U.S. patent number 3,695,788 [Application Number 05/001,707] was granted by the patent office on 1972-10-03 for apparatus for pumping fluids.
Invention is credited to Bernard A. Loomans.
United States Patent |
3,695,788 |
Loomans |
October 3, 1972 |
APPARATUS FOR PUMPING FLUIDS
Abstract
This disclosure relates to a fluid pump for pumping fluids with
opposed reciprocating pistons which periodically displace fluid
between inlet and outlet ports. The pistons, which are mounted in a
passage communicating with the ports, may be moved apart to provide
an opening for accepting fluid from the inlet port. The pistons are
next moved to a location adjacent the outlet port while the volume
of the opening remains constant. The pistons are then moved
together to close the opening and force the fluid through the
outlet port. The volume of fluid displaced may be selectively
varied.
Inventors: |
Loomans; Bernard A. (Saginaw,
MI) |
Family
ID: |
21697423 |
Appl.
No.: |
05/001,707 |
Filed: |
January 9, 1970 |
Current U.S.
Class: |
417/488 |
Current CPC
Class: |
F04B
49/12 (20130101); F04B 9/02 (20130101); F04B
3/00 (20130101); F04B 7/045 (20130101); F04B
53/14 (20130101) |
Current International
Class: |
F04B
53/00 (20060101); F04B 7/04 (20060101); F04B
3/00 (20060101); F04B 53/14 (20060101); F04B
7/00 (20060101); F04B 9/02 (20060101); F04B
49/12 (20060101); F04b 037/00 (); F04b
019/00 () |
Field of
Search: |
;417/487,488
;92/69,70,75,206 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Croyle; Carlton R.
Assistant Examiner: Glick; Richard E.
Claims
I claim:
1. Apparatus for pumping liquids comprising:
a frame;
a pump housing on said frame having an axial passage therein and
inlet and outlet ports at inlet and outlet pumping stations
communicating with said passage;
first and second pistons therein a common driving source;
first connecting means connected with said driving source and said
first and second pistons for simultaneously moving said first and
second pistons in a to-and-fro axial path of travel between said
inlet and outlet stations while maintaining their relative axial
positions; and
second connecting means always intercoupling said common driving
source and only one of said pistons for moving the pistons relative
to each other in timed relation with the composite movement of said
pistons in said path of travel such that said one piston moves away
from the other at said inlet station to receive liquid therebetween
from said inlet port and toward said other at said outlet station
to discharge the liquid through said outlet port.
2. The apparatus set forth in claim 1 wherein said first connecting
means comprises a sub-frame mounted on said frame for axial
movement relative thereto, and linkage means connected to said
sub-frame and said driving source for moving said sub-frame in said
to-and-fro path of travel, said other piston being fixed to said
sub-frame for movement therewith in said to-and-fro path, said one
pistons being supported on said sub-frame for movement therewith as
said sub-frame moves in said to-and-fro path and for axial movement
relative thereto at said inlet and said outlet stations, said
second linkage means comprising additional linkage means connected
to said driving source and said one piston for moving said one
piston relative to said other piston and said sub-frame at said
inlet and outlet stations.
3. The apparatus set forth in claim 1 wherein said common driving
source comprises a rotary cam means, said first connecting means
comprises first linkage means coupled to said cam means for
translating rotary motion of said cam means into linear motion of
said pistons, said second connecting means comprises second linkage
means including cam follower means reactable with said cam means
for effecting said relative movement.
4. The apparatus set forth in claim 1 wherein said pistons each
include a surrounding seal having adjustable means connected
thereto for urging said seal into sealing engagement with the
housing adjacent said passage.
5. The apparatus set forth in claim 1 including means for
selectively varying the volume of fluid displaced between said
ports even while said pistons are moving between said inlet and
outlet stations.
6. The apparatus set forth in claim 5 wherein said second linkage
means comprises lever means swingably mounted about a fulcrum on
said frame, means biasing one end of said lever into engagement
with said cam means, the other end of said lever being connected to
said one piston for moving it relative to the other piston when
said cam means rotates and pivots said lever about said
fulcrum.
