Improvements in the Construction of Centrifugal Fans, and the Regulation of the Air Currents Passing Through the same.
Year: 1894

page_text: Date of Application, 3rd Dec., 1894
Complete Specification Left, 3rd Sept., 1895-Accepted, 12th Oct., 1895
Improvements in the Construction
of Centrifugal Fans, and the
Regulation of the Air Currents Passing Through the same.
I, GEORGE MARIE CAPELL, Clerk in Holy Orders, of Passenhamn. in the
County of Northampton, do hereby declare the nature of this invention to be as
follows:-
:-
My improvements consist of two parts (1) the lightening of the fan by special
construction and (2) the regulation of the passage of the air in the body of the fan
itself.
In the construction of this fan, I use a central disc in a double inlet fan, and
a side disc in a single inlet fan with driving boss attached in each case.
To the central disc I attach wings of suitable shape by angle irons running for
choice under the wings which if, the disc does not reach the periphery, may be cut
so as to admit the disc in the centre. The angle irons are secured to the disc and
the wings, leaving a space equal to the thickness of the disc between them.
Between these angle irons and near the periphery of the fan, I place two broad
strips of plate metal rivetted between the angle irons extending backwards from
the edge of each wing. These two strips of plate fall down towards the centre and
embrace the central disc for some distance, being securely rivetted to it. I also
stiffen the outer sides of the outer wings by a flat or half round bar rivetted from
a point about half the width of each outer wing and being brought at an angle to
the central disc and securely rivetted in pairs to each side of the disc for each
pair of wings. In some cases for great strength, I run angle irons along the outer
edges of the wings to which these are rivetted. To secure rigidity, I use a broad
angle iron hoop coming to the edge of the inlet. Under each wing edge and
extending towards the circumference, I use a gusset plate of metal secured to the
wing angles and to the angle iron hoop round the inlet. In the case of the inner
wings being placed in advance of the outer wings and a bent angle being employed,
extending the length of each wing and the interval between them, I use à plate
of triangular forin securing the outer wing angle iron, the interval portion, and the
portion of angle iron on the inner wings.
The outer angles attached to the wings are secured to a boss on the shaft and
form thus a rigid construction.
A single inlet fan can be formed on one disc as I have described. The next
point in construction is where in a fan having inner and outer wings, the inner
wings project towards the periphery beyond the inlet circle.
I find that I can make a strong construction thus: the outer wing joins an inuer
wing at a point usually a little within the inlet circle, forming an obtuse angle.
It is secured across its whole width to the inner wing. The inner wing projects
outwards towards the periphery beyond the inlet circle. This end projecting
outwards is then joined to the back of the next outer wing in rear of the direction
of rotation by a piece extending the whole width of the wings. The space between
the inner and outer wings thus forms a chamber out of influence of the air passing
through the fan's body.
The wings will be combined with one or more dies with bosses and arins as
above described.

page_text: The next improvement is in the regulation of the air passing through the fan.
This relates principally to fans having inner & outer wings projecting outwards
beyond the inlet circle. Sliding on these inner wings and secured with bolts in
slots, I place shutters which can be moved outwards so as to decrease and enlarge
the area between the shutter and the outer wings. The shutters are the whole
width of the fan they may be inoved simultaneously by an eccentric motion fixed
on the fan shaft. Any of the above described fans can be worked with or without
casings and expanding outlets as desired.
Improvements in the Construction of Centrifugal Fans, and in the
Regulation of the Air Currents Passing Through the same.
i
I, GEORGE MARIE CAPELL, of Passenham Rectory, in the County of
Northampton, 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 relates to improvements in the construction of centrifugal fans
and in the regulation of the air currents passing through them, and the objects of
it are (1) to reduce the weight of a fan by holding its operative members together
according to a new method and (2) to provide improved devices for regulating the
air currents within the fan.
of this
Referring to the accompanying drawings which are to be taken as part
Specification and read therewith:-
Figure 1 is a side elevation, partly in section, of a double inlet fan.
Figure 2 is a transverse sectional elevation of the same fan.
Figure 3 is a detail side elevation illustrating a modified form of gusset plate.
Figure 4 is a sectional side elevation taken on the line 4-1 of Figure 5.
Figure 5 is a transverse sectional elevation taken on the line 5-5 of Figure 4
omnitting the mechanism for adjusting the position of the shutter.
A is the fan shaft. B is the disc upon and to which the outer and inner blades C
and are made fast.
The method of obtaining the first object of my invention is illustrated in
Figures 1, 2 and 3. When the fan in question is a double inlet fan this disc B
stands centrally of the two fans, as illustrated in Figures 1 and 2. When the fan
is a single inlet fan, it has the fan on one side of it, as illustrated in Figures 4 and 5.
In either case, the junction between the disc and shaft is effected by means of
a boss F on each side of the central disc and by one only in the case of the
side disc.
The disc inay or may not be of the same diameter as the fan. In the case
of the central disc fan illustrated in Figures 1 and 2, it is shewn as considerably
less, being in fact but a little larger than the inlet circle, while in the case of a side
disc fan, it may be of the same size as the fan. In either case the respective
diameters is a matter to be decided according to the circumstances of the particular
case.
I, I are the ribs of angle section upon which the blades are made fast.
I prefer
that these ribs shall stand under the respective blade plates instead of the latter
lying upon the ribs. The inner end of each rib may be cranked to fit up to the
respective face of the boss F.
The vertical flanges of the ribs I, I are rivetted to the disc B as heretofore
excepting in respect of those portions of them which necessarily project beyond the

