Improvements in Air Pumps.
Year: 1890

page_text: Date of Application, 2nd June. 1890-Accepted, 9th Aug.. 1890
COMPLETE SPECIFICATION.
Improvements in Air Pumps.
We, HERMANN SCHULZE-BERGE of Rochester, County of Beaver, State of
Pennsylvania, United States of America, Chemist, and FRANZ SCHULZE-BERGE of
West Orange, County of Essex, State of New Jersey, United States of America,
Electrician, do hereby declare the nature of our invention for IMPROVEMENTS IN
AIR PUMPS, and in what manner the same is to be performed to be particularly
described and ascertained by the following statement:-
…d in illustrated in the accompanying
Improvements in Air Pumps.
We, HERMANN SCHULZE-BERGE of Rochester, County of Beaver, State of
Pennsylvania, United States of America, Chemist, and FRANZ SCHULZE-BERGE of
West Orange, County of Essex. State of New Jersey, United States of America,
Electrician, do hereby declare the nature of our invention for IMPROVEMENTS IN
AIR PUMPS, and in what manner the same is to be performed to be particularly
described and ascertained by the following statement:-
Our invention consists in a rotary air pump and is illustrated in the accompanying
drawings, in which
Figure 1. is a front elevation, partly in section.
Figure 2 is a vertical section on the line II-II of figure 1.
Figures 3 to 6 show in detail different parts of the apparatus.
The figures on the second sheet illustrate a modification of the apparatus.
Figure 7 is a side elevation, partly in section.
Figure 8 shows details of figure 7.
Like symbols of reference indicate like parts in each.
In figure 1, the annular tube 1 is the rotary vessel of the pump, mounted upon a
frame, and revoluble around the axle 2. The shape of the end 3 of this tube, as shown
in figure 3, is somewhat contracted, bending first inwardly, and then outwardly, and
ending in the horizontal part 4, shown in figure 4. This horizontal part is some inches
A block 5 of wood, hard
long and is vertical to the plane of the annular vessel L.
rubber, or other suitable material, fastened to the frame of the pump, is illustrated in
section in figure 4. The open space at 6 embraces the above mentioned end of the
tube 1. A channel 7 is bored into this block, ending in the short tubes 8 and 9. The
horizontal part 4 of the end of the annular tube 1 passes through the wall of this
channel, as shown in figure 4, and ends concentrically with the opening of the tube 8.
To the other end 31 of the annular tube 1 (figure 1). a tube 10 is attached, shown
more particularly in figures 5 and 6. The lower part of tube 10 is bent horizontally,
as in figure 5, and in crossection at 11 in figure 1. The upper part of tube 10 leads
to a glass bulb 12, and through the opposite end of this bulb passes the tube 13, which
terminates in an open end at 14. The other end of the tube 13 leads to the interior of
the axle 2 of the pump, which axle is hollow, and is closed at the front end, as shown
in figure 2. The opposite end of the axle is open and is connected by an air-tight
stuffing-box 21 to a stationary horizontal tube, to which may be attached the vessel 4'
to be exhausted.
A tube 15 (figures 1 and 4) is connected by a flexible and air-tight joint 16 to the
end 4 of the annular tube 1. A wider tube 18 is similarly connected by a flexible
joint 17 to the tube S, so that the tube 15 passes down in the interior of the tube 18.
Another tube 19 (figure 5) is connected by a flexible joint 20 to the horizontal end 11.
of the tube 10. The lower ends of the tubes 18 and 19 are connected by a flexible
tube 21 (figure 1). The tube 15 is preferably made about as long as the direct distance
between the ends 3 and 3 of the tube 1, and the additional length of the height of a
barometric column of mercury, while the tubes 18 and 19 are somewhat longer than the
tube 15. A tube 22 forms a prolongation of the tube 9 (figures 1 and 4), and is open
at the upper end.
The flexible joints mentioned above may be formed by rubber tubes, the strength of
which can be increased by wire spirals placed inside, or embedded in the material of.
the tube. Any other flexible and air-tight material may, however, be employed instead
of rubber.
