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BACKGROUND OF THE INVENTION
The present invention relates to fluid-actuated pumps in general, and more
particularly to pneumatically actuated hydraulic pumps.
There is already known a variety of different pneumatically actuated pumps,
such as hydraulic pumps, either of the single acting or of the double
acting type. In such pumps there are usually provided interconnected
reciprocating actuating and pumping pistons both being accommodated in
their own chambers and the actuating piston having a larger active area
than the pumping piston. The reciprocation of the actuating piston is
controlled by a control valve which has a plurality of circumferential
lands that separate individual connecting compartments from one another
and also from control compartments provided at the one or the other end
face of the control valve. Depending on the position of the control valve,
one or both of the actuating compartments located to the two sides of the
actuating piston are alternatingly supplied with pressurized fluid, or
relieved of pressure, in that one of the connecting compartments
permanently communicates with a source of a pressurized actuating fluid,
while the other connecting compartment is permanently maintained at an
atmospheric pressure. In this context, it is also already known to employ
an auxiliary control valve which permanently communicates with the source
of the pressurized actuating fluid and which has a displacing portion
which extends into one of the actuating compartments and into the path of
movement of the actuating piston to be displaced by the latter.
The heretofore known constructions of hydraulic pumps of this type are very
complicated with respect to the pneumatically actuated part and the
associated control arrangement and, therefore, such constructions are
prone to malfunction. The control valve is relatively long and is
provided, at the circumference thereof, with a plurality of mutually
axially spaced lands equipped with sealing rings, as well as a plurality
of annular compartments separated from one another by such lands. The
control valve of the conventional construction is provided by an axial
bore which extends over almost the entire length of the control valve,
while two spaced radial bores each communicate the axial bore with one of
the circumferential compartments. The axial bore serves solely the purpose
of removal of expended air. The movement of the control valve by means of
compressed air is achieved, on the one hand, by means of a peripheral
annular surface and, on the other hand, by means of that end face of the
control valve which is diametrally opposite to the port of the axial bore.
Corresponding to the number of the circumferential annular compartments,
there is needed a corresponding number of bores or annular grooves in the
housing of the control valve. As a result of this, the control arrangement
is very complicated and expensive, which has the disadvantageous effect of
making the dimensions of the hydraulic pump with the associated equipment
large and thus limiting the utility of the hydraulic pump to only some
applications. A further disadvantage is to be seen in the fact that a
separate and differently configurated control arrangement must be designed
and manufactured, on the one hand, for a single acting pump and, on the
other hand, for a double acting pump. As a result of this, the manufacture
of the hydraulic pump is rendered more expensive and the keeping of the
individual components in stock is rendered more difficult. In addition
thereto, even the hydraulic part of the pump is complicated and, as a
result of this, prone to malfunction, in that it usually consists of
forged or wrought T-pieces or double-T-pieces with incorporated suction
and pressure valves, which can only be manufactured with the necessary
precision on special machines.
SUMMARY OF THE INVENTION
Accordingly, it is a general object of the present invention to avoid the
disadvantages of the prior art.
More particularly, it is an object of the present invention to devise a
fluid-operated pump which is not possessed of the disadvantages of the
prior-art pumps.
Still another object of the present invention is to provide a pneumatically
operated hydraulic pump which is simple in construction, reliable in
operation and inexpensive nevertheless.
A concomitant object of the present invention is to so construct the
pneumatically actuated hydraulic pump as to have only a small number of
simple and reliably operating components, both at the actuating side and
on the pumping side thereof.
A yet further object of the present invention is to so design the pump as
to have small overall dimensions for a given output thereof.
Finally, it is an object of the present invention to so construct a control
arrangement for the actuating part of the pump as to be usable, with only
a small modification, both in single acting and double acting pumps.
