U.S. patent application number 16/144522 was filed with the patent office on 2019-01-24 for pneumatic pulsation liquid color pumping.
The applicant listed for this patent is Stephen B. MAGUIRE. Invention is credited to Stephen B. MAGUIRE.
Application Number | 20190024653 16/144522 |
Document ID | / |
Family ID | 53797695 |
Filed Date | 2019-01-24 |
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United States Patent
Application |
20190024653 |
Kind Code |
A1 |
MAGUIRE; Stephen B. |
January 24, 2019 |
PNEUMATIC PULSATION LIQUID COLOR PUMPING
Abstract
A liquid color pump and method for operation thereof includes a
diaphragm displaceable into a chamber to displace liquid color
therefrom; a pair of solenoid valves, each having an inlet port, an
exhaust port, and first and second output ports; a potentiometer
sensing displacement position of the diaphragm and a processor
actuating the solenoid valves responsively to a diaphragm position
sensed by the potentiometer.
Inventors: |
MAGUIRE; Stephen B.; (West
Chester, PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MAGUIRE; Stephen B. |
West Chester |
PA |
US |
|
|
Family ID: |
53797695 |
Appl. No.: |
16/144522 |
Filed: |
September 27, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14700911 |
Apr 30, 2015 |
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16144522 |
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13913375 |
Jun 7, 2013 |
9188118 |
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14700911 |
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14168731 |
Jan 30, 2014 |
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14700911 |
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14587921 |
Dec 31, 2014 |
9599265 |
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14168731 |
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14617035 |
Feb 9, 2015 |
9637283 |
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14587921 |
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15298802 |
Oct 20, 2016 |
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14617035 |
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61986293 |
Apr 30, 2014 |
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61660326 |
Jun 15, 2012 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04B 49/06 20130101;
F04B 51/00 20130101; F04B 53/1082 20130101; F04B 49/22 20130101;
F04B 43/02 20130101; F04B 43/0733 20130101; F04B 43/028
20130101 |
International
Class: |
F04B 43/073 20060101
F04B043/073; F04B 49/06 20060101 F04B049/06; F04B 49/22 20060101
F04B049/22; F04B 43/02 20060101 F04B043/02; F04B 51/00 20060101
F04B051/00 |
Claims
1. A liquid color pump comprising: a) a diaphragm displaceable into
a chamber to displace liquid color therefrom; b) a pair of solenoid
valves, each having an inlet port, an exhaust port, a first output
port connecting to the inlet port when the valve is energized, and
a second output port connecting to the inlet port when the valve is
not energized; i) a first one of the valves having its inlet port
connected to a compressed air supply, its first output port
connected to the diaphragm, its second output port blocked, and its
exhaust port connected to the inlet port of the second valve; ii)
the second valve having its first output port connected to
atmosphere; c) a potentiometer sensing displacement position of the
diaphragm; and d) a processor actuating the solenoid valves
responsively to diaphragm position sensed by the potentiometer.
2. A liquid color pump comprising: a) a diaphragm displaceable into
a chamber for displacing liquid color therefrom; b) a pair of
solenoid valves, each valve having an inlet port, an exhaust port,
and an output port connected to the inlet port when the valve is
energized, and connected to the exhaust port when the valve is not
energized; i) a first one of the valves having its inlet port
connected to a compressed air supply, its output port connected to
the diaphragm, and its exhaust port connected to the inlet port of
the second valve; and ii) the second valve having its output port
connected to atmosphere c) a potentiometer sensing displacement
position of the diaphragm; d) a processor actuating the solenoid
valves responsively to diaphragm position sensed by the
potentiometer.
3. A liquid color pump comprising: a) a diaphragm displaceable into
a chamber to displace liquid color therefrom; b) a solenoid valve
for releasing repeated burst of air to displace the diaphragm into
the chamber; c) a potentiometer for sensing displacement position
of the diaphragm; and d) a processor for repeatedly actuating the
solenoid valve to provide the repeated bursts of air responsively
to diaphragm position sensed by the potentiometer.
4. The liquid color pump of claim 3 wherein the solenoid valve has
an inlet port connected to a supply of compressed air and an outlet
port that upon valve energization is connected to the diaphragm for
flow of air therethrough from the supply to the diaphragm.
5. The liquid color pump of claim 4 wherein upon de-energization of
the solenoid valve the outlet port connecting to the diaphragm is
connected to an exhaust port.
6. A liquid color pump comprising: a) a diaphragm displaceable into
a chamber to displace liquid color therefrom; b) a first solenoid
valve when energized supplying compressed air from a supply to the
diaphragm and when de-energized, connecting the diaphragm to an
exhaust port; c) a second solenoid valve when energized connecting
the exhaust port of the first solenoid valve to atmosphere; d) a
potentiometer for sensing displacement position of the diaphragm;
and e) a processor for actuating the solenoid valve responsively to
diaphragm position sensed by the potentiometer.
