Note: Descriptions are shown in the official language in which they were submitted.
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GEAR PUMP
FIELD OF THE INVENTION
[001] The present invention relates generally to pumps used to pump liquids
entrained
with abrasives, and more particularly, relating to a gear pump including
double-helical
gears of an construction which reduces end plate wear, reduces the tendency
for
contaminated fluids fouling pump shaft bearing assemblies, permits packing
seal
adjustment to compensate for seal wear, and permits the adjustment of gear gap
between
meshing gear teeth.
BACKGROUND OF THE INVENTION
[002] Pumping liquids and fluids, such as oils and distillates produced
from oil wells,
presents a problem as these fluids frequently contain entrained contaminating
materials
such as sand, grit and the like. The pumping of such fluids results in the
entrained
abrasive materials coming into contact with the pump elements, and in
particular, the
pump surface elements as well as the pump shaft bearings and seals.
Consequently,
pumps in service for pumping such liquids require frequent maintenance and
repair as a
result of premature wear and failure after a relatively short period of use.
Pumps
employing meshing gears are often used to pump such fluids. Such gear pumps
typically
include single-helical gears that in operation, as a result of contact between
the meshed
gear teeth, create axial thrust forces along the pump shafts, which causes an
increase in
end plate wear.
[003] To address these problems, pumps include modular designs to increase
the
serviceability of the pump and reduce overall pump downtime, include wear
plates to
take the axial thrust forces along the pump shafts to reduce end plate wear,
and include
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bearing assemblies and seal arrangements that operate to reduce the tendency
of
contaminated fluid contact with the bearing assemblies.
[004] Another problem encountered is leaking of fluid externally of the
pump due to a
worn dynamic packing seal that is used to provide a seal between the
protruding end of
the pump driving shaft and the pump housing or end plate. Heretofore,
servicing and
replacement of the packing seal required the pump to be shutdown.
[005] Another problem encountered is the formation of area of high
pressurized fluid at
the end of a pump shaft created during the pump operation. The pressurized
fluid creates
an axially loading on the pump shaft causing the pump shaft to be urged
towards the
opposite end resulting in an increase of pump component wear.
[006] Accordingly, there is a need for a pump design used to pump fluids
contaminated
with abrasives that has an increased service life and an improved
serviceability and that
overcomes the limitations associated with conventional pump designs
heretofore.
SUMMARY OF THE INVENTION
[007] In general, in one aspect, a gear pump is provided including a pump
housing
having opposite ends. A gear is disposed within the pump housing and includes
opposed
and outwardly facing first and second ends. The first end having a first gear
end seal
mount, and the second end having a second gear end seal mount. First and
second end
plates are sealingly joined to the opposite ends of the pump housing. The
first end plate
has a first shaft passage to receive a pump shaft therethrough and a first
seal disc mount
on an inner side of the first end plate coaxial with the first shaft passage.
The second end
plate has a second shaft passage to receive a pump shaft therethrough and a
second seal
disc mount on an inner side of the second end plate coaxial with the second
shaft passage.
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A first seal disc is mounted to the first seal disc mount. A second seal disc
is mounted to
the second seal disc mount. A pump shaft having a first shaft end extends
through the
first shaft passage and the first seal disc, and a second shaft end extends
through the
second shaft passage and the second seal disc. The gear is fixedly joined to
the pump
shaft for rotation therewith. A first gear end seal is mounted to the first
gear end seal
mount and forms a sealing contact between an inner facing side the first seal
disc and the
first outwardly facing end. A second gear end seal is mounted to the second
gear end seal
mount and forms a sealing contact between an inner facing the second seal disc
and the
second outwardly facing end.
[008] In general, in another aspect, a gear pump includes a first fluid
flow passage
between the first shaft end and a first discharge/suction port, and a second
fluid flow
passage between the first shaft end and a second discharge/suction port. Fluid
at the first
shaft end flows through either of the first or the second fluid passage upon
the fluid
reaching a pressure above a threshold pressure to vent the fluid at the first
shaft end to
either of the first or the second discharge/suction ports, respectively.