7. The apparatus set forth in claim 6 wherein said means for
selectively varying the volume comprises means for selectively
adjusting the position of said fulcrum relative to the opposite
ends of said lever to control the relative movement of said
pistons.
8. The apparatus set forth in claim 6 wherein said biasing means
comprises additional linkage means connected to said one end of
said lever engaging said cam means and including a cam follower
engageable with the opposite side of said cam means.
9. The apparatus set forth in claim 3 wherein said second linkage
means includes drive means movable in a to-and-fro path of travel
generally transverse to the axial path of travel of said pistons,
and means reactable between said drive means and said pistons for
forcing the pistons together when said drive means moves away from
said pistons and for forcing the pistons apart when said drive
means moves toward said pistons.
10. The apparatus set forth in claim 9 wherein said means for
axially moving said pistons includes means slidably mounted on said
drive means for movement in a to-and-fro axial path of travel.
11. Apparatus for pumping liquids comprising:
a frame;
a pump housing on said frame having an axial passage therein and
inlet and outlet ports in inlet and outlet pumping stations
communicating with said passage;
a pair of opposed pistons disposed in said passage for axial
movement;
a common piston driving source;
first connecting means connected with said driving source and said
opposed pistons for simultaneously compositely moving said opposed
pistons in a to-and-fro axial path of travel between said inlet and
outlet stations while maintaining their relative axial
positions;
second connecting means always intercoupling said common driving
source and only one of said pistons for moving the pistons relative
to each other in timed relation with the composite movement of said
pistons in said path of travel such that said pistons move away
from each other at said inlet station to receive liquid
therebetween from said inlet port and toward each other at said
outlet station to discharge the liquid through said outlet port;
and
means connected with said first and second connecting means for
selectively varying the volume of fluid displaced between said
ports even while said pistons are moving between said inlet and
outlet stations.
Description
This invention relates to a positive displacement pump having a
high volumetric metering accuracy. Liquid pumps of this type are
required as volumetric liquid metering devices, for instance, in
the chemical industry. The major advantage which metering pumps of
the genera type disclosed herein have over other types of positive
displacement pumps, such as gear-type pumps, is their capability of
producing high discharge pressures without erratic volumetric
displacement. This is mainly due to the elimination of leakage.
When check valves are utilized in a pump, serious difficulties
arise when the liquid is either contaminated and carries solid
particles in suspension, or when liquids with a high viscosity are
being pumped. If solid particles, which can be in a form ranging
from small crystalline particles through fiber-like particles to
larger soft gels, are suspended in the liquid, they can become
trapped between the valve and the valve seat, thus preventing the
valve from closing. As soon as this happens the volumetric
displacement of the pump becomes erratic, and eventually fluid
displacement may stop altogether. If high viscosity liquids are
being pumped, a similar situation can arise because the valves are
surrounded by the liquid and their motion in the viscous liquid
becomes too sluggish to follow the timing of the plunger stroke. As
a result, the valves never fully open or fully close, with
resulting unreliability and metering inaccuracies.
It is, therefore, a prime object of the present invention to
provide a simple and reliable pump for pumping viscous liquids or
low viscosity liquids carrying solid or semi-solid particles in
suspension and achieving high discharge pressures.
It is a further object of this invention to provide a pump for
pumping liquids which is selectively capable of varying the amount
of liquid displaced per unit of time while the pump is in
operation.
According to the present invention, there is provided a fluid pump,
including inlet and outlet means, reciprocating means for
displacing fluid between the inlet and outlet means, and control
means for controlling the movement of the reciprocating means.