In pursuance of these objects and others which will become apparent
hereafter, one feature of the present invention resides, in a
fluid-actuated pump, briefly stated, in a combination comprising at least
one pumping unit including a pumping chamber, a pumping piston received in
said pumping chamber for reciprocation to one end position in a suction
stroke and to another end position in a pumping stroke, and means for
admitting a medium to be pumped into said pumping chamber during said
suction stroke and for discharging the medium being pumped from said
pumping chamber during said pumping stroke; an actuating unit including an
actuating chamber and an actuating piston subdividing said actuating
chamber into two actuating compartments and connected to said pumping
piston for joint reciprocation; a source of pressurized actuating fluid; a
sink for the actuating fluid; and means for alternately communicating at
least one of said actuating compartments with said source and said sink,
including a main valve having a control chamber and an elongated main
valve member mounted in said control chamber for movement between an
extended and a retracted position and having a large first end face facing
a first, and a smaller second face facing a second, control compartment
into which said main valve member subdivides said control chamber, and a
first and a second connecting compartment at the circumference of said
main valve member intermediate said end faces and separate from each other
and from said control compartments. The communicating means further
includes first duct means permanently communicating said second connecting
and control compartments with said source for the pressurized actuating
fluid to urge said main valve member toward said extended position
thereof, second duct means communicating said first connecting compartment
with said sink, third duct means communicating said source with said first
control compartment, an auxiliary valve member interposed in said third
duct means for displacement from a closed toward and open position, means
for displacing said auxiliary valve member toward said open position
thereof when said pumping piston is at said one end position thereof,
fourth duct means communicating said first control compartment with said
sink when said pumping piston is at said other position thereof, and fifth
duct means communicating said one actuating compartment with said second
connecting compartment in said retracted, and with said first connecting
compartment in said extended, position of said main valve member.
Preferably, the above-mentioned medium is a liquid and the above-mentioned
fluid is a gas, such as compressed air, and then the active area of said
actuating piston considerably exceeds that of said pumping piston.
In a currently preferred embodiment of the present invention, said first
connecting compartment is closer to said second control compartment than
said second connecting compartment, and the first duct means includes a
duct in said main valve member which bypasses said first connecting
compartment and communicates said second control and connecting
compartments with one another.
Consequently, as far as the control arrangement is concerned, it has been
achieved by the present invention that the construction obtained thereby,
including the most important components thereof, is suited for use either
as a single acting or as a double acting pump. The control is constructed
in a simple and distinct manner and possesses comparatively small
dimensions. As a result of this, it is possible to manufacture the pumps
equipped with this control arrangement smaller for the same output than
the heretofore known pumps.
The main valve member is very short and possesses, at its circumference,
only two annular compartments separated from one another by lands, by
means of which connecting compartments the reversing functions for the
pneumatic actuating piston can be performed in a reliable manner either in
a single acting or in a double acting pump. Furthermore, the duct in the
main valve body, preferably constructed as an axial bore, is relatively
short, extending through the main valve member to an extent only slightly
extending a half of the length of the main valve member. The axial bore
has a port which is located at the small end face of the main valve body,
the small end face being constantly acted upon by the compressed air. As a
result of this, even the axial bore is always in communication with the
source of the pressurized air. On the other hand, the action of the
pressurized air on the larger end face provided at the opposite
longitudinal end of the main valve member from the small end face, is
controlled in dependence on the operating position of the auxiliary valve
member and thus in dependence on the position of the actuating piston.
This is particularly true when, according to another aspect of the present
invention, the displacing means includes a displacing portion of the
auxiliary valve member which extends into said one actuating compartment
and into the path of reciprocation of said actuating piston to be
displaced by the latter toward said open position when said pumping piston
approaches said one end position. Under these circumstances, the actuating
piston displaces the auxiliary valve member and thus admits the
pressurized air to the larger end face of the main valve member, or
relieves the pressure acting on the larger end face of the main valve
member. The main valve member is guided in a cylindrical bore of either
the pump housing or of a discrete control housing, with which there are in
communication only the relief channel for the actuating fluid, a
connecting channel to the one actuating compartment, and a connecting
conduit to the auxiliary valve member, as far as a single acting pump is
concerned. In a double acting pump, even the other actuating compartment
is connected to the cylindrical control chamber accommodating the main
valve member by a connecting channel. The larger end face constitutes a
part of a grooved land of an enlarged diameter which is accommodated in an
enlarged end portion of the cylindrical control chamber.
