U.S. patent number 3,802,805 [Application Number 05/152,734] was granted by the patent office on 1974-04-09 for pumping apparatus.
This patent grant is currently assigned to Otto Engineering, Inc.. Invention is credited to John O. Roeser.
United States Patent |
3,802,805 |
Roeser |
April 9, 1974 |
**Please see images for:
( Certificate of Correction ) ** |
PUMPING APPARATUS
Abstract
A pumping apparatus is provided which is particularly suitable
for pumping material in measured quantities. The apparatus includes
a cylinder having an axially extending bore and a piston slidably
received by the bore. The cylinder bore is provided with radially
enlarged inlet and outlet chambers which communicate with the
exterior of the cylinder, and the piston is provided with a central
bore which extends from the forward end of the piston to a
transverse opening in the intermediate portion of the piston. The
inlet chamber is positioned forwardly of the outlet chamber, and as
the piston moves forwardly, fluid in the outlet chamber is forced
through the bore of the piston, out of the transverse opening in
the piston, and into the outlet chamber. A check valve within the
piston bore permits the fluid to flow freely toward the opening in
the piston as the piston moves forwardly but prevents the fluid
from flowing from the piston opening toward the forward end of the
piston. The cylinder may include stop means engagable with the
piston for limiting the forward movement of the piston to permit
the apparatus to pump a measured amount of fluid during each
reciprocation of the piston.
Inventors: |
Roeser; John O. (Arlington
Heights, IL) |
Assignee: |
Otto Engineering, Inc.
(Carpentersville, IL)
|
Family
ID: |
26726747 |
Appl.
No.: |
05/152,734 |
Filed: |
June 14, 1971 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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48981 |
Jun 24, 1970 |
3684250 |
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Current U.S.
Class: |
417/398; 417/429;
417/489; 92/87; 417/437 |
Current CPC
Class: |
F04B
53/126 (20130101); B29B 7/603 (20130101); F04B
7/04 (20130101); F04B 53/00 (20130101); B01F
15/0462 (20130101); B01F 15/0237 (20130101); B01F
15/0454 (20130101) |
Current International
Class: |
B01F
15/04 (20060101); F04B 53/12 (20060101); B29B
7/30 (20060101); F04B 7/04 (20060101); B29B
7/60 (20060101); F04B 7/00 (20060101); F04B
53/10 (20060101); F04B 53/00 (20060101); F04b
035/00 (); F04b 007/04 () |
Field of
Search: |
;417/431,547,557,489,429
;92/13.4,13.41,13.5,13.51,13.6,13.7,87 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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710,293 |
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Jun 1931 |
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FR |
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316,184 |
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Dec 1919 |
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DD |
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611,478 |
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Oct 1960 |
|
IT |
|
Primary Examiner: Freeh; William L.
Parent Case Text
APPLICATION
This application is a continuation-in-part of my prior application
entitled, "Multi-Component Mixing Apparatus," Ser. No. 48,981,
filed June 24, 1970 now Patent No. 3,684,250.
Claims
I claim:
1. A positive displacement piston pump for pumping fluid comprising
cylinder means having a forward end and a rearward end and an
axially extending bore, a piston having a forward end portion
slidably received by said bore, the piston sized to provide a
substantially fluid-tight seal with the bore, and means for axially
moving the piston within the bore, the bore of the cylinder means
being provided with an enlarged inlet chamber and an enlarged
circumferentially extending outlet chamber spaced axially
rearwardly of the inlet chamber, said cylinder means having inlet
port means for communicating the inlet chamber with a source of the
fluid to be pumped and outlet port means for withdrawing fluid from
the outlet chamber, said piston having a bore extending axially
through the center of the piston from the forward end thereof and
an opening for communicating the piston bore with the bore of the
cylinder means, the opening in the piston being provided in an
annular groove in the piston, and sealing means within said pump
for sealing the annular groove in the piston and the piston opening
from the outlet chamber until the forward piston end passes
forwardly of the inlet chamber, the annular groove in the piston
permitting circumferential flow of fluid from the groove to the
outlet chamber when the groove communicates with the outlet
chamber.
