Note: Descriptions are shown in the official language in which they were submitted.
3. C. Czsilli - 1/2-1-3
3T3=saZ~aa~ U~O~ ~UMP
AND P. VALVE ARRA~GEME~T THEREFOR
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Back~round of the Invention
The present invention relates to pumps in general
and, more particularly, to air-operated diaphragm pumps
and to valve arrangements therefor.
There are already known various constructions of
pumps, among them such which are particularly suited f~r
pumping liquids with high viscosity, such as paint or
the like. Some of the known pumps are constructed as
diaphragm pumps in which compressed air or similar
gaseous medium is being used Lor achieving the pumping
action. In pumps of this type, a movable wall including
~t a flexible diaphragm extends across the internal space
of the pump casing to sealin~ly subdivide such interior
into a pumping chamber for the liquid to be pumped and
;' 15 an actuating chamber into which the pressurized gaseous
;
mèdium is admitted to exert i.s pressure on the movable
wall and from which it is discharged, thus to achieve
the pumping action. Such diaphragm pumps are often use~
in t2ndem, that is, two of such pumps are being used at
the same time, these pumps h2ving their movable walls
connected for movement in unison so that, while one of
the diaphragm pumps has the pressurized g2seous fluid
admitted into its actuating chamber and thus pumps the
liquid, the contents of the actuating chamber of the
2~ other pump is discharged 2S the movable wall moves in
unison with the first-mentioned pump movable wall and,
- hence, addition21 liquid is being drawn into the pumping
ch2mber of the 12tter pump.
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It will be apprecia-ted -that, to achieve the above-
described pumping action in the pump arrangement including the
two tandem pumps, it is necessary to provide for control of the
admission and discharge of the gaseous fluid or medium to and
from the actuating chambers of the -two pumps in an organized and
precisely -timed manner. To this end, there have already been
developed various constructions of con-trol and/or distributing
valve assemblies. ~owever, experience with the control assem-
blies or arrangements of this type which have become known so
far has shown that they suffer from many drawbacks. One of the
disadvantages of the control or distributing arrangements of
conventional constructions is that, more often than not, they
need to be lubricated, which is frequently done by entraining
droplets of oil in the pressurized gaseous medium. It will be
appreciated that, if the pressurized gaseous medium contains
any contaminants, such as particles of dust or the like, such
contaminants will be captured by the lubricant and thus perform
an abrading function in the valve arrangement, which will result
in excessive wear of the various components of the latter.
The present invention consists of a switching valve
assembly for use in a diaphragm pump including a movable wall,
with a casing bounding a bore and a duct that opens into the
bore at a predetermined region of the latter. An annular
element is stationarily mounted in the bore at the region to
subdivide the bore into two compartments one of which is closer
to the movable wall than the other, and including an axially
extending central passage connecting the compar-tments and a
substantially radial-passage that opens into the central pass-
age at a zone of the latter in-termediate the compartments and
communicates with the duct. Means are provided for discharging
fluid from the one compartment to maintain the pressure therein
substantially at a relatively low level, as
-2-
well as means for admitting pressurized fluid into the other
compartment to maintain the pressure therein at a relatively
high level. An elongated valve member is received in the bore
for movement axially of -the latter between a first and a second
end position. The elongated valve member includes a guiding
portion slidingly contacting the surface circumferentially
bounding the other compartment of the bore and an actuating
portion axially adjoining the guiding portion and extending
therefrom into and through the central passage of the annular
element and beyond the same into the one compartment and into
the path of movement of the movable wall at least in the first
end position of said valve member. The actuating portion
passing through the central passage with a larger Eirst clear-
ance between the other compartment and the zone, and with a
smaller second clearance between the zone and the one compartment,
for the second clearance to act as a throttling location. The
invention includes means for biasing the valve member toward
the first end position thereof for the valve member to be moved
by the movable wall against the action of the biasing means
toward the second end position thereof. An annular sealing
element is interposed between the annular element and the guid-
ing portion of the valve member around the actua-ting portion of
the valve member. The annular sealing element is operative for
interrupting communication between the other compartment and the
central passage in the first end position of the valve member so
that the pressure in said radial passage and in the duct is
relieved through the throttling location, and for establishing
such communication as the valve member is moved toward the
second end position thereof with resulting flow of the pressur-
ized fluid through the first clearance into, and pressure build-
up in, the radial passage and the duct.
