Year: 1886

page_text: We, WILLIAM WINSHIP WARDLE Engineer, and MICHAEL SHILLITO Manager of
The Blackman Air Propeller Ventilating Company Limited, both of No. 57 Fore
Street in the City of London do hereby declare the nature of.this invention to be
as follows:-
C
This invention relates to a ventilating fan of the kind having inclined or
helicoidal blades which by their revolution create a current in a direction parallel
or nearly so to the axis of the fan. The object in view is to obtain by a simple
construction, such form of blade as will propel the current almost entirely in an
axial direction without causing it to spread out in obedience to centrifugal force.
For this purpose a disc of sheet metal of about the diameter desired for the fan is
divided by equidistant cuts extending from near the centre to the circumference
into a number of sectors, such as 6 or 8, each of these sectors being intended to
form a blade. The cuts may be radial, but preferably they are curved somewhat
backward relatively to the direction in which the fan is intended to revolve, so
that each blade, instead of being a true sector, has one of its edges, the entering
edge convex, and the other, the leaving edge, concave, this latter edge making a
rather acute angle with the circumferential arc of the blade. Each blade is bent
out of the plane of the disc with a helicoidal curvature giving it a pitch increasing
from the convex entering edge to the concave leaving edge; and it is also curved
so that its circumferential arc is bent forwards in the direction of the intended
current, this forward bend increasing from the circumferential angle of the
entering to that of the leaving edge. The effect of this compound curvature is
that, while the increase of pitch accelerates the air passing along the face of the
blade in a forward, direction, the forward bend of the outer part of the blade by
directing the current towards the axis neutralises the centrifugal force that tends
to render the current divergent.
كيم
1000

page_text: We, WILLIAM WINSHIP WARDLE, Engineer, and MICHAEL SHILLITO Manager of
The Blackman Air Propeller Ventilating Company Limited, both of No. 57 Fore
Street in the City of London 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 a ventilating fan of the kind having inclined or
helicoidal blades which by their revolution create a current in a direction parallel
or nearly so to the axis of the fan. The object in view is to obtain by a simple
construction, such form of blade as will propel the current almost entirely in
an axial direction without causing it to spread out in obedience to centrifugal
force.
For this purpose we construct the fan as we will describe referring to the
accompanying drawings. Fig. 1 is a front view of a disc of metal of which the
fan blades consist, Fig. 2 is a side view and Fig. 3 a front view of the fan.
The disc Fig. 1 of sheet metal of about the desired diameter of the fan is divided,
by equidistant cuts extending from near the centre to the circumference, into a
number of sectors, such as 6 or 8, each of these sectors being intended to form a
blade. The cuts may be radial, but preferably they are curved as indicated by the
dotted lines in Fig. 1, so that each blade instead of being a true sector, has one of
its edges, the entering edge, convex, and the other, the leaving edge, concave, this
latter edge making a rather acute angle with the circumferential arc of the blade.
Each blade is bent out of the plane of the disc with a helicoidal curvature giving
it a pitch increasing from the entering edge A to the leaving edge B (see Figs. 2
and 3) and it is also curved so that its circumferential arc C is bent forwards in
the direction of the intended current, this bend increasing from the circumferential
angle next the entering edge A to that next the leaving edge B. The disc with its
sectors thus bent is fixed on a shaft S, and being caused to revolve in the direction
of the arrow D Fig. 3, operates as a fan with great efficiency. The effect of the
compound curvature of the blade is that while the increase of pitch from the
A edge to the B edge accelerates the air passing? along the blade in a forward
direction, the forward bend of the outer part C, by directing the air centripetally
towards the axis, neutralises the centrifugal force that tends to render the current
divergent. The arrows in Fig. 2. indicate generally the direction of the current
produced, the air being drawn in all round on the one side as indicated by the
arrows E, and being propelled in a column parallel or nearly so as indicated by
the arrows Fon the other side.

page_text: Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed we declare that what
we claim is:-
The construction and use of a ventilating fan, having for its blades sector
divisions of a plate disc, each bent with increasing pitch axially, and with
centripetal direction radially, substantially as and for the purpose herein set
forth.