Improvements in Centrifugal Fans and Pumps.
Year: 1899

page_text: Improvements in Centrifugal Fans and Pumps.
I, SAMUEL CLELAND DAVIDSON, of Sirocco Engineering Works, Belfast, Ireland,
Merchant, do hereby declare the nature of this invention to be as follows;
-
My invention has reference to the class or type of rotary fans or pumps in
which the fluid operated on is drawn in axially and discharged circumferentially,
and relates more particularly to the mounting of the blades in the fans or pumps
(hereinafter included in the word "fans") described in the Specification of
previous Letters Patent granted to me and dated 24th February 1898 No. 4609,
and hereinafter referred to as my previous Specification.
In said previous specification the fan blades are described as mounted upon
one or both sides of a disc or its equivalent, to which they are attached, but in
my hereinafter described invention, while I still employ a disc or radiating armis
or spokes for carrying the blades on the central hub of the fan as the equivalent
in operative effect of a disc as defined in my previous specification, I now employ
therewith improved devices as hereinafter described for connecting the blades
thereto, or mounting them thereon, and the object of my present invention is to
render the fans described in my previous specification better adapted for some
specific conditions under which they may sometimes have to be employed and
said improvements, in combination with the fans described in said previous
specification are of practical utility.
According to one modification of my invention, I employ blades which may be
of any of the types and similarly arranged relatively to one another and to the
axis of the fan as described in my previous specification, and I connect them
to one another at their respective ends by an encircling ring or annulus to the
inuer face of which they are rivetted, or otherwise securely attached, and through
suitable orifices (or their equivalent) in lips or brackets upon said encircling rings,
arms, stay rods or spokes (hereinafter called spokes) are projected from the hub
or centre of the fan wheel. The outer ends of said spokes are screwed and fitted
with nuts on the outer sides of the brackets of the encircling rings so that by
carefully screwing up the nuts on said spokes the encircling rings may be drawn
up to truly revolving circles relatively to the centre of the hub. The hub is then
mounted upon or keyed to a shaft or spindle revolving in suitable bearings, and
by this modification the fan as a whole can be made of a very light and, at
same time, strong construction.
According to a second modification, instead of having the spokes attached to
the encircling rings at the opposite ends of the blades, I may alternatively, and
In addition to said encircling rings employ an encircling hoop around the outer
edges of the central portion of the blades and to which hoop the said blades may

page_text: also be rivetted, and through equi-distant orifices around said hoop the outer ends
of the spokes are projected from the hub, and drawn up into tension as described
in previous modification, so that said encircling hoop will revolve in a true circle
around the centre of the hub.
Or according to a third modification, this central hoop may be attached to the
inner edges of the blades, and the spokes employed therewith similarly to the
second described modification.
Or according to a fourth modification, the encircling rings enclosing the extreme
ends of the blades may be dispensed with, and two encircling hoops employed
instead, a short distance inwards from each end, and to which the outer (or
alternatively, as a further modification) the inner edges of the blades may be
rivetted, and the spokes from the hub connected therewith, and drawn into
tension by nuts on the outer side of said encircling hoops in the same manner as
already described in respect of the second and third modifications.
According to a fifth modification, in lieu of the above described spokes,. I employ
a perforated or solid disc mounted upon a projecting flange around, or which
may form a part of, the central hub of the fan, with a single or double flange
around its periphery, to which the inner edges of the blades when suitably bent
therefor, may be rivetted at preferably midway between their ends and which
may, to give the blades more rigidity, be connected to one another by an encircling
ring around the extreme opposite ends of the blades, as in the first, second and
third of the above described modifications.
Dated this 95th day of September 1899
J. C. MEWBURN & ELLIS,
55 and 56, Chancery Lane, London, Chartered Patent Agents.
Improvements in Centrifugal Fans and Pumps.
I, SAMUEL CLELAND DAVIDSON, of Sirocco Engineering Works, Belfast, Ireland,
Merchant, 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 reference to the class of rotary fans or pumps (hereinafter
called the fans) in which the fluid operated on is drawn in axially and discharged
circumferentially, and in which the fan blades are of greater axial length than
radial depth, and are arranged in drum form around a hub or operating shaft,
so as to enclose within their inner edges a practically unobstructed intake chamber
of relatively large diameter; and more particularly to the type of such fans
described in the Specification of previous Letters Patent granted to me and dated
24th February 1898, No. 4609 (hereinafter referred to as my previous specification).
In said previous specification the fan blades are described as mounted upon one or
both sides of a disc or its equivalent, to which they are attached, but in my herein-
after described invention, while I continue to employ either a dise or radiating arms
or spokes for carrying the blades on the central hub of the fan as the equivalent
in operative effect of a disc as defined in my previous specification, I now employ
therewith improved devices as hereinafter described for connecting the blades
thereto, or mounting them thereon and the object of my present invention is to
render the fans described, in my previous specification better adapted for some
specific conditions under which they may have to be employed, and said improve-