7~;J
Brief Description of -the Drawing
Figure 1 is a side elevational view of the pumping
arrangement embodying the present inven-tion, in cross-section
except for its control arrangement;
Figure 2 is an exploded view of one version of control
arrangement usable in the pumping arrangement of F'igure l;
Figure 3 is a developed, somewhat diagrammatic, view
of the arrangement of Figure 2 taken basically along the plane
indicated by the reference numerals III - III in Figure 2.
Figure 4 is a view similar to that of Figure 2 but
showing a modified version of the con-trol arrangement; and
Figure 5 is a view similar to that of Figure 3 but
taken along the plane V-V of Figure 4.
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' J.C. Casilli - 1/2-1-3
Det2iled Descri~tion of '.he ?re~erred Embodiment
Referring now to the drawing in detail, and first
to Fio. 1 thereof, it may be seen .hat the re~erence
numer21 i h2s been used to iden.ify a pump constructed
in accordance with the present invention in its
~X entire,y. The pump 1 includes, 25 its main components,
support or frame 2, .wo pumping arr2ngements 3 and 4,
znd an 2ctuating 2nd control arr2ngement 5 interposed
between the two pumping arr2ngements 3 and 4 and
controlling the oper2tion thereo- in a manner which will
be discussed in greater det2il 12ter.
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4a
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.~ .. J. C. Cc--illi - 1/2-1-3
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The s~pport or frare 2 is hollow to bound 2
plurality of passages or compzr.ments yet to be
described. At its lower portion as considered in the
drawing, the frame 2 is provided with a suction or inlet
port 6 for the fluid to be pumped, while a discharge or
outlet port 7 for the fluid being pumped is arranged at
the upper portion of the frame 2. The inlet port 6
communicates with two inlet passages 8 and 9, and the
. outlet port 7 communicates with two outlet passages 10
and 11. The inlet pass2ges 8 and 9 open into respective
inlet valve compartments 12 and 13 that accommodate
respective inlet valve balls 14 and 15 and communicate, .
via respective apertures 16 and 17, with respective
pumping chambers 18 and 19. ~urthermore, annular
sealing elements 20 and 21 of elastic material are
- stationzrily arran~ed at the lower portions of the
respective compartments 12 and 13 to serve as valve
.. . seats for the respective valve balls 14 and 15.
. ~ The pumping chambers 18 and 19 respectively
- 20 co~municate, at their upper enas, with outlet valve
compartments 22 and 23 which, in turn, communicate with
the respective outlet passages 10 and 11 via apertures
24 and 25. The outlet valve compartments 22 and 23
accommodate respective outlet valve balls 26 and 27 as
`. 25 well as, at their lower parts, respective annular
sealing elements 28 and 29 constituting valve seats for
the respective outlet valve balls 26 and 27O
The frame 2 is shown to be constituted by separate
. lateral parts 31 and 32, and upper and lower transverse ~ 30 p2rts 33 and 3a which extend between anâ interconnect
the lateral parts 31 and 32. The parts 31 to 34 are
connected to one another by respective annular clamping
elements 35, 36, 37 and 38 which are of well known
constructiOn that needs no elaboration here. The
3; annular sealing elements 20, 21, 28 and 29 are zrranged
at t~e parting planes between the various parts 31 to 34
of the frame 2 so that, besides acting as the valve
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seats 'or the respective valve balls 14, 15, 26 and 27,
.hev also seal the interfacec ~etween the parts 31 to 34
of the frame 2, by being confined and hence held in
position between the parts 31 to 34 by the action of the
5 respective clamping elements 35 to 38.
The lateral portions 31 and 32 of the frame 2 have
respective extensions or flanges 39 and 40. The pumping
arrangements 3 and 4 include casings or shells 41 and 42
which are secured, in a conventional manner which is not
~ 10 specifically shown in the drawing, su~h as by screws or
similzr connectors, to the control arrangement S, and
which are respectively connected, by means of annular
clamping elements 43 and 44, to the flanges 39 and 40 of
the lateral portions 31 and 32 of the frame 2. Hence,
the shells 41 and 42 define with the associated lateral
portions 31 and 32 respective internal spaces. Each of
these internal spaces is subdivided by a respective
movable wall 45 and 46 into the aforementioned pumping
chamber 31 or 32, and an actuating chamber 47 or 48.