[009] In general, in another aspect, a gear pump includes a seal neck
including a body
having opposed first and second ends and a seal neck shaft passage extending
between
the first and second ends. The seal neck mounted to the end plate and the pump
shaft
extending through the seal neck passage and protruding beyond the second end
of the seal
neck. First and second bushings disposed in the seal neck shaft passage and
supporting
the pump shaft for rotation. A packing seal disposed within the seal neck
shaft passage
about the pump shaft and interdisposed between the first and the second
bushings. A
packing nut including a bore is threadably attached to the second end of the
body of the
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seal neck. The pump shaft extending through the bore of the packing nut,
wherein
threading the packing nut on the second end compresses the packing seal
between the
first and the second bushings. A pair of check balls, each disposed in a hole
extending
through a body of the packing nut. A collar attached to packing nut about the
body
thereof. The collar captivity retaining the pair of check balls in the holes
and rotatable
about the body between first and second positions. The collar including a pair
of cavities
on an interior surface thereof. The seal neck including a plurality of flat
lands
circumferentially spaced on an exterior surface thereof. The collar is rotated
into the first
position the cavities are registered with the holes through the packing nut
body and the
check balls are partially received within the cavities permitting the check
balls to float
across the flat lands as the packing nut is threaded, and wherein the collar
is rotated into
the second position the check balls are restrained from floating across the
flat lands.
[0010] In general, in another aspect, a gear pump includes double-helical
gears shrunk fit
to respective driving and idler pump shafts.
[0011] In general, in another aspect, a gear pump includes a plug member
threadably
received by a plug bore through the first end plate along the axis of the pump
shaft. The
first shaft end of the pump shaft including an axial bore. A ball is disposed
between the
first shaft end and a cup of an inward end of the plug member.
[0012] There has thus been outlined, rather broadly, the more important
features of the
invention in order that the detailed description thereof that follows may be
better
understood and in order that the present contribution to the art may be better
appreciated.
[0013] Numerous objects, features and advantages of the present invention
will be
readily apparent to those of ordinary skill in the art upon a reading of the
following
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detailed description of presently preferred, but nonetheless illustrative,
embodiments of
the present invention when taken in conjunction with the accompanying
drawings. The
invention is capable of other embodiments and of being practiced and carried
out in
various ways. Also, it is to be understood that the phraseology and
terminology
employed herein are for the purpose of descriptions and should not be regarded
as
limiting.
[0014] As such, those skilled in the art will appreciate that the
conception, upon which
this disclosure is based, may readily be utilized as a basis for the designing
of other
structures, methods and systems for carrying out the several purposes of the
present
invention. It is important, therefore, that the claims be regarded as
including such
equivalent constructions insofar as they do not depart from the spirit and
scope of the
present invention.
[0015] For a better understanding of the invention, its operating
advantages and the
specific objects attained by its uses, reference should be had to the
accompanying
drawings and descriptive matter in which there is illustrated preferred
embodiments of
the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The accompanying drawings, which are included to provide further
understanding
of the invention and are incorporated in and constitute a part of this
specification,
illustrate preferred embodiments of the invention and together with the
description serve
to explain the principles of the invention, in which:
[0017] Figure 1 is perspective view of a gear pump constructed in
accordance with the
principles of the present invention show assembled;
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[0018] Figure 2 is a top view of the gear pump schematically illustrating
a pressure
relieving system;
[0019] Figure 3 is a cross sectional view of the gear pump taken along
line 3-3 in FIG. 2;
[0020] Figure 4 is an exploded view of the gear schematically
illustrating components of
the gear pump;
[0021] Figures 5A-5C schematically illustrate embodiments of floating
dynamic seals
receivable in gear end seal mounts;
[0022] Figure 6 is an enlarged schematic view of the gear pump seal neck;
[0023] Figure 7 is an enlarged schematic, cross-sectional view of the
gear pump seal
neck taken along line 7-7 in FIG. 6, and illustrating an adjustable pump shaft
packing
seal;
[0024] Figure 8 is an enlarged schematic, cross-sectional view of the
seal neck taken
along line 8-8 in FIG. 6, and illustrating a lock assembly of the packing nut;
[0025] Figure 9 is an exploded, schematic perspective view of the seal
neck, packing nut
and packing nut lock assembly;
[0026] Figure 10 is a schematic view of a fluid pressure relief system of
the gear pump;
[0027] Figure 11 is perspective view of a modified end plate and
schematically
illustrating the fluid pressure relieving system;
[0028] Figure 12 is an enlarge, partial cross-sectional view of a gear
gap adjustment
mechanism of the gear pump;
[0029] Figure 13 is an enlarged side elevation view of a threaded plug of
the gear gap
adjustment mechanism;
[0030] Figure 14 is an enlarged end view of the threaded plug;
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[0031] Figure 15 is an enlarged cross-sectional view of the threaded plug
taken along line
15-15 in FIG. 14;
100321 Figure 16 is a schematic cross-sectional view of the gear pump
including heat
exchange features; and
[0033] Figure 17 is a schematic view of a fluid medium heat exchange
feature.
