Improvements in Rotary Fans, Blowers, or Exhausters.
Year: 1892

page_text: Date of Application, 12th Mar., 1892
Complete Specification Left, 12th Dec., 1892-Accepted, 28th Jan., 1893
PROVISIONAL SPECIFICATION.
Improvements in Rotary Fans, Blowers, or Exhausters.
We, AUGUSTE DESGOFFE and LEONIDAS ALEXANDRE DI GIORGIO, both of
Lille, France Engineers, do hereby declare the nature of this invention to be as
follows:-
--
This invention has reference to rotary fans, blowers or exhausters. The improved
fans, blowers or exhausters are composed of a number of blades or vanes (see
Figures 1 and 2 of the accompanying drawings) the number being varied according
to their diameter and to the purpose for which they are intended. These blades
or vanes which are marked p p p² are placed tangentially to the central boss M
and excentrically with the axis on which they rotate; they are spaced at equal
distances apart around the boss and are connected to it by a flat portion A as
represented in diagram X, this flat portion being of triangular form; its summit a
is at the end of the blade while the small side b°c extends parallel to the axis for
a length ordinarily equal to the fraction of the pitch of the screw, appertaining to
this blade when divided by the number of blades, after which the plain portion
follows a parabolic directrix c d regularly drawn in prolongation of the triangular
plane or heel of the blade, all the generatrices connecting the summit a to this
directrix being straight.
This combination of plane and parabolic surfaces following each other without
interval and forming by their combination a parabolic conoid has the effect of:
1stly. Giving to the fans a very accentuated centripetal action without any
centrifugal action whatever, so that if a flame be placed at any point of the
periphery F of the fan it will be drawn towards the centre of the apparatus when
in motion.
2ndly. Of producing at the driving surface of the fan a discharge of air parallel
to the axis forming a cylindrical column the base of which occupies all the active
section S.
The suction of the air taking place not only at the face E where the blades
project but also over the whole annular surface F which surrounds the series of
blades gives to these fans a very great delivery whilst the cylindrical projection of
air which is peculiar to this construction establishes from the driving side S a
pressure much stronger than that obtained with other constructions of fans of equal
diameter with the same expenditure of power.
Figures 3 and 4 represent a fan in which the lines of the blades follow the same
rules as those in Figures 1 and 2 but have another position on the boss. The flat
portion A turns at its point c (see diagram Y) first in the direction parallel to the
horizontal axis; then its summit a separates from the plane which is at right angles
to this axis drawing into this double evolution the parabolic projection which is
adjacent to it
Figures 5, 6, 7 and 8 represent two fans in which the lines of the three blades
are identical with those of the blades in Figures 1 to 4 and they produce the same
centripetal effects of suction and concentration on the driving side.
Our improved rotary fans, blowers or exhausters can be placed on an axis which
is either borizontal, vertical or inclined to adapt them to the special circumstances
in which they are to be employed. They can be driven either directly by a motor
or indirectly by any suitable gearing or by hand.
The boss which is fixed on the shaft and serves as a base to the blades is not
circular but has as many sides as there are blades; its diameter should increase
with the pressure of air which it is desired to obtain, that is to say, in order to