The respective movable wall 45 or 46 includes a
respective flexible diaphragm 49 or 50 which is
sealingly clamped at its outer periphèry between the
; flange 39 or 40 and the shell 41 or 42 by the action of
the respective clamping element 43 or 49. At its
central region, each of the diaphragms 49 or 50 is
sealingly secured to a common shaft 51 that passes
through the interior of the control arrangement 5 and
interconnects the two movable walls 45 and 46 for
movement in unison. To mount the respective diaphragms
49 and 50 on the common shaft 51, there are provideà two
mountins plates 52 and 53, or 54 and 55, on the common
shaft ~1, which confine the central region of the
respective diaphragm 49 or 50 between themselves. The
~ mounting plates 52 and 53, or 54 and 55/ are mounted on
3; ,he common shaft 51 by being confined between a
~ respective shoulaer 56 or 58, and a threaded fastener 57
or 59, such 2S a nut. Thus, the mounting plates 52 and
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J. C. C2silli ~ ~2-1-3
53, or 54 and 55, clamp the c~ntral region of the
respective diaphragm 49 or ~0 between themselves to
mount the diaphr2gms 49 and 50 to the common shaft Sl.
Having so described the construction of the
appzratus depicted in Fig. 1, its operation will now be
briefly discussed, leaving out for the time being the
details of construction and operation of the control
arrangement 5. It is sufficient to state at this
juncture that the control arrangement S controls the
admission of an actuating medium, especially a gaseous
medium such as compressed air, into the actuating
compartments or chambers 47 and 48, and the discharge of
such an actuating medium from the actuating chambers 47
and 48.
In the position shown in Fig. 1, the movable walls
45 2nd 46 are approaching the end of their rightward
stroke. This is achieved by admitting the pressurized
actuating medium into the actua.ing chamber 48 of the
pumping arrangement 4, while simultaneously allowing the
contents of the actuating chamber 47 of the pumping
arrangement 3 to escape from the actuating chamber 47 at
a rather low superatmospheric pressure. Because of the
pressure exerted by the pressurized actuating medium on
1 the movable wall 46, and the relatively low resistance
offered by the pressure of the medium contained in the
actuating chamber 47 on the movable wall 45, the shaft
51 and the movable w~lls 45 and 46 mounted thereon are
caused to move in the rightward airection. This causes
a reduction in the pressure in the pumping chamber 18,
so that t~he valve ball 14 is lifted off its valve seat
element 20 and the medium to be pumped is drawn into the
pumping chamber 18. Because of the reduced pressure in
the ?umping chamber 18, the v21ve ball 26 stays in its
sealing contact with its associated annul2r valve seat
_~ element 28, so that no medium being pumped will be drawn
into the pumping chamber 18 from the outlet pass2ge 10
or the outlet port 7. At the same time, the pressure in
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~ . C . C G S i ~ / 2 ~ 1 3
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.he pumping compartment 19 is increased, which means
t~at the valve ball 15 will rem2in in, or get into,
sealing contact with its associated annular valve seat
element 21, thus preventing the now pressurized contents
of the pumping chamber 19 from escaping back into the
inlet passage 9. On the other hand, the increased
press.ure of the medium contained in the pumping chamber
19 will cause the valve ball 27 to lift off from its
associated valve seat element 29, so th2t the medium
. 10 being pumped will be expelled from the pumping chamber
19 through the compartment 23 into the outlet passage 11
and ultimately into the outlet port 7. It will be
appreciated that, once the movable walls 45 and 46 have
reached the end of their rightward travel, the situation
is reversed, that is, the pressurized actuating medium
is admitted into the actuating chamber 47, and the
contents of the actuating chamber 48 is permitted to
~F escape from the latter, due to the action of the control
. arrangement 5. This will cause movement of the movable
20 walls 45 and fi6 in unison in the leftward direction,
with an attendant pressure reduction in the pumping
chamber 19 and increase in the pressure in the pumping
chamber 18, so that the valve balls 14, 15, 26 and 27
. will now move into their respective other positions in
which they prevent the medium being pumped from escaping
back from the pumping chamber 18 toward the inlet port
~: 6, cause the medium being pumped to flow from the inlet
t port 6 into the pumping chamber 19, prevent .flow of the
L medium being pumped back from the outlet port 7 into the
pumping chamber 19 and permit the pressurized medium
. being pumped to flow from the pumping chamber 18 toward
~ the outlet port 7. Another reversal takes place at the
'~` end of the leftward travel of the movable w211s 45 and
46, so that the initially described operating conditions
are re-established.