DETAILED DESCRIPTION OF THE INVENTION
[0034] Schematically illustrated In FIGS. 1-4 is a specially designed
gear pump 10 for
pumping liquids and fluids, such as oils and distillates containing entrained
contaminates
such as sand, girt and the like. The gear pump 10 is of the external gear pump
type
having a driving gear and a driven gear which are disposed within a pump
cavity of the
gear pump which mesh with each other. The two gears rotate to move a fluid
caught in
their tooth spaces from a suction side toward a discharge side, thereby
performing a
pumping action.
[0035] Gear pump 10 includes a pump housing 12 having opposite open ends
14, 15 and
a sidewall 16 extending therebetween. Sidewall 16 forms a pump cavity 18 and
includes
opposing suction/discharge ports 20 and 22 extending through the sidewall and
into the
pump cavity. A pair of end plates 24, 26 are sealingly attached to ends 14,
15,
respectively, and seal the pump cavity 18. Each end plate 24, 26 includes a
plurality of
peripherally disposed fastener mounts such as bolt holes 28 which are used to
fasten the
end plate to the pump housing 12 by bolts 30.
[0036] A pair of meshing gears 32 and 34 are disposed within the pump
cavity 18 and
extend between end plates 24, 26. Gear 32 is supported by pump shaft 36 which
is the
pump driving shaft. Gear 34 is supported by pump shaft 38 which is the pump
idler
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shaft. The gears 32, 34 are fixedly secured to driving shaft 36 and idler
shaft 38,
respectively, for conjoined rotation therewith. To eliminate undesirable play
between the
gear and shaft, and undesirable meshing between gears 32, 34 during high
torque startup,
the conventional key and keyway coupling between shaft and gear is replaced by
shrink
fitting gears 32, 34 to the driving shaft 36 and idler shaft 38, respectively.
In this manner,
gear 32 and driving shaft 36 become a unitary assembly, and gear 34 and idler
shaft 38
become a unitary assembly. The unitary gear/shaft assemblies eliminates
vibration
between the gear and shaft which serves to reduce pump noise, increase life
expectancy
of the gears, and to reduce cavity phenomena.
[0037] Gears 32, 34 are double-helical gears. The use of double-helical
gears eliminates
the problem of axial thrust on the pump shafts 36, 38 that is presented by
"single" helical
gears by having two sets of teeth that are set in a V shape. Each gear in a
double helical
gear can be thought of as two standard mirror image helical gears stacked.
This cancels
out the thrust since each half of the gear thrusts in the opposite direction.
In this manner
the use of wear plates employed to prevent end plate wear in gear pumps is
eliminated,
and thus reduces the cost of manufacture and maintenance of the gear pump.
[0038] Still referring to FIGS. 1-4, end plates 24, 26 are of a similar
construction and
each include an inward facing side 40 and an opposed outward facing side 42.
