Improvements in Ventilating or similar Fans or Wheels.
Year: 1887

page_text: [Communicated from abroad by JAMES EDWARDS BARNEY, of Pleasant Street, Hyde
Park, Massachusetts, in the United States of America, Ventilating Engineer.]
Improvements in Ventilating or similar Fans or Wheels.
1. Alfred Juluis BOULT of 323 High Holborn, in the County of Middlesex, M.L.M.E.
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 use of fans or wheels to induce the movement of currents of air is not novel.
Various forms of fans have been constructed prior to this invention consisting of a
wheel having a single series of blades of different and varying curvatures intended to
facilitate the gathering of air, and with various devices employed to prevent back
currents of air through the wheel.
In all prior constructions difficulty has been experienced not only from back
currents within the wheel but also from atmospheric pressure and resistance against
the discharging face of the wheel. In many instances on occasions of wind storms
the effect of pressure on the rear or discharging face of the wheel has been to very
appreciably diminish the volume of discharged air. As the object of the wheel or fan
is to circulate a volume of air in a given direction at a certain velocity it is obvious
that the above defect is a serious one.
My correspondent has by practical tests demonstrated that such defect can be over-
come by creating a vacuum at the rear of the wheel in advance of the discharged
column of air. This result is accomplished by the unique construction shown in the
accompanying drawings and more fully explained hereinafter.
The purpose of this invention is to increase the volume and velocity of columns of
air and to deliver them freely through the fan in such manner as to meet with a
minimum of atmospheric resistance at the discharge face of the fan.
A wheel is constructed in two sections each section consisting of a series of blades
mounted upon hubs at an angle to the axis of the shaft with the inner straight edge of
each blade lying in the plane of the rear face of the section and the outer curved edges

page_text: forming the front face of the section. I unite these two sections upon a common shaft
with the planes of their inner faces abutting and the outer ends of each blade secured
io a common peripheral central rim, the concave inner surfaces of each two alternate
opposite front and rear blades forming channels for the passage of air through the
wheel at an angle to the axis of the wheel corresponding in degree with the angle at
which the blades cross the shaft.
The compound wheel in central cross section presents an elliptical outline.
When this compound wheel is rotated the blades on the front and rear faces of the
wheel flaring in opposite directions, those on the front or feeding face will draw the
air into the wheel, while the blades on the rear or discharging face will beat off
the surrounding air and form a vacuum at the rear of the wheel and in advance of
the discharged column of air. In other words, the concave inner face of the front
blades acting as suction, in unison with the convex outer face of the rear blades acting
as plenum produce a practical vacuum at the rear of the wheel and in advance of the
discharged column of air thereby increasing both the volume and velocity of the
column of air moved through the wheel. This is a novel feature and an important
element in this invention.
The shaft is mounted in framing corresponding in outline with the outline of the
compound wheel. The whole is provided with suitable means for application of power
as is common in ventilator wheels. Four hubs may be mounted on the shaft-two
exterior and two intermediate; Or one of the intermediate may be omitted and the
two series of blades be secured to the three hubs retained. It may be desirable to
divide the central hub into two segments to facilitate removal of one series of blades―
should it become necessary to do so without disturbing the other series.
The construction and arrangement of the blades relatively to each other and to the
shaft prevent back flow or back currents of air in the wheel which would diminish its
effectiveness as it does in all other constructions heretofore known.
I will now describe this invention with reference to the accompanying drawings in
which Figure 1 is a front elevation of this compound wheel.
Figure 2 is a sectional top plan on line of Figure 1.
Figure 3 is a side elevation of the wheel.
Figure 4 is a plan of the template of the blade.
A A A A¹ represent respectively the front and rear blades which are formed from a
template of the form shown in B Figure 4. Each blade has a straight base line bb
and an indentation a short distance from the centre of the base line. The blades are
secured upon hubs CC at an angle to the axis of the shaft, the indentation receiving
the shaft and thereby permitting the base line to fall into the plane of the axis of
the shaft. The outer end of each blade in each series is secured to the peripheral
ring E with the convex face of each blade outward and the concave inner face inward,
and the said concave inner faces of each two alternate opposite front and rear blades
forming an air channel across the axis of the wheel and at the same angle thereto as
that made by their base lines.
The shaft D is suitably mounted in a framing F F not necessary to be fully shown
but preferably of elliptical outline to correspond with the outline of the horizontal
cross section of the wheel. Power is applied in the ordinary manner to a pulley P.
It is obvious that this compound wheel structurally is adapted to work with equal
effectiveness when rotated in either direction, the direct and reverse currents obtained
being of equal volume and velocity.
Having now particularly described and ascertained the nature of the said invention
as communicated to me by my foreign correspondent and in what manner the same
is to be performed I declare that what I claim is :-
1. A compound ventilating or similar wheel or fan composed of a double series of
blades A A A A combined with a shaft D and hubs CCC each blade being secured
upon its hubs at an angle to the axis thereof and the outer ends of each blade secured
to a common peripheral ring and the concave inner faces of each two alternate from

page_text: and rear blades arranged relatively as shown to form an air channel through the wheel
at an angle to the axis thereof substantially as described.
2. A compound ventilating or similar wheel or fan composed of a double series of
blades each blade secured upon the hubs at an angle to the axis of the shaft the outer
edges of the blades united to a common peripheral ring, the convex surfaces of each
series of blades forming the respective faces of the wheel and the concave inner
surfaces of each two opposite alternate blades forming an air channel diagonally aeross
the shaft the whole combined with a shaft and rotated in the same direction whereby
the concave of the face blades acting as suction in conjunction with the convex face
of the rear blades acting as plenum produce a vacuum at the rear of the wheel and
in advance of the discharged column of air substantially as specified.
::
3. In a compound ventilating or similar wheel or fan the template B provided with
a straight base line indented at one side of the centre as at 6 and with two sides of
unequal convex curvature substantially as shown converging to a point B when
combined with the hubs and peripheral ring of a wheel to form a blade in which the
base line lying in the plane of the axis of the shaft is longer than the peripheral flange
of the blade substantially as specified.
4. In a ventilating or similar wheel or fan the template B provided with a straight
base line and two sides of unequal convex curvature converging to a point 131 when
combined with hubs and peripheral ring of a wheel to form a fan blade all substantially
as specified and illustrated in the accompanying drawings.
W. P. THOMPSON & BOULT,
Agents.