Improvements in Air-pumps.
Year: 1897

page_text: Date of Application, 3rd July, 1897--Accepted, 7th Aug., 1897
COMPLETE SPECIFICATION.
Improvements in Air-pumps.
I, LUDWIG KAUFMANN, of Aachen, in the Province of the Rhine, German
Empire, Engineer, 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:-
This invention refers to pumps of the kind used for compressing or rarifying air,
and my improvements in pumps of this kind relate to providing the pump with
means for perfectly relieving the distributing valve or valves from any one-sided
pressure, and for doing away with the loss in effect caused by the compressed or
rarified air which remains in the clearances of the cylinder.
In
I attain these objects in general by forming the distributing valve of two hollow
pistons which are connected by a hollow rod. Said pistons are arranged to move
parallelly to the piston of the cylinder and each of them is provided with lateral open-
ings by means of which the hollow space of each piston may be put into communi-
cation with the clearance of the respective side or end of the cylinder.
consequence of the said two pistons being connected by a hollow rod the compressed
air passing from one of the clearances into the respective piston may flow over
into the other, i.e. larger space of the cylinder. In a vacuum pump the air con-
tained in this space will, of course, pass over into the respective clearance so as
thereby to bring about the equilibrium of pressure.
I have represented as an example a form of construction of my improved air-
pump in the accompanying drawing, which shows a longitudinal section through
the cylinder the valve casing and the adjacent parts.
In this form of construction the two pistons a a¹ are made integrally with the
hollow rod a. The parts a a¹ a form a cylindrical casing which is moved to and
fro in the valve casing 6 by means of the piston rod c; the latter extends through
the hollow rod a or connecting casing a² and is secured at its end to the piston a.
I wish it, however, to be understood that in a compressing pump the piston-rod c
may be secured to the piston a¹, whereas in a vacuum-pump I prefer to let the
piston rod c extend even through the piston a and through the opposite wall 63
of the valve casing, so that a perfect equilibrium of pressure is attained at both
ends of the piston valve.
The hollow rod or connecting casing a³ and the adjacent part of the valve cas
ing form a space d of an annular section. A downwardly extending part b¹ of
the valve casing 6 forms a chamber d' which communicates with the place of use
or store of the compressed air. The chamber dis separated from the chamber
or space d by a valve e. The air to be compressed is sucked in alternately through
the ports 63 64, the port 63 being intermittently put into communication with the
port g and the port 6* being alternately put into communication with the port g¹ of
the cylinder. The communication between the ports b* and g' is interrupted by
the hollow piston-valve a and the communication between the ports 6' and g¹ is
interrupted by the hollow piston-valve a.
The piston-valves a a¹ with their hollow connecting rod «² are operated in such

page_text: a manner with regard to the piston of the cylinder h, that they assume a medium
position when the piston ¹ is in one or the other of its two end-positions. When
the piston moves from the right to the left the position of the piston-valve a is
such that the air supplanted out of the cylinder, and compressed at the same
time, is driven into the annular space between the hollow connecting rod a² and
the adjacent part of the valve-casing b. From said spaced the compressed air
passes into the chamber, the valve & being, of course, depressed during this
time. At the same time air is sucked into the cylinder through the ports b
and g, the piston-valve a¹ having been displaced so far to the left that the ports b
and have been put in communication with each other. This communication is
established (or broken) by the edge a³ of the piston-valve a¹, whereas the communi-
cation of the port g' with the annular space d is established (or broken) by the
edge as of said valve. In just the same manner the communication between the
ports and 63 is established (or broken) by the edge a² of the piston-valve. a,
whereas the communication of the port g with the annular space is established
(or broken) by the edge at of this valve.
The valve casing is arranged as near as possible to the cylinder and extends
parallèlly to said cylinder, so that the clearance at either side of the piston is
reduced in the highest attainable degree.
.3
The hollow piston-valve a is surrounded by an annular channel the upper
part of which communicates with a port g, and said valve is further provided with
radial openings establishing a communication between said annular channel
and the inner space of the hollow connecting rod a². Also the piston-valve a³ is
surrounded by an annular channel 66, and this valve is provided with radial
tures a putting said channel & in communication with the inner space of the
hollow rod a².
aper-
Supposed, the piston ¹ be in the position shown in the drawing the compressed
air remaining in the clearance may pass through the port into the annular
channel 5, and further through the radial openings as of the piston valve a into
the inner space of the hollow connecting rod a². From this space the compressed air
passes through the radial apertures of the piston-valve a into the aunular
channel 6 and into the port gl so that thus an equilibrium of pressure on both
sides of the piston is attained.
Having now particularly described and ascertained the nature of my said in-
vention, and in what manner the same is to be performed, I declare that what I
claim is
1. In an air-pump, the combination with the pump-cylinder and piston, of a
valve-casing located near to said cylinder, and extending parallelly to the same,
two hollow piston-valves arranged in said casing, a hollow rod connecting said
piston-valves, and apertures provided in the latter and adapted to connect the
spaces at the two sides of the piston, as set forth.
2. In an air-pump, the combination with the pump-cylinder and piston, of a
valve-casing located near to said cylinder, and extending parallelly to the same,
two hollow piston-valves arranged in said casing, a hollow rod connecting said
piston-valves, and apertures provided in the latter and adapted to connect the .
spaces at the two sides of the piston, a chamber formed by a laterally extending
part of the valve-casing, and an annular space formed by said hollow rod and the
adjacent part of said casing, and a valve separating said annular space from said
chamber, as set forth.
11
LUDWIG KAUFMANN,
By Geo. Thos. Hyde,
1 Broad Street Buildings, London, E.C.