In some
aspects, end plates 24 and 26 are interchangeable, and can be mounted on
either ends 14,
15 of pump housing 12. Outward facing side 42 includes a pair of bearing cups
or
mounts 44, 46 extending outwardly therefrom. First and second shaft passages
48, 50
extend through end plate 24, 26 from the inward facing side 40 through bearing
cups 44,
46, respectively, to the outward facing side 42. Bearing cup caps 52A, 52C are
sealing
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attached to the outward facing side of end plate 24 and seal bearing cups 44,
46,
respectively. Bearing cup cap 52D is sealing attached to the outward facing
side of end
plate 28 and seals bearing cup 46. A packing neck 54 is sealing attached to
the outward
facing side 42 of end plate 28 and seals bearing cup 44. Bearing cup caps 52A,
52B and
52C can be fitted with grease zurks to permit greasing of the shaft bearing
assemblies
positioned therein.
[0039] Referring to FIGS. 3 and 4, end plate 24 includes seal disc mounts
58A and 58C
on the inward facing side 40 thereof and coaxial with shaft passages 48 and
50,
respectively. Likewise, end plate 26 includes seal disc mounts 58B and 58D on
the
inward facing side 40 thereof and coaxial with shaft passages 48 and 50,
respectively.
Seal discs 60A, 60B, 60C, and 60D are mounted to seal disc mounts 58A, 58B,
58C, and
58D, respectively, and cover the inward facing opening of the bearing cups 44,
46 of each
end plate 24, 26. In embodiments, seal disc mounts 58A, 58B, 58C, and 58D are
each a
recess formed on the inward facing side 40 of end plates 24 and 26,
respectively, into
which seal discs 60A, 60B, 60C, and 60D are received. Seal discs 60A, 60B,
60C, and
60D may be fastened to end plates 24 and 26, respectively by threaded
fasteners. In
embodiments, seal discs 60A, 60B, 60C, and 60D are flush with the inward
facing side
40 of end plates 24 and 26, respectively. Seal discs 60A, 60B, 60C, and 60D
may also be
referred to as pressure washers at they each taking loading forces from gear
end seals, as
further described below.
[0040] Still referring to FIGS. 3 and 4, end 62 of the driving shaft 36
extends through seal disc
64A and into shaft passage 48 of end plate 24 and is supported for rotation by
bearing
assembly 64A disposed in bearing cup 44. Bearing assembly 64A includes a
bushing
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66A which supports end 62 for rotation and a pair of end seals 68A and 70A
that are
disposed within recesses formed in opposing ends of bushing 66A. End seals 68A
and
70A provide sealing contact between the driving shaft 36 and bushing 64A.
Further, end
seal 68A provides a sealing contact between the bearing cup facing side of
seal disc 58A
and bushing 66A.
[0041] The opposite end 72 of driving shaft 36 extends through seal disc 64C,
shaft passage 48
of end plate 26 and through packing neck 54. End 72 is supported for rotation
by bearing
assembly 64C disposed in bearing cup 44. Bearing assembly 64C includes a
bushing
66C which supports end 72 for rotation and a pair of end seals 68C and 70C
that are
disposed within recesses formed in opposing ends of bushing 66C. End seals 68C
and
70C provide sealing contact between the driving shaft 36 and bushing 66C.
Further, end
seal 68C provides a sealing contact between the bearing cup facing side of
seal disc 58C
and bushing 66C.
[0042] Likewise, end 74 of idler shaft 38 extends through seal disc 58B
and into shaft
passage 50 of end plate 24, and is supported for rotation by bearing assembly
648
disposed in bearing cup 46. Bearing assembly 64B includes a bushing 66B which
supports end 74 for rotation and a pair of end seals 68B and 70B that are
disposed within
recesses formed in opposing ends of bushing 66B. End seals 68B and 70B provide
sealing contact between the idler shaft 38 and bushing 66B. Further, end seal
68B
provides a sealing contact between the bearing cup facing side of seal disc
58B and
bushing 66B
[0043] The opposite end 76 of idler shaft 38 extends through seal disc
58D and into shaft
passage 50 of end plate 26, and is supported for rotation by bearing assembly
64D
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disposed in bearing cup 48. Bearing assembly 64D includes a bushing 66D which
supports end 76 for rotation and a pair of end seals 68D and 70D that are
disposed within
recesses formed in opposing ends of bushing 66D. End seals 68D and 70D provide
sealing contact between the idler shaft 38 and bushing 66D. Further, end seal
68D
provides a sealing contact between the bearing cup facing side of seal disc
58D and
bushing 66D.
