Improvements in Air Propelling or Ventilating.
Year: 1891

page_text: Date of Application, 30th Apr., 1891
Complete Specification Left, 29th Feb., 1892-Accepted, 2nd Apr., 1892
PROVISIONAL SPECIFICATION.
Improvements in Air Propelling or Ventilating.
We, ROBERT MARSHALL and EDWARD FITZGERALD both of No. 121 Fen-
church Street in the City of London, Engineers do hereby declare the nature of
this invention to be as follows :-
Our invention relates to that description of apparatus for propelling air for
ventilating and other purposes, wherein a fan consisting of a series of helical or
oblique blades on a shaft, in being made to revolve rapidly, propels the air in the
direction of its axis.
In such apparatus as heretofore constructed, owing to the great speed at which the
fan is driven, the centrifugal action of its blades causes the air entering to be thrown
with great force to the circumference, thereby both rendering the greater part of
the blades surfaces inoperative for propelling the air in an axial direction, and also
causing a great loss of useful effect in the useless impact of the air against the
periphery of the casing, or the flange formed on the outer end of the blades when
such is employed.
Our present invention has for its object to obviate in a great measure both
these defects, and it consists in forming on the operative surface of the blades,
a series of projections more or less at right angles thereto, extending across the
blades at right angles or nearly so to the radius. By this means the surface of
the blade is divided as it were into a number of compartments or channels extending
in the direction of rotation, so that a separate body of air being caught up and
more or less confined in each channel, it is subject to the forward propelling action
of the part of the blade into which it enters, and is prevented from being thrown
by centrifugal force to the periphery, so that every part of the blade has an effective
propelling action, and only the comparatively small body of air contained in the
outermost channel is thrown with any considerable centrifugal force against the
surrounding casing. By preference we produce the said channels or compartments
on the blades by constructing these of thin sheet metal corrugated in such a
manner as to produce furrows, the outer part of which is approximately at right
angles to the plane of the fan, while the upper part slopes from the bottom of such
outer part up to the top or ridge of the next inner furrow. These blades are
secured by rivetting or otherwise to radial arms on the back surface of the blade,
such arms being made either to fit into the corrugations or merely to pass across
them.
The said arms are by preference fixed adjustably in the boss of the fan, so that
the blades can be made to assume any desired pitch.
The blades may also be formed with flat or more or less helical surfaces on which
are fixed a series of concentric ribs for dividing its surface into the before mentioned
compartments or channels, but we prefer the first described construction on account
of cheapness.
Another improvement, applicable not only to the above described fans but also
to those of other construction, relates to the mode of supporting the axis of the fan
in the framing.
With fans running at a high speed, the wear of the bearings causes a looseness
which produces unpleasant noises and requires the comparatively frequent stoppage
of the fan for some time to make good such looseness.
According to our improvement we obviate the above defect by forming on one
end of the fan spindle a coned shoulder, which fits into a correspondingly coned seat
in the casing; the other end of the spindle is screw-threaded and on it is screwed a
nut coned on its inner side to the same extent as the shoulder on the other end,,

page_text: which coned surface of the nut fits into a correspondingly coned seat in the casing.
Outside such coned nut a lock-nut is screwed on to the spindle, so that when the
spindle with the fan has been placed in position in its bearings, and the cone nut
has been screwed up into its seat so that the spindle will revolve easily but without
any looseness, the said nut is fixed in that position by the lock nut.
On any looseness through wear occurring, the lock nut is loosened, the coned nut
is screwed up so as to take up the slackness, and the lock nut is screwed up again,
which operation can be accomplished in the course of a few minutes.
The spindle with its coned shoulder, and small driving pulley beyond, may
advantageously be made of cast iron, thus doing away with any grooving and keying
beyond that for fixing the boss of the fan, which may however be effected by means
of a setting screw.
We
e prefer to construct the casing of the fan of two cast metal rings of a diameter
corresponding to that of the fan, having three narrow radial arms carrying the
central boss forming the bearings for the fan spindle.
