IMPROVEMENTS IN PUMPS FOR THE RAREFACTION AND COMPRESSION OF AIR AND FOR SIMILAR PURPOSESed
Year: 1882

page_text: LETTERS PATENT to William Robert Lake of the firm of Haseltine Lake
& Co Patent Agents, Southampton Buildings, London, for an invention
of "IMPROVEMENTS IN PUMPS FOR THE RAREFACTION AND COMPRESSION OF
AIR AND FOR SIMILAR PURPOSES Communicated to him from abroad by
August Burckhardt and Franz Joseph Weiss, both of Basle, Switzerland.
"
PROVISIONAL SPECIFICATION left by the said William Robert Lake at
the Office of the Commissioners of Patents on the 26th July 1882.
"
WILLIAM ROBERT LAKE, of the firm of Haseltine, Lake, and Co. Patent Agents,
Southampton Buildings, London, "IMPROVEMENTS IN PUMPS FOR THE RARE-
FACTION AND COMPRESSION OF AIR AND FOR SIMILAR PURPOSES [A communi-
cation to him from abroad by August Burckhardt and Franz Joseph Weiss, both of
Basle, Switzerland.]
This Invention relates to improvements in air, and other, pumps and has for its
object to reduce the prejudicial effect of the space between the piston and the end
of the cylinder.
The existence of this space in air or gas pumps generally, whether such pumps
be intended for expansion or compression, has the following effects, that is to say-
First, a certain limit is reached beyond which the expansion or compression
(whichever the case may be) cannot be effected by the machine.
Second, a smaller quantity of air or gas is drawn in than corresponds with the
space traversed by the piston.
The chief objects of this Invention are-
First, to extend the limit to which air or gas may be compressed or rarefied.
Second, to permit of an increased quantity of air being drawn in, that is to say,
to render the pump more efficient.
The principle of this Invention is most readily explained in connection with
a machine for the rarefaction of air, said machine consisting of two air-pumps of
equal size and of similar construction connected with each other in such a manner
as to cause the pistons to work in opposite directions.

page_text: The said Invention consists in connecting the aforesaid spaces of both pumps by
means of a comparatively narrow pipe generally kept closed by a cock or valve
which is opened only when the dead point positions are reached and closed again
immediately afterwards. Thus the air in the space below one of the pistons
having the tension of the outer atmospheric pressure will expand into the suction
space below the other piston. The pressure being, at this moment, the same in both
cylinders, is considerably lower than the atmospheric pressure. Consequently, when
starting to make its fresh stroke, the rising piston will already have below it this
lower pressure, and therefore-
First, a more considerable rarefaction of air will take place at the end of the
stroke, and―
Second, the suction valve of the cylinder will be raised sooner, that is to say,
more air will be drawn in.
If the pump, instead of being composed of two single acting pumps, be con-
structed double acting, then the ends of the cylinders, alternately forming the said
spaces at the end of each stroke, need only be connected by means of a pipe the
same as bereinbefore described with respect to two cylinders, and by means of a
cock, or valve, the two spaces above or below the piston are connected for a short
space of time when each dead point position of the said pistons is reached.
It is evident that in lieu of a cock, valves, slides, or similar contrivances may be
employed, while the temporary opening and closing of such distributing parts may
also be effected automatically by the machine itself.
As the action of a water-pump raising water by suction, is similar to that of an
air-pump during the commencement of its operation until the water has fully
entered the pump, it will be readily understood that this Invention may also be
applied with a similar advantage to any such pump. This Invention may also be
employed advantageously with pumps for compressing gas or air, the attainable
pressure, as well as the quantity of air or gas drawn in, being increased in this
instance, likewise.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Robert Lake in the Great Seal Patent Office on the
13th January 1883.
"
WILLIAM ROBERT LAKE, of the firm of Haseltine, Lake, and Co., Patent
Agents, Southampton Buildings, London "IMPROVEMENTS IN PUMPS FOR THE
A coin-
munication to me from abroad by August Burckhardt and Franz Joseph Weiss,
both of Basle, Switzerland,
RAREFACTION AND COMPRESSION OF AIR, AND FOR SIMILAR PURPOSES
This Invention relates to improvements in air-pumps, and has for its object to
reduce the detrimental effect of the clearance space, or space between one end of
the cylinder and the piston, when the latter is at that end of its stroke.