2. The pump of claim 5 in which the sealing means is positioned in
the bore of the cylinder means rearwardly of the outlet chamber,
the distance between the forward end of the piston and the annular
groove in the piston being greater than the distance between the
forward end of the inlet chamber and the sealing means whereby the
sealing means seals the annular groove in the piston from the
outlet chamber until the forward piston end passes the forward end
of the inlet chamber.
3. A positive displacement piston pump for pumping fluid comprising
cylinder means having a forward end and a rearward end and an
axially extending bore, a piston having a forward end portion
slidably received by said bore, the piston sized to provide a
substantially fluid-tight seal with the bore, and means for axially
moving the piston within the bore, the bore of the cylinder means
being provided with an enlarged inlet chamber and an enlarged
outlet chamber spaced axially rearwardly of the inlet chamber, said
cylinder means having inlet port means for communicating the inlet
chamber with a source of the fluid to be pumped and outlet port
means for withdrawing fluid from the outlet chamber, said piston
having a bore extending axially through the center of the piston
from the forward end thereof and an opening for communicating the
piston bore with the bore of the cylinder means, and sealing means
within said pump for sealing the piston opening from the outlet
chamber until the forward piston end passes forwardly of the inlet
chamber, the bore of the cylinder means including an enlarged
flushing chamber spaced axially rearwardly of the sealing means, a
cylindrical sleeve within the flushing chamber, the piston being
slidably received by the sleeve, and an O-ring within the flushing
chamber rearwardly of the sleeve, the O-ring sealingly engaging the
piston and being restrained against forward movement by the sleeve,
the cylinder means having a solvent inlet port for communicating
the flushing chamber with a solvent and a solvent outlet port
communicating with the flushing chamber for removing solvent from
the flushing chamber whereby solvent washes the piston as it
reciprocates within the flushing chamber.
4. The pump of claim 3 in which the sleeve is provided with a
plurality of openings to permit substantially free solvent flow
between the sleeve and the piston.
5. A positive displacement piston pump for pumping fluid comprising
cylinder means having a forward end and a rearward end and an
axially extending bore, a piston having a forward end portion
slidably received by said bore, the piston sized to provide a
substantially fluid-tight seal with the bore, and means for axially
moving the piston within the bore, the bore of the cylinder means
being provided with an enlarged inlet chamber and an enlarged
outlet chamber spaced axially rearwardly of the inlet chamber, said
cylinder means having inlet port means for communicating the inlet
chamber with a source of the fluid to be pumped and outlet port
means for withdrawing fluid from the outlet chamber, said piston
having a bore extending axially through the center of the piston
from the forward end thereof and an opening for communicating the
piston bore with the bore of the cylinder means, and sealing means
within said pump for sealing the piston opening from the outlet
chamber until the forward piston end passes forwardly of the inlet
chamber, the sealing means including a generally cylindrical sleeve
having a central bore positioned within the cylinder means, the
piston being slidably received by the sleeve, the sleeve being
provided with an annular groove extending radially outwardly from
the sleeve bore, and an O-ring positioned within the annular groove
of the sleeve and sealingly engaging the piston.
6. The pump of claim 5 in which the sleeve includes a second
annular groove extending radially outwardly from the sleeve bore,
and a second O-ring positioned within the second annular groove of
the sleeve and sealingly engaging the piston.
7. The pump of claim 5 in which the piston is provided with a
radially inwardly extending annular groove, the piston opening
being provided through the annular groove whereby the piston
opening is sealed from the outlet chamber until the annular groove
of the piston passes forwardly of the O-ring.