Other features of the invention will be apparent from a review of
the following specification describing a preferred form of
apparatus and reference to the drawing, in which:
FIG. 1 is a fragmentary view, partly in section, of the complete
assembly of the pump according to a preferred embodiment of the
invention;
FIG. 2 is an enlarged fragmentary side elevational view, partly in
section, illustrating the details of the pump cylinder and
plungers;
FIG. 3 is an enlarged, perspective elevational view of the control
portion of the pump;
FIGS. 4A-4H are diagrammatic illustrations illustrating the
movement of the two plungers in the cylinder, which produce the
pumping action;
FIG. 5 is a fragmentary schematic elevational view of the mechanism
producing the plunger motion;
FIG. 6 is a fragmentary elevational view illustrating a slightly
modified form of this mechanism;
FIG. 7 is a front elevational view of the cam which forms a part of
the mechanism particularly shown in FIGS. 3 and 6;
FIG. 8 is a side elevational view of the cam taken along the line 8
- 8 of FIG. 7;
FIG. 9 is a front elevational view, partly in section, disclosing
another embodiment of the invention;
FIG. 10 is a sectional view taken along the line 10 -- 10 of FIG.
9;
FIG. 11 is a sectional view showing a piston seal mounted on the
fluid displacement pistons utilized in the various embodiments of
the invention; and
FIG. 12 is a cross-sectional view of the piston and seal taken
along the line 14 -- 14 of FIG. 11.
Referring now to the drawings, and particularly to FIGS. 1 - 3
thereof, a housing or frame F supports a fluid pump assembly
generally designated P and having a reciprocating mechanism, shown
generally at R, and a control mechanism shown generally at C for
controlling the reciprocating mechanism. The inlet pipe 10 for the
pump is connected between a suitable source of pressurized fluid,
not shown, and inlet port 10a communicating with cylinder 14a
formed in pump housing 14. The outlet pipe 12 for the pump is
connected with outlet port 12a of cylinder 14a. The pump housing 14
is connected to the housing F through the bracket 20.
The reciprocating mechanism R includes first and second, oppositely
disposed portions designated generally R.sub.1 and R.sub.2 which
are axially movable with respect to each other as will be explained
more fully hereinafter. The reciprocating portion R.sub.1 includes
a left end plunger 21 connected with a hollow cylindrical tube 22
by means of tie rods 23 connected with spaced apart yokes 24. The
reciprocating portion R.sub.2 includes a right-end plunger 25 fixed
directly to an axially extending bar 26 by any suitable means such
as a key or a threaded connection (not shown). Plunger 21 moves
with tube 22 and plunger 25 moves with the bar 26 which is slidably
engaged with tube 22.
Cylinder chamber 14a communicates with the ports 10a and 12a and is
adapted to receive the plungers 21 and 25. A pair of seals 28 and
29 are provided for opposite ends of the cylinder bore 14a to
prevent the fluid which is being pumped from leaking. A cavity or
opening 30 is formed between the ends of plungers 21 and 25 to
receive fluid from inlet port 10a and transfer it to outlet port
12a, whence the plungers 21 and 25 close to reduce the cavity as
will later appear. The plunger seals 32 and 34, shown particularly
in FIG. 13 and to be described more fully hereinafter, prevent the
fluid from flowing to or from cavity 30, except at ports 10a and
12a.
The operation of plunges 21 and 25 inside the cylinder 14 during
one cycle will now be described with reference to FIGS. 4A - 4H
where their operation is depicted schematically. The position of
the parts at the beginning the the pumping cycle is illustrated,
shown in FIG. 4A, at which time the plunger ends 21a and 25a are
spaced apart a distance X inside the cylindrical bore 14a (having a
diameter D), thus creating an opening 30 having a volume equaling
1/4.pi.D.sup.2 X. In this position, both plungers are located such
that the opening 30 between the plunger ends 21 and 25 is in open
communication with the port 10a. During the time interval between
FIGS. 4-A and 4-B, which represents 1/8 of the total pumping cycle
or 45.degree. of rotation of the crankshaft 44 (FIG. 1), as will be
described more fully hereinafter, the distance between the plungers
21 and 25 is increased to Y. During the time interval between FIGS.
4-B and 4C, again representing 1/8 of the pumping cycle, the
spacing 30 between the plunger ends is further increased to "Z" and
the volume of opening 30 is increased to 1/4.pi.D.sup.2 Z. The
opening 30 is, of course, filled with the fluid which is fed
through port 10a under pressure. During the time interval from
FIGS. 4C through 4D and to 4E, representing a total of 1/4 of the
pump cycle, the spacing 30 remains unchanged while both plungers
travel together to the right. In position 4E, both plungers are
located such that the volume of the space 30 between the plunger
ends 37 and 32 is in open communication with the outlet port 12a.