page_text: ments, in combination with the fans described in said previous specification are
of practical utility.
According to one modification of my invention, I employ blades which may
be of any of the types and similarly arranged relatively to one another and to
the axis of the fan as described in my previous specification, and I connect them
to one another at their respective ends by an encircling ring or annulus (herein-
after called the ring) to the inner face of which ring the blades are rivetted, or
otherwise securely attached, and said rings are then mounted on the outer ends
of said arms, stay rods or spokes (hereinafter called spokes) so that said rings
and their attached blades are rigidly connected to the revolving hub or centre of
the fan wheel.. The outer ends of said spokes are screwed and fitted with nuts
on the outer sides of the rings or to brackets or flanges thereon so that by care-
fully screwing up the nuts, said spokes are brought into tensile strain, and by
careful adjustment of this strain on the individual spokes, the rings are thereby
drawn up to truly revolving circles relatively to the centre of the hub. The hub
is then mounted upon or keyed to a shaft or spindle revolving in suitable bear-
ings, and by this modification the fan as a whole can be made very light and, at
same time, of very strong construction.
According to a second modification, instead of having the spokes attached to
the encircling rings at the opposite ends of the blades, I may alternatively, and
in addition to said encircling rings employ an encircling hoop around the outer
edges of the central portion of the blades and to which hoop the outer edges of
said blades may also be rivetted, and through equi-distant orifices around said
hoop the outer end of the spokes are projected from the hub, and drawn up into
tension as described in previous modification, so that said encircling hoop will
revolve in a true circle around the centre of the hub and as a rigid connection.
thereto.
Or according to a third modification, this central hoop may be attached to the
inner edges of the blades, and the spokes are employed therewith similarly to the
second described modification.
or
Or according to a fourth modification, the rings enclosing the extreme
ends of the blades may be dispensed with, and two encircling hoops employed
instead, a short distance inwards from each end, and to which the outer
(alternatively, as a further modification) the inner edges of the blades may be
rivetted, and the spokes from the hub connected therewith, and drawn into
tension by nuts on the outer side of said encircling hoops in the same manner as
already described in respect of the second and third modifications.
According to a fifth modification, in lieu of the above described spokes, I employ
a perforated or solid disc mounted upon a projecting flange around, or which may
form a part of, the central hub of the fan, with a single or double flange around
its periphery, to which the inner edges of the blades may be rivetted at preferably
midway between their ends, and which may, to give the blades more rigidity, be
connected to one another by an encircling ring around the extreme opposite ends
of the blades, as in the first, second and third of the above described modifications.
Or said centrally located hoop may encircle and be rivetted to the outer edges
of the blades, and be attached by screws or bolts through the flange or flanges
around the periphery of the disc and through said encircling hoop. In this modifi-
cation the periphery of the disc is preferably a slack fit in respect of the inner
edges of the blades, so as to slide freely into position within same, and the tighten-
ing up of the nuts on the outer face of the encircling hoop puts the bolts on
which they operate into tensile strain between said hoop and the periphery of
the disc, and the proper adjustment of said nuts draws said hoop and the blades
attached thereto into a truly revolving circle around the centre of the hub. More
than one perforated disc may be employed according to the length of the fan
blades.
In the accompanying drawings I have shown by way of example several forms