These two rings are connected together at the required distance apart by three
or more distance pieces and screw bolts and nuts, and the cylindrical space between
their peripheries is enclosed by a piece of corrugated or plain sheet metal secured
to flanges or lugs on the rings by screws or rivets. The one ring may be provided
with a flange or lugs for fixing the fan against the support where it is to operate, or
the screw bolts connecting the two rings may have a screwed extension screwing
into metal sockets fixed on such support.
Dated this 30th day of April 1891.
ABEL & IMRAY,
Agents for the Applicants.
COMPLETE SPECIFICATION.
Improvements in Air Propelling or Ventilating.
We, ROBERT MARSHALL and EDWARD FITZGERALD, both of No. 121, Fen-
church Street in the City of London, Engineers, 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 :-
Our invention relates to that description of apparatus for propelling air for
ventilating and other purposes, wherein a fan consisting of a series of helical or
oblique blades on a shaft, in being made to revolve rapidly, propels the air in the
direction of its axis.
In such apparatus as heretofore constructed, owing to the great speed at which
the fan is driven, the centrifugal action of its blades causes the air entering to be
thrown with great force to the circumference, thereby both rendering the greater
part of the blade's surfaces inoperative for propelling the air in an axial direction,
and also causing a great loss of useful effect in the useless impact of the air against
the periphery of the casing, or the flange formed on the outer end of the blades
when such is employed.
Our present invention has for its object to obviate in a great measure both these
defects, and it consists in forming on the operative surface of the blades, a series of
projections more or less at right angles thereto, extending across the blades at right
angles or nearly so to the radius.
By this means the surface of the blade is divided, as it were, into a number of
compartments or channels extending in the direction of rotation, so that a separate
body of air being caught up and more or less confined in each channel, it is subject
to the forward propelling action of the part of the blade into which it enters, and is
prevented from being thrown by centrifugal force to the periphery, so that every
part of the blade has an effective propelling action, and only the comparatively
small body of air contained in the outermost channel is thrown with any considerable
centrifugal force against the surrounding casing. By preference we produce the said

page_text: corrugated in such a manner as to produce furrows, the outer part of which is
approximately at right angles to the plane of the fan, while the other part slopes
from the bottom of such outer part up to the top or ridge of the next inner furrow.
These blades are secured by rivetting or otherwise to radial arms on the back
surface of the blade, such arms being made either to fit into the corrugations or
merely to pass across them.
The said arms are by preference fixed adjustably in the boss of the fan, so that
the blades can be made to assume any desired pitch.
The blades may also be formed with flat or more or less helical surfaces on which
are fixed a series of concentric ribs for dividing its surface into the before mentioned.
compartments or channels, but we prefer the first described construction on account
of cheapness.
Another improvement, applicable not only to the above described fans but also to
those of other construction, relates to the mode of supporting the axis of the fan in
the framing.
With fans running at a high speed, the wear of the bearings causes a looseness
which produces unpleasant noises and requires the comparatively frequent stoppage
of the fan for some time to make good such looseness.
According to our improvement we obviate the above defect by forming on one
end of the fan spindle a coned shoulder, which fits into a correspondingly coned seat
in the casing; the other end of the spindle is screw threaded and on it is screwed a
nut coned on its outer side to the same extent as the shoulder on the other end,
which coned surface of the nut fits into a correspondingly coned seat in the casing.
Outside such coned nut a lock-nut is screwed on to the spindle, so that when the
spindle with the fan has been placed in position in its bearings, and the coned nut
has been screwed up into its seat so that the spindle will revolve easily but without
any looseness, the said nut is fixed in that position by the lock nut. Or such locking
may be effected by means of any other known device.
On any looseness through wear occurring, the lock nut is loosened, the coned nut
is screwed up so as to take up the slackness, and the lock nut is screwed up again,
which operation can be accomplished in the course of a few minutes.
The spindle with its coned shoulder, and small driving pulley beyond may advan-
tageously be made of cast iron, thus doing away with any grooving and keying
beyond that for fixing the boss of the fan, which may however be effected by means
of a setting screw.
