IMPROVEMENTS IN EXHAUST FANS AND BLOWERS
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by Frederick Morton Eden at the
Office of the Commissioners of Patents on the 2nd August 1882.
FREDERICK MORTON EDEN, of Boughton House, Kettering, in the County of
Northampton, "IMPROVEMENTS IN EXHAUST FANS AND BLOWERS,"
This Invention has reference to a new or improved construction or general
arrangement of the parts of fans (susceptible of considerable variation of detail) for
exhausting air and other gases or vapours, or for blowing the same, whereby they
are more simple in construction and efficient for the purpose than such fans
heretofore in use.
And the Invention or improvements consist all as follows:-
In making the fan in the form of a special construction of hollow annular narrow
or edge vane wheel, carried on the end of its driving shaft by an eye in the centre
of a flat disc web forming the close side or end of the wheel or fan, which exhausts
in through a large eye in the centre of an annular curvilinear disc forming the
other side of the wheel, with any desired number of curvilinear radial vanes inside
extending from the large eye to the outer perimeter, where the fan finally
discharges the air or gases through the spaces between the exhausting vanes. The
depth of the vanes at the inlet exhaust eye, would be such as to make the annular
area of the combined spaces between the exhausting vanes equal to that of the eye
leading the gases thereto. The vanes are made to diminish in depth by a gradual
curve towards the outer open perimeter of the wheel in proportion as their distance
from the axis of the fan increases, so as to make the cross area of the spaces
between them equal throughout from the inlet eye to the outlet perimeter. And
the curve of the exhausting blades or vanes which I have found to answer well is
made so that the inlet and outlet ends or edges at the eye and perimeter are almost
tangential to the circumference of the eye, curving backwards nearly equally from
the inner end to the outer end; but I do not confine myself to this precise back-
ward curve of the exhausting vanes, as other approximate curves may do equally
well or nearly so. A curvilinear cone is formed on the inside of the axis of the flat
disc of the wheel, with its apex projecting out towards the centre of the inlet eye
to lead the air or gas gradually and with the least possible friction to the inner
end of the exhausting spaces and vanes. In order to prevent leakage of air

page_text: between the end of the inlet exhaust pipe, which is made adjustable, and the edge
of the inlet eye of the fan, the ends or edges of both where they approach are truly
turned to make the interval between them as small as possible; and a number of
small exhausting curvilinear vanes are formed on the outer face of the annular disc,
which project over the said joint or interval, so as to exhaust the air out through
the joint and thus prevent inlet leakage as stated. The diameter of the fan in
proportion to the size of the air inlet may be greatly varied, but whatever the
diameter of the disc may be, the circumferential distance between them must
always be such that the openings thereby afforded for the escape of air be equal to
the area of the inlet opening or eye of the fan plus the space occupied by the vanes.
The number of exhausting vanes may be from four to twelve for fans up to four
.feet in diameter, and eight are found to answer for fans of from eighteen inches to
two feet six inches in diameter.
When the fan is used for blowing purposes its action is reversed when the
exhaust becomes the blowing nozzle; or it may be enclosed in a case and the air
projected in the usual way.