page_text: of my invention as applied to a fan of the general construction set forth in my
British Specification No. 4609 of 1898.
Figure 1 is a vertical mid-section of the preferred form of my invention, taken
on the line 1-1 in Figure 2, and showing the rotary member mounted in a
suitable casing;
Figure 2 is a vertical section taken on the line 2-2 in Figure 1;
The remaining figures show the rotary member of the fan removed from the
casing and on a larger scale.
Figure 3 is a mid-cross section, and Figure 4 is a diametrical section of the
construction shown in Figures 1 and 2;
Figure 5 is an end view, and Figure 6 is a diametrical section of a modified
construction in which the fan blades are supported at two points inwardly of their
ends by encircling rings;
Figure 7 is an end view, and Figure 8 is a diametrical section, of a modifi-
cation in which the blades are supported upon two rings arranged interiorly of
the blades;
"
Figure 9 is an end view, and Figure 10 is a diametrical section of a modifi-
cation in which the blades are supported upon three exterior annular supports.
Figure 11 is an end view, and Figure 12 is a diametrical section, of a modifi-
cation of Figure 9, the end supports being exteriorly arranged, and the middle
support interiorly arranged;
Figure 13 is an end view, and Figure 14 is a diametrical section of a modifi-
cation in which the blades are mounted upon two outer end supports and a middle
support, the latter being in the form of a disc.
Figure 15 is an end view,. and Figure 16 is a diametrical section of a modifi-
cation in which the blades are mounted upon a central outer support connected
to a middle support in the form of a disc.
Figure 17 is an end view, and Figure 18 is a diametrical section of a modifi-
cation in which the ports between the blades are closed.
In the drawings, A is the rotary member or fan, B its blades, C its operating
shaft, and D a casing within which the fan A is mounted.
Referring first to Figures 1 to 4 inclusive the blades B are shown as fixed upon
the inner sides of two annular supports or rings E E, which encircle the blades
at their ends, the latter being secured to the rings by rivets passing through
the rings and through flanges b formed on the ends of the blades. Any other
suitable means of fastening the blades to the supports may be employed. The
latter are preferably formed with perpendicular flanges e so as to stiffen them
and make them better resist the strains of use.
The fan is connected to its hub F by stays G, of which eight are shown, and
which at their inner ends are suitably fastened to the hub, preferably by screws
as shown. At their outer ends the stays G engage the rings or supports EE,
preferably by passing through plates or brackets H, fixed to said supports, being
secured to said brackets by nuts g. The rotary member or fan may be trued or
drawn to concentric form by the nuts g during manufacture or subsequently in
case the rotary fan or any part thereof assumes a position excentric to its operating
shaft. By the construction just described the rotary fan is supported in a very
strong and lasting manner, and it will be observed that as it is held from a central
hub the fan is balanced, that is to say, the pressure of the air and the strain of
centrifugal force act substantially alike upon both ends of the fan, and the tendency
to distortion is to a large extent avoided.
While fans of this construction may be operated with good results within a
casing with a single eye, I prefer that the intake to the rotary fan shall be through|
both ends thereof. I therefore form the casing D with two eyes dd, which are
oppositely arranged, and are of a diameter equal to that of the intake chamber;
or preferably when the ports between the blades of the fan are open at their
ends, the eyes may advantageously be of the full exterior diameter of the fan.
These ports may be closed at their ends, as shown in Figures 15 and 16, but in

page_text: that case the efficiency of the fan is somewhat decreased. Each of the eyes d
is preferably provided with a mouth d' for directing the air into the eyes. The
shaft bearings I may be constructed and supported in any suitable way; prefer-
ably they are connected to the mouths by suitable braces J, as shown in
Figure 2; this construction of bearings is set forth in my British Patent. No. 19,388
dated 12th. September 1898.
This preferred construction, where the fan takes in air at both ends of the
intake chamber, by doubling the area of intake, has the important advantage of
practically increasing the intake opening of a fan of a given diameter, and hence
the volumetric efficiency of the fan may be increased by increasing its length,
the diameter remaining the same.
In Figures 5 and 6 I have shown a modified form of my invention in which the
supports E are arranged inwardly of the ends of the blades, being formed prefer-
ably with inclined bearing faces 'h, which are engaged by the nuts g on the
stavs G.
Figures 7 and 8 illustrate a modified construction of Figures 5 and 6, in that
the supports are arranged interiorly of the fan blades, and engage the inner ends
of the blades. The flanges 6 are here formed on the inner edges of the blades
and are rivetted to the supports in the manner before described.
In Figures 9 and 10 the construction of Figures to 4 is modified in that while
the outer supports E E are still employed, a third support or hoop E is centrally
arranged exteriorly of the blades, and to this central support the stays G are
connected. In this case suitable flanges b' are formed on the inner edges of the
blades, which are rivetted to the support E¹. bod
Figures 11 and 12 show a similar construction; the central support E¹ in this
case being arranged interiorly instead of exteriorly as in Figures 9 and 10.
In Figures 13 and 14 the central support E is formed integrally with the hub,
a solid disc or web G¹ being in this case substituted for the stays G. The disc
or web G¹ may thus constitute a wall dividing the cylindrical intake chamber;
or it may be perforated, as shown in dotted lines at g3 in Figure 13, in which case.
more than one perforated disc or web may be employed according to the length
of the fan blades.
In Figures 15 and 16, the blades are carried by a centrally located outer support
or hoop E2 which encircles their outer edges and is attached to a middle support-
ing disc G¹ by means of stay bolts H that screw into the periphery of the disc:
Flanges bare formed on the blades for rivetting to the support E2. The periphery
of the disc G¹ which is suitably formed with lateral strengthening flanges E,
stops short of the inner edges of the blades B as shown but may in some cases
be made a sliding fit against the said inner edges.
The tightening up of the stay bolts H puts the same into tensile strain, and
their proper adjustment draws the support or hoop 12 and the blades attached
thereto into a truly revolving circle around the centre of the hub F.
The disc G¹ may be formed as in Figures 13 and 14, with perforations 92 as
indicated in dash dotted lines in Figure 15, and more than one perforated disc
may be employed. Where additional strength is required, the blades may be
further formed at their ends or their outer edges with flanges b for rivetting to
outer annular supports E of the kind shown in Figures 13 and 14. This arrange-
ment is indicated in dash dotted lines in Figure 16.
In the construction shown in Figures 17 and 18 the supports E E are arranged
on the outer edges of the blades, inwardly of the ends, in a manner similar to
the construction shown in Figures 5 and 6. In this case loose triangular blocks h¹
may be placed on the supports E E to form bearing faces for the nuts g of the
stays G. The spaces or ports between the blades B are shown as closed by the
supports E the latter constituting flat rings arranged at the ends of the blades.
The blades in this case are preferably formed with square ends, which are formed
with suitable flanges 62 by which they are connected to the rings E by rivets as
shown. While ordinarily prefer that the ports between the blades should be.

