Improvements in Centrifugal Fans and Pumps.
Year: 1898

page_text: Date of Application, 13th Dec., 1898
Complete Specification Left 4th Sent 1800 Accented 7th Oct
1000
PROVISIONAL SPECIFICATION.
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 centrifugal fans and pumps and the improve-
ments relate more particularly to the construction of the enclosing cover or
casing (hereinafter called the casing) of the type of centrifugal fans or pumps
(hereinafter referred to as the fans) in which the fluid operated on is drawn in
axially and discharged circumferentially into and through the casing which
consists mainly of a spirally formed duct or passage around the fan.
In the construction of said casing as hitherto ordinarily made, the inlet
aperture therein for admitting the fluid to the eye of the fan, is considerably
smaller than, and usually about one-half the diameter of that of the clear outer
circumference of the fan, and the insertion of the fan into its position or its
withdrawal from the casing has consequently to be provided for by having the
main body of the casing made in two or more detachable sections, which have to
be taken asunder to admit of the fan being inserted into or withdrawn from
the interior of said casing. This construction of the casing with detachable
sections, involves a greater cost in manufacture, and its strength and rigidity
are less than if it were made as one integral structure, and so arranged that the
fan could nevertheless be easily inserted or withdrawn, and its spindle or shaft
adjusted satisfactorily in its bearings.
Accordingly, the objects amongst others of my invention are to so construct
the main body of the casing, that it shall consist of one integral part, and at
same time be provided with a convenient and suitable device or arrangement
whereby the fan can be inserted or withdrawn from the interior of said casing,
its spindle or shaft properly adjusted in its bearings and the strength and
rigidity of the casing increased at a less cost for manufacture, than if it were
made in two or more sections detachable from one another.
According to my invention I construct the enclosing casing from the circum-
ference of the fan outwards, as one integral part, with a circular aperture, con-
centric with the fan (hereinafter called the aperture) on both sides of said casing,
and one (or, under certain circumstances, each) of which apertures admits the
fluid into the eye and is of sufficient diameter to freely allow of the fan being
inserted through same into, or withdrawn from the interior of the casing, and
its spindle inserted into and adjusted in its bearings.
Around said apertures I have a projecting ring (hereinafter called the fixed
ring) of equal diameter to that of said apertures, bolted or otherwise securely
attached to the casing, and within this fixed ring another ring (hereinafter called
the cone ring) which on the side or sides through which the fluid enters the fan,
tapers from the mouth of said fixed ring inwards towards the fan, in the form
of an annular cross section of a hollow cone, so that the inner diameter of the
open space within said cone ring corresponds with the diameter of the intake
opening or eye to the fan blades, which construction of said cone ring causes a
gradual concentration of the current of fluid passing into the fan, up to the entry

page_text: into said eye, whereby the detrimental effect of what is known as "vena con-
tracta" at the entrance of said current into the fan eye, is reduced to a minimum.
When the construction of the fan is such that the fluid enters it from one
side only, and the bearings for the fan spindle are on the other side, so that the
fan is overhung therefrom, the aperture and fixed ring on this side of the casing
are preferably smaller than the circumference of the fan and the fixed ring has
the fan bearings centrally supported within it by stay rods under a tensile strain
between said ring and said bearings; but when I employ a cast metal bracket
instead of said fixed ring the bearings for the fan spindle form an integral part
thereof, and in either case the cone ring may be dispensed with, as in this con-
struction of fan no current of fluid enters the blades through the aperture on
this side as it is practically closed by the disc on which the fan blades are
mounted; but should the fan be so constructed that the fluid enters it from both
sides of the casing, and its bearings are at both ends of the spindle, then in such
modification I employ the cone ring, or an equivalent device thereto, in conjunc-
tion with either the fixed ring or the cast-metal bracket; and in either of the
above modifications, and to prevent said fixed rings or cast-metal brackets having
any inward or outward spring or vibration, owing to the sides of the casing
around the apertures being deficient in rigidity, I attach struts from the exterior
of the projecting edge or edges of the fixed ring or cast-metal bracket, as the
case may be, in approximately radial lines from the spindle of the fan to the
outer edges or angles of the casing, whereby said fixed ring or cast metal bracket,
and the fan bearings therein, are held in position with rigid firmness.
Total + 191
11900
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:-
This invention has reference to centrifugal fans and pumps and the improve-
ments relate more particularly to the construction of the enclosing cover or
casing (hereinafter called the casing) of the type of centrifugal fans or pumps
(hereinafter referred to as the fans) in which the fluid operated on is drawn in
axially and discharged circumferentially into and through the casing which
consists mainly of a spirally formed duct or passage around the fan.
In the construction of said casing as hitherto ordinarily made, the inlet
aperture therein for admitting the fluid to the eye of the fan, is considerably
smaller than and usually about one-half the diameter of that of the clear outer
circumference of the fan, and the insertion of the fan into its position or its
withdrawal from the casing has consequently to be provided for by having the
main body of the casing made in two or more detachable sections, which have to
be taken asunder to admit of the fan being inserted into or withdrawn from
the interior of said casing. This construction of the casing with detachable
sections, involves a greater cost in manufacture, and its strength and rigidity
are less than if it were made as one integral structure, and so that the fan could
nevertheless be inserted or withdrawn, without having to take asunder any
portion of the main body of the casing itself.
Accordingly, the objects amongst others of the invention are to so construct

