Note: Descriptions are shown in the official language in which they were submitted.
B ck~round of the _vention
This invention relates to check valve assemblies
adapted particularly for use with high pressure reciprocating
pumps.
A check valve assembly adapted for use with high
pressure (e.g. up to 60,000 psi or greater) pumps must be
capable of operating at such high pressures without experienc-
ing premature fatigue failure or being subject to exeessive
wear in connection with its moving parts. Further, because
some such wear is inevitable, such check valve assemblies
should be adapted for quick and economical repair or replace-
ment of worn parts.
One col~non check valve assembly comprises a pair
of check valves joined in a "T" configuration. Thls configur-
ation, however, is quite subjeet to fatigue failure due to
stress concentrations at the intersecting bores of the "T".
IJnwanted stress concentrations have been to a considerable
extent avoided by the use of a configuration in which the c'neck
valves are coa~ial with respect to a high pressure outlet
passage. Such a coaxial configuration, however, does not of
itself address the problem of wear in connection with the
moving chec]c valve elements. The wear problem in high pressure
check valves occurs because during each pump stroke, the
moveable valve element or poppet is thrust against its seating
surface with considerable force, so that both the poppet sur-
face and the seating surface are subject to rapid deterioration.
There remains a need for a check valve assembly adapted for
easy and eeonomical repair or replacement oi such surfaces.
Summary of the Invent
The present invention provides a chec}c valve assem-
bly comprising novel inlet and outlet check valves havincJ
sealing surfaces, i.e. valve elements and their respective
seating surfaces, which may be ~uickly and easily accessed
or removed for resurfacing. In one embodiment, all such
surfaces are planar, a feature which further facilitates
resurfacing and which reduces manufacturing cost. The pres-
ent invention also provides a novel configuration for inlet
and outlet passages which avoids stress concentrations in such
passages subject to cyclic pressure fluctuations therein, thus
greatly reducing metal fatigue.
The check valve assembly is adapted for connection
to a high pressure reciprocating pump cylinder, and comprises
valve body means, inlet check valve means and outlet check
valve means. The valve body means has an inlet end adapted
for connection to the pump cylinder and an outlet end adapted
for connection to a high pressure outlet line. The inlet end
has a planar surface adapted to be exposed to the interior of
the pump cylinder. The valve body means also includes a low
pressure inlet passage opening in the planar surface for pro-
viding communication with a source of low pressure fluid and
a high pressure outlet passage extending between the planar
surface and the outlet end. Such passages are parallel to
one another and spaced apart a distance at least as great as
the radius of the high pressure outlet passage.
The inlet check valve means is mounted entirely on
the exposed planar surface in assoclation with the inlet passage
and prevents high pressure fluid backflow into the inlet passage.
The outlet check valve means is associated with the outlet end
and prevents fluid backflow from the outlet line. The outlet
check valve means includes a valve seating element removable
from the valve assembly for servicing thereof, and an outlet
valve element moveable to and from a position in which it abuts
the seating element and prevents fluid flow into the outlet
passage during low pressure fluid flow through the inlet check
æ;~
valve means into the pump cylinder.
These and other features and advantages of the in-
vention will be apparent from the detailed description and
claims to follow taken in conjunction with the accompanying
drawings.
Brief Description of the Drawin(3s
Fig. 1 is a perspective view of the check valve
assembly of the present invention;
Fig. 2 is a cross sectional view taken along the
line 2-2 in Fig. l;
Fig. 3 is an end elevational view of the inlet end
of the check valve assembly with the inlet valve element
swung away to reveal the inlet passage;
Fig. 4 is a schematic cross sectional view of the
check valve assembly and pump cylinder during the compression
stroke;
Fig. 5 is a schematic cross sectional view of the
check valve assembly and pump cylinder during the intake stroke;
Fig. 6 is a perspective view of the outlet valve
element of the check valve assembly of the present invention.