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~ - J C Casilli - 1/2-1-3
.
As mentioned before, the control arrangement 5
controls the flow of the actuating medium in and out of
the actuating chambers 47 and 48 A first and a second
version of the construction of the control arrangement 5
will now be particularly described in connection
respectively with Figs. 2 and 4 of the drawing, and their
operation will then be described particularly in
connection respectively with Figs. 3 and ~ of the
~!1 drawing. These versions are similar to one another in
many respects so that the same reference numerals will be
~, used to identify corresponding parts. Both versions will
be jointly discussed below and only the differences
between them will be particularly pointed out.
Fig~ 2 and 4 are respective exploded views of the
first and second versions of the control arrangement 5
showing the various components constituting the same. Qne
of the main components of the control arrangement 5 is a
housing 60 through which the common shaft 51 passes, as
shown, substantially centrally, being suppprted in a self
lubricated sliding hearing or bearings 30. The housing 60
has three bores 61, 62 and 63 which are indicated to
ëxtend substantially parallel at the axis of the common
shaft 51, and at a radial spacing therefrom~ However, it
will be appreciated that the bore 62 could extend
transversely of the housing 60 if so desired, for
instance, in order to reduce the overall dimensions and
the weight of the housing 60
The bQre 62 serves for receiving 2 distributing
v21ve body 64 which is cons.ructed 2s a spool v21ve.
~he distribu.ing vzlve body 64 is provided with two
cistribu,ing channels 65 znd 66 sepzra.ed from one
2nother by 2 sep2rcting collar 67 cno delimite~ at their
o.her cxizl ends by respective Qel imiting collars 68 and
69 ~he distributing vzlve body 64 fur.her includes, at
,; its respective zxi21 enàs, termin21 coll2rs 70 and 71
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~ J.C. Casilli ~ 3
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; whic~ bound respective orooves 72 and 73 be~ween
themselves and .he respective aelimitin~ collars 68 anc
69. Res~ilient expansion rings 74 and 75 are received in
the respec.ive grooves 72 and 73 in the assembled
condition of the v21ve body 64, these expansion rings 74
and 75 being surxounded by res?ective split separa,ing
rings 76 and 77 which are also received in the
respective ~rooves 72 and 73 at least when the
distributing valve body 64 is accommod2ted in the bore
62.
i The bores 61 and 63 accommodate respective switching
or limiting valve assemblies 78 and 79 which are
structually identical so that the various components
thereof will be identified by the same reference numerals
in the following description and the drawing. The
respective switching valve assembly 78 or 79 includes, as
one of its main components, a switching valve member 80
which includes a guiding portion 81 and a stem portion 82
at one end of the guidin9 portion 81. The guiding portion
81 is shown to be hexagonal in cross-section. The reason
for this cross-sectional configuration will be given
.
later. The stem portion 82 of the first version is
~ ~provided with a groove 83 that serves to partially
ili accommodate an abutment washer 84. Next to the abutment
washer 84, there are arranged, around part of the stem
portion 82 which extends between the groove 83 and the
guiding portion 81, in successionj a spring washer 85, a
separating washer 86, a sealing ring 87, and an additional
sealing ring 88. On the other hand, in the second
~ 30 version, on~y the sealing ring 88 is provided being
; ~ arranged around the stem portion 82 upon assembly.
L Furthermore, in both versions, a helical compression
spring 89 is accommodated in the respective bore 61 or 63
at the opposite axial end of the guiding portion 81 from
3; the stem portion 82. Figs. 2 and 4 also indicates that an
annular element 90 is arranged at one axial end of the
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~ J.C. Casilli - 1/2-1-3
.
.
bore 63. Similarly, another such annular element 90 is
arranged in the bore 61, but at the opposite axial end
thereof. It is also shown in Figs. 2 and 4 that the
housing 60 has an internally threaded discharge bore 91,
and that a discharge nipple or connector 92 having an
externally threaded end portion is threaded into the bore
91 in its assembled condition. The housing 60 also has a
~`; feeding `nipple or connector similar to the discharge
nipple or connector 92, but not visible in Figs. 2 and 4
since it is obscured by the housing 60.
