Improvements in Centrifugal Fans.
Year: 1891

page_text: Date of Application, 23rd Jan., 1891
Complete Specification Left, 23rd Oct., 1891-Accepted, 28th Nov., 1891
PROVISIONAL SPECIFICATION.
Improvements in Centrifugal Fans.
I, GEORGE MARIE CAPELL, of Passenham Rectory, in the County of North-
ampton, Clerk in Holy Orders, do hereby declare the nature of this invention to
be as follows:-
My invention has for its object the regulation of the air-flow in centrifugal fans.
I have found from experiment that the air is discharged in gradually increasing
volume on the side on which the inlet is placed; and it is very desirable to remedy
this tendency, and to get a more equal flow of air over the discharging blades.
In carrying my invention into effect, I use inner and outer blades, as in my
former Patents 3130 and 311783. The inner blades dip into the circle forming the
inlet, and are placed diagonally to the axis of the fan at a suitable angle, according
to the special requirements of each case. The ends of the blades on the inlet side
are in advance of the ends at the side opposite the inlet, this advance being in the
direction of rotation. The outer blades are placed parallel with the axis, and meet
the inner blades at the side opposite the inlet. Thus a triangular blank piece of
the inner or outer blades forms the connection between each pair of inner and outer
blades. These blades may be united to each other by rivetting or any suitable
device. The blades have side discs on each side to which they are directly
secured.
Fans made according to the present invention may have either one or two
inlets. On the outer side, around the inlet, I place a baffle-ring secured to the disc
to form the joint between the fan and its casing in a closed fan, and with the framing
or masonry of the air-drift, if an open fan.
This ring may be prolonged outwards towards the air-passage leading to the
inlet, in cases where it is desirable to increase the width of the inner blades, which,
acting like a screw propeller, by reason of their diagonal position, sweep the air
into the body of the fan, towards the side opposite to the inlet, to be discharged
by the parallel outer blades into the casing or the atmosphere.
The fan is provided with a suitable boss for the shaft, and has a boss with arms
on the inlet side also.
In large fans with double inlets, I build two fans on a strong dividing disc, and
form an inlet on each side.
I may employ an expanding spiral casing; and in large exhaust fans, I may use
an expanding Evasé chimney fixed to the casing as an outlet.
The fans have the usual supports and bearings. The blades may be either straight
or curved.
Dated this 23rd day of January 1891.
PHILLIPS & LEIGH,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Centrifugal Fans.
1, GEORGE MARIE CAPELL, of Passenham Rectory, in the County of North-
ampton, Clerk in Holy Orders, 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 has for its object the regulation of the air-flow in centrifugal fans.
I have found from experiment that the air is discharged in gradually increasing