In order to assure that, during the movement of the relief port, there is
obtained a reliable sealing effect between the components of the control
arrangement which communicate with the source and with the sink,
respectively it is proposed, according to a currently preferred concept of
the present invention, to separate the two annular connecting compartments
from one another by three mutually parallel radial lands, and two sealing
rings respectively accommodated between the three lands and axially fixed
thereby.
The function of the two annular connecting compartments which immediately
follow one another in the longitudinal direction of the main valve member,
is exactly predetermined. While the first connecting compartment which is
located adjacent the smaller end face is always in communication with the
sink, such as the ambient atmosphere, regardless of the instantaneous
position of the main valve body, that is, it serves to release the
actuating fluid from the actuating compartment of the actuating unit, the
other annular connecting space is permanently connected, via the
above-mentioned duct, such as axial and radial bores in the main valve
member, with the source of the pressurized actuating fluid. In this
connection, it is further advantageous according to the present invention
that the first connecting compartment is longer than the second connecting
compartment so as to be always in communication with a conduit
communicating with the sink. While one radial bore is sufficient, a
plurality of such radial bores may be provided, being located in a common
plane and extending radially between the axial bore and the second
connecting compartment.
When the above-discussed control arrangement is used in a hydraulic pump
which is single acting and where a resiliently yieldable arrangement, such
as a helical spring, is used for returning the actuating piston towards
its initial end position, it is proposed by the present invention to equip
the actuating piston with a guiding element, such as a pin, which is
received in and slides in a cylindrical receiving chamber of the pump
housing. The guide pin serves to stabilize the actuating piston, together
with the hydraulic piston which reciprocates in a corresponding pumping
chamber of the hydraulic pumping unit.
In addition thereto, the cylindrical receiving chamber for the guide pin of
the actuating piston has the purpose of rendering escape of the actuating
fluid from the first control compartment possible. To this end, the
present invention proposes that the duct which communicates with the first
control compartment communicate with the cylindrical receiving chamber of
the pump housing. As a result of this, the guide pin not only constitutes
a stabilization member for the pneumatic actuating piston, but also
represents a closing member which obstructs the escape route of the
pressurized actuating fluid from the first control compartment during a
large part of the axial movement of the actuating piston.
According to a further concept of the present invention, the pumping unit
includes a pumping casing which is accommodated in said pump housing and
has an extension extending to the exterior of said pump housing. Then, the
admitting and discharging means includes a valve casing, an admitting and
discharging valve accommodated in said valve casing, and means for
detachably connecting said valve casing to said extension of said pumping
casing, including a passage in said valve casing for fittingly receiving
said extension. Thus, the pumping casing of the hydraulic pumping unit
constitutes a detachable component of the pump housing. The extension
emerging out of the pump housing is preferably cylindrical in
configuration, and the valve casing with the admitting and discharging
valve is then slid over the extension, enclosing an angle of 90.degree.
therewith, and arrested thereon in the proper position. In the event that
the pump is double acting, it is to be understood that even the pumping
casing of the second pumping unit has a similar extension which emerges
from the pump housing at the opposite side thereof. Then, similarly to
what has been explained above in connection with a single acting pump,
another valve casing is slid over and arrested to the other extension. The
admitting valves, on the one hand, and the discharging valves, on the
other hand, of each side can communicate with the same conduits.