The àistributing valve body 64, and the limiting
v21 ve 2ssemblies 78 and 79 are shown in ~ig. 3 in .he
assembled conditions and as accommodated in the respective
bores 62, 61 and 63. It may be seen that the sealing
elements or rings ~6 ad 88 are arranged at the opposite
axial sides of the annular element 90 in the first version
and that the sealing element or ring 88 is arranged at the
same axial side of the annular element as the guiding
portion 81 in both versions. It may also~be seen that,
because of its hexagonal cross section, the guiding
portion 81 is in contact with, and thus7is guided by, the
surface bounding the bore 61 or 63, as shown in connection
with ~the limiting valve assembly 78. Yet, as shown in
~; connection with the switching or limiting valve assembly
; 79, gaps 110 exist between the regions of contact of the
guiding portion 81 with the surface bounding the
~; respective bore 61 or 63, these gaps 110 providing for
communicatio~ between the spaces accommodating the helical
springs 89 and those accommodating the sealing element 88
in the respective bores 61 or 63. While the guiding
ortion 81 has been shown to have a hexagonal
cross-section, it will be appreciated that the same
combination of guiding and bypass functions could also be
achievea by giving the bores 61 and 63 and the guiding
3; ?ortions 81 other non-complementary cross-sections with
multiple con~act areas therebetween.
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J C. Casilli - 1/2-1-3
.
Figs. 3 and 5 also illustrate that each of the annular
elements 90 has a central passage 93 through which the
stem portion 82 of the respective limiting valve body 80
passes with clearance. In the first version, the central
passage 93 has a substantially constant of diameter over
its entire axial length. On the other hand, in the second
version, the central passage 93 has a larger-diameter
first section 71 closer to, and a smaller-diameter second
section 112 more remote from, the guiding portion 81 of
the respective valve member 80 as considered in the
assembled condition of the respective valve assembly 78 or
7g. The first section 111 is so dimensioned as to permit
virtually unimpeded flow of air past the stem position
82. On the other hand, the second section 112 is so
dîmensioned relative to the stem portion 82 as to cause a
throttling action in the clearance between the stem
portion 82 and the surface bounding the second passage
1120 Advantageously, the latter clearance is in the order
of 1/10000 of an inch. In both cases, the annular element
80 further has a substantially radially extending passage
94 which communicates the central passage 93 (intermediate
the sections 111 and 112 in the second version) with a
rèspective passage 95 provided in the housing 60 and
opening into an actuating space 96 or 97 which is
delimited in the bore 62 by the respective shell 41 or 42
and the respective terminal collar 70 or 71 that is close
to it. The housing 60 also has a feeding duct 98 which is
connecte~d to the aformentioned feeding connector and opens
into the bore 62 substantially centrally thereof, and a
branched or bifurcated discharge duct 99 which opens into
the bore 62 at locations at least axially spaced by a
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- J. C. C~siiii - ' /2-1-3
?reaetermined distance from and at opposite axi21 sides
of the feeding duct 98. The ~ischarge duct 99 leads to
the discharge nipple 92 mentioned above.
The housing 60 further hzs two discharge channels
100 each of which communicates, at one of its ends, with
a space 101 of the respective bore 61 or 63 next to the
respective annular element 90 and, at its other end, in
a manner which is not shown in the drawing, with the
discharge nipple 92. Furthermore, the housing 60 has; 10 two feeding channels 102 each of which communicates, at
its one end, with a space 103 of the respective bore 61
or 63 that accommodates the helical spring 39 and, at
its other end, in a manner which is also not
illustrated, with the aforementioned feeding nipple or
connector. The channels 100 and 102 are covered, in a
sealing manner, by the respective shells 41 and 420
Finzlly, the housing 60 also has supply and relief ducts
104 and 105 which open into the bore 62 at locations
situated axially spaced from znd between the locations
zt which the feeding duct 98 and the discharge duct 99
open into the bore 62.
. The respective shells 41 and 42 are provided with
orifices 106 through which the supply and relief ducts
104 and 105 are in communication with the respective
chambers 47 and 48 of the pumping units 3 and 40 The
shells 41 and 42 further have openings 107 through which
the stem portions 82 of the respective valve members 80
pass into the respective chambers 47 and 48, being
sezled in the openings 107 by respective self lubricating
seals 108 of â conventional construction.
Thè housing 60 is advantageously made of aluminum
znd is provided, at least all over the surface bounding
the bore 62, with a hard anoaized coating layer 109.