page_text: increase this pressure while preserving to the fan its diameter and speed the active
surface, or the thickness of the crown of air projected should be diminished by
increasing the diameter of the boss which on its exhausting side is generally of
parabolic form to facilitate the entrance of the air to the blades.
The number of the blades will vary with the diameter of the fan. The blades
should be placed so that one blade is not covered by another which would produce
throttling or diminution of the surface where the air is taken in and similarly a
large distance between the blades would be injurious to the effect of the apparatus
which is calculated by multiplying the active surface by the product of the number
of turns with the inclination of the blade.
The fans can be formed of a single piece or of a boss to which the blades are
fixed by suitable means; and the blades may be made of one piece or of several
superposed pieces. The fans can be covered with a suitable coating or be enamelled.
Sometimes we place around the blades one or more continuous rings of small section
which are rivetted to the periphery of the blades and connect them together and
thereby strengthen the fan without sensibly affecting the inlet of the air which
takes place all round the outer edge of the blades.
Dated this 10th day of March 1892.
J. C. MEWBURN,
55 & 56, Chancery Lane, London, Chartered Patent Agent.
COMPLETE SPECIFICATION.
Improvements in Rotary Fans, Blowers, or Exhausters.
We, AUGUSTE DESGOFFE and LEONIDAS ALEXANDRE DI GIORGIO both of
63 Rue de Lens Lille, France, 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:-
This invention has reference to rotary fans, blowers or exhausters. The improved
fans, blowers or exhausters are composed of a number of blades or vanes (the
number being varied according to their diameter and to the purpose for which
they are intended) placed tangentially to a central boss and excentrically with the
axis on which they rotate; they are spaced at equal distances apart around the
boss, and are connected to it by a flat part of triangular form; its summit is at
the end of the blade while a small side extends parallel to the axis for a length
ordinarily equal to the fraction of the pitch of the screw appertaining to this blade
when divided by the number of blades, after which the flat part is followed by a
parabolic directrix regularly drawn in prolongation of the triangular plane or heel
of the blade, all the generatrices which connect the summit of the triangle to this
directrix being straight.
Figures 1 and 2 of the accompanying drawings represent a fan, blower or
exhauster constructed as above explained. P, P1, P2, P3, P4, P³, are the blades
or vanes placed tangentially on the central boss M and excentrically with the axis
on which they rotate. They are connected to the boss by the flat part A of
triangular form as represented in the diagram X; the summit a of this triangle is
at the end of the blade while its small side c extends parallel to the axis for a
length ordinarily equal to the fraction of the pitch of the screw appertaining to,
this blade when divided by the number of blades, after which the flat part is
followed by the parabolic directrix cd regularly drawn in prolongation of the
triangular plane or heel of the blade, all the generatrices which connect the summit a
to this directrix being straight.
This combination of plane and parabolic surfaces following each other without
interval and forming by their combination a parabolic conoid has the effect of
Firstly. Giving to the fans a very accentuated centripetal action without any

page_text: centrifugal action whatever, so that if a flame be placed at any point of the
periphery F of the fan it will be drawn towards the centre of the apparatus when
in motion;
Secondly. Of producing at the driving surface of the fan a discharge of air
parallel to the axis, forming a cylindrical column the base of which occupies all
the active section S.
As the suction of the air takes place not only at the face E where the blades
project but also over the whole annular surface F which surrounds the series of
blades these fans have a very great delivery whilst the cylindrical projection of air
which is peculiar to this construction establishes from the driving side S a pressure
much stronger than that obtained with other constructions of fans of equal diameter
with the same expenditure of power.
Figures 3 and 4 represent a fan in which the lines of the blades follow the same
rules as those in Figures 1 and 2 but have another position on the boss. The
flat portion A turns at its point c (see diagram Y) first in the direction parallel to
the horizontal axis; then its summit a separates from the plane which is at right
angles to this axis drawing into this double evolution the parabolic projection
which is adjacent to it.
Figures 5 and 6, and Figures 7 and 8 respectively represent two fans in which
the lines of the three blades are identical with those of the blades in Figures 1 to 4,
and they produce the same centripetal effects of suction and concentration on
the driving side.
Our improved rotary fans, blowers or exhausters can be placed on an axis which
is either horizontal, vertical or inclined according to the special circumstances in
which they are to be employed. They can be driven either directly by a motor
or indirectly by any suitable gearing or by hand.
The boss which is fixed on the shaft, and serves as a base to the blades is not
circular but has as many sides as there are blades; its diameter should be greater
or less according to the greater or less pressure of air which it is desired to obtain,
that is to say in order to increase this pressure whilst preserving to the fan its
diameter and speed the active surface or the thickness of the crown of air projected
should be diminished by increasing the diameter of the boss which on its
exhausting side is generally of parabolic form to facilitate the entrance of the air
to the blades.
The number of the blades will vary with the diameter of the fan. The blades
should be placed so that one blade is not covered by another as this would produce
throttling or diminution of the surface where the air is taken in and similarly
a large distance between the blades would be injurious to the effect of the
apparatus.
The fans can be formed of a single piece or the boss and blades can be formed
separately and be fixed together by suitable means; further, the blades may each
be made of one piece or of several superposed pieces.
The fans can be covered with a suitable coating or be enamelled. Sometimes
we place around the blades one or more continuous rings of small section which are
rivetted to the periphery of the blades and connect them together and thereby
strengthen the fan without sensibly affecting the inlet of the air which takes place
all round the outer edge of the blades.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
1. Constructing rotary fans, blowers or exhausters with blades or vanes placed
tangentially to a central boss and excentrically with the axis on which they rotate,
the said blades or vanes consisting of a combination of plane and parabolic surfaces,
substantially as hereinbefore described and represented in the drawings.

page_text: 2. The improved rotary fans, blowers or exhausters herein before described and
represented in the drawings.
Dated this 8th day of December 1892.
J. C. MEWBURN,
55 & 56, Chancery Lane, London, Chartered Patent Agent.