U.S. patent application number 13/837147 was filed with the patent office on 2014-09-18 for variable orifice outlet assembly.
This patent application is currently assigned to GRACO MINNESOTA INC.. The applicant listed for this patent is GRACO MINNESOTA INC.. Invention is credited to Mark J. Brudevold, Shaun M. Cook, Douglas B. Farrow, John S. Lihwa, Robert J. Lind, Nicholas D. Long, Paul R. Quam, Daniel P. Ross, Michael J. Sebion, Mark W. Sheahan, Joseph E. Tix, Mark T. Weinberger.
Application Number | 20140263451 13/837147 |
Document ID | / |
Family ID | 51523032 |
Filed Date | 2014-09-18 |
United States Patent
Application |
20140263451 |
Kind Code |
A1 |
Ross; Daniel P. ; et
al. |
September 18, 2014 |
VARIABLE ORIFICE OUTLET ASSEMBLY
Abstract
A pumping system comprises a pump, first and second channels, a
valve, and an actuator. The pump pumps fluid according to a pumping
cycle. The first channel has a first fluid flow orifice with a
first diameter, while the second channel has a second fluid flow
orifice with a second diameter greater than the first diameter. The
valve is configured to direct fluid from the pump to the first
channel in a first state, and to the second channel in a second
state. The actuator is configured to switch the valve into the
first state during a high pressure period of the pumping cycle, and
into the second state during a low pressure period of the pumping
cycle.
Inventors: |
Ross; Daniel P.; (Maplewood,
MN) ; Quam; Paul R.; (Brooklyn Center, MN) ;
Lind; Robert J.; (Robbinsdale, MN) ; Farrow; Douglas
B.; (Plymouth, MN) ; Lihwa; John S.;
(Willowick, OH) ; Tix; Joseph E.; (Hastings,
MN) ; Brudevold; Mark J.; (Fridley, MN) ;
Weinberger; Mark T.; (Mounds View, MN) ; Sheahan;
Mark W.; (Inver Grove Heights, MN) ; Cook; Shaun
M.; (Tampa, FL) ; Long; Nicholas D.;
(Broadview Heights, OH) ; Sebion; Michael J.;
(Apple Valley, MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GRACO MINNESOTA INC. |
Minneapolis |
MN |
US |
|
|
Assignee: |
GRACO MINNESOTA INC.
Minneapolis
MN
|
Family ID: |
51523032 |
Appl. No.: |
13/837147 |
Filed: |
March 15, 2013 |
Current U.S.
Class: |
222/146.2 ;
417/248; 417/28; 417/504; 417/53 |
Current CPC
Class: |
F04B 53/16 20130101;
F04B 49/22 20130101; F04B 5/02 20130101; F04B 15/04 20130101; F04B
15/02 20130101 |
Class at
Publication: |
222/146.2 ;
417/504; 417/28; 417/248; 417/53 |
International
Class: |
F04B 49/22 20060101
F04B049/22; F04B 15/04 20060101 F04B015/04; F04B 5/02 20060101
F04B005/02 |
Claims
1. A pumping system comprising: an pump that pumps a fluid
according to a pumping cycle; a first passage with a first orifice
having a first diameter; a second passage with a second orifice
having a second diameter greater than the first diameter; a valve
configured to direct the fluid from the pump to the first passage
in a first state, and to the second passage in a second state; and
an actuator configured to switch the valve into the first state
during a high pressure period of the pumping cycle, and into the
second state during a low pressure period of the pumping cycle.
2. The pumping system of claim 1, wherein the first orifice is
disposed through a first removable plug in the first passage, and
the second orifice is disposed through a second removable plug in
the second passage.
3. The pumping system of claim 1, wherein the actuator comprises an
electronic switch.
4. The pumping system of claim 3, wherein the electronic switch
actuates the valve in response to sensed pressure readings from the
pump.