We prefer to construct the casing of the fan of two cast metal rings of a diameter
corresponding to that of the fan, having three or more narrow radial arms carrying
the central boss forming the bearings for the fan spindle.
These two rings are connected together at the required distance apart by three
or more distance pieces and screw bolts and nuts, and the cylindrical space between
their peripheries is enclosed by a piece of corrugated or plain sheet metal secured
to flanges or lugs on the rings by screws or rivets. The one ring may be provided
with a flange or lugs for fixing the fan against the support where it is to operate, or
the screw bolts connecting the two rings may have a screwed extension screwing
into metal sockets fixed on such support.
The accompanying drawing shews an air propeller constructed according to our
before described invention.
.
Fig. 1 shews a front view, Fig. 2 a perspective view from the back, and Fig. 3
shews a part enlarged section, with the before described improved construction of
spindle.
:
The helical blades A A of the propeller are formed of corrugated sheet metal of
the toothed section shewn at Fig. 3 these blades being secured by rivetting or
otherwise to arms B B which are fixed to the boss C secured on the spindle D.
It will be seen that the corrugations are such that faces more or less at right
angles to the surface of the blade are presented at intervals apart in the direction
of its length, so that the body of air acted upon by each section of the blade

page_text: between two such faces, instead of being thrown by centrifugal action to the
periphery of the blade as in ordinary air propellers, will be more or less arrested
by the said projecting face of each section, and will consequently be subject to the
full propelling action of such section in the direction parallel to the axis of the
propeller, and thus the propelling action of the whole surface of the blade is
effectually utilised, only the comparatively small volume of air contained in the
outermost section being propelled by centrifugal action against the cylindrical
casing when such is used.
The framing cf the air propeller consists of the two metal rings E E having each
four narrow radial arms E' carrying the central boss E2 which forms the bearing
for the fan spindle.
The two rings are connected together at the requisite distance apart by
four distance bolts F so as to form the space between them for the propeller,
the periphery of the rings being, according to the mode of applying the propeller,
either left open as shewn, or enclosed by a cylindrical sheet metal covering.
The propeller frame may either be provided with a foot G for fixing to any
support, or it may be secured in position in any other manuer.
Fig. 3 shews the before described improved construction of spindle for the above
described or any other similar construction of air propeller. The one end of the
spindle is formed with a coned enlargement H which fits into a corresponding
coned seating in the one boss E² of the frame. As here shewn, it also has the
driving pulley H' cast in one with it, but this may be made separate and keyed on.
The other end of the spindle is formed with a screw thread and is fitted with a
screw nut I having a coned outer surface corresponding to that of the part H, and
fitting a correspondingly coned bearing surface in the other boss E2 of the frame. A
jam nut is screwed on to the outer end of the spindle, so as to lock the nut I in
position when it has been adjusted on the spindle so as to allow this to rotate with-
out looseness in the bearings E³.
Having now particularly described, and ascertained the nature of this inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :
1. Constructing the blades of helical air propellers with ribs or flanges projecting
at certain distances apart from the acting surfaces thereof, more or less at right
angles thereto, and extending across the same, so that the air which is being acted
upon by the several sections of the blades between each two projections shall be
more or less prevented from being thrown by centrifugal action to the periphery,
substantially as described.
2. Constructing the blades of helical air propellers of corrugated sheet metal, the
corrugations being made to extend across the surface of the blade, and being of
such a form that the inner face of each ridge is presented more or less at right
angles to the plane of the propeller, substantially as described.
3. In rotary air propellers or fans, constructing the one end of the spindle with a
conical enlargement, while the other end is threaded and screws into a nut having a
coned outer surface corresponding to the said conical enlargement, such conical
enlargement and nut being made to fit correspondingly coned bearing surfaces in
the casing or frame, so that any slack that may occur through wear can be taken
up by screwing up the nut, this being locked in position by a jam nut or equivalent
device substantially as described.
4. The construction of helical air propelling or ventilating apparatus combined
and operating substantially as herein described.
Dated this 20th day of In1000
ABEL & IMRAY,
Agents for the Applicants.