Improvements in Rotary Vacuum Pumps.
Year: 1891

page_text: Date of Application, 8th June, 1891-Accepted, 11th July, 1891
COMPLETE SPECIFICATION.
[Communicated from abroad by WILLIAM EMERY NICKERSON, of 111, North
Avenue, Cambridge, Middlesex, Massachusetts, United States of America,
Chemist.]
Improvements in Rotary Vacuum Pumps.
I HENRY HARRIS LAKE of the firm of Haseltine Lake & Co., Patent Agents
45 Southampton Buildings in the County of Middlesex 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:-
My invention relates to that class of pumps usually called rotary pumps. The
object being to so construct, combine and arrange the pistons and their enclosing
case that by the use of a sealing liquid, which in fact is a component part of this
pump, a good vacuum may be produced.
This object I attain by the mechanism shown in the accompanying drawings, in
which―
Figure 1 is a vertical section taken through the centre of the enclosing case, but
showing the rotating pistons and a driving gear-wheel in elevation.
Figure 2 is a horizontal section of the same.
Figure 3 is a cross-vertical section of the case and showing the driving gear and
one of the pistons in side elevation.
This case consists of
In the drawings, A, B, B1, represent the enclosing case.
the two side pieces B and B', and the shell A, to which the side pieces B and B
are bolted by screw bolts C-C. The joints between the said pieces B, B',
and the shell A, are made tight by gaskets G, G, arranged as shown in Figs. 2
and 3.
The two pistons D and D', are made alike, and without journals, they being
arranged in connection with the side pieces B, B', so that they may rotate on the
cone-formed re-entering parts c c c'e of the side pieces B, B', the rotating pistons
having cone-shaped recesses d d' d' d, on each side, as shown.
The rotating pistons D and D' are provided with teeth, the teeth of one piston
interlocking with those of the other, so that the two pistons must rotate together.
One of the rotating pistons is turned by the pinion E, the shaft E of which passes
through a stuffing box F' into the pocket P, thence through the stuffing box F, the
inner end of the shaft E' running in a socket E, made for it in the case, as shown
in Fig. 3. The pipe L, Fig. 3, leads from the upper part of the pump to the
lower, and is adapted to let oil flow from above the pistons to the space below
them. This pipe has a stop cock or valve L', by which the amount of oil that
passes may be regulated. Usually enough oil will leak down or be carried down
between the pistons to supply the oil required, but in case there should not be
enough so supplied, then the pipe L may be used.
K, Figs. 1 and 3, is the outlet pipe.
This pump draws air from the article to be exhausted through the pipe N, N'
Fig. 3. The pipe N, N', after leaving the lower part of the pump chamber, turns
upward to a level higher than that of the oil in the pump chamber so that oil
cannot run back into the article being exhausted but will run out into the lower
part of the pump chamber as soon as the pump starts.
This may be better understood by the following explanation
While the pump is in action no oil can run back even if the pipe N, N', did not
turn upward, but when the pump is not in action the oil would by the impulse of
gravity alone flow back from the pump into the pipes N, N', and this flowing back
would of course be much accelerated if a vacuum existed in the pipe N, N', and its
connections, as the pump would when not working admit of leakage through it,

page_text: thus allowing the atmospheric pressure to drive the oil back through the pipe N, NI,
and thence to the articles being exhausted. To guard against any possible back
flow of oil, the pipe N, N' may be carried to such a height that the pressure of oil
in it would exceed the pressure of the atmosphere, then the lamps or other
articles that have been exhausted could be left in connection with the vacuum
apparatus.
H, H, are vertical grooves made in the interior of the casings, and are
intended to collect any air that may have leaked between the end surface of
the rotating piston and the side of the casings, and admit its return to the top.
The operation of the pump is as follows:-There is an amount of oil in the
chamber sufficient to seal all the parts, as shown in Figure 1. Now as the pistons
rotate in the direction of the arrows, the excess of oil in the lower part of the
pump chamber will be carried up by the teeth; that is the oil will fill the spaces
between the teeth and the shell A, and as the ends of the teeth are nearly in
contact with the shell A, between the points and ¹, on both sides of the
chamber, their movement must carry the oil up with them, and as the oil is taken
out of the lower part of the pump chamber a partial vacuum is formed there, and
air is drawn in through the pipe N. When the pump is working the oil will stand
about as indicated in the drawing, Fig. 1, there being some air and some oil in each
tooth space, as indicated, and there will be air in bubbles, passing up through the
oil in the upper part of the pump chamber. Oil from the upper part of the
chamber will be carried down between the rotating pistons and thus keep
the necessary supply in the lower part of the chamber.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is performed as communicated to me by
my foreign correspondent I declare that what I claim is
1st. In a rotary pump the combination of a piston case adapted to hold a scaling
liquid, rotary pistons immersed in said sealing liquid and so located in relation to
each other that the scaling liquid lies above and around the pistons and on the
bottom of the case so that the teeth of the pistons dip into it, while a clear space
is left about the inlet port with an inlet port connected by a pipe with the
article to be exhausted, said inlet port being above the level of the liquid
in the bottom of the case and below the level of the centres of the pistons,
and an outlet port located above the pistons, substantially as and for the purpose
set forth.
2nd. In a rotary pump, a case adapted to receive and retain a sealing fluid, in
combination with rotary pistons, having conically recessed ends adapted to fit
accurately upon corresponding conical parts formed on the interior of the case,
said conical parts being thereby adapted for bearings for the pistons to rotate
upon, no other bearings being required, substantially as and for the purpose set
forth.
3rd. In a rotary vacuum pump, the combination of rotary pistons and their case,
adapted to hold a sealing liquid above the level of the lowest dip of the members of
the pistons, and also to hold a scaling liquid above the level of the centres of the
pistons as described with an inlet port connected by a pipe with the articles to be
exhausted, said inlet being above the level of the liquid in the bottom of the case
and below the level of the centres of the pistons and the outlet port and pipe L,
adapted to convey the excess of the sealing liquid from above the pistons to beneath
them, substantially as and for the purpose set forth.
4th. In a rotary pump, the combination of a case adapted to contain rotary
pistons, and to hold above said pistons a scaling liquid, and also to hold a sealing
liquid at the bottom of the case as described, two rotary co-acting pistons, the
bearings of which do not extend through the case, and inlet and outlet ports as
described with a gear located within said case adapted to drive the said rotary
pistons, and a shaft for said gear adapted to transmit motion to it from without the
case, substantially as and for the purpose set forth.
:

page_text: :
5th. In a rotary pump, the combination of rotary pistons and their case adapted
to hold a sealing liquid above the pistons, and in the bottom of the case as described,
and an outlet port located above said pistons with an inlet port located below the
centres of the pistons and above the normal level of the sealing liquid in the bottom
of the case, said port having a pipe connecting the pump to the article to be
exhausted and extended upward to a height which exceeds the level of the sealing
liquid in the case so that when the pump is not in action the sealing liquid in it
will not run out of the case through the inlet port, substantially as and for the
purpose set forth.
Dated this 8th day of June 1891.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, Agents for the Applicant.