5. The pumping system of claim 3, further comprising: a pump motor
configured to drive the pump; and a controller configured to
control the pump motor and the electronic switch according to the
pumping cycle.
6. The pumping system of claim 1, wherein the actuator comprises a
hydraulic switch.
7. The pumping system of claim 6, wherein the hydraulic switch is
controlled by a hydraulic pilot line driven by changes in pressure
in the pump.
8. The pumping system of claim 1, wherein the pump is a
double-action piston pump.
9. An adhesive system comprising: a melt system for melting
adhesive; a pump disposed to pump the adhesive from the melt system
according to a pumping cycle; a dispenser configured to receive and
dispense the adhesive from the pump; and an outlet assembly
disposed between the pump and the dispenser to smooth melted
adhesive pressure at the dispenser by routing the adhesive through
a first diameter orifice during a first portion of the pumping
cycle, and through a second diameter orifice during a second
portion of the pumping cycle.
10. The adhesive system of claim 9, wherein the first diameter
orifice has a narrower diameter than the second diameter orifice,
and wherein the outlet assembly further comprises a valve disposed
to route the adhesive through the second diameter orifice during
changeover of the pump, and through the first diameter orifice
otherwise.
11. The adhesive system of claim 10, wherein the valve is a shuttle
valve.
12. The adhesive system of claim 10, wherein at least one of the
first and second diameter orifices is situated in a removable
plug.
13. The adhesive system of claim 9, further comprising a supply
hose configured to carry adhesive from the outlet assembly to the
dispenser.
14. An outlet assembly for a pump, the outlet assembly comprising:
an inlet plenum disposed to receive fluid from the pump; an outlet
plenum disposed to supply fluid to a downstream component; a first
orifice fluidly disposed between the inlet and outlet plena, and
having a first orifice diameter; a second orifice fluidly disposed
between the inlet and outlet plena, and having a second orifice
diameter greater than the first orifice diameter; a valve with two
valve states: a first valve state routing fluid from the inlet
plenum to the outlet plenum via the first orifice; and a second
valve state routing fluid from the inlet plenum to the outlet
plenum via the second orifice; and an actuator configured to switch
the valve from the first valve state to the second valve state
during changeover of the pump.
15. The outlet assembly of claim 14, wherein the first orifice is
situated in a first passage connecting the inlet and outlet plena,
and the second orifice is situated in a second passage connecting
the inlet and outlet plena.
16. The outlet assembly of claim 15, wherein the valve is a shuttle
valve disposed to open the inlet plenum to either the first passage
or the second passage.
17. The outlet assembly of claim 14, wherein the downstream
component is a fluid dispenser.
18. The outlet assembly of claim 14, wherein the fluid is hot melt
adhesive.
19. A method for controlling outlet pressure of a pump having a
pumping cycle, the method comprising: directing fluid through a
first orifice during a high pressure period of the pumping cycle
corresponding to a sustained pump stroke; and directing fluid
through a second orifice wider than the first orifice during a low
pressure period of the pumping cycle corresponding to pump
changeover.
20. The method of claim 19, wherein: directing fluid through the
first orifice comprises switching a valve to a first valve state
that fluidly connects the pump to the first orifice; and directing
fluid through the second orifice comprises switching the valve to a
second valve state that fluidly connects the pump to the second
orifice.
21. The method of claim 20, further comprising actuating the valve
based on pressure in the pump.
Description
BACKGROUND
[0001] The present disclosure relates generally to systems for
dispensing hot melt adhesive. More particularly, the present
disclosure relates to a pump outlet assembly for pressure
control.
[0002] Hot melt dispensing systems are typically used in
manufacturing assembly lines to automatically disperse an adhesive
used in the construction of packaging materials such as boxes,
cartons and the like. Hot melt dispensing systems conventionally
comprise a material tank, heating elements, a pump, and a
dispenser. Solid polymer pellets are melted in the tank using a
heating element before being supplied to the dispenser by the
pump.