It is of a particular advantage in this connection when said connecting
means includes a pair of connecting elements each being of a
doubly-conical configuration and each having a central channel
communicating the interior of said extension with the interior of said
valve casing at said admitting valve and at said discharging valve
respectively, and a pair of threaded members each respectively pressing
one of said connecting elements into contact with said extension of said
pumping casing. After the sliding of the valve casing over the extension
of the pumping casing, or of the two valve casings over the two
extensions, the connecting elements, which are conical at their ends and
cylindrical at the center portions thereof, are introduced through the
hollow threaded portions of the valve casing and are inserted, by one of
the conical end portions of each, in a correspondingly configurated recess
provided at the circumference of the extension of the pumping casing. The
cylindrical center portion of the respective connecting element is
received in a corresponding bore of a transverse portion of the valve
casing. Subsequently, the respective connecting element is held in a
proper position by means of the respective threaded member which is
threaded into the threaded portion of the valve casing and which
possesses, at its free end, a conically configurated recess which comes
into contact with the second conical end portion of the respective
connecting element. In this manner, the valve casing is sealingly
connected to the extension of the pumping casing, without additional
threaded connections.
This results in a very advantageous situation wherein the conical
connecting elements reliably seal the hydraulic pumping chamber relative
to the threaded members. What is achieved thereby is that the hydraulic
medium is confined in a system of bores having relatively small diameters.
This has a further advantage that the pressure forces, as a result of the
small diameters and small affected surfaces, do not become exceedingly
great and, as a result thereof, the various components can be made with
walls having relatively small thicknesses. Similarly configurated,
assemblable constructions, are already known, but the valve casing for the
admitting and discharging valves is sealed, in the transverse bore, by
means of O-rings and supporting rings. These O-rings and supporting rings,
however, are exposed to high loads at high pressures especially in pulsing
operation. Furthermore, it is known to build the valve casing together
with the pumping casing from a single forged or wrought T-piece or
double-T-piece. Even in this construction, the hydraulic fluid is confined
in bores of relatively small diameters. However, the forged pieces can
only be manufactured which much more difficulty than those of the
assembled construction according to the present invention. The latter
construction, furthermore, has the significant advantage that all of the
individual components can be manufactured from stock material on
automatically operating material-removing machines, such as lathes. In
addition thereto, it is reliably avoided that the hydraulic medium could
escape from the circuit therefor.
In the case of a double acting actuating piston to which there are
connected two hydraulic pumping pistons extending to opposite sides of the
actuating piston, there are provided two auxiliary valve members having
displacing portions each of which extends into one of the actuating
compartments and into the terminal portion of the path of reciprocation of
the actuating piston at the two end positions thereof. Under these
circumstances, it is advantageous according to a further facet of the
present invention that the above-mentioned fourth duct means communicates
with the sink via the additional auxiliary valve member. Then, the
communicating means of the present invention further comprises sixth duct
means communicating said other actuating compartment with said source in
said extended, and with said first connecting compartment in said
retracted, position of said main valve member.
The novel features which are considered as characteristic for the invention
are set forth in particular in the appended claims. The invention itself,
however, both as to its construction and its method of operation, together
with additional objects and advantages thereof, will be best understood
from the following description of specific embodiments when read in
connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a somewhat diagrammatic sectioned side elevational view of a
single acting pump according to the present invention in one end position;
FIG. 2 is a view similar to FIG. 1 but in another end position;
FIG. 3 is a view similar to FIG. 1 but of a double acting pump; and
FIG. 4 is a view similar to FIG. 2 but of a double acting pump.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawing in detail, and first to FIGS. 1 and 2 thereof,
it may be seen that the reference numeral 1 indicates a pump housing which
is provided with an approximately centrally located actuating chamber 2.
An actuating piston 3 which has a relatively large diameter but is
relatively thin, is mounted in the actuating chamber 2 for reciprocation
in response to admission of pressurized air thereto. The actuating
compartment 2 is bounded by a surface 5, and the actuating piston 3 has
mounted thereon a sealing ring 4 which sealingly contacts the surface 5.