According to the said Invention I construct the said pumps in such a manner
that the spaces on each side of the piston are connected, either when the piston
reaches one or the other of its dead points, or immediately thereafter, and the said
Invention comprises various modifications in the construction of pumps for this
purpose, as hereinafter set forth-Such connection should not take place before the
piston has completed its stroke, but only with the completion of such stroke or
immediately thereafter, that is to say, when the passages communicating with the
suction and pressure spaces of the cylinder have been closed by the ordinary
devices, such as valves, cocks, or slides. The result of this arrangement will be that
the pump will effectually draw in, and press out, air until the stroke of the piston
has been completed; the air being prevented from returning through the pump
into the suction space during the connection of the spaces on each side of the piston,
which it might do if the valves, cocks, or the like were not entirely closed at the
time.
The practical application of the principle of construction above described is
illustrated in the accompanying drawing, both as applied to air-pumps with
continuous stroke and to those with temporarily interrupted stroke.
Figures 1 and 2 are, respectively, longitudinal and transverse sections of the
cylinder and adjoining parts of an air-pump with continuous stroke.
Figure 3 represents, in longitudinal section, a modification of the same.
Figure 4 is a longitudinal section of the cylinder of an air-pump with continuous
stroke, illustrating another manner of applying the said Invention.
Figures 5 and 6 are respectively, longitudinal and transverse sections of the
cylinder of an air-pump of peculiar construction with temporarily interrupted
stroke, shewing the application of the said Invention thereto.
In the apparatus shewn in Figures 1 and 2, the temporary connection of the
spaces on each side of the piston is effected by means of a slide having motion
transmitted to it, instead of by the self-acting valves usually employed. The
motion of the distributing slide-valve is similar to that of a three-port slide-valve
of a steam engine, with the exception that the course traversed by the air is exactly
opposite in direction to that of the steam, the so-called exhaust-pipe serving for
drawing in the air, while the inlet pipe is used for expelling the air, and the slide
is consequently pressed against its sliding surface on the cylinder by the superior
density of the air in the slide-casing. The excentric or cam for imparting motion to
the slide follows the crank at an angle of about ninety (90) degrees, while in a
steam engine it would lead the same at about that angle. The connection of the
said spaces is effected by a channel a arranged in the slide-valve which channel
connects the space in front of the piston with that behind the same, at the medium
position of the slide-valve. The outer and inner laps of the slide-valve are of such
size that the channel a is about to be closed when the outer and inner edges of the
slide-valve, in their turn, open the air-channels for the purpose of connecting
the pressure space with one end of the cylinder, and the suction space with the

page_text: other end thereof. Moreover, if the outer and inner laps are made of the saine
size and the cam or excentric is arranged at such an angle that the outer, or in
torn the inner, edges of the slide-valve shut off the air-channels or passages
exactly at the end of a stroke of the piston, then the required conditions are
attained, that is to say, an effective delivery of air is caused until the piston has
completed its stroke, and a connection of the spaces on each side of the piston is
effected immediately after the completion of the stroke and while the pressure and
suction spaces are shut off. The eduction valve R, shown in Figure 2, (which in a
modified construction of the slide may be arranged directly above the latter) may
be dispensed with, if desired, as it does not increase the effectiveness of the pump,
as far as the volume of air delivered is concerned, but only as regards its force, the
piston not having to overcome the superior pressure in the pressure space from
the commencement of its stroke, since the pressure in front of the piston increases
only gradually, in accordance with the movement of the piston.
In the modification shewn in Figure 3 two slide-valves are employed, the object
being thereby to diminish the detrimental effect by reducing the size of the ports
or passages. This, however, will not be found necessary in most cases, as the
detrimental effect of such space is diminished by the means hereinbefore described.
Figure 3 shows how the channel a may be arranged in a very simple manner in
this form of apparatus.
The use of slide-valves in air-pumps, in place of the valves ordinarily employed,
allows of about the same rate of speed for the pistons as in steam engines.
The construction shewn in Figures 5 and 6 is intended to illustrate how the said
Invention may be applied to air-pumps with a temporarily interrupted stroke, the
connection of the spaces on each side of the piston, in this instance, being effected
while the piston is stationary at the completion of its stroke, that is to say, while
the same is at its dead point and after all the other devices, such as valves, have
been closed. While the first of these conditions prevails without doubt, the second.is
established only with that degree of certainty or approximation with which it may
be supposed that self-acting valves (possibly assisted by spring action,) are really
The pump shewn is
closed immediately after the completion of the stroke
supposed to have self-acting suction and pressure valves, and its peculiarity consists
in the construction of the annular piston K, provided with suitable packing and
loosely surrounding the body L of the piston rod so as to allow of its being
moved reciprocally thereon in the direction of its axis, the two discs m and n are
firmly connected with the body of the piston-rod and form flanges which carry the
loosely fitting annular piston K along with them at every stroke; the interval
between the inner faces of the discs m and n is slightly larger than the length of
the annular piston K. In consequence of this construction the annular piston K
will remain stationary for a short while after the completion of each stroke,
The edges of the discs m and n
until it is again carried along by one of the discs.