[0003] It is desirable in many hot melt applications that adhesive
be dispensed at a substantially constant rate so as to provide a
uniform layer of adhesive. Accordingly, conventional hot melt
systems often use heated supply systems wherein the pump and
dispenser are connected by a heated hose. The pump (typically a
linear displacement piston pump with a single reciprocating piston)
discharges melted adhesive from the tank with pressure that varies
over the course of each pumping cycle. The hose carries melted
adhesive from the pump to the dispenser, and acts as a fluid
accumulator or pressure dampener to alleviate changes in pressure
over the course of the pumping cycle of the pump.
SUMMARY
[0004] According to one embodiment of the present invention, a
pumping system comprises a pump, first and second channels, a
valve, and an actuator. The pump pumps fluid according to a pumping
cycle. The first channel has a first fluid flow orifice with a
first diameter, while the second channel has a second fluid flow
orifice with a second diameter greater than the first diameter. The
valve is configured to direct fluid from the pump to the first
channel in a first state, and to the second channel in a second
state. The actuator is configured to switch the valve into the
first state during a high pressure period of the pumping cycle, and
into the second state during a low pressure period of the pumping
cycle.
[0005] According to a second embodiment of the present invention,
an adhesive system comprises a melt system, a pump, a dispenser,
and an outlet assembly. The melt system melts adhesive, and the
pump pumps the adhesive from the melt system according to a pumping
cycle. The dispenser is configured to receive and dispense the
adhesive from the pump. The outlet assembly is disposed between the
pump and the dispenser to smooth melted adhesive pressure at the
dispenser by routing the adhesive through a first diameter orifice
during a first portion of the pumping cycle, and through a second
diameter orifice during a second portion of the pumping cycle.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is a schematic view of a system for dispensing hot
melt adhesive.
[0007] FIG. 2 is a simplified cross-sectional view of an outlet
assembly for the system of FIG. 1.
[0008] FIG. 3 is an exemplary graph of inlet and outlet pressure in
the outlet assembly of FIG. 2 as a function of time.
DETAILED DESCRIPTION
[0009] FIG. 1 is a schematic view of system 10, which is a system
for dispensing hot melt adhesive. System 10 includes cold section
12, hot section 14, air source 16, air control valve 17, and
controller 18. In the embodiment shown in FIG. 1, cold section 12
includes container 20 and feed assembly 22, which includes vacuum
assembly 24, feed hose 26, and inlet 28. In the embodiment shown in
FIG. 1, hot section 14 includes melt system 30, pump 32, and
dispenser 34. Air source 16 is a source of compressed air supplied
to components of system 10 in both cold section 12 and hot section
14. Air control valve 17 is connected to air source 16 via air hose
35A, and selectively controls air flow from air source 16 through
air hose 35B to vacuum assembly 24 and through air hose 35C to
motor 36 of pump 32. Air hose 35D connects air source 16 to
dispenser 34, bypassing air control valve 17. Controller 18 is
connected in communication with various components of system 10,
such as air control valve 17, melt system 30, pump 32, and/or
dispenser 34, for controlling operation of system 10.
[0010] Components of cold section 12 can be operated at room
temperature, without being heated. Container 20 can be a hopper for
containing a quantity of solid adhesive pellets for use by system
10. Suitable adhesives can include, for example, a thermoplastic
polymer glue such as ethylene vinyl acetate (EVA) or metallocene.
Feed assembly 22 connects container 20 to hot section 14 for
delivering the solid adhesive pellets from container 20 to hot
section 14. Feed assembly 22 includes vacuum assembly 24 and feed
hose 26. Vacuum assembly 24 is positioned in container 20.
Compressed air from air source 16 and air control valve 17 is
delivered to vacuum assembly 24 to create a vacuum, inducing flow
of solid adhesive pellets into inlet 28 of vacuum assembly 24 and
then through feed hose 26 to hot section 14. Feed hose 26 is a tube
or other passage sized with a diameter substantially larger than
that of the solid adhesive pellets to allow the solid adhesive
pellets to flow freely through feed hose 26. Feed hose 26 connects
vacuum assembly 24 to hot section 14.