The actuating piston 3 is provided, at its side 6, with a guide pin 7 which
is received for sliding in a cylindrical receiving chamber 8 of the pump
housing 1. The receiving chamber 8 is in communication with the ambient
atmosphere. The actuating piston 3 is connected, at its other side 9, with
a cylindrical hydraulic pumping piston 10 which is received for sliding in
a cylindrical pumping chamber 11 of a hydraulic pumping casing 12.
The hydraulic pumping casing 12 is received in a recess 13 of the pump
housing 1 constituting a continuation of the actuating chamber 2, and has
a shaft-shaped extension 14 which emerges out of the pump housing 1 to one
side thereof. The connection of the hydraulic pumping casing 12 to the
pump housing 1 is achieved by means of a connecting ring 15. Between an
annular flange 16 of the hydraulic pumping casing 12 and an annular groove
17 in the actuating piston 3, there is provided a helical compression
spring 18. The hydraulic pumping casing 12 is sealed relative to the
hydraulic pumping piston 10 by means of a seal 19, and the guide pin 7 for
the actuating piston 3 is sealed with respect to the pump housing 1 by
means of a seal 20. The reference numeral 21 designates a venting bore
communicating the actuating chamber 2 with the exterior of the pump
housing 1.
The extension 14 of the hydraulic pumping casing 12, extending out of the
pump housing 1, is introduced into a valve casing 22. The longitudinal
axes of the hydraulic pumping casing 12 and of the valve casing 22
intersect with one another at a right angle. The connection of the valve
casing 22 to the extension 14 of the pumping casing 12 is achieved by
means of doubly-conical coupling or connecting elements 23. For this
purpose, there are provided, in two transverse walls 24 of the valve
casing 22, at internally threaded portions 25 thereof, bores 26 into each
of which there is introduced a cylindrically configurated center portion
of one of the connecting elements 23. One of the two conical end portions,
for instance, 27, of the respective connecting element 23, is accommodated
in a correspondingly conically configurated recess 28 provided at the
circumference of the extension 14, while the other conical end portion 29
extends into the threaded portion 25 of the valve casing 22. Threaded
members 30 are then threaded into the above-mentioned threaded portions
25, each of such threaded members 30 being provided, at its leading end,
with a conical inner surface 31 which comes into contact with the conical
end portion 29 of the connecting element 23 during the tightening of the
threaded member 30. In this manner, the valve casing 22 is sealingly
connected to the shaft-shaped extension 14 of the pumping casing 12.
As can be further ascertained from the drawing, the connecting members 30
are provided, at their trailing end portions, with inwardly threaded
sections 32 for connecting hydraulic conduits thereto, and in a
continuation of each of such sections 32, with central bores 33 in which
there are arranged the suction or pressure valves, respectively. While on
the one side (left side of the drawing), a ball 34 is pressed by a spring
35 against a port of a further cylindrical bore 36 of the threaded member
30, the spring 35 resting against the connecting member 23, a ball 37 is
accommodated in the other threaded member 30 and pressed by a compression
spring 39 against a portion of a transfer bore 38 in the connecting member
23. The other end of the compression spring 39 rests against the inner end
face of the threaded member 30.
An auxiliary valve member 41 is located in a corresponding recess 40 of the
pump housing 1 and extends parallel to the longitudinal axis of the
actuating piston 3 which coincides with that of the hydraulic pumping
piston 10. The auxiliary valve member 41 has a displacing portion 42 which
is capable of extending into the actuating chamber 2, being urged into
such position by a helical compression spring 43 which abuts, at its free
end, against a seting screw 44. The auxiliary valve member 41 is sealed
with respect to the actuating compartment 2.
Parallel to the longitudinal axis of the auxiliary valve member 41 and to
that of the actuating piston 3 and the pumping piston 10, there is
received in a further cylindrical recess 45 of the pump housing 1 or of a
discrete control housing (for the sake of simplicity, pump housing 1 has
been selected), a main valve member 46 for axial movement. The
channel-shaped cylindrical recess 45 is in direct communication with a
conventional source of compressed air which has not been illustrated.