- The vzlve member or spoo1 64 is made, either in its
- 35 entirety, or at least at its portion that comes into
con.zct with the layer 109, o, a material that needs no
lubrication or is self-lubriczting. Many such
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` J. C. Ccsilli - 1/2-1-3
self-lubric2ting ma.eri21s 2re known, but p2rticularly
good results were obt2ined with the spool 64 being made
of polytetrafluoroethylene mixed with a mica filler.
However, since this ma.erial has a tendency to swell
; under certain operating conditions, it was attempted to
make the spool 64 with a core of a metallic material and
with a cladding layer of the polytetrafluoroethylene.
The results of this attempt were even better than
those obtained before, especially when the core was made
of aluminum. Experience hzs shown that these two
materials, that is, the mica-filled
polytetrafluoroethylene of the spool 64 an~ the hard
anodi7ed aluminum of the coating layer lU9 o~ the
1 15 housing 60 cooperate with one another very well and that
c it is not necessary to lubricate the valve body 64 by :
oil or another lubricant to achieve free sliding of the
spool 64 in the bore 62 solely in response to pressure
differentials acting in the axial directions of the
2~ spool 64. It appears that during the operation, some of
the mixture rubs off onto the coating layer 109, further
~ improving the sliding conditions.
?I~ Having so described the construction of the pump 1
inclusive of the control arrangement 5 thereof, the
~i .,
` 2; operation of the two versions of the control arrangement 5
will now be described with reference to Figs. 3 and 5 of
the drawing.
The positions of the v2rious components of the
control arrangement 2 as illustrated in Fis. 3 are those
3~ which such com~onents assume at the time of reversal
~ from movement OL the shaft 51 (see Fig. 1) in the
.~
rightward direction to the movement in the leftward
direction, and more p2rticularly at the beginning of the
leftwGrd movement. At this tlme, the v21ve member 80 of
_ the l'miting v21ve 79 is in its rightmost position, being maintained therein by the action of the spring 89
ana .he difference be.ween the ~ressures acting on the
valve member 80 in the opposite axi21 directions. This
J C Casilli - 1/2-1-3
J C C~silli - 1
me2ns t~het .he sea' 8~ is in 2 se21ing con,act ~ith both
.he annul2r elemen, 90 and the cuiding portion 81 of the
limiting valve ~ssem~ly 79, so that it interrupts
communica,ion between .he g2ps 110 znd the central
t~ , passage S3 ~t ,he same time, the sealina element 87 is
spaced from the 2nnular element 90, which means that an
uninterrupteà path is established between the chamber 97
.hrough the duct 95, the radial p2ssace 94, the central
passage 93, the sp2ce 101 and the channel 100,
ultima.ely with the aischzrae nipple 92 8ence, the
; pressure then prevciling in ,he chamber 97 will be
substan.i211y equal to the ambient pressure, while the
pressure in the space 103 is superatmospheric, resulting
in the a orementioned ~ressure cifference.
Figs. 3 and 5 also show that the mounting element 53,
of which only a fragment is shown, has previously, duri~g
its rightward movement, contacted the stem portion 82 of
the valve member 80 of the limiting valve assembly 78 and
depressed it, so that the entire limiting valve assembly
78 has been shifted in the rightward direction from its
position into which it is urged by the spring 89. This
movement in the rightward direction eventually resulted in
~1 the illustrated situation where in the first version the
sealing element 87, aiàed by the resilient action of the
spring washer 85, seals the interfaces between the annular
element 90,~the stem portion 82 and the annular washer 86,
thereby interrupting the communication between the passage
¦ g3 and the space 101, the channel 100 and ultimately the
L discharge nipple 92 ~owever, this rightward movement of
the valve memDer 80 of the limiting valve assembly 78 also
results, in both versions, in a termination of the sealing
action of the sealing element 88, so that an uninterrupted
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J.C. Casilli - 1/2-1-3
path is created from the aforementioned feeding nipple
through the channel 102, the space 103, the gaps 110 past
the guiding portion 81, the central passage 93, (the
larger diameter section 111 of the latter is the second
version) and the duct 95 to the space 96~ In this manner,
the superatmospheric pressure supplied to the feeding
nipple is able to propagate into the space 96 to act on
the end face of the spool 64, thus shifting it into the
illustrated rightward position thereof against
'` 10 non-existent or negligible superatmospheric pressure in
the space 97. At this time, in the second version,
communication still exists between the passage 93 and the
space 101, the channel 100 and ultimately the discharge
q nipple 92. However, since this communication takes place
. 15 through the clearance between the stem portion 82 and the
surface bounding the smaller-diameter section 112 of the
passage 93, which clearance/ as mentioned before, is small
enough to cause a considerable throttling effect, the
superatmospheric pressure will still be able to propagate
virtually undiminished, into the space 96, at least as a
pressure jolt sufficient to shift the spool 64, despite
leakage of the pressurized fluid through the section 86 of
the passage 93. Once the shifting occurs, any subsequent
reduction of the pressure in the space 96 does not have
, ,.
