cavendish House, Harbert road, New Wandsworth, in
the County of Surrey, but now of Summer Cottage, Summer, Road, East Moulsey,
in the same County, Engineer, do hereby declare the nature of my said invention
and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement:-
Whereas it has hitherto been the custom and practice to construct rotary air
propellers, either with the periphery enclosed in a fixed stationary cylinder or
casing, or with part of the periphery enclosed with segmental plates, enclosing
portions thereof, and so fixed as to revolve with the blades, as part of the
revolving propeller.
Now the object of my invention is to form revolving propellers open and free to
the suction chamber; and my invention relates to the construction of that class of
rotary fans, which propel air by means of screw blades rotating upon a central
axle: the air being caused to travel in a line parallel to that of the axis, or
approximately thereto.
In carrying out my invention, I fit a suitable number of screw blades to the axle,
either at right angles thereto, or at an inclination to the line of axis.
The blades of the screw are (preferably) curved so that they may possess the
form known as an "increasing pitch," that is to say, the forward part of the blade
has a comparatively fine pitch, and the after part, or back of the blade, has a much
coarser pitch; whereby the air is gradually increased in speed, as it is operated
upon by the screw blades. In some cases however I make use of blades of uniform
pitch.
The supply of air to the screw takes place from an area far exceeding that of the
screw; there being not only a parallel motion of air towards the screw from the
front, equal to the whole of the screw area, but also a supply of air from beyond
the screw area towards the blades, whereby a vortex action is obtained, and a
small diameter of screw produces a partial vacuum over a larger area than that of
the propeller and concentrates the induced current thereby acquired: driving the
same with greatly enhanced effect, compared with the action of ordinary screws.
In order to afford free access of air to every part of the fan, I eliminate, as much
as possible, all framing not absolutely required for strength and safety; and
especially dispense with rings, casings and cylinders surrounding the blades; and,
where such adjuncts are required, I reduce them to the smallest possible dimensions,
in order to remove all obstruction to the accessibility of the air.
I prefer to mount the axles in brasses which are self-adjusting; and for this
purpose I make some portion of the brasses globular, and resting in globular
supports in the plummer blocks, or other bearings.

page_text: In some cases I fit additional short blades between the main blades, in order to
increase the efficiency of the fans.
.
When using my improved fans as exhausters, for ventilation or otherwise, I fit
the casing close to the front edge of the fan, but without actual contact, and so
form the casing that the air entering the fan has free access to the periphery, as
well as to the remainder of the screw area.
And in order that my said invention may be particularly described and ascer-
tained, reference is hereby made to the accompanying drawings, in which similar
letters and figures of reference indicate corresponding parts.
Fig. 1 is an end elevation of the boss, and Fig. 2 is a plan of the same, to which
I fit the arms which carry the blades or fans.
Fig. 3 is a front view and Fig. 4 a section of my improved adjustable bearing.
Figs. 5 to 9 represent different methods of mounting blades or fans and other
details of my invention.
The boss shewn in Figs. 1 and 2, to an enlarged scale, is so formed that the rods
or bars are screwed into their sockets, at right angles, or thereabouts to radial lines
drawn from the centre.
In Fig. 1 the front sockets are numbered 1 to 6, and the back bars are dotted
and numbered 7 to 12. In Fig. 2 the sockets 1, 2, 5, 6, 7, 8, 11, 12 are shewn.
The dotted line a b (Fig. 2) shews the position of a screw blade, with increasing
pitch, a being the front edge and b the back edge of the same. This blade would
be supported by two rods fitted respectively into the sockets numbered 5 and 8;
and the remainder of the blades would be fitted in accordance with the same scheme.
An elevation of a propeller, so fitted, is shewn in Fig. 5, in which a a are the leading
(or front) edge, and b b are the following (or back) edges of the blades.
In Fig. 7 the disposition of the rods is shewn, for supporting the blades shewn
in Fig. 5, the pairs of rods being numbered with reference to Figs. 1 and 2.
Number 5 is the front rod and Number S (shaded black) is the back rod, which,
together, support one blade. Numbers 2 and 11 support the opposite blade, and so
on with the rest of the blades.
Although I have shewn six blades in the drawings, I do not confine myself to
that number, as a greater or less number may be fitted. Nor do I confine myself
to any particular angle of the rods or blades, to the scheme of pairing the rods
above described, as it is obvious that by pairing the rods in various ways other
forms of blades may be fitted; thus, by pairing rods 5 and 7 together, a blade
approximating to a true helice may be fitted; and by pairing the rods as shewn
in Fig. 8 a Guibal fan, with flat or curved blades may be formed; but I do not
claim such Guibal fan.
In some cases I form the boss of a more solid construction (when preferred) as
indicated by the dotted lines (Fig. 2); and by lengthening the distance between
the ends of the boss, the pitch can be increased, and vice versa.
Sometimes I fit the blades shewn in Fig. 5 in an inclined position, the inclination
being in all in one direction, and, in other cases I fit the same inclined alternately
in opposite directions, as shewn in Fig. 6; Fig. 9 being a plan view of such an
arrangement, shewing only two opposite blades.
In Figs. 3 and 4 my method of forming the adjustable globular bearings is shewn.
c is the axle which turns in the cast iron, gun metal, or other bearing d. This
bearing d has a globular enlargement d¹, which rests in a lining e, of lead or
other suitable metal. f is a portion of the frame, g is the main bearing, and h
is the cap.
I sometimes make the axle tubular, and supply the same with water or other
fluid, and pass such fluid to the blades through suitable perforations in the form
of spray, whereby dust of any kind may be precipitated, or the air cooled, as.
desired.
I sometimes find it advantageous to fit a ring to the arms, outside the central 5
propeller blades, and fit to the outside of such ring a. larger number of blades,
projecting therefrom in a radial or inclined position.

page_text: 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
1 claim is
1. The manufacture and use of rotary fans or air propellers, with free, unob-
structed, suction and delivery, operating substantially as herein before described,
and as partially illustrated on the drawings.
2. In the construction of my improved rotary fans, the particular form and
arrangement of boss for mounting the same, substantially as herein before
described and shewn in Figs. 1 and 2, and further illustrated in Figs. 7 and 8
of the drawings.
3. In the construction of my improved rotary fans, the particular form and
arrangement of self-adjusting bearings, substantially as herein before described and
shewn in Figs. 3 and 4 of the drawings.
4. The manufacture and use of air propellers constructed as aforesaid, fitted with
hollow, or tubular spindles or axles, for distributing jets of water or other fluid, as
spray or otherwise, substantially as herein before described.
5. The general arrangement, construction and combination of the several and
respective parts, together forming any 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 partly illustrated
on the drawings.