Detailed 3escription of the Drawings
Referring initially to Fig. 2, the check valve
assembly of the present invention generally comprises a body
lO, an inlet check valve 50 and an outlet check valve 70.
Body lO has a cylindrical external configuration with an in-
let end 12, an outlet end 14 and a central axis 16. Inlet
end 12 includes a projecting cylindrical portion 18 disposed
centrally about axis 16 and having a planar outer surface 17.
Threads 19 are located on the outer surface of body 10 adjacent
inlet end 12. By means of such threads, the check valve
assembly may be connected to a cylinder 2~ (Figs. 4 and 5)
of a reciprocating pump such that the planar surface 17
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of projecting portion 1~ is exposed to the interior 22 of
cylinder 20. Cylinder 20 contains a reciprocating piston
not shown in the drawings. Suitable sealing means (not showr.)
are disposed between projecting portion 18 and cylinder 20.
Fluid lea]sing past such sealing means is collected in
cylindrical trough 23 in inlet end 12 and vented therefrom
via slot 25 shown in cross section in Fig. 2. Outlet end
14 of body 10 includes a cylindrical recess 24 whose central
axis is offset from axis 16. ~ecess 24 receives and mounts
the outlet check valve as hereinafter described in detail.
Body 10 includes low pressure inlet passage 26 and
high pressure outlet passage 30 formed therein, inlet passage
26 extending from surface 17 to cross passage 28 and outlet
passage 30 extending parallel to the inlet passage from
surface 17 to recess 24 in outlet end 14. Cross passage 28
extends radially between inlet passage 26 and a circumferen-
tial recess 32 formed on the outer surface of body 10. All
internal openings such as passages 26, 28 and recess 30 are
spa¢ed away from the outer walls of passage 30 by at least
the radius thereof. This feature provides a body 10 which is
substantially as resistant to failure due to metal fatigue as
a thick walled cylinder. Outlet passage 30 may be formed either
directly in body 10, as shown in Fig. 2, or by pressin~ a
hollow tapered cylindrical sleeve into an opening therethrough.
In either case, the bore of passage 30 is polished to a high
surface finish. ~oth inlet passage 26 and outlet passage
30 have circular cross sections, the diameter of inlet passage
26 being somewhat greater than that of outlet passage 30.
Outlet passage 30 contains an enlarged diameter portion 31
adjacent face 17 for a purpose described below. Such en-
larged portion is confined within cylindrical portion 1~ in
~5~
order to receive the benefit of compression by the seal
between portion 18 and cylinder 20 and thereby avoid metal
fatigue at such enlarged portion.
Cylindrical collar 34 is disposed about body 10
intermediate its ends such that the collar overlies circum-
ferential recess 32. Collar 34 contains passage 36 extending
radially therethrough, which passage is adapted to receive
inlet fitting 38, the inlet fitting being connected to a
source of low pressure fluid. By such means, low pressure
inlet fluid may be introduced through passage 36 into recess
32, and from there into inlet passage 26. "O" rings 40, 42
positioned in circum~erential grooves on the outer surface
of body 10 prevent leakage of the inlet fluid between collar
34 and body lO. Snap ring 44, positioned in a similar groove,
prevents the collar from shifting laterally.
The inlet check valve, indicated generally at 50, ;
is positioned entirely on exposed surface 17 of inlet end 12.
The inlet check valve comprises an inlet valve element 52
mounted by leaf spring 54 such that the valve element is
positioned overlying inlek pa~sage 26. In Fig. 3, the valve
element and leaf spring have been swung aside for purposes
of illustration to reveal inlet passage 26. Leaf spring 54 is
in turn mounted by hollow screw member 56 and spacer 58. Screw
member 56 is threaded into enlarged diameter portion 31 of
outlet passage 30 and contains an axial opening 60 therethrough
such that fluid can pass directly through the screw member into
the outlet passage. The shank of screw member 58 passes
through hollow cylindrical spacer 53 and through an opening
in one end of leaf spring 54, such that the leaf spring and
spacer are firmly held between the head of the screw and sur-
face 17 with the leaf spring spaced away from and parallel to
such surface.
