Improvements in and connected with the Valve-gearing and Distributing-devices of Compressors and the like.
Year: 1898

page_text: Date of Application, 9th Feb., 1898-Accepted, 19th Mar., 1898
Improvements in and connected with the Valve-gearing and
Distributing-devices of Compressors and the like.
I, JOHANN STUMPF, of 19, Lessing Strasse, Berlin, in the Kingdom of Prussia,
German Empire, Professor, do hereby declare the nature of this invention, and in
what manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement :-
This invention relates, more particularly, to improvements in air-compressors
though, generally stated, my improvements are applicable to fluid compressing and.
forcing pumps generally.
My object is to provide the compressor-cylinder with valves and valve-operating.
means of an improved construction which renders them particularly quick, smooth,..
and noiseless in action, and capable of a greater lift than the valves hitherto
employed in the same connection, all to the end of rendering the compressor more
desirable for its purpose.
The drawing shows a view which, in the main, is a vertical longitudinal section
of an air-compressor cylinder with my improvements applied.
A is a shell or casing formed of shell-members fitted and bolted together. In the
shell is a cylindrical piston-chamber B having end-walls or heads B₁ B². Working
in the chamber B is the piston C on a stem C¹ which passes through the wall B
and through a stuffing-box t. On the walls B¹ B2 are eduction-chambers D D¹
opening into a common passage D2 having an outlet 8, which, in practice, will
communicate with the air discharge-pipe. In each of the chambers D D¹ is a plug:
or valve-shell E, each comprising a hollow body-portion provided in its outer end
with a wall and with a series of openings around its circumference. The..
opposite or inner ends of the plugs are open and extend through openings in the..
walls B B2, preferably flush with the inner surfaces of the said walls. The wall l
of each plug is provided with a central forward projecting hollow guide-sleeve ™³¸..
and extending through the said wall about the guide-sleeve are one or more
openings. The outer circumference of the wall r¹ of each plug is threaded to..
receive a screw-cap r5, which, with the adjacent wall r¹, forms a chamber 8. The
inner end of each valve-shell or plug E affords a valve-seat ³, preferably
flush with the respective wall of the chamber B. In the chamber r' of
each shell or plug E is a piston q having a central boss q¹ on its rear
face, a central opening q² through it, and a recess q³ in its outer face about
the opening q. A valve p at each shell E is adapted to seat against the seat r
and has a stem-portion p which works through the guide 73 and is screwed at its
outer end upon the boss q¹ of the piston q, which latter thus forms a part of the valve.
Extending longitudinally through each valve p and stem p¹ is a passage opening
into the passage q² of the piston q. The arrangement is such that air compressed
by the piston C in the chamber B in the direction of one of the valves p will pass
through the hollow stem of the latter and the passage q² into the recessed portion q³
of the piston q; and as the said recessed face presents a greater area to the
pressure than the front of the valve p, the tendency will be to force the piston q³
away from the wall ³, presented by the screw-cap, and thus move the valve p from