During the time interval from FIG. 4E to FIG. 4F, the spacing 30 is
reduced from "Z" to "Y". During the time interval from FIG. 4F to
4G, the spacing between the plunger ends 37 and 32 is further
reduced to "X", forcing the fluid through outlet port 12a. During
the time interval from FIG. 4G through FIG. 4H to a position
identical to FIG. 4A, the spacing 30 remains unchanged, while at
the same time both plungers travel to the left to begin a new
cycle.
It is plain from this description that during one pumping cycle a
volume equal to 1/4.pi.D.sup.2 (X - X) is transferred from the port
10a to the port 12a. It is further clear that in pumping
non-compressible fluids, the spacing between the plunger ends must
remain completely unchanged during the periods that the volume of
fluid being transferred is not in open communication with either
port 10a or port 12a because such a change would lead to extremely
high stresses in the mechanism and unavoidable failure. Further, is
is advantageous if the relative displacement between the two
plunger ends 21a and 25a can be varied such that the volume
transferred is selectively variable, preferably without stopping
the pump. Mechanisms having the capability of fulfilling all these
conditions will be described hereinafter.
The drive mechanism producing the plunger motion described in FIG.
4A - 4H requires a combination of two independent motions. The
first of these is an oscillating motion with a constant stroke,
which moves both plungers with equal velocity from the inlet 10a to
the discharge port 12a. During this basic motion a second relative
motion is provided which produces the relative motions of two
plungers at each end of the stroke to increase the space between
the plungers at the inlet port and decrease this space at the
discharge port. The second motion in the mechanism of the present
invention is also selectively variable in magnitude.
Referring now to FIGS. 1 and 3, the control mechanism for producing
these two motions is generally shown at C mounted in the housing F.
Reference will be made to FIG. 5 in first describing the control
mechanism C, particularly shown in FIGS. 1 and 3, which controls
the relative motion of the plungers 21 and 25 relative to the inlet
and outlet ports 10a and 12a. A crankpin 36, connected to a shaft
44 by cam 45 and driven by a source of power such as a synchronous
electric motor (not shown), rotates in a circle having a radius r.
A connecting rod 37 connects the crankpin 36 to a lug 38 which is
rigidly attached to the hollow cylindrical tube 22. Tube 22 is
supported in tubular slide bearing members 39 and 39a which are
rigidly attached to the housing F to enable tube 22 to slide
lengthwisely in these bearings. Inside the hollow tube 22, the
solid cylindrical bar 26 is supported such that it can slide
lengthwisely inside, and relative to the tube 22. Connecting rod 40
has one end connected to bar 26 by pin 40a and at its other end is
connected to an equilaterally formed triangular plate 41 by a pin
40b. The triangular plate 41 is pivotally connected to the lug 42
by a pin 42a, lug 42 being rigidly attached to the tube 22.
As shown in FIG. 5, upon rotation of the crankpin 36, the complete
assembly of tube 22, bar 26, and plungers 25 and 21 will receive a
lengthwise motion with a stroke equal to 2r during each complete
revolution of shaft 44. If a pin 42b attached to triangular plate
41 and connecting it to actuating linkage, to be described, is
moved vertically in an arc around pin 42a a distance D, the pin 40b
moves horizontally to the left the same distance D. Through the
Connecting rod 40, the bar 26 is moved to the left essentially the
same distance relative to the tube 22. The manner in which pin 42b
is moved vertically will be presently treated.
The portion of control mechanism C shown in FIGS. 1 and 3 for
moving the first and second opposed movable portions R.sub.1 and
R.sub.2 relative to each other will now be described. A cam
follower roller 46 is connected to one end of a lever 47 which is
pivotally supported on the pin 48a. As will be described more fully
hereinafter, pin 48a is supported on a longitudinally adjustable
stand, such as that shown at 50 in FIG. 1. At its opposite end, the
lever 47 is connected by the pin 48 to a link 49 which forms the
bottom link of a double parallelogram linkage shown generally at P.