'
The inlet valve element 52 is a solid cylindrical
member having a diameter greater than that of inlet passage 26
and a thickness eq~al to that of spacer 5~. The outer end of
valve element 52 contains a centrally located flared pro-
jection 62 which ls pressed into an opening in leaf spring
54 at the opposite end thereof from its connection to screw
56. The fit of projection 62 in this opening is such that
valve element 52 is ca~able of a small rocking motlon with
respect to leaf spring 54. Washers (not shown) may be employed
between leaf spring 54 and valve element 52 to help distribute
pressure on the valve element for optimum sealing thereof.
The inner end of valve element 52 is planar so that it is
capable of sealinyly abuttiny planar surface 17 about inlet
passage 26.
When the reciprocating pump is on its inta}ce stroke
the fluid pressure in the interior 22 of pump cylinder 20
(Fig. 5) drops below l-he pressure of the low pressure inlet
Eluid, and valve element 52 is forced away from surface 17
against the force of leaf sprincJ 54. The motion of valve
element 52 has been exaggerated in Fig. 5 for clarity. Thus
on this stroke the pump freely draws supply fluid through the
inlet passage and the inlet check valve into cylinder 20. ~s
the pump changes to its compression s-troke (Fig. 4), the pressure
in the interior of cylinder 20 rapidly increases to a value con-
siderably in excess of the pressure in the inlet passage, and
valve element 52 is forced against surface 17, isolating the
inlet passage from the interior of cylinder 20 and preventing
backflow of fluid into the inlet passage. The high pressure
fluid in such cylinder is thus forced through hollow screw
member 56 into outlet passage 30.
The above described check valve of the present
invention is en-tirely located on an exposed outer surface of
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s~l~z
the valve assembly body, making such chec}; valve extremely
accessible and easy to repair or replace. Resurfacing the
valve element and the associated portion of surface 17 in-
volves merely removing the valve element by extracting screw
member 56 and lapping the sealing surfaces with emery paper
against a flat block, a rapid operation that can be c~arried
out in the field with only simple hand tools. The inlet check
valve of the present invention further combines a comparatively
massive valve element capable of standing up to the high
pressure differential during the compression stroke with a
comparatively light spring element for optimum performance.
An additional feature of the check valve is the slightly loose
connection between spring 54 and valve element 52, a feature
which helps insure flat sealing despite random irregularities
and/or wear in the valve element or in surface 17.
The outlet check valve, generally indicated at 70,
is mounted in cylindrical recess 24 of outlet end 14. Recess
24 is positioned so as to be concentric with cylindrical
outlet passage 30. The outlet check valve comprises seating
element 72, outlet housing 74 and outlet valve element 78.
Outlet housing 74 holds seating element 72 between itself and
body lO, and also mounts valve element 78 such that the valve
element is moveable to and from a position in which it abuts the
seating element and prevents backflow of fluid into the outlet
passage.
Outlet housing 74 has an irregular cylindrical ex-
terior configuration including a cylindrical projection 94
having a diameter equal to that of recess 24. Projection 94 and
recess 24 have matching threads 76 for mounting the outlet
housing in recess 24 as shown in Fig. 2. Outlet housing 74
contains a series of cylindrical openings entirely through the
outlet housing, such passages consisting of valve chamber 96,
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connecti31g passage 8~, and mounting recess 90. Valve chamber
96 communicates with outlet passage 30 during the compression
stroke of the pump, as hereafter described in detail. ~ounting
recess 90 is adapted to receive outlet fitting 92 of outlet
line 98 for carrying high pressure fluid away from the check
valve assembly.