[0011] Solid adhesive pellets are delivered from feed hose 26 to
melt system 30. Melt system 30 can include a container (not shown)
and resistive heating elements (not shown) for melting the solid
adhesive pellets to form a hot melt adhesive in liquid form. Melt
system 30 can be sized to have a relatively small adhesive volume,
for example about 0.5 liters, and configured to melt solid adhesive
pellets in a relatively short period of time. Pump 32 is driven by
motor 36 to pump hot melt adhesive from melt system 30, through
supply hose 38, to dispenser 34. Motor 36 can be an air motor
driven by pulses of compressed air from air source 16 and air
control valve 17. Pump 32 can, for instance, be a linear
displacement pump such as a double-action piston pump driven by
motor 36. In the illustrated embodiment, dispenser 34 includes
manifold 40 and dispensing module 42. Hot melt adhesive from pump
32 is received in manifold 40 and dispensed via module 42.
Dispenser 34 can selectively discharge hot melt adhesive whereby
the hot melt adhesive is sprayed out outlet 44 of module 42 onto an
object, such as a package, a case, or another object benefiting
from hot melt adhesive dispensed by system 10. Module 42 can be one
of multiple modules that are part of dispenser 34. In an
alternative embodiment, dispenser 34 can have a different
configuration, such as a handheld gun-type dispenser. Some or all
of the components in hot section 14, including melt system 30, pump
32, supply hose 38, and dispenser 34, can be heated to keep the hot
melt adhesive in a liquid state throughout hot section 14 during
the dispensing process.
[0012] System 10 can be part of an industrial process, for example,
for packaging and sealing cardboard packages and/or cases of
packages. In alternative embodiments, system 10 can be modified as
necessary for a particular industrial process application. For
example, in one embodiment (not shown), pump 32 can be separated
from melt system 30 and instead attached to dispenser 34. Supply
hose 38 can then connect melt system 30 to pump 32.
[0013] Outlet assembly 100 connects pump 32 to supply hose 38.
Outlet assembly 100 is a variable orifice outlet assembly
configured to reduce variation in fluid pressure at supply hose 38
and manifold 40 across the pumping cycle of pump 32. Outlet
assembly 100 is described in detail below, with respect to FIGS. 2
and 3.
[0014] FIG. 2 illustrates outlet assembly 100 disposed between pump
32 and supply hose 38. In the depicted embodiment, outlet assembly
100 comprises inlet plenum 102, first passage 104, second passage
106, outlet plenum 108, valve 110 (with shuttle 112 and first and
second openings 114 and 116, respectively), actuator 118, first
orifice plug 120 (with first orifice 124) and second orifice plug
122 (with second orifice 126). Outlet assembly 100 is a variable
orifice outlet assembly configured to selectively switch between
two (or more, in alternative embodiments) fluid paths from pump 32
to supply hose 38.
[0015] Pump 32 pumps hot melted adhesive from melt system 30 into
inlet plenum 102 of outlet assembly 100 at inlet pressure P.sub.I.
Inlet plenum 102 and outlet plenum 108 are chambers, passage, or
reservoirs that accumulate liquid adhesive. Inlet pressure P.sub.I
of liquid adhesive entering inlet plenum 102 varies as a function
of the pumping cycle of pump 32 (see FIG. 3, discussed below). In
an exemplary embodiment, pump 32 is a linear displacement
double-action piston pump. As pump 32 reciprocates between up- and
down-strokes, liquid is forced into inlet plenum 102. During
changeover between strokes of pump 32, inlet pressure P.sub.I
temporarily drops. Opposite strokes of pump 32 may also differ
somewhat in pumping pressure.
[0016] Valve 110 is a switching valve that provides a path from
inlet plenum 102 to either first passage 104 or second passage 106.
