Note: Descriptions are shown in the official language in which they were submitted.
CA 02549264 2011-06-13
TWO STAGE GREASE GUN
BACKGROUND OF THE INVENTION
[0002) The present -invention pertains to portable grease guns, whether
manually operated
or driven by air power or by electric batteries. Typical hand operated grease
guns include a piston
which forces grease from a nozzle, the grease being fed to the compression
chamber from an
attached mounted barrel containing bulk grease ors grease cartridge. Most
existing grease guns
provide only one output pressure of the grease expressed from the gun.
[0003] Frequently the user of a grease gun encounters a grease zerk which will
not accept
grease because it is seized or clogged. In that case, little can be done
without replacing the zerk to
correct the problem. One prior art grease gun requires changing position of
the handle to adjust the
mechanical advantage. This device cannot provide the 5:1 ratio pressure
increase needed to
overcome a resistant zerk, Another prior art grease gun uses a complex
labyrinth and a mechanical
switch to engage or disengage a ball check valve to vary pressure of grease
exiting the grease gun.
This device does not permit supply to the grease gun from an attached barrel
and therefore the
portability and versatility of the device is limited.
[0004] The foregoing problems are addressed by the present two stage grease
gun
invention.
BRIEF SUMMARY OF THE INVENTION
[0005] A portable grease gun is provided with a dual pressure output
capability which can
be selectively changed by the user with little effort. The grease gun includes
a plunger assembly
which includes a larger diameter volume plunger which is selectively coupled
longitudinally to a
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plunger extension by screw threads. The length of the volume plunger with the
plunger extension
attached may be varied by inserting the extension into the bore of the volume
plunger a greater or
lesser amount. This. is accomplished by rotating the plunger extension
relative to the volume
plunger thereby moving the coupled end of the plunger extension in and out of
the screw threads
within the bore of the volume plunger. The volume plunger and its plunger
extension are received
in a longitudinal passageway of a plunger retainer which limits the
longitudinal movement of the
volume plunger, and prevents rotational movement of the volume plunger
relative to the plunger
retainer. A smaller diameter pressure plunger is slidable within the bore
through the volume
plunger and the attached plunger extension. The plunger assembly is
longitudinally received within
a bore of the grease gun body.
100061 An actuating lever is pivotal upon the grease gun body which includes
the plunger
assembly within the longitudinal bore through the body. The lever includes a
push block which
abuts the plunger assembly to urge the pressure plunger and selectively the
volume plunger toward
the output orifice of the grease gun.
100071 The desired pressure of the grease expelled from the grease gun body is
controlled
by selective rotation of the plunger extension to shorten or extend the
effective length of the volume
plunger and plunger extension combination, When the plunger extension is
maximally received
into the bore of the volume plunger, the volume plunger is prevented from
longitudinal travel_
However, the smaller diameter pressure plunger may slide along the bores of
the volume plunger
and the plunger extension, traveling into the compression chamber to
pressurize grease at a high
pressure and low volume. When the plunger extension is minimally received
within the bore of the
volume plunger, the effeciive length of the volume plunger and plunger
extension combination is
increased, allowing the volume plunger to be moved into the compression
chamber when the push
block of the actuating lever applies force to the end of the pressure plunger
and the plunger
extension, causing both the volume plunger and the pressure plunger to move in
concert.
100081 When the plunger extension is moved to an intermediate insertion within
the bore of
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the volume plunger, the actuation of the lever will first cause movement of
the pressure plunger
alone, providing a high pressure grease delivery during the first part of the
stroke of the actuating
lever and subsequently a low pressure grease delivery'when the push block
begins to abut the
plunger extension and the pressure plunger together, thereby urging both the
pressure plunger and
the volume pressure together toward the output body of the grease gun. The
grease gun can
therefore be used to apply high pressure grease to a resistant zcrk during the
first part of the stroke
of the actuating lever and then to deliver high volume grease at low pressure
after the resistance of
the zerk is overcome.
100091 It is a primary object of the invention to provide a portable grease
gun which can be
adjusted to deliver grease at high pressure and low volume or at low pressure
and high volume. It
is a further object of the invention to provide a portable grease gun which
can be adjusted to
overcome a clogged or seized zerk and then to inject grease into the corrected
zerk at lower
pressure and higher volume. It is also an object of the invention to provide a
grease gun which is
easily adjusted for pressure output by the user without tools. It is an
additional object of the
invention to provide an easily manufactured grease gun which will expel grease
at more than one
pressure.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE IDRAWING(S)
NMI FIG. 1 is an exploded view in perspective of a preferred embodiment grease
gun
according to the present invention.