page_text: the main body of the casing, that it shall consist of one integral part, and 'at
same time be provided with a convenient and suitable arrangement whereby the
fan can be inserted into or withdrawn from the interior of the casing, and its
strength and rigidity increased at a less cost of manufacture, than if it were
made in two or more component sections detachable from one another:
According to the invention, the enclosing casing from the circumference of
the fan outwards is constructed as one integral part, with two circular apertures
of equal diameter concentric with the fan (hereinafter called the apertures).
one on each side of said casing, and one (or, under certain cir-
cumstances, each) of which apertures admits the fluid into the eye of the fan,
through an annular mouthpiece mounted around it, while an annular bracket
containing the fan spindle or shaft is mounted around the other aperture."
Both apertures are of sufficient diameter to freely allow of the fan being in-
serted through same into or withdrawn from the interior of the casing, and each
being of equal diameter to the other, and the casing surrounding same being
duplicated for connection thereto of the bracket containing the bearing of the
fan shaft, or for the annular mouthpiece through which the fluid is admitted
into the eye of the fan, these can be applied on either side of the casing as may
be required to suit the position in which the fan may have to be located in actual
operation, and it is of much practical advantage to have the fan casing and mount-
ings thereon so constructed that the bracket for the fan bearing on the one side,
and the annular mouthpiece on the opposite side, can be reversed when necessary,
without involving any structural changes or adjustments in the casing. itself.
The annular mouthpiece around the apertures through which the fluid enters
the eye of the fan, consists of a projecting ring (hereinafter called the fixed
ring) of equal diameter to that of said aperture, bolted or otherwise securely
attached to the casing, and within this fixed ring another ring (hereinafter
called the cone ring) which tapers from the mouth of said fixed ring inwards to-
wards the fan, in the form of a hollow cone, so that the inner diameter of the
open space within said cone ring corresponds with the diameter of the intake
opening or eye to the fan blades. This construction of said cone ring causes a
gradual concentration of the current of fluid passing into the fan, up to the
entry into said eye, whereby the detrimental effects of what is known as " rena
contracta at the entrance of said current into the fan eye, is reduced to a
minimum.
33.
Around the opposite aperture to that through which the fluid enters the eye
of the fan is mounted an outwardly projecting ring or annular bracket (herein-
after called the annular bracket) in which the bearing wherein the fan spindle
rotates is centrally supported by stays acting under tension between the ends
of said bearing and the annular bracket which on the end next the fan has an
inwardly turned flange the interior diameter of which is less than the exterior
diameter of the fan disc so that the outer edge of the latter projects beyond the
inner edge of the former, whereby the passage of air between them is prevented.
The improved construction of casing is suitable for employement with any
type of centrifugal fan, but in the accompanying drawings it is illustrated as
adapted to a special construction in which the intake opening or eye thereto is
of equal diameter to that of the fan itself.
In the accompanying drawings,--
Figure 1 is a sectional elevation at right angles to the axis of the fan, through
the line A B of Figure 2.
Figure 2 is a cross-section through the axis of the fan, on the line C D of
Figure 1.
a a are the two vertical sides of the fan casing and b b are two continuous
angle irons to which said sides a a are respectively attached, e is the delivery
nozzle or port. d is a sheet rivetted to the angle irons b b and constituting the
circumferential wall of the casing and also forming the outer wall of the spiral
duct between the fan and the casing. The angle irons bb form the outer angles

