Improvements in Centrifugal Pumps and Ventilators.
Year: 1896

page_text: Date of Application, 4th May, 1896-Accented, 3rd Oct., 1896
COMPLETE SPECIFICATION.
Improvements in Centrifugal Pumps and Ventilators.
I, FRIEDRICH PELZER of No. 18 Holländische Strasse Dortmund, in the Empire of
Germany, Engineer, do hereby declare the nature of my said invention and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement :-
Almost all the centrifugal pumps and ventilators now in use draw in the air,
or other fluid, in axial direction. The object of this invention, however, is to so
construct such pumps or ventilators, that the fluid enters at the periphery of
revolving wheels, this being effected by keying two bladed fan-wheels of different
diameters on to the same shaft without any separating partition being provided
between same.
The principle on which my invention is based is as follows:
232
If a fan wheel, the periphery of which is of uniform diameter and whose sides
are tightly closed by discs, is rotated rapidly, the pressure inside the wheel falls
below that of the surrounding atmosphere, as indicated by the equation 2 g'
being the pressure of a column of air, the specific gravity of which is equal to
that of the atmospheric air surrounding the wheel; v the peripheral velocity of the
wheel and 9 the acceleration due to gravity. After the wheel has revolved a very
short time the centrifugal force of the air between the blades of the wheel becomes
equal to the reduction of the air pressure within the latter, as indicated by the
above equation. If, now, the wheel is altered so that a part is of somewhat less
diameter and so that the peripheral velocity of such lesser part is correspondingly
less than the part of the wheel greater in diameter, the centrifugal force of the air in
the part of the wheel having a reduced diameter cannot maintain the reduction of
air pressure h, but the latter is reduced to 1. Seeing, however, that the centrifugal
force of the air between the blades of the wheel having a larger diameter is
equivalent to the reduction of air pressure h, a current of air of the force h-h'
enters at the whole periphery of the part of the wheel less in diameter, the part of
the wheel which is larger in diameter then forcing such air out again.
1 will now describe the application of the above principle with reference to the
accompanying drawing, in which :-
Fig. 1 is an elevation of two wheels of different diameter and placed side by side.
Fig. 2 is a section on line -y of Fig. 1,
Fig. 3 shows the same arrangement with a double set of wheels.
Fig. 4 is a similar arrangement to Fig. 1, the blades of the wheels being in this
case set at an angle to the axle of the latter.
Fig. 5 shows the arrangement of the fan wheels in spiral closed casings.
Fig. 6 is a section on line - of Fig. 5.
Fig. 7 is a further modified construction in section.
As shown in Fig. 1, the blades of the wheels are arranged radially to the axis
and so as to intersect, or be parallel to, such axis. If so formed, however, air, or
other fluid, entering the smaller wheel A from without, on coming within the range
of the revolving blades would be caused to perform a circular motion, in addition
to the radially, inwardly-directed motion. Seeing, that such action would impart a
strong whirling motion to the fluid, and that the result would not be so effective,
the blades should be constructed as shown in Fig. 2 viz., so that their outermost
parts are bent in the direction of the rotating wheel.

page_text: In the construction shown in Fig. 3, the smaller
arranged at each side of the larger wheels B, B for expel.
ction-wheels A, A are
the fluids or the air.
The construction shown in Fig. 4 is similar to that illustrated in Fig. 1, the
only difference being that the blades in the former case are inclined to the axle of
the wheel in order to more effectually drive the air from the wheel A to the wheel B.
Figs. 5 & 6 show the wheels arranged in spiral casings. In case the ventilators
or centrifugal pumps are provided with such closed casings, the side-walls of which
tightly close the axle, the side-walls of the wheels need not be tightly closed.
Fig. 7 is a further modified construction, the periphery of the wheel A being
inclined towards B, i.e. so as to form a truncated cone. Such arrangement of the
ventilator in front of a .centrifugal pump is of great importance, seeing that in
proportion as the peripheral velocity decreases, the force with which the fluid or
the air is drawn in by the wheel B increases; seeing, further, that such of the air,
or other fluid, as enters the wheel A, nearest its outermost side has the greatest
course to perform, as indicated by the arrows (besides at the same time describing
a circular motion) a greater force is therefore necessary to impel the air so as to
maintain a uniform current of air through the wheels and so as to avoid any whirling
motion.
When it is necessary to draw the fluid from a certain place, the present apparatus
may be connected with a passage ending in a spiral casing at the end of the
ventilator or centrifugal pump, such casing distributing the air or other fluid over
the circumference of the suction wheel, this arrangement being the customary one
employed in connection with centrifugal ventilators or pumps when the fluid is to
be taken from a place more or less distant from the pump or ventilator. Seeing,
however, that the spiral casing of the expelling wheel increases in size in the
direction of the revolving movement of the wheel, the spiral casing of the suction-
wheel must increase in the opposite direction.
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. Improvements in centrifugal pumps, fans or ventilators, the arrangement of
closed fan wheels (A, B or A, A B, B) of different diameter and not separated by
a partition in such manner that the air, or other fluid, is drawn in between the blades
at the periphery of the smaller wheel or wheels (A) and expelled by the larger
fan-wheel or wheels (B), substantially as described and shown.
2. A modification of the construction of centrifugal pumps, fans or ventilators as
set forth in Claim 1, in which the suction wheel (A) is in the form of a truncated
cone, the base of which abuts against the side of the expelling-wheel (B),
substantially as described and shown in Fig. 7.
Dated 4th day of May 1896
F. PELZER
Per W. H. Beck,
115 Cannon Street, London, Agent.