page_text: volume on the side on which the inlet is placed; and it is very desirable to remedy
this tendency, and to get a more equal flow of air over the discharging blades.
In carrying my invention into effect, I use inner and outer blades, as in my
former Patents Nos. 3130's and 311783. The inner or collecting blades dip, into
the circle forming the inlet, that is to say they are continued by the side of the said
inlet пр to within a certain distance of the fan shaft, as in the said previous Patents,
but they are placed diagonally to the axis of the fan at a suitable angle, according
to the special requirements of each case. How this angle is settled so as to secure
the maximum effect is specified further on. The ends of the blades on the inlet
side are in advance of the ends at the side opposite the inlet, this advance being
in the direction of rotation: The outer blades are placed parallel with the axis,
and meet the inner blades at the side opposite the inlet. Thus a triangular or
approximately triangular blank piece, are shaped in side elevation, forms the
connection between each inner and outer blade. These blades may be united
to each other by rivetting or any suitable device and are secured to two side discs.
Fans made according to the present invention may have either one or two inlets.
On the outer side, around the inlet, I fix a baffle ring. This is secured to the
respective disc, and its function is to make the joint between the fan and its casing
in a closed or blast fan, and with the framing or masonry of the air-drift, in the case
of an open or exhaust fan..
This ring may be prolonged outwards towards the air passage leading to the
inlet, in cases where it is desirable to increase the width of, or prolong the inner
blades, which latter acting, by reason of their diagonal position, like a screw
propeller, sweep the air into the body of the fan, towards the side opposite to the
inlet, from where it is discharged by the parallel outer blades into the casing or
into the atmosphere.
In order that my invention, and the means by which it is to be carried into
practical effect, may be thoroughly understood, I will now describe them in detail,
referring in so doing to the accompanying drawings which are to be taken as part
of this Specification and read therewith.
Fig. 1 illustrates a single inlet fan constructed according to my invention and
mounted in a casing with an expanding Evasé chimney serving as an outlet. The
left-hand half is a sectional elevation of the internal, and the right hand half, of
the external construction.
Fig. 2 is a side elevation of the fan only.
Fig. 3 is an elevation, side as to the right half and sectional side as to the left
half of the figure, of my invention, illustrating two modifications.
Fig. 4 is a front elevation corresponding with Fig. 3.
Referring to Figs. 1 and 2, a, a are the outer; and b, b, the inner blades. The
former are shewn as, and may always be, curved to any suitable arc, but they are
always parallel with the axis of the fan. They are made fast to the side plates or
discs c, c, preferably, by means of angle irons and rivets.
The inner blades b, instead of being parallel with the outer ones, as it has
hitherto been the practice to make them, are set at an angle with the axis of the
fan. This angle may be varied according to the special requirements of the work
for which any particular fan is being made. The greater the volume of air required
per unit of time, the more acute must the angle be. The pressure at which the air
is delivered will of course, in any fan constructed according to the present invention,
increase with the volume. Besides, in the case of a wide fan, the said angle must
always be more acute than in a narrow. one, for the purpose of sweeping the air
more effectually into the spaces between the outer blades. In fact it is the power
of collecting an increased volume of air, that is one of the practical advantages of
my present invention, and at the same time one of its principal features.
It is to be noted that the ends d of the inner blades next to the inlet of, the fan.
are always in advance of the ends e of respectively the same blades on the opposite
side of the fan. is the consequent triangular, or approximately triangular, piece
connecting any outer to its respective inner blade. This piece may be of the shape

page_text: illustrated in Fig. 2, that is to say, a right angle triangle less its acute end, or it
may be a true triangle as illustrated by the dotted line in Fig. 2. q is a comple-
mentary triangular piece behind each outer blade, and its purpose is to make a side
to the opening or throat between the said and the next following blade, which
side shall be parallel with the face of the following inner blade, and at the same
time to contract the throat. But this piece 7 can be dispensed with, leaving the
throat irregular in outline. h is the baffle ring around the inlet. It is rivetted or
otherwise made fast to the adjacent disc c. The usual boss j is provided by which
the fan can be fixed to its shaft. j and k are respectively the boss and arms on
the inlet side of the fan.
Referring to Figs. 3 and 4, the nature of the modifications illustrated are as
follows:
According to one of these, the blades are straight instead of being curved as
illustrated in the foregoing figures, and according to the other of them, the baffle
ring is prolonged outwards towards the air passage, the inner blades being continued
along such prolongation. C' is the prolonged baffle ring and a', a¹, the prolonged
inner blades. The latter are straight if the inner blades b arc themselves straight.
If the latter are curved as represented in Figs. 1 and 2, then the prolongations a¹
will be curved. Straight prolongations as illustrated in Figs. 3 and 4 have their
leading side edges a³ curved forwards. The angle at which the prolongations a¹, a¹,
are set with the axis of the fan may be more acute than that of the respective
inner blades.
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,
1. In a centrifugal fan, the combination of outer blades parallel with the axis of
the fan and inner blades set at an angle with the said axis.
2. The combination with a centrifugal fan of the prolongation of a baffle ring
and prolongations of the inner wings of a fan, as and for the purpose herein before
set forth.
T111
tabox 1001
PHILLIPS & LEIGH,
22, Southampton Buildings, Chancery Lane, W.C.,
Agents for the Applicant.