When the interior of the apparatus is open to atmospheric pressure, a quantity of
mercury is introduced, sufficient to fill the channel formed by the tubes 18, 21 and 19,
and a certain part of the annular tube 1.
.

page_text: It will be readily understood how the device attached to the ends of the annular
tube will act as a perfect air valve, allowing the air exhausted to escape into the open
atmosphere, and preventing any return or regress of the same.
Let the open end of the axle be connected with a vessel 4' to be exhausted (figure 2),
and then let the apparatus be rotated in the direction of the arrow in figure 1. The
mercury will proceed in the opposite direction in the tube 1, and when the end 3¹ of
the tube 1 is raised to a certain vertical height, a partial vacuum there will be formed,
and the air will expand from the vessel to be exhausted into the tube 1. At the same
time, the pressure of the air contained between the end 3 and the mercury level 23 is
increased, and causes the mercury in the tube 15 to sink to the lower end of this tube,
when the air will find its way into the tube 18, and will escape through the mercury of
this tube to the tube 22, and thence to the open atmosphere.
The pressure which is necessary to drive the air out of the lower end of the tube 15
must be counterbalanced by the column of mercury contained in the tube 1, and the
sweep and width of this tube, as well as the quantity of mercury contained therein
must. be selected suitably for the purpose.
It may be remarked that less pressure is required to drive the air out of the tube 15
as described, if this tube be brought into an inclined position, as shown in dotted lines
in figure 2, than when it keeps the vertical position.
By further rotating the apparatus in the same direction, the mercury will pass
through the tubes 15, 18, 21 and 19, and begin a new turn of its circulation, by which
means the air exhausted during the first turn will be removed. through the tube 15,
and another quantity of air will be drawn from the axle of the pump. During each
revolution of the painp, the valve itself undergoes a turning or dangling motion, since
in the condition shewn in figure 1, the tube 18 is at the left and the tube 19 at the
right, while, as is easily understood, after half a revolution, the tube 18 will be at the
right and the tube 19 at the left. This motion goes on without difficulty on account,
of the flexibility of the joints 16, 17 and 20.
Any mercury which might, during the rotation of the apparatus, run over from the
tube 19 while the prolongation 10 of this tube is in a downwardly inclined position,
will be gathered in the bulb 12, and will run back therefrom when the tube 10
approaches again its initial position. After each rotation of the pump, the pressure
of the vacuum in its interior has decreased a certain amount, and since at the same
time the full pressure of the atmosphere acts upon the level of the mercury contained
in the tube 18, this level will be depressed. But if the length of the tube 15 be
properly chosen, the said level can never reach the lower end of the tube 15, and then
it is evident, that outside air can never find its way through the liquid seal into the
interior of the pump, while the apparatus is working..
The interior volume of the pump vessel may be considerably increased if the tube 1 is
not shaped as a simple ring, but as a spiral, consisting of a number of convolutions
similar in circumference to the sweep of the ring.
The tubes of the apparatus described may be made of glass, iron, or any suitable
material. The tube 15 must not be too wide in diameter, otherwise the mercury
would not be able to press the air down through the tube, but several tubes of this
kind may be attached at the same time to the end 3 of the main tube in order to
increase the speed of the flow of mercury through the valve.
By the valve as described, both ends of tube l'are protected by a liquid seal against
any access of outside air. In case the tube 15 be omitted, only the end 3 of the
tube would be protected. Still with a suitably chosen quantity of mercury, the
device would act as a practical valve, the air being pressed out of the end 3 of tube 1
directly to the atmosphere.
The apparatus represented in figure 7, in which the rotary pump vessel 1 has the
shape of a double spiral coil mounted upon an inclined hollow axle 2 by means of a
spider and ribs 25, is similar in operation to the apparatus shown in figure 1, but differs
therefrom in that respect that the air-valve or vessel containing the liquid seal is rigidly
connected with the pump vessel. The axle 2 which makes connection with the vessel
to be exhausted by the air-tight stuffing-box 2', has an inclined position. The degree

page_text: of inclination may vary, but is preferably about forty-five degrees. The same inclina-
tion is given to the vessel of the air-valve 18, 19, so that the inclination of this vessel
remains unaltered during the rotation of the apparatus, as indicated by the trap shown
in dotted lines and disconnected from the apparatus in figure 7. The length of the
shanks of the valve must be in this case so much greater than in the apparatus
represented in figure 1, that the vertical difference between the upper and lower end
of this tube resembles the whole length of the corresponding tubes in figure 1, and
correspondingly surpasses the length of a barometric column of mercury which'
is indicated by the vertical difference in the level marked a.