[0044] Still referring to FIGS. 3 and 4, gear end seal 78A is disposed
about driving shaft
36 and between the inward facing side of seal disc 58A and end 80 of gear 32.
Gear end
seal 78A provides a sealing contact between end 80 of gear 32 and the inward
facing side
of seal disc 58A. Gear end seal 78A is mounted to gear end mount 82A on end 80
of
gear 32. Gear end seal 78C is disposed about driving shaft 36 and between the
inward
facing side of seal disc 58C and end 84 of gear 32. Gear end seal 78C provides
a sealing
contact between end 84 of gear 32 and the inward facing side of seal disc 58C.
Gear end
mounts 82A and 82C are recesses in ends 80 and 84, respectively which gear end
seals
78A and 78C are disposed.
[0045] Gear end seal 78B is disposed about idler shaft 38 and between the
inward facing
side of seal disc 58C and end 86 of gear 34. Gear end seal 78B provides a
sealing contact
between end 86 of gear 34 and the inward facing side of seal disc 58B. Gear
end seal
78B is mounted to gear end mount 82B on end 88 of gear 34. Gear end seal 78D
is
disposed about idler shaft 38 and between the inward facing side of seal disc
58D and end
88 of gear 34. Gear end seal 78D provides a sealing contact between end 88 of
gear 34
and the inward facing side of seal disc 58D. Gear end mounts 82B and 82D are
recesses
in ends 86 and 88, respectively which gear end seals 78B and 78D are disposed.
In
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embodiments, gear end seals 78A, 78B, 78C and 78D are floating seals. However,
it is
contemplated the floating seals could be replaced with non-floating seals and
provide a
sealing contact as intended.
[0046] Fluids from the pump cavity 18 are kept from contact with bearing
assembly 64A
by means of end seal 68A, seal disc 58A and gear end seal 78A, from bearing
assembly
64B by means of end seal 68B, seal disc 58B and gear end seal 78B, from
bearing
assembly 64C by means of end seal 68C, seal disc 58C and gear end seal 78C,
and from
bearing assembly 64D by means of end seal 68D, seal disc 58D and gear end seal
78D.
To this end, debris entrained in the pumped fluid are prevented from contact
with bearing
assemblies 64A, 64B, 64C and 64D, and thus extending the service life thereof.
[0047] With reference to FIGS 5A, 5B and 5C, a plurality of embodiments
of gear end
seals 78A-78D are shown. In FIG. 5A, there is shown an elastic frontal
labyrinth seal. In
FIG. 5B, there is shown a frontal labyrinth seal with 0-ring as elastic
element. In FIG.
5C, there is shown a frontal labyrinth seal with wave spring as elastic
element.
[0048] Schematically depicted in FIGS. 6 ¨9, is gear pump 10 having an
adjustable
driving shaft packing seal assembly 100. Packing seals are conventional used
to prevent
fluid that is being pumped from leaking through the exposed interface between
the
protruding pump shaft and the pump housing. As the packing seal becomes worn,
the
seal begins to fail and leak. Heretofore, the only solution to a worn, leaking
packing seal
is to shutdown the pump to allow the disassembly and the replacement of the
worn
packing seal components. The assembly 100, embodied herein, permits an
operator to
adjust the packing seal as it becomes worn in order to extend the service life
of the
packing seal without requiring the pump to be shutdown.
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[0049] Seal neck 54 comprises a body 102 having opposed ends 104 and 106,
and a
longitudinal shaft passage 108 extending through ends 104 and 106. End 104 is
adapted
to be mounted to bearing cup 44 with driving shaft 36 extending through shaft
passage
108 and beyond end 106 with end 72 protruding externally to permit operable
coupling of
the driving shaft to a source of rotational power, such as an engine or motor.
