Improvements in Centrifugal Fans.
Year: 1887

page_text: PROVISIONAL SPECIFICATION.
Improvements in Centrifugal Fans.
I NOËL CHANDLER of The Cannock Chase Foundry & Engine Works Hednesford
Stafford, Engineer, do hereby declare the nature of this invention to be as
follows:-
I employ a number of vanes or blades radiating from a common centre, cach
somewhat of the shape of the letter "S," that is to say, the outer part of the
blades shall be curved in the opposite direction to the inner part of the blades.
The object of my employing blades of this particular form is to enable the fan to
pass (or inhale & exhale) a larger volume of air than a fan having all its blades curved
in one direction. I prefer to make the inner portion of the blades curved in a direction
so that they act as collectors of air, that is to say, the ends of the blades
nearest to the centre shall present their edges in the direction in which the fan is
revolving, and thus scoop up and inhale the air; acting upon the air in the
same manner that the plane-iron of a carpenter's plane shaves a piece of wood.
To further explain the nature of my invention, 1 may state that if an elevation
of the fan be taken, shewing all the blades, and the direction of rotation being similar
to that of the hands of a watch, the outer half of each blade shall present a convex
curved surface, and the inner half of each blade shall present a concave curved
surface, on its front or forward side; the curve of the outer half of each blade
being struck from a centre behind the blade, and the curve of the inner half being
struck from a centre in front of the blade.
Dated this Thirteenth day of December 1887.

page_text: NOËL CHANDLER of the Cannock Chase Foundry and Engine Works Hednesford,
Staffordshire 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 :-
I employ a number of vanes or blades radiating from a common centre, each some-
what of the shape of the letter S that is to say, the outer parts of the blades shall be
curved in the opposite direction to the inner parts of the blades.
The object of my employing blades of this particular form is to enable the fan to
pass on (inhale and exhale) a larger volume of air than a fan having all its blades
curved in one direction.
I prefer to make the inner portion of the blades curved in a direction so that they
act as collectors of air, that is to say, the ends of the blades nearest to the centre, sball
present their edges in the direction in which the fan is revolving, and thus scoop up,
and inhale the air acting upon the air in the same way that the plane iron of a hand
plane shaves a piece of wood.
To further explain the nature of my invention I may state that if an elevation of
the fan be taken shewing all the blades or vanes, and the direction of rotation being
opposite to that of the hands of a watch, and as shewn in the drawing Fig. 1. the
outer part of the front of each blade shall present a convex curved surface and the
inner part (nearest to the spindle and with which the fan revolves) of each blade shall
present a concave curved surface on its front or forward side; the curve of the outer
part of each blade being struck from a point or centre behind the blade, and
the curve of the inner part being struck from a point or centre in front of the
blade. The front being that surface of the blade facing the direction of rotation.
I prefer to form the blades so that the edges or sides of the blades are slightly
in advance of the middle parts of the blades, as shewn in Fig. 2. this gives to
the air a tendency to pass or move inwards towards the middle of the fan, and
so tends to equally distribute the moving air over the whole of the surface of
the blades.
The drawings annexed shew an example of a centrifugal fan constructed as above
described.
Fig. 1. is an elevation shewing the concave and convex curves of the blades.
Fig. 2. is an elevation at right angles to Fig. 1. and shewing that the faces
of the blades are not at a right angle with the centre plate on which they are
secured. Like figures refer to like parts on both drawings.
A is the front convex part of the blade B. C. is the front concave part of the same
blade B. D. is the centre plate on which all the blades are secured. E is the angle
which forms the flange of the blade. F is the flanged coupling between the faces of
which the centre plate is held. G is the shaft or spindle on which and with which the
fan revolves.

page_text: Having now particularly described and ascertained the nature of my inven-
tion and in what manner the same is to be performed, I declare that what 1
claim is :-
1. The particular shape of fan blades somewhat of the form of the letter S the
part of the blade nearest the centre of the fan presenting a thin edge in the direction
of rotation.
2. A fan having blades, the working or front faces of which possess both convex
and concave curves these faces not being at right angles to the centre plate, the outsides
or edges (farthest from centre plate) of the blades being in advance of the edges
nearest to the centre plate.
3. The form of fan blades in combination with the working faces of the same being
at an acute angle with the centre plate, substantially as hereinbefore described and
illustrated by the drawing annexed."