8. A positive displacement piston pump for pumping fluid comprising
cylinder means having a forward end and a rearward end and an
axially extending bore, a piston having a forward end portion
slidably received by said bore, the piston sized to provide a
substantially fluid-tight seal with the bore, and means for axially
moving the piston within the bore, the bore of the cylinder means
being provided with an enlarged inlet chamber and an enlarged
outlet chamber spaced axially rearwardly of the inlet chamber, said
cylinder means having inlet port means for communicating the inlet
chamber with a source of the fluid to be pumped and outlet port
means for withdrawing fluid from the outlet chamber, said piston
having a bore extending axially through the center of the piston
from the forward end thereof and an opening for communicating the
piston bore with the bore of the cylinder means, and sealing means
within said pump for sealing the piston opening from the outlet
chamber until the forward piston end passes forwardly of the inlet
chamber, check valve means within the bore of the piston for
permitting fluid flow from the forward end of the piston toward the
piston opening when the piston is moving forwardly but preventing
fluid flow from the piston opening toward the forward end of the
piston when the piston is moving rearwardly, the check valve means
including an externally threaded generally cylindrical plug
threadedly received by the forward end of the piston bore and
provided with a central opening therethrough, the rearward end of
the plug being generally concave to provide a valve seat having an
opening therethrough, a ball having a diameter greater than the
opening through the plug and having a radius of curvature less than
the radius of curvature of the concave end of the plug, the ball
being resiliently biased forwardly against the valve seat to close
the opening therethrough.
9. The pump of claim 8 including a rod extending forwardly within
the piston bore from the rear end of the bore, the diameter of the
rod being less than the diameter of the piston bore, and a spring
carried by the forward end of the rod resiliently biasing the ball
against the valve seat.
10. A positive displacement piston pump for pumping fluid
comprising cylinder means having a forward end and a rearward end
and an axially extending bore, a piston having a forward end
portion slidably received by said bore, the piston sized to provide
a substantially fluid-tight seal with the bore, and means for
axially moving the piston within the bore, the bore of the cylinder
means being provided with an enlarged inlet chamber and an enlarged
outlet chamber spaced axially rearwardly of the inlet chamber, said
cylinder means having inlet port means for communicating the inlet
chamber with a source of the fluid to be pumped and outlet port
means for withdrawing fluid from the outlet chamber, said piston
having a bore extending axially through the center of the piston
from the forward end thereof and an opening for communicating the
piston bore with the bore of the cylinder means, and sealing means
within said pump for sealing the piston opening from the outlet
chamber until the forward piston end passes forwardly of the inlet
chamber, the means for axially moving the piston including a motor
having a reciprocating piston rod, a pivotally mounted lever arm
having a pair of ends, one end of the lever arm being pivotally
connected to the piston rod of the motor, the other end of the
lever arm being provided with an elongated slot, connecting means
carried by the slotted end of the lever arm and secured to the
piston, and means for selectively securing the connecting means in
a predetermined position along the slot.
11. A pumping apparatus comprising a frame, cylinder means on the
frame having an axially extending bore, a piston slidably received
by the bore, means for reciprocating the piston within the bore,
the cylinder means having inlet port means for communicating the
bore with a source of fluid to be pumped and circumferentially
extending outlet port means communicating with the bore for
permitting fluid to be pumped from the bore, said piston having a
bore extending axially through the center of the piston from the
forward end thereof and having an opening for communicating the
piston bore with the bore of the cylinder means whereby fluid may
flow from the inlet port through the bore of the piston to the
outlet port, the opening in the piston being provided in an annular
groove in the piston, sealing means between the cylinder means and
the piston for sealing the annular groove in the piston and the
piston opening from the outlet port means when the annular groove
in the piston is positioned rearwardly of the sealing means, the
bore of the cylinder means including an enlarged flushing chamber
spaced axially rearwardly of the sealing means, the cylinder means
having a solvent inlet port for communicating the flushing chamber
with a solvent and a solvent outlet port communicating with the
flushing chamber for removing solvent from the flushing chamber
whereby solvent washes the piston as it reciprocates within the
flushing chamber.
12. The apparatus of claim 11 including check valve means within
the bore of the piston for permitting fluid flow from the forward
end of the piston toward the piston opening when the piston is
moving forwardly but preventing fluid flow from the piston opening
toward the forward end of the piston when the piston is moving
rearwardly.
Description
BACKGROUND AND SUMMARY
This invention relates to a pumping apparatus, and, more
particularly, to a pumping apparatus which is particularly suitable
for pumping measured quantities of viscous materials such as epoxy
resins and the like.
As described in my said prior application, it is often desirable to
deliver a mixture comprised of a plurality of flowable materials
which must be mixed in definite proportions just prior to delivery,
for example, multi-component flowable adhesives, sealers, foams
such as epoxides, polyurethanes, polyesters, and the like.