The double parallelogram linkage P includes link 49 which is
connected with two links 50 and 50a which are connected at their
upper ends by a link 51. The two links 52 and 52a which are
connected at their lower ends to link 51 are connected at their
upper ends to the triangular plate 41, by the pins 42a and 42b. The
pin 49a which pivotally connects the lever 49 with link 50b is
supported on the lug 18b which is rigidly attached to the frame F.
The action of the double parallelogram is such that, regardless of
the position of pin 42a, which slides horizontally along with the
tube 22, the links 49 and 51 and a line passing through the axes of
pins 42a and 42b are always parallel, therefore, when the pin 48
undergoes a vertically upward movement, the link 49 swings upwardly
and the equilateral triangle 41 rotates about the pin 42a.
Simultaneously, the pin 40b swings to the left and through the
connecting rod 40 and pin 40a, the bar 26 moves to the left
relative to the tube 22 over essentially the same distance as the
pin 48 moved upward.
The stand 50', according to the preferred embodiment, shown in
FIGS. 1 and 3, adjustably mounts the pivot pin 48a which is
attached to a nut 64 movably mounted in housing 65. Opposite ends
of screw 66 are journaled in bushings 66a and 66b formed in the
screw housing 65 mounted on frame F. The threaded portion of screw
66 passes through a nut 64 which is adapted to reciprocably slide
in a channel 65b formed in housing 65. By turning hand crank 67,
screw 66 moves nut 64 and pin 48a to the right or left, as desired.
By lengthwise movement of pivot 48a, the pump displacement can be
varied through the variation of the relative movement of the
plungers. It is thus clear that the more pin 48a, which is the
pivot of lever 47, is moved to the left, the longer the lever arm
between pin 48a and the roller 46 becomes, and the shorter the
lever arm between the pin 48a and the pin 48 becomes. Thus, the
vertical motion of the pin 48, and consequently the relative motion
of the bar 26 with respect to the tube 22, is variable depending
upon the position of the pin 48a.
As can best be seen in FIG. 3, the roller 52a is connected to the
roller 46 by the link 70 and laterally guided by the link 71. The
two rollers 117 and 46 cooperate through link 70 to maintain the
rollers in engagement with the cam 45 at all times. If desired, the
axis of the pivot pin 48a can be made to coincide with the axis of
the pin 48 in FIG. 3. This results in a zero motion of the pin 48,
and thus zero displacement of the pump. The importance of this
mechanism is that the displacement of the pump can thus be varied
from zero or a very small displacement to maximum displacement
without stopping the mechanism. The cam 45, shown in FIGS. 1 and 3
will be described by referring to FIGS. 7 and 8, which show the
symmetrically formed cam 45 in detail. The cam profile consists of
two circular sectors, one with a radius r.sub.1, and one with a
radius r.sub.2, connected by two portions c on either side. Both
circular sectors have an arc length B substantially equal to
90.degree.. The crankpin 36, which is attached to the cam at a
radius r.sub.3 from the shaft axis, is angularly off set by an
angle A from the line of symmetry of the cam. The reason for this
will become clear from the description of the operation of the
mechanism.