A pair of
bushings 110 and 112 are disposed within shaft passage 108 about driving shaft
36 and
provide rotational support to the driving shaft. A packing seal 114, such as a
Teflon rope,
is interdisposed between bushings 110 and 112 about drive shaft 36, and
provides a seal
interface between driving shaft 36 and shaft passage 108. A packing nut 110 is
threaded
onto end 106 of seal neck 54 with driving shaft 36 extending through shaft
bore 116.
[0050] Bushing 110 is disposed in shaft passage 102 with end 118 thereof
abutting
against shoulder surface 120 of shaft passage 102 and with the opposite end
122 engaged
with end 124 the packing seal 114. End 124 may be inwardly chamfered to
provide a
seat into which end 124 of the packing seal is received. Busing 112 is
disposed in shaft
passage 102 with end 126 thereof extending beyond end 106 of seal neck 54 and
engaged
with surface 128 of the pack nut 110. The opposite end 130 of bushing 112 is
engaged
with end 132 of packing seal 114. End 130 may be inwardly chamfered to provide
a seat
into which end 132 of the packing seal 114 is received. Threading packing nut
110 onto
seal neck 54 causes bushings 110 and 112 to compress packing seal 114 between
ends
118 and 130 of bushings 110 and 112, respectively, and creates a sealing
contact between
driving shaft 36 and shaft passage 108.
[0051] The assembly 100 further includes a packing nut lock 140 that
operates to either
preclude the turning of packing nut 110 when moved into one position or to
permit the
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turning of packing nut when moved into another position. As best seen in FIGS
7 and 8,
the packing nut lock 140 includes a collar 142 fitted about packing nut body
144. Collar
142 is secured to body 144 for axial rotation about packing nut body by a pair
of pins 146
and 148 that are inserted through holes 150 and 152, respectively, of collar
142 and at
least partially into slots 154 and 156, respectively, of packing nut body 144,
as best seen
in FIG. 8. In this manner, the collar 142 is limited to a few degrees of
rotation about
packing nut body 144 between a first position and a second position. The
assembly of
collar 142 with packing nut body 144 captivity retains a pair of check balls
158 and 160
in holes 162 and 164, respectively, of the packing nut body 144 by the inner
surface 146
of the collar. A plurality of flat lands 170 are circumferentially located on
the exterior
surface of the seal neck 54.
[0052] When collar 142 is rotated into the first or ON position, as shown
in FIG. 8,
cavities 166 and 168, formed on the interior surface of collar 142, are
registered with
holes 162 and 164. This registration permits check ball 158 to be partially
received by
cavity 166 and check ball 160 to be partially received by cavity 168. In this
manner,
packing nut 110 is permitted to be rotated about seal neck 54 with check balls
158 and
160 floating over lands 170. When collar 142 is rotated into the second or OFF
position,
cavities 166 and 168 are moved out of registration with holes 162 and 164, and
the inner
surface 146 presses check balls 158 and 160 against a flat land 170, as shown
in FIG. 8 in
dashed line. In this manner, packing nut 110 is precluded from rotating about
seal neck
54, and therefore, is locked.
[0053] In operation, as packing seal 118 becomes worn and leaks, an
operator may
further compress the packing seal 118 to tighten the seal between the shaft
passage 108
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and the driving shaft 36 to preclude the leaking without shutting down the
operation of
the pump. The packing seal 118 is further compressed by rotating collar 142
into the ON
position and then rotating the packing nut 110 further onto the seal neck 54.
Once fluid
stops leaking, collar 142 is rotated into the OFF position, thereby locking
the threaded
position of the packing nut 110 on the seal neck.