page_text: edge of the said disc, such projection occurring in all Capell fans the discs of which
are no larger than the respective inlet circles. The said projecting portions stand
off froin each other for a distance equal to the thickness of the said disc. The
outer ends of each pair of ribs are tied to the disc by a pair of ties J, J. the
junction between the ties and the pair of ribs being further strengthened by a gusset
plate K. In shape this latter is triangular with one convex edge which is cut to
the radius of the respective ribs. The convex margin of each gusset is held
between and rivetted to the rib ends with its edge flush with the horizontal flanges
of the said ends. The outer straight margin of each gusset is held between and
rivetted to the ties J with its edge flush with the adjacent edges of the latter.
The outer ends of the ties J stand between the outer ends of the ribs I, I. which
are cranked to receive them. The inner ends of these ties are firmly rivetted to
the centre disc B while their opposite ends are made fast in the same way to the
gusset K and the ribs I, I.
It will be noticed that the outer blades C extend past the periphery of the disc B
in the direction of the axis of the fan.
Each blade C is slotted centrally for the desired distance to enable it to straddle
the disc edge and to bed down upon the ribs.
The said outer edge of the blades are themselves stiffened and tied to the central
disc B along radial lines close up to the periphery of the bosses F, by stays L. L.
There are two of these to each blade, one on each side of the disc and each standing
symmetrically with its fellow. Their outer ends are made fast to the outer blade
along its tip at any suitable distance from the central disc. I have shewn them in
Figures 1 and 2 as rivetted to the corners made by the blade sides with its tip, but
the position of the junction of ties and blade may be varied. The inner ends of
the ties are bent to stand parallel with the disc so as to bed up to it on each side,
as shewn in Figure 2, where they are rivetted to it.
The outer side edges of the blades both outer and inner may, when great
strength is required, have angle section strengthening ribs M, M, incorporated with
them. The bases or inner ends of these latter are made fast to bosses M¹, M¹, fast
on the axle A.
N is a broad angle section hoop within its widest flange standing round each
inlet to the fan. The vertical flanges of this hoop is rivetted to the series of
gusset plates O, O next described. Each of these is a triangular plate with one
convex side. The convex margin fits over the adjacent portion of the vertical
flange of the angle rib M to which it is rivetted. The bottom or inner edge of the
gusset stands behind the adjacent arc of the vertical flange of the angle section
ring N to which it is rivetted.
It is well known that the Capell fan frequently has the inner blades set in advance
of the respective outer blades, in advance that is when the fan is made to revolve
with the convex sides of the blades leading. This involves the insertion between
the two blades- outer and inner-of the well known transverse piece G---Figure 3,
and consequently in the improved construction of fan which forins the subject of
the present invention, the shape of the side angle iron ribs M, M is modified
accordingly to follow the edge of the said pieces G, as they pass from the inner to
the outer blades, by the introduction of the angle section pieces G¹, G¹. This
nodification in the contour of the blades and the blade ribs M, M, necessitates
a corresponding change in the contour of the gusset plates 0, 0. This change is
illustrated in Figure 3. The gusset plate O' is of a quasi triangular shape, to
include the respective portions of the vertical flange of the blade rib M, the vertical
web of the piece G¹ and the respective portion of the vertical rib of the angie
section ring N. It is made fast to the blade rib M by the line of rivets m, to the
interruediate piece G₁ by the line of rivets 7 and to the angle section ring N by the
line of rivets n.
It is obvious that a single inlet fan can be constructed upon one side of a disc B,
according to the inethod described above and illustrated in Figures 1, 2 and 3. In