When the shaft 44 rotates in the direction indicated by the arrow
s, the tube 22 with its attachments is moved to the right by the
crank pin 36 through the connecting rod 37. The cam follower roller
46 is at this time following the concentric circular section of the
cam 45 having radius r.sub.2 (see FIG. 7). When the cam 45 has
turned through an angle equal to 1/2 of angle B, or approximately
45.degree., the cam follower 46 contacts the noncircular curved
part of the cam 45 and starts to move downward. Just before this
downward movement, pistons 21 and 25 will be in the position shown
in FIG. 4E. During the downward movement the lever 47 is rotated in
a clockwise direction around the pivot 48a. This causes the pin 48
to swing upwardly, and through the double parallelogram also causes
pin 42b to swing upwardly around the pivot 42a. This, in turn,
through the pin 40b and the connecting rod 40, causes the bar 26 to
move to the left relative to the tube 22. Thus, while the tube 22
slides to the right, the bar 26 moves inside and relative to the
tube 22 to the left. This motion continues until the cam has
rotated over the full nonconcentric curved part c, or approximately
90.degree., and the cam follower roller 46 starts to contact the
concentric circular sector of the cam with radius r.sub.1. This
90.degree. of cam movement corresponds to the movement of pistons
21 and 25 from the position shown in FIG. 4E through FIG. 4F and to
the position shown in FIG. 4G. During this time the crank 36
rotates from position 53 to position 54 in FIG. 5. The roller 46
has thus swung down around the pivot 48 over a distance equal to
r.sub.1 - r.sub.2. When pivot 48 is in the position shown in the
drawing relative to lever 47, the length of the lever from the
center of the roller 46 to the pivot 48a is equal to the lever
length between 48 and 48a. Hence, pin 48 moves up a distance equal
to r.sub.1 - r.sub.2, which is also the distance D moved by pin
42b.
Since the sides of the triangle formed by the pins 42b, 42a and 40b
are equal, pin 40b and rod 40 also move a distance D and the rod 26
moves relative to and inside the tube 22 to the left over distance
essentially equal to r.sub.1 - r.sub.2. This 90.degree. movement
over the noncircular portion of the cam corresponds to movement of
pistons 21 and 25 from the position shown in FIG. 4E through the
position of FIG. 4F to that shown in FIG. 4G.
Over the next 90.degree. rotation of the cam, the roller 46 follows
the circular part with radius r.sub.1, which does not cause any
vertical movement of the roller 46. Thus, the relative positions of
the tube 22 and the bar 26 remain unchanged. During this period the
crank 36 rotates from position 54 to position 55 in FIG. 5 and
moves the tube 22 with its attachments to the left. This 90.degree.
circular movement corresponds to the movement of plungers 21 and 25
from the position shown in FIG. 4G to that shown in FIG. 4A. At
this time, the roller 46 contacts the nonconcentric curved part of
the cam between radius r.sub.1 and radius r.sub.2 and consequently,
while the crank 36 moves from position 55 to position 56, the
roller 46 swings upward a distance r.sub.1 - r.sub.2 and the bar 26
is moved over essentially the same distance to the right inside and
relative to the tube 22. Here the cam movement corresponds to
movement of pistons from the position shown in FIG. 4A to that
shown in FIG. 4C. Further rotation of the crank about radius
r.sub.2 returns the pistons to the position shown in FIG. 4E. It is
thus obvious that at each end of the stroke of the crank 36 between
positions 55 and 56, and between positions 53 and 54 in FIG. 5, the
bar 26 undergoes a relative movement with respect to the tube 22.
At the right hand end of the stroke the bar 26 is pushed out of the
tube 22, and at the left hand end of the stroke it is pulled into
the tube.
The embodiment illustrated in FIG. 6 is similar to that of FIG. 1,
however, the rollers 117, and links 70 and 71 have been replaced by
a spring 115 urging the roller 46 of the slotted lever 47' into
contact with cam 45. The lever 47' is slotted at 63 to receive the
pivot pin 48a' mounted on the stand 50' which is longitudinally,
adjustably mounted on frame F by bolts 62 passing through an
elongated slotted opening t in the base of frame F. Thus, if bolts
62 are loosened, the stand 50' can be slid to the left which allows
the pin 48a' to slide in the groove 63 over a distance L. The
operation of this embodiment is similar to that of FIG. 1 and the
description will not be repeated.
Referring now to the alternate embodiment shown in FIGS. 9 and 10
wherein the movable portions R.sub.1 and R.sub.2 of the
reciprocating means consist primarily of plungers 21 and 25 mounted
in opposed relation in cylinder 14a, the housing F' which is
similar to housing F includes an opening 86' with a support member
75 spanning the opening. Member 75 forms a support for cylinder 14a
and the bearings 39b and bearings 39c are formed in opposite sides
of housing F'. Plungers 21 and 25 are slidably mounted in bearings
39b and 39c.
