Improvements in Rotary Pumps.
Year: 1898

page_text: Date of Application, 30th Nov., 1898
Complete Specification Left, 26th July, 1899-Accepted, 2nd Sept., 1899
Improvements in Rotary Pumps.
We, SIEMENS BROTHERS & Co. LIMITED, of 12, Queen Annes Gate, Westminster,
S.W., Electrical Engineers, do hereby declare the nature of this invention (as
communicated to us from abroad by Siemens & Halske Aktien Gesellschaft,
Markgrafen Strasse, No. 94, Berlin, S.W., Electrical Engineers) to be as
follows:-
Rotary pumps as heretofore constructed could not be employed with advantage
as exhaust pumps for air on account of the difficulty of obtaining a sufficiently
air-tight sliding contact between the cylindrical piston and pump casing.
According to the present invention this difficulty is obviated by the following
construction.
The pump is of the kind consisting of a cylindrical casing through which the
driving shaft passes centrally having fixed upon it an eccentric cylinder that
revolves within a cylindrical piston or slide and which is so arranged that by
its rotation the piston, which does not revolve, is always in sliding contact at
one point with the inner cylindrical surface of the casing.
According to the present invention the cylindrical piston or slide has projecting
from it a flat plate which, as the piston performs the above described motion
slides with a combined up and down and slight lateral to and fro motion in a
corresponding vertical rectangular shaped extension of the cylindrical casing
of sufficient width to leave the piston extension free play. In one side of this
extension, near its lower end, is formed the inlet branch by which the pump
is connected to the chamber to be exhausted of air, and the upper end of the
piston extension has on the same side a lateral rounded projection which, in
bearing against the side of the casing extension above the air inlet, causes a
space to be left between the piston extension and the casing through which the
air passes from the inlet into the cylindrical part of the casing on one side of
the piston, which by its before described excentric motion first causes the air
to be drawn in on that side and then expels it on the other side of the piston
and extension, the air being made to escape through lateral holes in the upper
end of the casing extension.
The above mentioned lateral projection of the piston extension is kept in
close contact with the surface of the casing by a spring or springs placed between
the back surface of the extension and the opposite wall of the casing. A suitable
more or less viscous lubricant is introduced into the upper end of the casing
extension and flows down firstly between the projection of the piston extension
and the casing, so as to insure an air tight contact between the two, and
secondly down vertical channels formed in the piston extension (in which may
be contained loose rods for facilitating the flow) and between the excentric
cylinder and the annular piston or slide, from the ends of which it passes into
the casing, forming air tight joints at all sliding contact surfaces between piston
and casing. The excess of lubricant is then expelled from the casing together
with the air on the expelling side of the piston, passing up between the back

page_text: surface of the piston extension and the casing extension and eventually escaping
through the before mentioned holes in the latter. From these the lubricant
flows down in external vertical channels the lower ends of which communicate
with the bearings of the driving shaft the lubricant being made to pass through
channels in such bearings into the pump casing again where it is made to circu-
late as before.
Thus a continuous circulation of one and the same body of lubricant through
the pump is effected insuring the perfect air-tight working thereof, while any
loss is made good from a cup at the top of the casing extension kept charged
with lubricant.
Dated this 30th day of November 1898
ABEL & IMRAY,
Agents for the Applicants.
Pay &umps.
We, SIEMENS BROTHERS & Co. LIMITED, of 12, Queen Annes Gate, Westminster,
S.W., Electrical Engineers, do hereby declare the nature of this invention (as
communicated to us from abroad by Siemens & Halske Aktien Gesellschaft,
Markgrafen Strasse, No. 94, Berlin, S.W., Electrical Engineers), and in what
manner the same is to be performed, to be particularly described and ascertained,
in and by the following statement:-
Rotary pumps as heretofore constructed could not be employed with advantage
as exhaust pumps for air, on account of the difficulty of obtaining a sufficiently
air-tight sliding contact between the cylindrical piston and pump casing.
According to the present invention this difficulty is obviated by a construction
which we shall describe with reference to the accompanying drawings, Figs. 1
and 2 which are sections on planes at right angles to each other.
The pump is of the kind consisting of a cylindrical casing a through which
the driving shaft 6 passes centrally having fixed upon it an eccentric cylinder c
that revolves within a cylindrical piston or slide d and which is so arranged that
by its rotation the piston which does not revolve, is always in sliding contact
at one point with the inner cylindrical surface of the casing a.
According to the present invention the cylindrical piston or slide d has pro-
jecting from it a flat plate e which, as the piston performs the above described
motion, slides with a combined up and down and slight lateral to and from
motion, in a corresponding vertical rectangular shaped extension f of the cylindri-
cal casing of sufficient width to leave the piston extension e free play. In one
side of this extension, near its lower end is formed the inlet branch g by which
the pump is connected to the chamber to be exhausted and the upper end of the
piston extension e has on the same side a lateral rounded projection h which,
in bearing against the side of the casing extension f above the air inlet
a space to be left between the piston extension and the casing through which
the air passes from the inlet into the cylindrical part of the casing on one side
of the piston which by its before described excentric motion first causes the air
to be drawn in on that side and then expels it on the other side of the piston
and extension, the air being made to escape through lateral holes k k in the
upper end of the casing extension as indicated by the arrow.
g causes
The lateral projection h of the piston extension is kept in close contact with
the surface of the casing by a spring or springs / placed between the back surface
of the extension e and the opposite wall of the casing f. A suitable more or

page_text: less viscous lubricant is introduced into the upper end of the casing extension f
and flows down between the projection h and the side of the casing f so as to
insure an air tight contact between the two, and also down vertical channels
formed in the piston extension (in which may be contained loose rods for facilitat-
ing the flow by their reciprocation) and between the excentric cylinder c and the
annular piston d from the ends of which it passes into the casing a forming air
tight joints at all sliding contact surfaces between piston and casing. The excess
of lubricant is then expelled from the casing together with the air on the
expelling side of the piston, passing up between the back surface of the piston
extension e and the casing extension f and eventually escaping through the
holes k. From these the lubricant flows down in external vertical channels n
the lower ends of which communicate with the bearings of the driving shaft b
the lubricant being made to pass through channels in these bearings into the
casing a again where it is made to circulate as before.
Thus a continuous circulation of one and the same body of lubricant through
the pump is effected insuring the perfect air-tight working thereof while any
loss is made good from a cup 2 at the top of the casing extension kept charged
with lubricant.
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 :-
For lubricating and keeping tight a rotary pump having a cylindrical piston
caused to reciprocate in an excentric path by an excentric cylinder revolving
within it, the said piston having an extension which reciprocates in an extension
of the casing, the construction of the piston extension with channels for passage
of lubricant to the revolving eccentric and of the extension of the casing with
channels leading from the air outlets for passage of lubricant to the shaft bearings
and thence into the casing, so that the motion of the piston causes continuous
circulation of the lubricant, substantially as described.
Doted this Ofith day of Tul, 1800
ABEL & IMRAY,
Agents for the Applicants.