The invention provides a pump for delivery of such flowable
materials in measured quantities which can be readily disassembled
for cleaning, replacement of parts, and the like. The central bore
of the pump includes radially enlarged inlet and outlet chambers to
provide full annular flow, and the central bore of the pumping
piston is provided with a check valve which permits fluid to be
pumped but which prevents reverse flow of the material as the
piston is retracting. A solvent bearing is positioned rearwardly of
the outlet chamber and is provided with a flushing chamber to
permit the piston to be washed with solvent as the piston
reciprocates. Adjustable stop means may be provided which are
engagable with the piston for limiting forward movement thereof and
adjustably mounted for selectively varying the amount of material
pumped during each reciprocation of the piston.
DESCRIPTION OF THE DRAWING
The invention will be explained in conjunction with illustrative
embodiments shown in the accompanying drawings, in which;
FIG. 1 is a schematic view of a mixing system embodying the
invention;
FIG. 2 is a sectional view of one of the measuring pumps of FIG.
1;
FIG. 3 is an enlarged fragmentary sectional view of the solvent
bearing sleeve shown in FIG. 2;
FIG. 4 is an end view of the sleeve of FIG. 3;
FIG. 5 is a fragmentary sectional view of the intermediate portion
of the piston shown in FIG. 2;
FIG. 6 is a side elevational view of the solvent bearing;
FIG. 7 is a sectional view taken along the line 7--7 of FIG. 6;
FIG. 8 is an enlarged exploded fragmentary view of the forward
portion of the cylinder;
FIG. 9 is a sectional view of a modified pump; and
FIG. 10 is a sectional view taken along the line 10--10 of FIG.
9.
DESCRIPTION OF SPECIFIC EMBODIMENTS
The invention will be explained in conjunction with a mixing system
shown schematically in FIG. 1 for use in pumping and mixing two
component materials such as epoxy resins A and B, one of which may
be a base resin and the other an accelerator. The system includes
measuring pumps 15 and 16 for resins A and B, respectively, which
are driven by an air cylinder or air motor 17 and which pump the
resins to a mixer 18. Pump 15 is connected to a source of the A
resin by conduit 19 and supplies the A resin to the mixer through
conduit 20. Similarly, pump 16 is connected to a source of B resin
by conduit 21 and pumps the B resin to the mixer through conduit
22.
The air cylinder or air motor can be a conventional double-acting
pneumatic cylinder which includes a piston rod 23 which is
connected to piston 24 of the pump 15 for reciprocating the piston.
Piston 25 of the pump 16 is also driven by the air cylinder by
means of a crank assembly 26 which includes a lever arm 27
pivotally mounted by a pin 28 and pivotally connected at 29 to the
connecting block 30 which connects the piston rod 23 and the piston
24. A connecting arm 31 is pivotally secured at 32 to the end of
the piston 25 and includes a pin 33 which is slidable within an
arcuate slot 34 provided in the lever arm 27. Suitable nut means
are provided on the pin 33 for securing the pin at any desired
point along the arcuate slot. The proportions of the A and B resins
which are delivered to the mixer during each reciprocation of the
piston rod 23 can therefore be selectively varied by moving the pin
33 within the arcuate slot 34 to change the effective length of the
lever arm between the fulcrum 28 and the connection between the
lever arm and the piston 25. As the effective length of the lever
arm decreases, less resin will be pumped. The arcuate shape of the
slot permits the length of the lever arm to be changed without
affecting the rearwardmost or starting position of the piston, the
slot lying along a circle having its center at 32.
The mixer 18 may be of the type described in my said prior
application, Ser. No. 48,981, filed June 24, 1970, and need not be
described herein.
The pumps 15 and 16 are identical and will be explained with
reference to pump 16 which is shown in FIG. 2. The pump includes an
elongated cylinder 37 which is secured to a solvent bearing 38 by
bolts 39, and the solvent bearing is suitably secured to a
supporting frame 40 as by bolts (not shown). The particular
cylinder illustrated is formed of three separate cylindrical
portions, an outlet chamber block 41, an inlet chamber block 42 and
a pumping chamber block 43, which are removably secured together by
a pair of axially extending bolts which extend through blocks 43
and 42 and are threadedly engaged with the block 41.