2; any influence on the position of the spool 64. Of course,
the clearance in the larger-diameter section 85 of the
passage 93 will have to be sufficient to not only
compensate for the aforementioned leakage through the
~.~ section 86, but also to permit flow of a sufficient excess
i~! 30 amount of the compressed fluid into the space 96 to fill
the same as the spool 64 recedes during its rightward
shift.
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J.C. Casilli - 1/2-1-3
Once this shift occurs, the previously existing
communication between the chamber 47 through the orifice
106, the duct 104, the channel 65 with the left-hand
branch of the discharge duc, 99 and thus with the
; discharge nipple 92 is discontinued and instead
communication is established between the chamber 47
through the orifice 106, the duct 104, the channel 65
with the feeding duct 98 and ultimately with the feeding
nipple so that the superatmospheric pressure from the
feeding nipple propagates into the chamber 47~ Thus,
this superatmospheric pressure will now act on the
movable wall 45 to urge the same in the leftward
direction. The above-mentioned rightward shift of the
spool 64 has also interrupted the previously existing
communication between the chamber 4B through the orifice
: ~. 106, the duct 105, the channel 66 and the duct 98
j,;
... ultimately with the feeding nipple. On the other hand,
~, the rightward shift of the spool 64 has established
communication between the chamber 48 through the orifice
, . .
106, the duct 105, the channel 66 and the right-hand
branch of the duct 99 ultimately with the.discharge
nipple 92. This, of course, means that the pressure in
the actuating chamber 48 is relieved, for all intents
`~ and purposes, to the level of the ambient pressure so
that;it does not counteract the action of the
superatmospheric pressure now prevailing in the
. actuating chamber 47 on the movable wall 45. Hence, the
shaft 51 and the movable walls ~5 and 46 mounted thereon
will commence their movement in the leftward direction,
with attendcnt pumping action on the medium con.ained in
~ "! the pumping chzmbers 18 and 19 as described above in
: connection with Fig. 1. This leftward movement, which
: L also involves the leftward movement of the mounting
element ;3, will be accompanied by concurrent leftward
movement of the valve member 80 of the limiting valve
assembly 78 under the action of the associated helical
spring 89~, until communication of the space 96 with the
channel 102 is interrupted with attendant cessation of
supply of the pressurized fluid into the passages 93 anc
-15a-
J.C. Casilli - 1/2-1-3
34, the duct 95 and the space 96. In the first version,
he communication of the space 96 with the channel 100 is
established at the same time whereby the pressure in the
space 96 is relieved. In the second version, the
clearance in the passage section 112 continues to permit
the throttled flow of the fluid therethrough into the
space 101 and the channel 100, whereby the pressure in the
space 96 is relieved. However, in both instances, the
spool 64 will remain in its then assumed position since
~i 10 the pressure in the space 97 is substantially the same as
that in the space 96 or, at least initially, lower. The
spool 64 remains in this position until the mounting
;i~ element 55 of the movable wall 56 contacts the stem
portion 82 of the valve member 80 of the limiting valve
assembly 79 and depresses the same to the extent necessary
to interrupt the communication of the space 97 with the
channel 100 and establish communication of the chamber 97
!~i," with the channel 102.