The main valve body 46 has a small end face 47, the outer diameter of which
corresponds to the diameter of the admission channel 45. The end face 47
constitutes a part of a radially projecting land 48 which, together with a
further land 49, axially fixes a sealing ring 50 in place, the sealing
ring 50 sealingly contacting an inner surface 51 bounding the channel 45.
An annular connecting compartment 52 immediately adjoins the land 49, the
annular connecting compartment 52 being separated from another annular
connecting compartment 53 following the connecting compartment 52 in the
axial direction of the main valve member 46, by three circumferentially
extending radially projecting lands 54, 55 and 56, and by two axially
fixed sealing rings 57 which also sealingly contact the surface 51 of the
channel 45. The annular connecting compartment 53 is axially shorter than
the annular connecting compartment 52. The annular connecting compartment
53 is delimited, at its other end, by a land 58 which, together with a
further land 59, axially fixes a sealing ring 60 which sealingly contacts
the surface 51 of the channel 45.
At an axial distance from the last-mentioned land 59, there are provided
two further lands 61, 62 which are larger in diameter, the lands 61, 62
axially confining between each other a sealing ring 63. These lands 61, 62
slide in a control chamber which is increased in diameter relative to the
channel 45, the land 62 being provided, at the axial end of the main valve
member 46, with a large end face 65. The space between the land 59 and the
land 61 may be communicated with the ambient atmosphere by a passage 59a.
Four radial bores 66, angularly distributed by 90.degree. relative to one
another, communicate with the shorter annular connecting compartment 53
and with a central axial bore 67. The axial bore 67 extends over somewhat
more than a half of the length of the main valve member 46 an communicates
with the channel 45 at the smaller end face 47.
In the operating position of the pump which is illustrated in FIG. 1, the
compressed air flows through the channel 45 and through the axial bore 67
to the radial bore 66, and from there through the connecting compartment
53, a duct 68 to the one side 6 of the actuating piston 3, displacing the
latter, against the force of the helical compression spring 18, toward the
other end position which is illustrated in FIG. 2. During such
displacement, the hydraulic pumping piston 10 performs a pumping stroke so
that the hydraulic medium, which has been previously drawn into the
pumping chamber 11 through the admitting valve 34, 35, is now discharged
or pumped through the discharge valve 37, 39.
During the displacement of the actuating piston 3, the displacing portion
42 of the auxiliary valve member 49 move jointly with the actuating piston
3 until a disk 69 of the auxiliary valve member 41 sealingly contacts a
seal 70. As a result of this, a duct 71, which is in permanent
communication with the channel 45, is sealingly separated from a
connecting duct 72 leading to the larger end face 65 of the main valve
member 46. Thus, the source of compressed air communicates only with the
channel 45 and thus acts on the smaller end face 47. However, the main
valve member 46 cannot yet be displaced from the retracted position
illustrated in FIG. 1 into the extended position illustrated in FIG. 2 in
that the compressed air which is present in the control compartment 64
cannot escape through the duct 73 inasmuch as a port of this duct 73 is
still obstructed by the guide pin 7 of the actuating piston 3. Only when
the free end of the guide pin 7 clears the port of the duct 73 (see FIG.
2), the main valve member 46 is able to displace the air out of the
control compartment 64 via the duct 73 and the cylindrical receiving
chamber 8 to the exterior of the pump housing 1.
When this happens, the main valve member 46 is displaced into its extended
position illustrated in FIG. 2. In this position, the duct 68 leading to
the actuating chamber 2 of the actuating piston 3 is separated from the
connecting compartment 53 and, after the clearance by the lands 54 to 56
separating the connecting compartments 52 and 53, the actuating chamber 2
is communicated, via the longer connecting compartment 52, with a
discharge duct 74. Thus, the actuating chamber 2 of the actuating piston 3
communicates with the ambient atmosphere. The helical compression spring
18 can now become active and return the actuating piston 3 into the end
position thereof which is illustrated in FIG. 1.