The cylinder is provided with a central bore 44 which extends
through the blocks 41 and 42 and which terminates in the pumping
block 43, and the elongated pumping piston 25 is slidably received
by the bore for reciprocation therein. The pumping block 43 defines
the forward end of the bore 44 and is provided with an elongated
bore 45 having a diameter just slightly greater than the diameter
of the piston 25, a radially enlarged annular groove 46, a second
annular enlargement 47, and an annular groove 48 which extends both
radially outwardly from the enlargement 47 and axially forwardly of
the enlargement 47. Referring also to FIG. 8, O-rings 49 and 50 are
received by the grooves 46 and 48, respectively, and a washer 51,
having an outside diameter approximately the same as the inside
diameter of the O-ring 50 is positioned in the enlargement 47. The
forward end of the pumping block 43 abuts the forward end of the
inlet chamber block 42, and the gasket 50 sealingly engages the
block 42 to prevent the escape of the material being pumped. The
O-ring 49 sealingly engages the piston 25 and is retained in the
groove 46 by the washer 51, which has an inside diameter
intermediate the inside and outside diameters of the O-ring 49.
The cylinder bore 44 through the block 42 is defined by a first
bore 52 which has a diameter approximately the same as the diameter
of the bore 45 and a radially enlarged bore 53 which defines an
inlet chamber surrounding the piston. An inlet port 54 extends
radially inwardly through the inlet block 42 to the inlet chamber,
and the inlet port is adapted to be connected to the conduit 21 for
supplying the B resin. A seal is provided between the blocks 41 and
42 by means of a pair of concentric O-rings 55 and 56 which are
received by annular grooves 57 and 58, respectively, in the
rearward end of the inlet block 42, the O-ring 56 also sealingly
engaging the piston 25.
The central bore of the outlet chamber block 41 includes a first
portion 60 having a diameter approximately the same as the diameter
of the bores 52 and 45 and a radially enlarged portion 61 which
defines an outlet chamber. An outlet port 62 extends radially
outwardly from the outlet chamber 61 and is adapted to be connected
to the conduit 22 for delivering the B resin to the mixer.
The rearward portion of the block 41 is radially enlarged still
further at 63 to provide a radially extending shoulder 64, and a
washer 65, a generally cylindrical sleeve 66, and a washer 67
having a generally T-shaped cross section are received in the
radial enlargement 63. The washer 65 has an inside diameter of
approximately the same as the diameter of the piston and abuts the
shoulder 64. The forward end of the sleeve 66 also has an inside
diameter approximately the same as the diameter of the piston, and
the forward end of the sleeve includes a forwardly extending rib 68
which abuts the washer 65. A pair of O-rings 69 and 70 are
positioned outwardly and inwardly, respectively, of the rib 68, the
O-ring 69 sealingly engaging the washer 64, sleeve 66 and the
outlet chamber block 37 and the washer 70 sealingly engaging the
washer 65, the sleeve 66, and the piston 25. The rearward end of
the sleeve 66 is provided with an annular groove 71 which receives
a gasket 72 having a generally U-shaped cross section which
sealingly engages the sleeve 66, the washer 67, and the piston
25.
The washer 67 abuts the sleeve 66, and O-rings 73 and 74 are
positioned outwardly and inwardly, respectively, of the rib 75 of
the washer, the O-ring 74 sealingly engaging the piston 25, and the
O-ring 73 providing a seal between the outlet chamber block 41 and
the solvent bearing 38.
Referring to FIGS. 6 and 7 in addition to FIG. 2, the solvent
bearing 38 is seen to be generally rectangular in elevation and is
provided with a central bore 78, having a diameter approximately
the same as the diameter of the piston 25 and a radially enlarged
flushing chamber 79. An inlet port 80 extends downwardly from the
top of the solvent bearing to communicate with the flushing chamber
79, and an outlet port 81 extends laterally outwardly from the
flushing chamber. As can be seen best in FIG. 7, the inlet port 80
is laterally offset from the center of the flushing chamber to
accommodate the bolt openings 82 which receive the bolts 39.
