Improvements in Ventilating Fans.
Year: 1892

page_text: Date of Application, 12th Aug., 1892
Complete Specification Left, 11th May, 1893-Accepted, 8th July, 1893
PROVISIONAL SPECIFICATION.
Improvements in Ventilating Fans.
I, WILLIAM GEORGE WALKER, of 2 Barmeston Road, Catford in the County
of Kent, M. Inst. M.E., Engineer, and Demonstrator in Engineering at University
College Bristol, do hereby declare the nature of this invention to be as follows:-
My invention relates to those ventilating fans or air propellers of the screw-
propeller type, used for ventilating purposes, or for the production of air currents;
and consists of an improved construction of the blades having for its object to
render such blades more efficient as producers of air currents.
My invention refers to the rearward or non-propelling face of the blades, which
face in comparison with those heretofore in use, project or extend rearward from
the propelling face, formed by the erection of a hollow or solid protuberance and
extending for the full or major part of the length of the blade; so that the
transverse section of the blades is hollow or solid, and the section in outline, plano-
convex, concavo-convex, polyangular, triangular, or other similar section, and may
be of a uniform or non-uniform kind and size of section; the area of the section
being by reason of the protuberance, greater in comparison than the section of the
blades heretofore in use.
As an illustration of my principle; let a semi-cylinder, formed by cutting a pipe
or tube longitudinally, be fixed with its flat section on a blade or plate the width
of which equals the diameter of the cylinder, and with the long edges of the semi-
cylinder and the blade or plate coincident, the transverse section of this improved
blade would be hollow plano-convex, its convex surface being formed by the
erection of the semi-cylinder or protuberance, and constitutes the non-propelling
face. I do not bind myself to this particular kind of section of the blade or mode
of construction.
By this improved construction the tendency of the air to rush back from the
propelling face into the partial vacuum existing immediately in the wake of each
revolving blade heretofore in use, would be in most part prevented, and the
efficiency of the fan thereby increased.
Dated this 11th day of A nanet 1000
W. G. WALKER.
COMPLETE SPECIFICATION.
Improvements in Ventilating Fans.
I, WILLIAM GEORGE WALKER of 2 Barmeston Road, Catford, in the County
of Kent, 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 :-
My invention relates to those ventilating fans of the screw-propeller type, used
for ventilating purposes, or for the production of air currents, and consists of an
improved construction of the blades, having for its object to render such blades
more efficient as producers of air currents.
My invention refers to the rearward or non-propelling face of the blades, which
face in comparison with those heretofore in use, project or extend rearward from
the propelling face; formed by the erection of a hollow or solid protuberance and
extending for the full or part only of the length of the blade, so that the transverse
section of the blades is hollow or solid, and the section in outline, plano-convex,
concavo-convex, triangular, or other suitable section, and may be of a uniform or
[Price 8d.]

page_text: non-uniform kind and size of section, the area of the section being by reason of the
protuberance, greater in comparison than the section of the blades heretofore
in use.
As an illustration of my invention; let a semi-cylinder, formed by cutting a pipe
or tube longitudinally, be fixed with its flat section on a blade or plate the width
of which equals the diameter of the cylinder, and with the long edges of the
semi-cylinder and blade or plate coincident, the transverse section of this improved
blade would be hollow plano-convex, its convex surface being formed by the
erection of the semi-cylinder or protuberance, and constitutes the non-propelling
face. I do not bind myself to this particular kind of section of the blade or mode
of construction.
Referring to the accompanying sheet of drawings-
Fig. 1. is an elevation of a fan to which my invention applies, the blades may be
of a greater or of a less number than six, and their general configuration may also
be varied, they are fixed to a boss marked C. in the drawing. My invention is
clearly illustrated by Fig. 2 and Fig. 3., which are transverse sections through a
blade of the fan at A. A, and B. B. respectively marked on Fig. 1., the propelling
surface or face is marked p, the non-propelling surface or face being marked n.
these two portions are rivetted or otherwise suitably attached to each other.
Figs. 4 and 5 are transverse sections through other forms of blades embodying iny
invention, the propelling and non-propelling faces being marked p. and n.
respectively. The blades of the foregoing examples, may be made from a single
sheet of metal curved into the required shape, or from two or more pieces suitably
fixed or attached to each other.
Figs 6. and 7. illustrate a transverse section of a solid form of blade, the pro-
pelling and non-propelling surfaces being marked p. and n. respectively. This
solid form of blade is in my invention always made of two or more different
materials, attached to each other, one of these portions generally that which has
the greatest thickness or bulk, as marked D. and D, in the drawings is preferably
of a lighter material than the other portion or portions of the blade, for it must be
distinctly understood, that this addition to the thickness or bulk of the blades, is
not for reasons of strength, although it does perhaps add to their strength, but is
to render such blades more efficient as producers of air currents.
The object of this improved construction, is to fill up or distroy the partial
vacuum which exists at the back of each revolving blade, which enables them to
pass off a greater quantity of air in an axial direction, instead of churning it.
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:
Constructing the blades of a ventilating fan of the. screw-propeller type, such
that the non-propelling face or surface, generally called the back of the blades in
most part extends or projects rearward to a greater extent from the propelling face
or front of the blades, in comparison with blades heretofore in use, constructed
and arranged in the one or the other of the two following forms, firstly, by making
the blades from sheet metal so that a hollow space exists in their interior, secondly,
by constructing them of a solid form, that is without a hollow space, but with
distinctly of two or more different materials, the thicker or that which has the
greatest bulk being the lightest of the materials, substantially as in this Specification
described, and in reference to the drawings illustrated.
Dated this 10th day of May 1893