During such return displacement, the guide pin 7 of the pneumatic actuating
piston 3 first obstructs the port of the channel 73 and thus interrupts
communication thereof with the ambient atmosphere. Shortly before reaching
the end position illustrated in FIG. 1, the actuating piston 3 contacts
the displacing portion 42 of the auxiliary valve member 41 and displaces
the same into its open position illustrated in FIG. 1. As a result of
this, the compressed air present in the channel 45 can flow through the
duct 71 and the duct 72 into the control compartment 64 to act at the
larger end face 65 of the main valve member 46, thus displacing the latter
into the position illustrated in FIG. 1. As a result of the displacement
of the main valve member 46, the discharge duct 74 is separated from the
channel 68 communicating with the actuating chamber 2. After the central
lands 54 to 56 have cleared the port of this duct 68, the latter is
connected, via the shorter annular connecting space 53, the radial bores
56, and the axial bore 67, with the channel 45 and the full cycle
described above repeats itself.
The double acting pump illustrated in FIGS. 3 and 4 also has a pump housing
1 which has a central actuating chamber 2' for a pneumatic actuating
piston 3'. The actuating piston 3' is sealed by a peripheral seal 4
relative to the surface 5' bounding the actuating chamber 2'. To the two
sides of the actuating piston 3', there extend two hydraulic pumping
pistons 10', 10" into corresponding hydraulic pumping casings 12 of which
only the casing 12 associated with the pumping piston 10' is illustrated.
Each of the pumping casings 12 has a shaft-shaped extension 14 extending
to the exterior of the pump housing 1. The hydraulic pumping casing 12,
the shaft-shaped extensions 14, and the valve casings 22 including the
valve components thereof, mounted on these shaft-shaped extensions 14, are
identical to those which have been discussed above with reference to FIGS.
1 and 2. Thus, a renewed discussion of these components can be dispensed
with.
Also the construction of the main valve member 46 and its arrangement in
the pump housing 1 identically corresponds to that of the embodiment of
FIGS. 1 and 2. The only addition to the embodiment of FIGS. 1 and 2, which
is encountered in the embodiment of FIGS. 3 and 4, is an additional
auxiliary valve member 41', necessitated by the construction of the pump
as a double acting pump, which additional auxiliary valve member 41' is
provided at the other end of the actuating chamber 2'. However, even this
additional auxiliary valve member 41' is constructed identically to the
auxiliary valve member 41 which has been discussed above in connection
with the embodiment of FIGS. 1 and 2.
In the illustration of FIG. 3, the compressed air in the compressed air
admission channel 45 acts on the smaller end face 47 of the main valve
member 46, having displaced the latter in the illustrated end position
thereof. In this end position, the auxiliary valve member 41 is in its
closed position so that the compressed air admitted to the auxiliary valve
member 41 via the duct 71 cannot proceed to the larger end face 65 of the
main valve member 46.
Furthermore, the compressed air acts on the side 9' of the pneumatic
actuating piston 3', via the channel 45 and a duct 75 in the pump housing
1. The other side 6' of the pneumatic actuating piston 3' is in
communication, via the duct 68 and the long annular connecting compartment
52, with the discharge conduit 74. As a result of this, the pneumatic
actuating piston 3' can be moved into the other end position thereof which
is illustrated in FIG. 4.
During such displacement, the displacing projection 42' of the additional
auxiliary valve member 41' follows the displacement of the pneumatic
actuating piston 3'. The additional auxiliary valve member 41' thus moves
into its closed position illustrated in FIG. 4. Shortly before the
pneumatic actuating piston 3' reaches its other position, it comes into
contact with the displacing projection 42 of the auxiliary valve member 41
and displaces, via the displacing portion 42, the disk 69 so far against
the return force exerted thereon by the helical compression spring 43,
until the compressed air prese | | |