A cylindrical spacer sleeve 83 (see also FIGS. 3 and 4) is
positioned within the flushing chamber and is provided with four
circumferentially spaced openings 84. The spacer sleeve is spaced
from outer wall of the flushing chamber 79 and the piston 25 to
permit free flow of solvent within the flushing chamber, and the
sleeve serves to maintain an o-ring 85 against the shoulder 86 of
the flushing chamber and to maintain the O-ring 74 against the
washer 67. The O-ring 85 sealingly engages both the shoulder 86 and
the piston 25.
A bottle 87 (FIG. 1) of solvent is connected to the solvent inlet
port 80 for gravity feed of solvent to the flushing chamber. The
solvent is selected depending upon the particular material being
pumped and washes the piston of any material which may escape
rearwardly of the seal means provided by the gaskets 70, 71 and 74
during each reciprocation of the piston before the material can be
carried externally of the cylinder where it might solidify. The
solvent outlet port 81 can be kept normally closed and need be
opened only when it is desired to flush the solvent from the
flushing chamber or to replace the solvent with fresh solvent.
The exterior surface of the piston may be polished chrome plate,
and the piston is provided with an annular groove 90 intermediate
the ends thereof and an axially extending bore 91 which extends
from the forward end of the piston to a point just rearwardly of
the annular groove 90. Four cross-drilled holes 92 spaced
90.degree. apart communicate the bore 91 with the annular groove
90.
The forward end of the piston bore is closed by an externally
threaded cylindrical plug 92a which threadedly engages internal
threads at the forward end of the piston. The plug 92a includes a
central bore 93, and the rearward end of the plug provides a
concave valve seat 94. A ball 95 is resiliently urged against the
valve seat 94 by a helical spring 96 which is supported by an
elongated rod 97. The spring 96 is ensleeved on a radially reduced
end portion 98 of the rod and abuts the shoulder which joins the
radially reduced end portion with the remainder of the rod. The rod
is not secured to the piston but is maintained generally centrally
within the bore 91 by the spring 96 which urges the forward end of
the rod against the conical rearward end 99 (FIG. 5) of the bore
91. The conical end 99 is provided merely by drilling the piston to
provide the internal bore 91.
The ball 95, which has a diameter larger than the opening through
the plug 92a but a radius of curvature less than the radius of
curvature of the concave valve seat 94, acts as a check valve
member to permit fluid to flow through the plug member into the
piston bore but prevents reverse flow. The ball also acts as a
relief valve by choosing the spring 96 so that the spring exerts a
greater force on the ball than is exerted by the resin flowing
through the inlet port. Resin will therefore not flow past the ball
until the piston begins its forward stroke.
The reduced forward end portion 98 of the rod 97 not only supports
the helical spring 96 but serves as a limit stop against rearward
movement of the ball 95.
The resin to be pumped can be supplied to the inlet port 54 either
by gravity feed or by pressure feed, and the material flows through
the inlet port into the inlet chamber 53 and the bore 45 of the
pumping block 43. As the piston moves forwardly into the bore 45,
the material is forced through the plug member 92a, past the ball
95, and into the piston bore. The material can flow freely around
the spring 96 and the rod 97 and is forced rearwardly through the
piston bore and through the cross-drilled openings 92. As the
annular groove 90 in the piston passes forwardly of the gasket 70,
the material begins to flow into the outlet chamber 61 and through
the outlet port 62. The forward end of the annular groove 90 in the
piston is positioned relative to the O-ring or gasket 70 so that
the forward end of the groove will not pass forwardly of the O-ring
until the forward wall of the groove 90 passes forwardly of the
O-ring 70 to permit the material to be forced into the outlet
chamber.
Since the material flows through the cross-drilled openings 92 into
the annular groove 90, there is full 360.degree. flow of the
material into the outlet chamber as soon as the forward end of the
groove passes the O-ring 70. Similarly, the radially enlarged inlet
chamber 53 permits 360.degree. flow of material through the inlet
port around the forward end of the piston, and this substantially
eliminates the possibility of compression lock or binding of the
piston which might be caused by forcing the material through the
inlet port against one side of the piston.