Between the annular piston K
are snugly fitted on their seats on the piston K.
and the solid body of the piston-rod are formed a number of channels a¹ by means
of which the connection of the spaces on cach side of the piston, at the end of each
stroke, is effected, the piston K is held stationary by friction against the inner
sides of the cylinder and, when one of the discs m or n is removed from the piston,
the other disc touches the same and covers it with its face, thus forming a valve
and again cutting off the connection between the two spaces in the cylinder. The
faces,, (or valve seats) of the discs m and n should be made to fit the interior of
the cylinder as closely as possible, so as to prevent the pressure, (of the air confined
in the clearance space at the end of each stroke), upon the annular surface of the
piston between 7,7, and the inner sides of the cylinder, from becoming greater than
the frictional resistance of the piston-Should this occur, the stationary position
of the piston, and with it the connection of the two spaces, would take place at a
longer or shorter period of time after the commencement of the fresh stroke, tha
is to say, at the moment when the air-pressure in the clearance space is so much
reduced as to.be less than the friction of the piston.

page_text: Another peculiar construction is shown in Figure 4, similar to that above
described, but adapted for pumps with continuous stroke and having suction and
pressure valves instead of slide valves.
the channel for equalizing the pressure on each side of the piston. A rod b passes
The piston K has a perforation forming
through the said perforation and also through the heads or ends of the cylinder,
and projects a suitable distance beyond the said ends, which are provided with
suitable stuffing boxes. Two valves v, v³, are firmly secured to the said rod so as
to be a little further apart than the valve-seats in the piston.
moves forward, the first valve v is closed, in consequence of the friction of the rod b
When the piston
in the stuffing box, and the valve is pressed firmly against its seat by the increased
air-pressure in front of the piston. During the subsequent change of stroke (the
respective nuts having been previously tightened until the friction of the stuffing
box becomes greater than the pressure of air on the delivery side of the piston)
this friction holds the rod b, and with it the valves, stationary until the opposite
valve v covers its seat. In the interval, that is to say, immediately after the
piston has passed its dead point, the connection of the two spaces is established and
the pressure thereby equalized.
In lieu of single valves v, v, two equilibrated double-seat valves may be
used and the pressure of air on the valves, and consequently the requisite friction
of the stuffing boxes on the rod b, may be reduced to a minimum.
to
It is evident that the improved made of construction above described is applicable
pumps for the rarefaction, as well as for the compression, of air.
Having thus fully described the said Invention as communicated to me by my
foreign correspondents and the manner of performing the same I wish it understood
that I claim :-
First. The construction of a pump for the rarefaction, or for the compres, on, of
air, in such a manner that the spaces on each side of the piston are connected
immediately, or very shortly after, the piston has completed its stroke, and after
the valves or other devices in the inlet and outlet passages have been closed,
substantially as, and for the purpose, set forth.
Second. In a pump provided with a slide-valve, or valves, the arrangement in
he said valve, or in each of the said valves, of a channel for equalizing the
pressure on both sides of the piston, substantially as, and for the purpose, set forth.
Third. In a pump with an interrupted stroke, the construction of the piston K
8 shewn in Figures 5 and 6, the said piston being arranged between the solid
liscs m, n, and loosely surrounding the body of the piston-rod in such a manner as
o permit of its being reciprocated thereon, and thereby opening the channels a¹
uring the intervals between the strokes of the piston, substantially as described,
nd for the purpose specified.
Fourth. In a pump with continuous stroke, the perforated piston K, as shewn in
igure 4, the perforation thereof being arranged to be opened by the valve v, or v',
y reason of the friction between the rod b and the stuffing boxes, shortly after
he piston arrives at one of its dead points, and to be closed immediately after
he piston commences its return stroke, substantially as, and for the purpose, set
orth,
In witness whereof I the said William Robert Lake have hereunto set my
hand and seal this Eleventh day of January in the year of our Lord On