The two plungers 21 and 25 are connected to a pair of connecting
rods 76 and 77 by pins 78 and 79, respectively. At their point of
intersection, rods 76 and 77 are connected to block 80 by pins 81a
extending from opposite sides of block 80. Block 80 is slidably
mounted on a guide bar 81 (FIG. 10) which 81 is rigidly connected
to a bar 82 which is slidable vertically in bearings 83 and 84. The
pin 85 connects a lever 86 which pivots on a pin 87 to bar 82. At
its other end, lever 86 is connected with a roller 88 which is
connected to roller 89 by a link 90, such that this combination
follows the contour of the cam 45 when it rotates. Roller 89 is
connected with a lug 75a on support 75 by means of arm 89a and pin
89b. The crank pin 36 which is attached to the cam 45 is connected
to the pins 81a by a connecting rod 91 which may conveniently
comprise an extension of link 77. Upon rotation of the crank 36,
pins 81a move horizontally back and forth with a stroke equal to
the diameter of the crank circle. This would normally result in
block 80 sliding to and fro on guide bar 81 and plungers 21 and 25
being moved relative to inlet and outlet ports 10a and 12a without
being moved relative to each other. The movement of plungers 21 and
25 relative to each other is dependent upon the vertical movement
of pivot pins 81a. When the pins 81a move down vertically as a
result of the downward motion of the guide bar 81, they pull the
plungers 21 and 25 closer together through the scissors action of
the connecting links 76 and 77. When pins 81a move upward, plungers
21 and 25 move apart.
The vertical movement of pins 81a is dependent upon the vertical
movement of bar 80 and lever 86 which depends upon the position of
cam 45. As the roller 88 moves up, pin 85 and bar 82 move downward,
causing plungers 21 and 25 to move closer together. As roller 88
moves down, pin 85, bar 82, and pin 81a move upward, causing
plungers 21 and 25 to move apart. The movement of plungers 21 and
25 relative to ports 10a and 12a is similar to that illustrated in
FIGS. 4A - 4H, and will not be repeated. The inlet and outlet ports
are reversed in position in the view, as will be noted. The cam and
crank combination which is driven by an outside power source not
shown operates in such a manner that, at the right hand end of the
crank stroke, the plungers are pushed apart when the cavity between
them is in open communication with the inlet 10a. At the left hand
end of the stroke they are brought close together when they are in
communication with the discharge port 12a, thus creating a pumping
action as described before.
Pivot pin 87 which is fixed to bracket 89' is slidably mounted in a
slot 23a formed in lever 86. Bracket 89', which is slidably mounted
in a slot S in the housing, has an internally threaded portion
adapted to receive screw 92a which is journaled in the housing at
92b and 92c. By turning hand crank 92d, screw 92a moves the bracket
89' and pin 87 to the right or left, as desired. Hence, the
displacement of the pump can be varied by changing the limits of
the movement of one plunger relative to the other.
Referring now to FIGS. 11 and 12 for a specific disclosure of the
plunger mechanism, the plunger 21a is shown removed from its
cylinder 14 and is shown connected to the driving mechanism R.sub.1
by the "open" coupling 108 which is located outside the cylinder 14
and comprises separate halves clamped together by the bolts 109.
Coupling 108 allows access to the hexagon head 110 of a bolt 111,
which has a cylindrical foot 112 fixed on its other end. A tapered
nut 113 is in threaded engagement with the bolt 111, and supports a
resilient seal 114 having a complementally tapering bore. The seal
114 which is preferably formed of a semi-hard neoprene or
fluorocarbon, is subject to wear. When a seal 114 wears to a point
where internal liquid leakage takes place, a slight turn of the
hexagon head 110 of bolt 111 will move the tapered nut 113 to the
left to radially expand the seal 114 and reseal the plunger against
leakage. A lock nut 110a may then be retightened to lock bolt 111
in position. The sealing pressure is adjustable in this way without
requiring disassembly of the machine.
The invention is defined in the claims.
* * * * *