[0054] Schematically depicted in FIGS. 2 and 10, is gear pump 10 having
pressure relief
system to vent fluid pressure that may occur at end 62 of driving shaft 36 to
prevent axial
forces along driving shaft and avoiding end plate wear. The pressure relief
system
includes first and second fluid passages 200 and 202, each in fluid
communication with
fluid located at end 62 of the driving shaft 36. The first passage 200 is
further in fluid
communication with suction/discharge port 20, and the second passage 202 is
further in
fluid communication with suction/discharge port 22. A check valve 206 and
needle valve
208 are positioned across the first passage 200 and a check valve 210 and
needle valve
212 are positioned across the second passage 202. Check valves 206 and 210
operate to
permit fluid to follow through passages 200 and 202, respectively, only in the
direction
towards suction/discharge ports 20 and 22. Needle valves 208 and 212 are each
adjusted
to permit fluid flow through passages 200 and 202, respectively, when fluid at
end 62 of
the driving shaft 36 is at a threshold pressure. In FIG. 11, end plate 24 is
schematically
depicted including ports 214 and 216 for connection with fluid passages 200
and 202
with suction/discharge ports 20 and 22, respectively. Needle valves 208 and
212 are
optional. Additionally, while the pressure relief system is illustrated and
described with
reference only to end 62 of driving shaft 36, the pressure relief system can
be employed
to release pressure at the ends of any of the pump shafts.
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[0055] Schematically depicted in FIGS. 12 ¨ 15, is gear pump 10 having a
gear gap
control mechanism 300 to adjust the meshing of gears 32 and 34 by axially
displacing
driving shaft 36. In this embodiment, bearing cup cap 52A is replaced by
bearing cup
cap 52A' and end 62 of driving shaft 36 has been milled to include axial bore
302.
Mechanism 300 further includes a plug member 304 threadably received by bore
306 that
extends through end plate 24 along longitudinal axis 307 of driving shaft 36.
Inward end
308 of plug 304 includes bore 310 into which is disposed is cup member 312.
Ball 314 is
interdisposed between end 62 of the driving shaft 36 and cup member 312, and
is
partially seated within cup member 312 and axial bore 302. Ball 314 provides a
dynamic
bearing interface between cup member 312 and end 62 of the driving shaft 36.
Threading
plug 304 into bore 306 causes ball 314 to urge against end 62 of the driving
shaft 36.
Further threading of plug 304 into bore 306 results in a longitudinal
displacement of
driving shaft 36 along axis 306, and thus moves the longitudinal position of
gear 32
relative to the longitudinal position of gear 34. The threaded position of
plug 304 can be
adjusted to control relative longitudinal positions of gears 32 and 34, and
thus the gap
between the gear teeth. The threaded position of plug 304 can be locked in
place by a
screw or threaded pin 316 threadably received within bore 318 that extends
normal to
bore 306. Threading pin 316 into bore 318 caused end 320 of the pin to be
received by
one of a plurality of circumferentially spaced and longitudinally extending
grooves 322
on the exterior of plug barrel 324, and thus locking plug 304 from rotation
within bore
306. An 0-ring seal 326 can provide a sealing interface between bore 306 and
plug 304.
Additionally, while the gap control is illustrated and described with
reference only to end
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62 of driving shaft 36, the gap control can be employed at the ends of any of
the pump
shafts.
[0056] Schematically depicted in FIGS. 16 and 17, is gear pump 10 having
one or more
heat exchange features to either cool the gear pump in hot climates or heat
the gear pump
in cold climates. In one aspect, a heat exchanger body 402 is mounted to the
exterior of
the pump housing 12, for example by welding. One or more electric heating
elements
404 are disposed within body 402 that are operably connected to a source of
electrical
power (not shown) by leads 405. When operating, electric heating elements 404
output
radiant heat that is transmitted into the pump casing 12 and heating the
components of
the pump 10 to prevent lockup due operating in cold climates. In another
aspect, a heat
exchanger body 406 is mounted to the exterior of the pump housing 12, for
example by
welding. Body 406 include an internal serpentine fluid flow passage 407
extending
between inlet and out let ports 408 and 410. Ports 408 and 410 are fitted with
couplings
412 that permit the flow passage 407 to be fluidically connected to an engine
cooling
system (not shown) to receive the flow of antifreeze or other heat exchanging
fluid
medium 414 from the engine cooling system. The flow of fluid through flow
passage
407 heats or cools the pump housing 12 and thus the pump components to prevent
lockup
due to freezing weather or from over heating.
17