As mentioned before, it is not necessary to
lubricate the spool 64 since it is made 2t least at its
periphery of a synthetic plastic material which needs no
lubrication. Moreover, instead of using elastic sealing
rings on the spool 64, as customary in the valve
manufacturing field, the arrangement of the present
2~ invention uses the sep2rating rin5s 76 and 77 which are
' made of a relatively rigid synthetic plastic material
which is also of the self-lubrica.ing type. A material
particularly well suited for this purpose is
olyte-rafluoroethylene filled with graphite. Hence, 2S
these separating rings 76 and 77 slide along the inner
surface of the coating layer 109, they will gradually
wear OLf to a slight extent, which will deposit a layer
of polytetrafluoroethylene znd/or graphite on the
internal surface of the c02ting lzyer 109. This
ceposited layer including the insredients which have
~ecome dissociated from the spool 64 and/or the
se?ar~ting rings 76 and 77 will act as a lubricant and
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ul. C. C2sil~ - ~2-1-3
elimin2te or 2t le2st slow aown the further ~ear of the
se?ar2ting rings 76 cnd 77. I~oreover, the deposited
m2terial will fill any crevices or depressions in the
hard anodized coa.ing layer 109, thus presenting a
; highly smooth sliding surface to the spool 64 and the
separating rings 76 and 77.
r~
The back-up resilient expansion rings 74 and 75
urge the separating rings 76 and 77, respectively, in
~, the radially outward direction into sliding contact with
the internal surface of the coating layer lO9. This
introduces a certain 2mount of drag or hesitation into
the movement of the spool 64 so that, even if the spool
64 is subject to vibrations, such as may occur during
the operation of the pump, it will not accidentally
l; shift out of its respective end position toward the
other end posit-ion.
The separating rings 76 and 77, as shown in Fig.
~i 2, are split to be able to radially outwardly expand in
response to the urging of the resilient exp2nsion rings
~ 20 74 and 75. This split, of course, introduces a
discontinuity into the separating ring 76 or 77, through
which fluid could flow between the channel 65 and the
space 96 or the channel 66 znd the space 97~ However,
.......... ...experience has shown that such leakages are negligible
~ 25 and do not adversely effect the operation of the control
arrangement 5. Additional amounts of the compressed
gzseous medium could flow past the separating rings 76
and 77 at the interfaces thereof with the deiimiting
collars 68 or 69 and the terminal collars 70 ~nd 71.
Rowever,~even this leakage is negligible p~rticularly
. since, as soon as the spool 64 starts its movement out
of its one end position tow2rds it other en~ position,
the arag acting on the respective sep2r2tins rings 76 or
77 will cause the s2me to se21ingly contact one of the
'~ coll2rs 68 or 70, or 71 and 69, depending on the
direction of movement of the spool 6~. This sealing
- con.zct will be preserved un.il the spool 6~ st2rts
moving in the opposite direction.
-17-
~. C. ~silli - j2-1-3
.
In any event, the presence and sealing effect of
the separz.ing rings 76 and 77 prevent more serious
leakages of the pressurized 2ir through the interfaces
between the spool 64 and the coating layer 109, which
_ would otherwise result in unaesired pressure buildups or
reductions, with attendant reduction in or loss of
operating reliability.
The guiding portions 81 of the valve members 80
are preferably of such a material and have such a shape
as also to need no lubrication. This means that the
limiting valve assemblies 78 and 79 will not have t~ be
lubricated either, so that the pressurized air which is
used to operate the control arrangement 5 need not have
to have any oil droplets entrained therein. This is a
1~ pronounce~ advantage as compared to conventional valve
or pump arrangements, in that any dust or other
contaminants which may be present in the pressurized air
will not be caused to adhere to the various components
of the control arrangement 5 by the action of the
entrzined oil or similar lubricant. The hexagonal
cross-section of ~he guiding portions 81, with the
attendant limited contact between the respective g~iding
~ .
portion 81 and the surface bounding the bore 61 or 63,
is particularly useful in eliminating the need for
2~ lubrication.
The outlet nipple connector 92 is shown to be
constructed as a silencer, so that it can be used in an
ambient environment with discharge of the spent air into
the ambient atmosphere. However, for use of the pump 1
in submersed applications, that is, where the pump is
immersed in liquid at least to the level of the-
dischzrge nipple or connector 92, it is possible to
connect a hose or a similar conduit to the connector 92
and to have such 2 ho5e lead to the exterior of the
_, li~u~a medium in which the pump 1 is submersed.
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7~
. J. C. Ccsiili - l/2-1-3
;~hile I have cescribed a~ove the principles of my
invention in connection with specific apparatus, it is
to be clearly understood that ~his description is mzde
only by way of example and not as a limitation to the
sco?e of my invention as set forth in the objects
thereof and in the accompanying claims.
October 30, 1984
PRR:ems
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