page_text: the seat r7. When the piston C is moved in the direction away from one of the
valves p the suction of air through the valve-stem and opening q² will cause
the pressure of the air in and surrounding the valve-shell to be exerted through the
openings and in the chamber against the piston q, pressing the latter to the
wall and thus holding the valve p closed. Thus each of the valves P when
opened and closed is held in such position by pressure exerted in the direction
contrary to the movement of the piston C.
As 1 prefer to construct the parts described the piston C as it nears the end of
its stroke in the opposite directions strikes a valve p and closes it against the
resistance of the air pressure, the meeting face of the valve and the stop or portion
of the piston C which strikes the valve being sufficiently out of conformity with
each other to permit the free escape of air from behind the piston q through the
stems of the valves. It will be seen that the lift, or degree of opening of the
valve p is not effected by the sweep or traverse of the piston C, and the valve may,
therefore; be caused to lift and open the ports at 77 very wide. The air pressed
from behind the piston g as the valve p is being closed operates as a cushion, and
prevents jarring of the valve. When a valve p is opened under pressure exerted
from the piston C its operation though quick is against the back pressure of the air
in the chamber 6, which, while escaping through the ports, produces a cushion
against the piston q sufficient to obviate all jar of the valve in opening. The
valves p, furthermore, when opened or closed are held in either position by air
pressure with comparatively great force, thus obviating the necessity of springs,
which are always undesirable. Owing to the fact that in the final movement of the
anain piston while closing a valve p an increased compression of the fluid between
the piston and adjacent end wall is effected, particularly when running above a
certain speed, there would be a danger of the valves being opened momentarily by
the back-pressure in the chamber or recess q³, unless means are provided to prevent
it. To obviate this difficulty I provide each valve p with a forward projecting
part which may be tubular, as shown, and provided with a slot or vent-
opening p3. In each side of the piston C I provide a recess i, with a bolt or
threaded pin extending through the piston at the centre of the recesses and
. confined in place by nuts 2. On the outer ends of the pin i¹ are stops or nuts 23,
and surrounding the pin in the recesses are loose discs or cups it held normally
against the stops and flush with the surfaces of the piston by means of cushioning
springs confined in the recesses. In practice the parts p² would project say or
of an inch beyond the faces of the valves p, whereby as the piston approaches one of the
valves one of its cushioned discs i engages and is compressed by contact with the
projection p² until the piston engages the valve to close the latter. In the initial return
movement of the piston the pressure of the cushioning disc against the valve will
tend to hold the same to its seat until the evacuating action of the piston has
become sufficient to prevent the valve from jumping, or momentarily leaving its
As a further precaution against the jumping of the valves, as described, or in
lieu of the cushioning devices, I provide at the top of the cylinder toward each end
a bye-pass h, both ports h¹ of which open to opposite sides of the piston when the
latter completes its stroke in that direction. The bye-pass effects immediate
equalization of pressure on opposite sides of the piston, or lowering of pressure
between it and the adjacent wall, so that before the piston moves away from the
respective valve p the pressure in the chamber q³ there at will be reduced below the
point where it will cause the valve to jump. I show valves h² at the bye-passes,
which may be turned to regulate the sizes thereof or close them altogether if desired.
FF are induction valve shells each comprising a cylindrical plug portion n,
open at its inner and outer ends, and passing at its inner end through the
respective wall of the piston-chamber B and extending flush with the inner
surface of the wall. In each plug n is a series of circumferential openings n',
communicating with the outside air, and the outer end-portion is threaded to
receive a screw-cap F". Each plug n presents an inner circumferential guide-
surface n², an outlet n³ to the chamber B, and an annular shoulder or stop n at its outer
seat.

page_text: end. In the outer face of each plug n is an annular recess n³ communicating through
small passages with the surrounding atmosphere. Each cap F₁ is formed with
an enlarged part m, at which it is screwed upon the plug, and which affords an
inner annular guide-surface m²; a somewhat reduced part m² affording an
inner circumferential guide-surface m3; and a central tubular extension m' closed
at its outer end. In each of the shells F is a hollow cylindrical valve F2 sliding
in the guide formed by the surfaces n² m³. Each valve is open at its inner end
and closed by a wall at its outer end. In the wall of each valve F is a
central guide-opening and one or a series of openings or ports 12. Integral with
each valve F2, and extending around its circumference, is an annular flange 13,
which slides upon the guide-surface m'. In each cap-portion F¹, in the position
shown, is a passage m³ into which projects a regulating screw me which may be
turned to regulate the size of the passage.
On each side of the piston C, in line with the ports n³, and working through
the latter, are cylindrical projections CC from which extend central stems C²,
passing through the guide-openings in the valves F2, and provided at. their
ends beyond said guide-openings with cushioned heads or stops C³ which slide
loosely in the guides formed by the tubes m*. The cylindrical projections C¹ are
of a size to cause them to slide loosely through the ports n³ and also loosely into
the valves F2.
The view shows the piston C nearly but not quite at the limit of its movement
toward the wall B2, and the valve F, at the wall B', open. In the movement of
the piston, wherein it closes the valve p at the wall B2, the. head C³ on the
stem C, to the left in the figure, engages the outer end of the valve F³ and
moves it until it seats against the port n³, and crosses and closes the ports n'
through which air is supplied to the chamber B. In the reverse movement of the
piston C, toward the wall B', the air, as it is compressed in the direction of said
wall, exerts pressure through the ports 12 in the valve F2, at said wall, and through the
port or passage m³ against the flange of the valve, thereby holding the latter
to its seat at the shoulder n' and maintaining the induction-ports n¹ closed. In
the initial movement of the piston C, in the direction of the wall B', the cylindrical
projection to the right in the figure, produces a suction of air through the adjacent
ports and passage m³, thereby withdrawing pressure from behind the flange (3
and causing the air, under surrounding atmospheric pressure, to enter through the
ports n' and move the said valve to the right in the figure to open the respective
ports n' and admit air to the chamber B on the side B2 thereof. The valves Fº are
held open and closed by fluid pressure exerted in the direction contrary to the
direction of movement of the piston C, and they open, as described, simultaneously
with the initial movement of the piston in the direction away from them. As
before stated the valves F2 are held closed by the pressure of air passing through
the passages m³, and by means of the screws m' these passages may be so
regulated as to size that they cause the valves to be closed with all necessary
quickness against a back pressure without jar, and so gently that they are
practically noiseless. The withdrawal of pressure, through the passages m³, from
behind the flanges l, under the suction action of the piston C, causes the valves to
open with all necessary quickness but noiselessly and without jar. The induction-
valves F2, like the eduction-valves p, may have any desired lift, and, being without
springs, present comparatively little resistance against opening and are particularly
durable and desirable for their purpose.
While I prefer that both the induction and eduction valves shall be closed by the
direct engagement therewith of the piston, or a part movable with or carried by
the piston, in the final movement of the piston toward the limit of its traverse, as
described, the valves may be closed, if desired, by the fluid pressure in the initial
movement of the piston from the limit of its traverse, so that the valves will be
closed, as well as maintained closed by the force of fluid pressure, brought about
by the compression and suction actions of the piston,
My improvements may be applied with benefit to gas or other pumps or com-