In the same
proportion, the diameter of the sweep of the tube 1 must be increased com-
paratively with the diameter of the ring in figure 1. The air-valve or trap is
illustrated more particularly in figure 8. The tube 10 terminates in the hollow
axle 2 while the tube 22 is open and leads to the atmosphere. This tube is
made long enough to prevent any mercury from running out. A shunt tube 24 is
shown in figure 8 which may serve the purpose of increasing the speed of the flow of
mercury from the end 3 to the end 3 of tube 1. While generally closed during
the rotation of the apparatus, it can be opened when the air has been driven out by the
liquid piston through the tube 15, and closed again when the liquid piston has passed
through the shunt.
This shunt may contain a stop-cock or a rubber tube adapted to be closed by a
pinch-cock or some equivalent device. Evidently the shunt does not form an essential
part of the apparatus, and therefore may be dispensed with, as in figure 7.
If the shunt is omitted, and if also the tube 15 is dispensed with, the outside
atinospherical air has access to the end 3 of the tube 1, while access of the open
atmosphere to the end 3 of the tube 1 connecting with the vessel to be exhausted (by
means of the tube 10 and shaft 2) is permanently prevented by the liquid in the trap,
and by the liquid piston travelling in the spiral 1 in the opposite direction to the arrows
which indicate the rotation of the air-pump.
In figure 7 the air valve or trap is joined to the ends 3 and 31 of the double spiral
coil at the lower end of the coil that is in direction towards the driving gear, but it is
evident that such ends 3 and 31 of the spiral coil can be located at the upper end of
the coil, towards the stuffing-box 21. In the latter case, the valve or air-trap may be
located within the drum or space formed by the spiral coil around the shaft 2 thus
decreasing the height of the apparatus.
In the air pump described the pump vessel rotates in one direction only, and the
liquid piston passes through the interior of the pump vessel always in one direction.
This is made possible by the arrangement of the valve. Of course the same purpose
could be reached by a valve of different construction, or by stopcocks provided with
bores or passage ways adapted to establish the connections required, or by some other
equivalent device, and we do not limit ourselves to the special construction of the valve
described.
If other liquids be employed instead of mercury in the apparatus described, the
dimensions of the apparatus can be selected according to the specific gravity of the
liquid used.
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. In an air pump a tubular vessel journaled in suitable bearings in which it is
rotatable, said vessel containing a liquid piston and having its ends connected together
so as to permit the passage of the liquid piston therethrough continuously in one
direction.
2. In a vacuum pump a rotary tubular pump vessel, the axis of rotation of which
keeps a constant direction while the pump vessel is rotated, said pump vessel containing
a liquid piston and having its ends connected together so as to permit the passage of
the liquid piston therethrough continuously in one direction, whereby the pump is
adapted to exhaust without reversal.

page_text: 3. The combination with a rotary mercurial air-pump revoluble in bearings, of an
air-valve consisting of a trap or vessel containing a liquid seal.
4. In a rotary air-pump, the combination with a rotary curved tube,. of a trap
containing a liquid seal connecting the ends of the tube, a pipe 15 extending from one
end of the tube into said trap, and an exhaust opening or pipe 22 leading to the
atmosphere, the other end of the tube being adapted to be connected with the vessel
to be exhausted.
5. In a rotary air-pump, the combination of a tubular vessel containing a liquid
piston, with an inclined axle or shaft revoluble in stationary bearings, and an air-valve
consisting of a trap containing a liquid seal and connecting the ends of the tubular
vessel.
Dated this 93rd day of Mar 1800
FRANZ SCHULZE-BERGE.