100111 FIG. 2 is a cross section of the preferred embodiment of the invention
shown with
the actuating lever fully retracted and with the plunger assembly adjusted for
delivery of grease at
high pressure and low volume as the actuating lever is moved toward the
handle.
100121 FIG. 3 is a cross section of the preferred embodiment of the grease gun
adjusted as
in Fig. 2 but with the actuating lever abutted to the handle of the grease gun
and the pressure
plunger advanced to the outlet check valve.
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[00131 FIG. 4 is a cross section of the preferred embodiment of the invention
shown with
the actuating lever fully retracted and with the plunger assembly adjusted for
delivery of grease at
low pressure and high volume as the actuating lever is moved toward the
handle.
100141 FIG. 5 is a cross section of the preferred embodiment of the grease gun
adjusted as
in Fig. 4, but with the actuating lever abutted to the handle of the grease
gun and with both the
pressure plunger and the volume plunger fully advanced into the compression
chamber of the
grease gun.
100151 FIG. 6 is a cross section of the preferred embodiment of the invention
shown with
the actuating lever fully retracted and with the plunger assembly adjusted for
delivery of grease at
high pressure during the beginning portion of the stroke of the actuating
lever and at low pressure
during the remainder of the stroke.
100161 FIG. 7 is a cross section of the preferred embodiment of the grease gun
adjusted as
in Figure 6 with the actuating lever actuated part way such that the high
pressure portion of the
stroke is completed and the plunger assembly is in position for delivery of
grease at high volume
and low pressure for the remainder of the stroke of the actuating lever toward
the handle.
[0017[ FIG. 8 is a cross section of the preferred embodiment of the grease gun
adjusted as
in Figure 6 with the actuating lever shown abutted to the handle with the
pressure plunger
advanced maximally into the compression chamber and with the volume plunger
advanced partially
into the compression chamber.
DETAILED DESCRIPTION OF THE INVENTION
[00181 Reference is drawn to Figs. 1-8 and specifically to Fig. 1, initially.
Fig. I
discloses a grease gun body 1 according to the present invention with the
plunger assembly 27
thereof shown in exploded view. Plunger assembly 27 is received within
longitudinal bore 28 of
grease gun body 1. Plunger assembly 27 comprises a volume plunger 3 which is
slidably received
within an elongate hollow cylindrical plunger retainer 9. Plunger retainer 9
is provided with an
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opening 29 on its sidewall 30 into which guide pin 17 is received. Volume
plunger 3 includes an
elongate slot 31 into which guide pin 17 may extend such that volume plunger 3
is prevented from
rotation relative to plunger retainer 9, while remaining free to move
longitudinally within plunger
retainer 9 over a range limited by a stop within plunger retainer 9.
[0019] 0-ring 23 and backup ring 25 are received on inner end 32 of plunger
retainer 9.
Opposing outer end 33 of plunger retainer 9 is threaded to be received in
threaded bore 28. Slots
56 are provided on outer end 33 to aid threading plunger retainer 9 into bore
28.
(0020] Plunger extension 11 is received in longitudinal bore 36 of plunger
retainer 9 and is
coaxially retained to volume plunger 3. at a selected depth, by selective
insertion of inner end 34 of
plunger extension 11 into passageway 35 of volume plunger 3. Threads 55 on
inner end 34 of
plunger extension I J mate with internal threads 54 within passageway 35 of
volume plunger 3.
Plunger extension 11 with volume plunger 3 attached coaxially thereto is
biased toward push block
4 by volume plunger spring 12. Bearing ring 18 provides a sliding surface
between shoulder 53 of
plunger extension 11 and volume plunger spring 12.
100211 By rotating plunger extension 11 clockwise or counterclockwise, the
effective
length of the coaxially connected plunger extension 11 and volume plunger 3
may be selected.
Thumb wheel 48 on plunger extension 11 facilitates rotation thereof by the
user.
[0022] Pressure plunger 2 is slidably received within the longitudinal bore 37
of plunger
extension 11 and the longitudinal passageway 35 of volume plunger 3 and is
biased toward push
block 4 by pressure plunger spring 13. Pressure plunger 2 comprises inner end
41 from which
extends needle 42 having pressure face 43 on free end 44 thereof.