page_text: fact, a vertical line down the centre of Figure 2, divides the latter into two single
inlet fans constructed upon the sides of their respective discs.
The second object of the invention is attained by the construction and mechanism
illustrated in Figures 4 and 5. G, G are the transverse pieces already described
with reference to Figure 3. The inner blades D, D are continued past the
transverse pieces G, G into the spaces between the outer blades C, C. The tips of
these continuations d, d are joined to the respectively following (assuming that the
fan is rotated with the convex sides of the blades) outer blades by connecting
pieces d¹, d¹ concentric with the pieces G, G. These pieces dextend from one
side of the fan to the other so as to enclose and cut off from the air currents within
the fan, each space between a piece G, a piece d¹ a continuation d and an outer
blade C. The pieces d', d', also serve as traces between the blades. Q, Q, are
adjustable shutters slides, one upon each inner blade D, and extending for the full
width thereof. The object of the shutters is to place the sectional area of the air
passages between the tips of the inner blades D, D, and the opposite concave faces
of the outer blades C, C, under the control of the user of the fan from the outside
thereof. Each shutter Q is therefore long enough, and has a sufficiently long
radial motion upon its blade D for the purpose. The sliding motion is provided
for by means of bolts or studs q, q on the blade D engaging in slots q¹, q¹ in the
shutter. Motion may be imparted to all the shutters together by means of a
sleeve q² on the axle A rotatable thereon in either direction through an arc limited
by any suitable device such as an arcual slot q' in the bore of the sleeve and a
stop of fast on the shaft and projecting therefrom into the said slot in combination
with pairs of links q pivotted by their outer ends near the sides and inner edges of
each blade D and by their opposite ends to flanges q' on the sleeve. The position
of the links with reference to the periphery of the sleeve q² must obviously be
tangential. The outer blades may be continued downwards towards the centre so
as to join the inner blades, as shewn by dotted line, F1, Figure 4, in which case the
transverse piece G may be dispensed with.
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. The combination in a centrifugal fan, of blade, angle section rib holding the
same to a side or to a central disc, and gusset and tie holding the rib end to the
disc, as set forth.
2. The combination in a centrifugal fan, of blade, angle section rib fast to its
outer side edge; angle section ring about the inlet circle and a gusset plate fast to
the said angle section ring and the angle section rib, as set forth.
3. The combination in a centrifugal fan, of blade, angle section rib holding the
same to a side or to a central disc; gus et plate and tie holding the said rib end to
the disc; angle section rib fast to the outer side edge of the blade; angle section
ring about the inlet circle and a gusset plate fast to the said angle section ring and
outer angle section rib, as set forth.
4. The combination in a centrifugal fan, of blade, side or central disc and stay
extending from the tip of the blade to near the centre of the disc and having its
ends made fast to the said tip and disc respectively, as set forth.
5. The combination in a centrifugal fan, of blade, angle section rib holding the
same to a side or to a central disc; gusset and tie holding the rib end to the disc
and stay extending from the tip of the blade to near the centre of the disc and
having its ends made fast to the said tip and disc, respectively, as set forth.
6. The combination in a centrifugal fan, of blade, angle section rib fast to its
outer edge; angle section ring about the inlet circle and a gusset plate fast to the
said angle section ring and angle section rib, and stay extending from the tip of the
blade to near the centre of the disc and having its ends made fast to the said tip
and disc, respectively, as set forth.

page_text: 7. The combination in a centrifugal fan, of blade; angle section rib holding the
same to a side or to a central disc; gusset plate and tie holding the said rib end to
the disc; angle section rib fast to the outer side edge of the blade; angle section
ring about the inlet circle; a gusset plate fast to the said angle section ring and
outer section rib; and stay extending from the tip of the blade to near the centre
of the disc and having its ends made fast to the said tip and disc respectively, as
set forth.
8. The combination in a centrifugal fan of outer and inner blade, transverse piece,
connecting piece and continuation of the inner blade into the space between two
outer blades; as set forth.
9. The combination in a centrifugal fan having inner and outer blades, of outer
blades joined to inner blades at a point within inlet circle, and a connecting piece
between outward projection of said inner blades and the outer blades, as set
forth.
10. The combination in a centrifugal fan of adjustable shutters adapted to
regulate the sectional area of the air passages between the tips of the inner blades
and the opposite faces of the outer blades, with mechanism for moving the said
shutters to and from the axis of the fan, as set forth.
1
1007
PHILLIPS & LEIGH,
22 Southampton Buildings, Chancery Lane, W.C.,
Agents for the Applicant.
PHILLIPS & LEIGH,
22 Southampton Buildings, Chancery Lane, W.C.,
Agents for the Applicant.