page_text: open, yet when operating upon a heavy fluid, as water, I find that the construction
just described is advantageous, because the ends of the blades are thus strongly
and rigidly supported.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is-
1. In centrifugal fans or pumps of the class herein before referred to, the employ-
ment of means for attaching and connecting the fan or pump blades to the hub
or operating shaft, substantially as and for the purposes described and as repre-
sented in the accompanying drawings.
2. In centrifugal fans or pumps of the class hereinbefore referred to, the com-
bination with the fan or pump blades and the hub or operating shaft, of one or
more rings, hoops or other annular supports to the inner or to the outer faces of
which the said blades are attached, with arms, rods or spokes extending from said
annular support or supports to said hub or operating shaft, substantially as and
for the purposes described and as represented in the accompanying drawings.
3. In centrifugal fans or pumps of the class herein before referred to, the com-
bination with the fan or pump blades and the hub or operating shaft, of one or more
rings, hoops or other annular supports to the inner or to the outer faces of which
the said blades are attached. with arms, rods or spokes extending from said annular
support or supports to said hub or said operating shaft, and one or more additional
rings, hoops or other annular supports to the inner or to the outer faces of which
the said blades are also attached. substantially as and for the purposes described
and as represented in the accompanying drawings.
4. In centrifugal fans or pumps of the class herein before referred to, the com-
bination with the fan or pump blades and the hub or operating shaft, one or more
perforated supporting webs or discs, or a single imperforate supporting web or
disc, fixed to said hub or said operating shaft and to or near the periphery of which
the said blades are attached, substantially as and for the purposes described and
as represented in the accompanying drawings.
5. In centrifugal fans or pumps of the class herein before referred to, the com-
bination with the fan or pump blades and the hub or operating shaft, of one or
more perforated supporting webs or discs, or a single imperforate supporting
web or disc, fixed to said hub or said operating shaft and to or near the periphery
of which the said blades are attached, with one or more rings, hoops or other
annular supports to the inner or to the outer faces of which the said blades are
also attached, substantially as and for the purposes described and as represented
in the accompanying drawings.
6. In centrifugal fans or pumps of the class herein before referred to, the com-
bination with the fan or pump blades and the hub or operating shaft, of a centrally
located perforated or imperforate supporting web or disc fixed to said hub or said
operating shaft and formed with a peripheral flange or flanges fitting the inner
edges of the said blades, with a centrally located ring, hoop or other annular support
encircling the outer edges of the blades and to the inner face of which the said
blades are attached, and means for connecting the said ring, hoop er other annular
support to the peripheral flange or flanges of the said web or disc, with or without
further encircling rings or other annular supports at the intake ends of the blades,
substantially as and for the purposes described and as represented in the accom-
panying drawings.
7. In centrifugal fans or pumps of the class herein before referred to, the com-
bination with the fan or pump blades and the hub or operating shaft. of one or
more rings, hoops or other annular supports to the inner or to the outer faces of
which the said blades are attached, with arms, rods, or spokes, or one or more
perforated supporting webs or discs or a single imperforate web or disc connected
to and extending from said annular support or supports to said hub or operating
shaft, and with one or more additional rings or other annular supports to which

page_text: the said blades are attached at one or at both ends, substantially as and for the
purposes described and as represented in the accompanying drawings.
8. Centrifugal fans or pumps, constructed, arranged and operating all substan-
tially as and for the purposes described and as represented in the accompanying
drawings.
iloted thi. 05th 1
T
1000
J. C. MEWBURN & ELLIS,
55 and 56, Chancery Lane, London, Chartered Patent Agents.