page_text: or corners of the spiral duct and extend from the angle iron e at the top side of
the nozzle c all round the casing to the angle iron f at the lower side of said
nozzle; but for convenience of manufacture the said angle irons b b are carried
vertically from the top side e of the nozzle and therefore diverge at this part
from the starting point of the spiral curvature of the spiral duct, the continuation
of which from the top of said vertical line is effected by means of a bent sheet g;
this sheet may be conveniently secured in position by attachment at one end to
the angle iron e and by flanges secured to the vertical sides a a of the casing.
The two sheets forming said vertical sides a a are carried down so as to con-
stitute a pedestal h and rivetted thereto are outer angle irons ii by which the
base of the fan may be firmly secured to the ground or floor by bolts or otherwise.
The necessity for a basement pedestal, which hitherto has usually been made
in the form of an iron casting is thus obviated, the result being a lighter and
cheaper construction of fan casing than hitherto made. are apertures in the
two vertical sides a a respectively; they are concentric with the fan and are
preferably of equal diameter as shown and sufficiently large to admit of the
fan being readily passed through either aperture as may be required so that
when the fan has to be inserted into or withdrawn from the casing this can be
done through one of the apertures and so that the annular bracket t and
fixed ring may be applied to either aperture as may be required to suit the place
or position in which the fan has to work. Around each of the apertures kl
and on the inner face of the casing sides a a in order to strengthen the same I
mount an angle iron m and firmly rivet or otherwise secure it to the correspond-
ing side a of the casing.
r is the
nn are the fan blades; they are mounted at one end on a disc o and at their
other or intake ends they are secured to each other by an enclosing iron ring p.
The disc o is shown as mounted upon a conical centre piece or boss g.
fan spindle. It rotates in bearings s s which are centrally supported within an
annular bracket t by means of stay rods u u acting under tension and extending
between the bearings s. s and the bracket t. This bracket is strengthened by.
external angle iron rings vv mounted upon its outer face and it is bolted by
means of the inner of these rings to the side a of the casing around the aper-
ture. The bracket t extends inwardly beyond the said ring to the point w
and around such extended portion an angle iron ring a is mounted; one of the
flanges of this ring is turned inwards towards the centre of the aperture so
that the diameter of the open circle between the inner edges of the ring
less than the outer edges of the fan or of the fan disc o. yy are connecting
struts or stays extending from the outer angle iron ring of the bracket to
the outer edge or corner of the casing; these struts or stays y y firmly hold the
bracket and its centrally located bearings ss in proper position relatively to
the casing and with perfect rigidity.
4.
is
Around the aperture & through which the entering fluid is admitted to the
eye of the fan is a fixed ring or annular mouthpiece attached to the side a of
the casing by means of the angle iron ring 1. 2 is another angle iron ring
around the outer edge of the fixed ring z and 3, 3 are struts or stays extending
from the ring 2 to the outer edge or corner of the casing for a similar purpose
to that described with reference to the struts yy.
4 is an annular cone ring within the fixed ring it tapers inwardly from
the outer edge of the ring so that the diameter of the inner end of the cone
ring 4 shall correspond with that of the intake opening or eye of the fan blades.
The cone ring 4 is temporarily removed when the fan is being inserted or with-
drawn. The fixed ring z serves not only to support the angle iron ring 2 and the
outer end of the cone ring 4 but also to prevent any of the current of fluid escap-
ing from the fan casing around the outside of the cone ring 4.
The struts or stays yy in combination with the fixed annular bracket ton
one side of the fan casing and the struts or stays 3, 3 in combination with the
fixed ring z on the other side of the fan casing practically make the whole frame-

page_text: work of the casing a sort of lattice girder whereby lightness of construction is
combined with rigidity and strength. This combination in conjunction with
the facility with which the fan can be inserted into or withdrawn from the
casing and with which the annular mouthpiece for the inflow of the fluid, and
the annular bracket for the bearing for driving shaft of the fan can be optionally
applied to either side of the fan casing, so that the fan can be driven on either
side of the casing as required, without necessitating any alteration of the casing
itself, is of much practical importance and utility.
And 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 a centrifugal fan or pump having a spirally formed casing around its
circumference, a casing having a main body in one integral part and an aperture
on both sides of said casing concentric with the fan or pump and sufficiently
large for the fan or pump to be inserted or withdrawn through same, substan-
tially as and for the purposes herein before described.
2. In a centrifugal fan or pump having a spirally formed casing around its
circumference, the combination with a casing having the main body thereof in
one integral part and a fluid inlet aperture on one side of said casing concentric
with the fan or pump and sufficiently large for the fan or pump to be inserted
or withdrawn through same, of a projecting ring attached to said casing around
said aperture and an annular cone ring within said projecting ring fitting closely
at its outer edge within said projecting ring and tapering inwards thereform, to
the eye of the fan or pump with which its inner edge corresponds in diameter
substantially as and for the purpose set forth.
3. In a centrifugal fan or pump having a spirally formed casing around its
circumference, the main body of said casing being formed as one integral part
and having a fluid inlet aperture at one side of said casing and an aperture at
the other side of said casing, both said apertures being concentric with the fan
or pump, the combination with the second named aperture of an annular bracket
fixed around said aperture, centrally located bearings for the fan or pump
spindle and stay rods under tensile strain between said bearings and said bracket,
substantially as and for the purpose set forth.
4. In a centrifugal fan or pump having a spirally formed casing around its
circumference, the main body of said casing being formed as one integral part
and having an aperture on both sides of said casing concentric with the fan or
pump and of sufficiently large diameter to admit or withdraw the fan through
either, the combination with projecting rings attached to the casing around said
apertures of struts extending from the outer edges of said projecting rings to the
corresponding outer edges or corners of the casing, substantially as and for the
purpose set forth.
5. The combination of parts substantially as herein before described and shown
in the drawings constituting an improved centrifugal fan or pump.
1
eal1800
J. C. MEWBURN & ELLIS,
55 and 56, Chancery Lane, London, Chartered Patent Agents.