100231 Volume plunger 3 is slidable over a limited range within the
longitudinal bore 36 of
plunger retainer 9. Guide pin 17 is received in sidewall 30 of plunger
retainer 9 and rides in slot
31 of volume plunger 3.
[0024] The range of longitudinal retroactive movement of volume plunger 3 is
limited by
an internal stop 57 (see Fig. 6) spaced apart from inner end 32 of plunger
retainer 9. Volume
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plunger 3 comprises a counterbore 50 extending from outer end 49 part way
therethrough.
Counterbore 50 accommodates inner end 34 of plunger extension 11 while the
remainder of
passageway 35 is reduced in size to accommodate body 38 of pressure plunger 2
for sliding
movement therealong.
(0025] To reach into and be slidable within passageway 35 of volume plunger 3,
pressure
plunger must pass along bore 37 of plunger extension 11. Pressure plunger
spring 13 biases head
39 of pressure plunger 2 longitudinally outward along bore 37 while volume
plunger spring 12
biases the interconnected plunger extension I I and volume plunger 3
longitudinally outwardly
along bore 36. Inward longitudinal travel of volume plunger 3 is limited by
contact of the thumb
wheel 48 against outer end 33 of plunger retainer 9.
(0026J Referring now to Figs. 2 and 3, grease gun 26 further comprises an
actuating lever
pivotally retained to grease gun body 1 by hinge pin 46. Push block 4 is
retained to actuating
lever 5 by spring pin 10 allowing push block 4 to rotate about spring pin 10
in order to maintain a
flat surface against outer end face 40 of pressure plunger 2.
[0027) Handle 8 depends from grease gun body I at an approximate perpendicular
to the
longitudinal axis of grease gun body 1. Output body 6, which may be a noz2le,
is received within
longitudinal bore 28 grease gun body t at output end 22 and includes an output
check ball 20
biased by output spring 15 which is retained in output body 6 by output check
screw 16.
[00281 Grease gun body I further comprises a barrel mount 47 which houses
inlet valve
body 7. which includes valve spring 14 which biases inlet check ball 21. A
barrel 24 may be
selectively mounted to grease gun body I at barrel mount 47, Grease gun 26 is
shown with the
inner end 34 of plunger extension 11 substantially fully inserted into
counterborc 50 of volume
plunger 3. In this condition, grease gun 26 is adjusted to deliver grease at a
high pressure.
100291 In Fig. 2, the grease gun 26 as shown is ready to begin to expel grease
from
compression chamber 45 through output body 6 at high pressure, that is, in the
range of about
10,000 psi. Actuating lover 5 has been retracted from handle 8 allowing
pressure plunger spring
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13 to urge pressure plunger 2 to follow push block 4 as it retreats from
grease gun body I as it is
carried on spring pin 10 on actuating lever 5. Volume plunger 3 is maximally
retracted from
compression chamber 45 while needle 42 of pressure plunger 2 remains partially
within
compression chamber 45. Compression chamber 45 may be filled with grease which
passes inlet
check ball 21 from barrel 24-
100301 Fig. 3 discloses the position of the plunger elements after actuating
lever 5 has been
moved back to rest against handle & Volume plunger 3 remains in the same
position as in Fig. Z
while pressure plunger 2 has further protruded into compression chamber 45
with needle 42
thereof inserted within the output duct 51 thereby forcing grease from
compression chamber 45
past outlet check ball 20. The force upon outer end face 40 of pressure
plunger 2 exerted by push
block 4 compresses pressure plunger spring 13.
100311 Referring now to Figs. 4 and 5, grease gun 26 is illustrated in
condition to expel a
large volume of grease at a low pressure- Fig. 4 shows the location of
pressure plunger 2 and
volume plunger 3 when actuating lever 5 is maximally retracted from handle S.