Because there is full circumferential flow around the forward end
of the piston, this end need be positioned only slightly rearwardly
of the O-ring 46 before the beginning of a pumping stroke, and the
piston need travel only a short distance between the point at which
the forward or inlet end of the piston is fully opened and the
outlet end provided by the annular groove is fully closed and the
point at which the outlet end of the piston is fully opened and the
inlet is fully closed. As soon as the piston engages the O-ring 46,
the inlet chamber is completely and suddenly closed from the piston
bore. At the outlet end of the piston bore, as soon as forward end
of the annular groove 90 passes the O-ring 70, the annular groove
permits full 360.degree. flow and the outlet end becomes fully
opened.
At the end of the forward stroke of the piston, the air motor is
reversed to retract the piston 25, and the spring 96 forces the
ball 95 against the valve seat 94 to prevent material within the
piston from being sucked back into the bore 45. As the forward end
of the piston passes rearwardly of the O-ring 46, the material in
the inlet chamber is drawn into the bore 45 by the vacuum created
by the withdrawal of the piston, and inward flow of the material is
also aided by the pressure which may be provided at the material
source or by gravity.
If it is desired to use the pump without the check valve within the
piston, back flow of material from the outlet chamber 61 which
might be caused by a vacuum created in the bore 45 during
retraction of the piston would be prevented as soon as the forward
end of the annular groove 90 passed rearwardly of the gasket
70.
A modified pump 110 shown in FIG. 9 includes a cylinder 111 having
a bore 112 and a piston 113 slidably received in the bore. The
cylinder includes an outlet block portion 114 and an inlet block
portion 115 which are boltably secured by bolts 116 and which are
mounted on a suitable supporting frame (not shown). The outlet
block 114 includes a bore 117 having a diameter substantially the
same as the diameter of the piston 113, a radially reduced outlet
bore 118 which terminates in a concave valve seat 119, and a valve
bore 120. A ball 121 is positioned within the bore 120 and is
resiliently biased toward the valve seat 119 by a helical spring
122 which abuts an end cap 123 secured to the block 114 by the
bolts 116. An outlet bore 124 extends radially outwardly from the
valve ball 120.
The forward end of the block 114 includes a cylindrical projection
125 which is received by a correspondingly shaped bore 126 in the
block 115, and a seal is maintained between the blocks 114 and 115
by O-rings 127 and 128, the latter O-ring being positioned in a
groove 129 in the block 114.
The block 115 is provided with a central bore 130 having
approximately the same diameter as the piston 113, and an inlet
port 131 extends radially inwardly into communication with the bore
130. The inlet port 131 preferably has a diameter slightly greater
than the diameter of the piston and extends beyond the bore 130 to
permit material to flow completely around the piston.
The rearward end of the block 115 is provided with an annular
groove 132 for receiving a gasket 133 which sealingly engages the
piston 113 and the end cap 134.
The piston 113 is solid, and forward movement of the piston forces
material in the bore 117 of the pumping block 114 past the ball
valve 121 and through the outlet port 124. As the piston is
retracted, the ball valve is forced against the valve seat 119 by
the spring 122, and back flow of material from the outlet port is
prevented. As the forward end of the piston passes rearwardly of
the O-ring 127, the vacuum within the bore 117 draws material from
the inlet port 131 into the bore 117.
Means for selectively varying the pumping stroke of the piston is
provided in the form of a stop plate 135 which is slidably mounted
on support rods 136 and 137 secured to the cylinder. Referring to
FIG. 10, the stop plate 135 is provided with a central opening 138
having a diameter approximately the same as the diameter of the
piston 113 and a pair of outer openings 139 and 140 for receiving
the support rods 136 and 137. The stop plate may be secured at a
desired point along the support rods by conventional lock nuts 138
which can be tightened about the support rods. A radially enlarged
abutment 139 is carried by the piston 113, and forward movement of
the piston is stopped when the abutment engages the stop bar. The
amount of material pumped during each reciprocation of the piston
can thereby be accurately controlled.
While I have described the stop means in conjunction with the pump
110, it will be understood that a similar stop means can be
provided for the pumps 15 and 16, and the stop means can be mounted
directly on the frame rather than on the cylinders.
While in the foregoing specification, detailed descriptions of
specific embodiment of my invention was set forth for the purpose
of illustration, it is to be understood that many of the details
herein given may be varied considerably by those skilled in the art
without departing from the spirit and scope of the invention.
* * * * *