In the depicted embodiment, valve 110 is a shuttle valve with
sliding shuttle 112 having first and second openings 114 and 116.
Inlet and outlet plena 102 and 108 are depicted as forked passages
having separate branches leading respectively to and from inlet
first passage 104 and second passage 106. First passage 104
includes first orifice 124, while second passage 106 includes
second orifice 126. First and second orifices 124 and 126 are
apertures narrower than first and second openings 114 and 116 and
first and second passages 104 and 106. First and second orifices
124 and 126 have diameters selected to produce desired permanent
pressure drops .DELTA.P.sub.1 and .DELTA.P.sub.2, respectively,
between inlet plenum 102 and outlet plenum 108, as described in
further detail below. First and second passages 104 and 106 have
identical diameters, as do first and second openings 114 and 116,
such that the diameters of first and second orifices 124 and 126
determine the difference between .DELTA.P.sub.1 and
.DELTA.P.sub.2.
[0017] In the depicted embodiment, valve 110 has first and second
valve states V1 and V2 corresponding to locations of sliding
shuttle 112. Valve 110 is shown in first valve state V1, wherein
sliding shuttle 112 aligns first opening 114 with first passage 104
and seals second passage 106, thereby providing a fluid path from
inlet plenum 102 to outlet plenum 108 via first passage 104 and
first orifice 124. In second valve state V2 (not shown), shuttle
112 aligns second opening 116 with second passage 106 and seals
first passage 104, thereby providing a fluid path from inlet plenum
102 to outlet plenum 108 via second passage 106 and second orifice
126. In alternative embodiments, valve 110 may, for instance, be a
ball valve or similar valve type with a single configurable or
redirectable opening instead of separate first and second openings
114 and 116. When valve 110 is in first valve state V1, the
permanent pressure drop between inlet and outlet plena 102 and 108
is .DELTA.P.sub.1, as described above. When valve 110 is in second
valve state V2, the permanent pressure drop between inlet and
outlet plena 102 and 108 is .DELTA.P.sub.2. Actuator 118 switches
valve 110 between first and second valve states V1 and V2 over the
course of the pumping cycle of pump 32. As described in further
detail below, valve state V1 is used during each sustained stroke
of pump 32, while valve state V2 is used during pump
changeover.
[0018] Actuator 118 is a valve actuator such as a motor-driven or
hydraulic actuator coupled to valve 110. Actuator 118 drives valve
110 in accordance with control line cl, a mechanical or electrical
control line that matches states of valve 110 to the cycle of pump
32 as described in further detail below with respect to FIG. 3.
Control line cl can, for instance, be a hydraulic pilot line driven
by changes in pump pressure within pump 32, and actuator 118 can be
a hydraulic switch. Alternatively, actuator 118 can be an
electrical switch and control line cl can be an electrical line
carrying electrical signals to actuator 118. These electrical
signals may be provided by controller 18 so as to synchronize
actuator 118 with the commanded pump cycle (discussed above with
respect to FIG. 1) of pump 32, or may reflect pressure readings
from a pressure sensor within or adjoining pump 32. By switching
valve 102 between valve states V1 and V2, actuator 118 controls
whether fluid flowing through outlet assembly 100 passes through
first orifice 124 or second orifice 126. In this way, actuator 118
controls whether the pressure drop between inlet and outlet plena
102 and 108 is .DELTA.P.sub.1 (corresponding to valve state V1) or
.DELTA.P.sub.2 (corresponding to valve state V2).
[0019] In the depicted embodiment, first orifice 124 has a narrower
diameter than second orifice 126. As is well known in the art,
narrower apertures produce greater permanent pressure drops.