page_text: pressors, and they may be modified in the matter of details to meet all requirements
without departing from the spirit of my invention, as defined by the claims.
I desire also to mention that the invention forming the subject of the present
application renders it also possible for the suction valves herein before described to
be replaced by a more simple arrangement.
I have shown an example of such simplified construction or arrangement in
Figure 2 of the accompanying drawing.
In the said example (Figure 2) the suction valves of the compressor are replaced
by Corliss valves Fs, which are actuated in known manner by rods C*.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what I
claim is :-
1. In a compressor, the combination with the cylinder and piston, of a fluid-
passage at the cylinder, a valve movable to open and close said passage and held
alternately in opening and closing positions by fluid-pressure brought about by the
compression and suction action of the piston, the pressure of the valve being in the
diréction toward, the interior of the cylinder under the movement of the piston
toward said passage, and in the direction away from the interior of the cylinder
under the movement of the piston away from said passage, substantially as
described.
2. In a compressor, the combination with the cylinder and piston, of a valve at
the cylinder and in open communication at both its front and rear sides with the
cylinder, the rear face of the valve being of greater area than its front face, whereby
it is pressed to and from its seat under the compression and suction actions of the
piston, the pressure, in each instance, being in the direction contrary to the move-
ment of the piston, which brings it about, substantially as described.
3. In a compressor, the combination with the cylinder and piston, of an inwardly
lifting valve at the cylinder in open communication at its outer side with the cylinder
to be pressed to and from its seat under the compression and suction actions of the
piston, the pressure, in each instance, being in the direction contrary to the move-
ment of the piston, which brings it about, substantially as described.
4. In a compressor, the combination with the cylinder and piston, of an
outwardly lifting valve at the cylinder in open communication at its rear side with
the interior of the cylinder to be pressed to and from its seat under the compression
and suction actions of the piston, the pressure, in each instance, being in the
direction contrary to the movement of the piston, which brings it about,
substantially as described.
.
5. In a compressor, the combination with the cylinder and piston, of a fluid
passage at said cylinder, a valve at said passage in the path of a stop movable with
the piston, whereby the valve is closed in the movement of the piston to the end of
its traverse, the valve, at its rear side being in open communication with the
cylinder and there presenting a greater area to pressure than at its front side,
whereby the valve when closed is maintained closed by fluid pressure under the
action of the piston, substantially as described.
6. In a compressor, the combination with the cylinder and piston, of an
induction passage at the cylinder an outwardly opening valve at said passage
exposed at its rear side to pressure from the cylinder, whereby it is opened under
the suction action of the piston, and in the path of a stop movable with the piston,
whereby in the movement of the piston to the limit of its traverse away from said
passage the valve. is closed by the engagement with it of the stop, and in the
movement of the piston toward said passage the valve is maintained closed by the
fluid pressure generated by the piston, substantially as described..
7. In a compressor, the combination with the cylinder and piston, of an eduction
passage at said cylinder, an inwardly opening valve at said passage in the path of
a stop movable with the piston, and exposed at its rear face to pressure from the
cylinder, whereby under the force of fluid pressure generated by the piston the

page_text: valve is opened, and in the movement of the piston toward said passage the valve is
engaged and closed by said stop, and in the movement of the piston away from said
passage the valve is maintained closed by the suction action of the piston,
substantially as and for the purpose set forth.
8. In a compressor, the combination and arrangement of parts, substantially as
shown and described with regard to Figure 1.
9. In a compressor, the combination and arrangement of parts, substantially as
shown and described with regard to Figure 2.
Dated this 9th day or repruary Toy0.
JOHANN STUMPF,
By Geo. Thos. Hyde,
i, Broad Street Buildings, London, E.C., Agent for the Applicant.