Seating element 72 is a cylindrical disk having a
diameter slightly less than the diameter oE recess 24, such
that the seating element is freely insertable in and removable
from such recess. The seating element has planar outer sur-
face 108, a slightly tapered inner surface ]04, and a passage
102 e~tending cer~rally thexethrough. The seating element is
tightly held between projection 94 of outlet housing 74 and
interior surface 106 of recess 24. When so held, inner sur-
face 104 of valve element 72 sealingly abuts surface 106, and
the inner surface 91 of projection 94 sealingly abuts the outer
surface 108 of the valve element. Both surface 104 and surface
91 are slightly tapered for improved sealing, the angle of
taper being about 5. Such fluid that does leak past these
seals is vented by a passage 110.
Passage 102 of seating element 7~ is polished to a
high surface finish and has a circular cross section and a
diameter slightly greater than that of outlet passage 30.
When the seating element is held between projection 94 and
surface 106, passage 102 is aligned concentrically with
passage 30 and becomes in effect an extension thereof.
Outlet valve element 78 is slidably mounted in valve
chamber 36 of outlet housing 74, the valve chamber having a
full diameter portion 97 and a reduced diameter portion 99
(Fig. 2)~ As shown in Fig. 6, valve element 78 has a
cylindrical shape of constant diameter except for an enlarged
diameter shoulder 82. The diameters of shoulder 82 and the
remainder of valve element 78 correspond to those of the full
and reduced diamet~r portions respectively of valve chamber
96. ~eferring to Fig. 2, rightward or rearward motion of
valve element 7~ in valve chamber 96 is limited by the rear
surface 93 of such valve chamber. Forward, or leftward, mo-
tion of valve element 78 is limited by seating element 72.
Forward end lO0 of the valve element is planar and of a dia-
meter greater than that of passage 102, so that the valve
element in its forward position sealingly abuts planar sur-
face 108 of seating element 72. The valve eleMent is biased
into such a sealing position by spring 80 extending between
shouldex 82 and a shoulder 95 formed in the wall of valve
chamber 96.
As best seen in Fig. 6, radial intersecting passages
84, 86 extend through valve elernent 78 just forward of shoulder
82, such passages communicating with each other and with axial
passage 87 extending from such radial passages to the rear
surface of the valve element. When the valve element is in
its non-sealing position with forward end 100 spaced away from
seatiny element 72, such passages provide a path through which
fluid emerging from passage 102 can pass through the valve
element and into connecting passage 88.
The operation of the entire check valve assembly may
now be described. When the reciprocating pump is on its in-
take stroke, the 1uld pressure in the interior 22 of pump
cylinder 20 drops to a low value. As already described, the
result is that inlet check valve 50 opens and inlet fluid is
drawn into cylinder 20. Since outlet passage 30 and passage
102 communicate directly with the interior of the cylinaer,
the pressure in these passages is likewise lo~ at this time.
The high pressure in outlet line 98 and in connecting passage
88 therefore cause outlet valve element 78 to be firmly held
_g_
S~2
against seating element 72, preventing backflow of fluid into
outlet ~;assage 30 during the intake stroke. When the pump
changes to its cornpression stroke, the inlet check valve
closes and the pressure in the outlet passage increases to
a value in excess of that in outlet line 98. This pressure
difference causes valve element 78 to move away from seating
elernent 72 against the force of spriny 80, permitting fluid t
flow from passages 30, 102 through the passage in valve ele-
ment 78, through connecting passage 88, and into outlet line
98.
The above described outlet valve is adapted for simple
and rapid servicing of seating element 72 and valve element
78. To access these parts, outlet housing 74 is unscrewed
from body lO, seating element 72 is withdrawn from recess 2~,
and valve element 98 withdrawn from valve chamber 96. The
flat sealing surfaces lO0 and 108 may then be resurfaced simply
by lapping with emery paper against a flat block, a quick and
easy operation which can be performed in the field with only
simple hand tools.
While the preferred embodiment of this invention has
been illustrated and described herein, it should be understood
that variations will become apparent to one skilled in the art.
~ccordingly, the invention is not to be limited to the specific
embodiment illustrated and described herein and the true scope
and spirit of the invention are to be determined by reference
to the appended claims.
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