Accordingly, .DELTA.P.sub.1 across first orifice 124 is greater
than permanent pressure drop .DELTA.P.sub.2 across second orifice
126. By matching larger pressure drop .DELTA.P.sub.1 with periods
of high inlet pressure P.sub.I, and smaller pressure drop
.DELTA.P.sub.2 with periods of low inlet pressure P.sub.I, outlet
assembly 100 reduces fluctuation in outlet pressure P.sub.O. To
this end, actuator 118 switches valve 100 to valve state V1 during
relatively high pressure sustained strokes of pump 32, and to valve
state V2 during relatively low pressure changeover periods of pump
32. In this way, outlet assembly 100 produces a relatively uniform
outlet pressure P.sub.O that varies substantially less over the
course of each pumping cycle of pump 32 than inlet pressure
P.sub.I.
[0020] In the depicted embodiment, first and second orifices 124
and 126 pass through first and second orifice plugs 120 and 122,
respectively. First and second orifice plugs 120 and 122 are
removable inserts that fit into outlet assembly 100 to provide
orifices of desired diameters. First and second orifice plugs 120
and 122 may, for instance, be sealed threaded cylindrical
components that screw into outlet assembly 100 to situate orifices
124 and 126 in first and second passages 104 and 106, respectively.
First and/or second orifice plugs 120 can be swapped out for
similar plugs with different diameter orifices so as to tune
permanent pressure drops .DELTA.P.sub.1 and .DELTA.P.sub.2 to
achieve reduced variation in outlet pressure P.sub.O across the
pump cycle of pump 32. In alternative embodiments, first and second
orifices 124 and 126 may be permanent structures formed within
outlet assembly 100.
[0021] Although outlet assembly 100 has been described above as a
variable outlet assembly having two separate orifices 124 and 126
with differing diameters, alternative embodiments may include more
or fewer apertures. Some alternative embodiments, for instance, may
dispense with valve 110 and replace orifices 124 and 126 with a
single aperture with continuously variable diameter controllable to
compensate for fluctuations in inlet pressure P.sub.I from pump 32.
In other embodiments, valve 110 may switch between three or more
orifice passages for greater granularity of pressure control as
compared to the two-orifice embodiment described above.
[0022] FIG. 3 is a graph of an inlet pressure P.sub.I and outlet
pressure P.sub.O of outlet assembly 100 as a function of time,
illustrating the switching of valve 110 from valve state V1 to
valve state V2 during pump changover. FIG. 3 is only intended as an
illustration of fluid pressure in outlet assembly 100, and is not
drawn to scale. As described above with respect to FIG. 2, actuator
118 switches valve 110 of outlet assembly 100 between valve states
V1 and V2. Valve state V1 routes fluid through first orifice 124,
while valve state V2 routes fluid through second orifice 126.
Because first orifice 124 is narrower than second orifice 126,
permanent pressure drop .DELTA.P.sub.1 in valve state V1 is greater
than permanent pressure drop .DELTA.P.sub.2 in valve state V2. By
switching from valve state V1 to valve state V2 during relatively
low pressure pump changeover periods, outlet assembly reduces
pressure fluctuation in outlet pressure P.sub.O, as shown. P.sub.I
may experience different pressure drops at the top and bottom
changeover of pump 32, as illustrated in FIG. 3. Inlet and outlet
plena 102 and 108 can, in some embodiments, act as fluid
accumulators, further smoothing the outlet pressure P.sub.O as a
function of time. Outlet assembly 100 thus increases the uniformity
of outlet pressure P.sub.O, allowing dispenser 34 to uniformly
apply hot melt adhesive. Although outlet assembly 100 has been
described as feeding supply hose 38, alternative embodiments may
dispense with supply hose 38 and pump adhesive directly into
dispenser 34, as outlet assembly 100 substantially obviates the
need for the accumulator function of supply hose 38. Outlet
assembly 100 thus enables smooth application of adhesive in a more
compact system.
[0023] Although the present invention has been described with
reference to preferred embodiments, workers skilled in the art will
recognize that changes may be made in form and detail without
departing from the spirit and scope of the invention.
* * * * *