In the condition of
grease gun 26 in Figs. 4 and 5, plunger extension II has been retracted from
counterbore 50 of
volume plunger 3 by selective rotation of plunger extension 11 by manipulation
of thumb wheel 48
thereof effectively unscrewing inner end 34 of plunger extension 11 from
counterbore 50. This
effectively extends the length of the combined volume plunger 3 and plunger
extension 1I,
allowing outer end 52 of plunger extension 11 to extend from longitudinal bore
28 and from
plunger retainer 9. As should be understood, as actuating lever 5 starts to
move toward handle 8,
push block 4 forces both pressure plunger 2 and volume plunger 3 toward output
body 6 across
compression chamber 45. This movement causes volume plunger 3 combined with
pressure
plunger 2 to force a large volume of grease at low pressure past output check
bal120 against output
spring I5.
(00321 After actuating lever 5 has been fully rotated into abutment on handle
8, as shown
in Fig. 5, volume plunger 3 as well as pressure plunger 2 have traversed
compression chamber 45
a
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toward output duct 51 causing low pressure grease to pass along output duct 51
and pass output
check ball 20 of output body 6.
[00331 Figs. 6.8 illustrate the adjusted position of grease gun 26 in which
plunger
extension 1 I is mounted to volume plunger 3 midway into counterbore 50
thereof. By selective
rotation of plunger extension 11 by manipulation of thumb wheel 48, inner end
34 may be moved
into an intermediate position along counterbore 50 of volume plunger 3. In
this position grease
gun 26 is capable of delivering grease at high pressure or at high volume
depending on the extent
of retraction of the actuating lever 5. Specifically, in Fig. 6, actuating
lever 5 is shown fully
retracted such that grease gun 26 is ready to expel grease at high pressure,
such as when a resistant
zerk must be overcome. Volume plunger 3 is stationed at a rest position
determined by the
retractive urging created by volume plunger spring 12 as limited by internal
stop 57 of plunger
retainer 9. Pressure plunger 2 is retracted from output body 6 by the urging
of pressure plunger
spring 13 but such retraction is limited by the abutment of head 39 thereof
against push block 4.
100341 As seen in Fig. 7, as actuating lever 5 has moved from a fully
retracted position
partway toward handle 8, pressure plunger 2 has been urged into compression
chamber 45 while
volume plunger 3 has remained in its rest position as seen in Fig. 6. As
needle 42 of pressure
plunger traverses compression chamber 45, grease therein is forced at high
pressure past output
check ball 20 to be expelled into a zerk (not shown) which would be inserted
into a coupler and
extension (not shown) attached to output body 6 proximal to output check screw
16. Therefore,
high pressure grease could be forced into a resistant zerk to overcome its
clog or seizure. From the
position of actuating lever 5 seen in Fig. 7, grease gun 26 is in condition to
deliver grease at low
pressure as actuating lever 5 continues to be moved toward handle 8.
[00351 Fig. 8 illustrates the position of volume plunger 3 and pressure
plunger 2 after
actuating lever 5 has completed its travel and come into abutment with handle
8. Volume plunger 3
has advanced substantially into compression chamber 45 coincident with
movement of pressure
plunger 2, with plunger assembly 27 propelling grease from compression chamber
45 through
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output body 6 at high volume and low pressure.
100361 Therefore it should be understood that grease gun 26 may be adjusted to
deliver
grease at high pressure and low volume when inner end 34 of plunger extension
I 1 is maximally
inserted into counterbore 50 of volume plunger 3. However, when inner end 34
of plunger
extension I1 is minimally inserted into counterbore 50 of volume plunger 3.
grease gun 26 will
expel grease at low pressure and high volume. Furthermore, plunger assembly 27
may be adjusted
such that a first portion of the stroke of actuating lever 5 from its fully
retracted position will
deliver grease at high pressure while a remaining portion of the stroke of the
actuating lever 5 will
deliver grease at low pressure. This adjustment is made by varying the depth
of insertion of inner
end 34 of plunger extension 11 into counterbore 50 of volume plunger. By
selective adjustment,
the proportion of stroke of the actuating lever 5 which causes the grease gun
26 to deliver high
pressure grease may be varied, that is, the shorter the effective length of
the combination of the
volume plunger 3 and the plunger extension 11, the larger (he proportion of
stroke of the actuating
lever 5 from its fully retracted position which will deliver high pressure
grease from grease gun 26.
As the effective length of the volume plunger 3 and plunger extension 11
increases, the smaller the
proportion of the stroke of actuating lever 5 from full retraction will be
which causes the grease
gun 26 to deliver high pressure grease, with the remainder of the compression
stroke of actuating
lever 5 toward handle 8 causing low pressure grease to be expelled from grease
gun 26.