7. A method for pumping liquid color comprising: a) positioning a
diaphragm in a pump housing to displace liquid color out of the
pump upon displacement of the diaphragm; and b) applying compressed
air in a series of pulses to the diaphragm by: i) opening a valve
in a pressurized air supply line leading to the diaphragm thereby
permitting air from a pressurized supply to contact the diaphragm;
ii) closing an exhaust line valve leading from the diaphragm
thereby maintain the air applied to the diaphragm to remain in
contact therewith; iii) repeatedly opening the supply line valve
thereby applying additional air to the diaphragm until displacement
of liquid color is complete; iv) opening the exhaust line valve to
allow pressurized air to escape from contact with the
diaphragm.
8. The method of claim 7 further comprising: a) sensing position of
the diaphragm; b) regulating the opening of the supply line valve
in response to sensed position of the diaphragm.
9. The method of claim 8 wherein the sensing is performed
continuously.
10. The method of claim 8 wherein the sensing is performed by
contacting the diaphragm with a riding member and detecting
movement of the member.
11. The method of claim 8 wherein sensing is performed by a
potentiometer.
12. The method of claim 10 wherein the member connects to the
potentiometer.
13. The method of claim 7 wherein regulating opening of the supply
line valve comprises regulating the valve open time.
14. The method of claim 7 wherein regulating opening of the supply
line valve comprises regulating the valve closed time.
15. The method of claim 7 wherein regulating opening of the supply
line valve comprises regulating the time between valve
openings.
16. A method for pumping liquid color, comprising: a) providing
first and second valves, each having inlet and exhaust ports and
each a supply port, the supply port being connected to the inlet
port when the valve is energized and being connected to the exhaust
port when the valve is not energized; b) connecting the inlet port
of one valve to a supply of pumping fluid; c) connecting the first
supply port of the first valve to a pumping diaphragm; d)
connecting the exhaust port of the first valve to the inlet port of
a second valve; e) applying pressurized fluid in a series of pulses
to the diaphragm by energizing the one valve thereby permitting the
pressurized fluid to contact the diaphragm while de-energizing the
second valve thereby forcing the pressurized fluid applied to the
diaphragm to remain in contact therewith.
17. The method of claim 16 further comprising sensing positional
displacement of the diaphragm and adjusting the duration of the
fluid pulses in response thereto.
18. The method of claim 17 further comprising sensing positional
displacement of the diaphragm with a potentiometer.
19. The method of claim 16 further comprising sensing positional
displacement of the diaphragm and using a microprocessor to adjust
the duration of the pulses in response thereto.
20. The method of claim 19 further comprising adjusting interval
timing of the pulses.
21. The method of claim 19 further comprising adjusting "on" time
of the pulses.
22. The method of claim 19 further comprising adjusting "off" time
of the pulses.
Description
CROSS-REFERENCE TO RELATED PATENT APPLICATION
[0001] This patent application is a 35 USC 120 division of
Applicant's U.S. Ser. No. 14/700,911, filed 30 Apr. 2015 in the
name of Stephen B. Maguire and entitled "Pulsed Pneumatic Control
of liquid color Pumps."
[0002] This patent application is also a 35 USC 120
continuation-in-part of Applicant's co-pending U.S. Ser. No.
15/298,802, filed 20 Oct. 2016 in the name of Stephen B. Maguire,
published 9 Feb. 2017, and entitled "Pump Actuator and Method for
Pump Operation"
[0003] The '911 patent application was a 35 USC 120
continuation-in-part of U.S. patent application Ser. No.
13/913,375, filed 7 Jun. 2013 in the name of Stephen B. Maguire,
entitled "Injection Molded Diaphragm Pump for Liquid Color with
Quick Release." published as US 2013/0334258 A1, issued 17 Mar.
2015 as U.S. Pat. No. 9,188,118,
[0004] The '911 patent application was also a 35 USC 120
continuation-in-part of U.S. patent application Ser. No.
14/168,731, filed 30 Jan. 2014 in the name of Stephen B. Maguire,
entitled "Pump Actuator and Method for Pump Operation," published
as U.S. 2014/0147288 on 29 May 2014, now abandoned.
[0005] The '911 patent application was also a 35 USC 120
continuation-in-part of U.S. patent application Ser. No. 14/587,921
filed 31 Dec. 2014 in the name of Stephen B. Maguire and entitled
"Multiple Plate Quick Disconnect Fitting, published 23 Apr. 2015,
issued 21 Mar. 2017 as U.S. Pat. No. 9,599,265."
[0006] The '911 patent application was also a 35 USC 120
continuation-in-part of U.S. patent application Ser. No. 14/617,035
filed 9 Feb. 2015 in the name of Stephen B. Maguire, entitled
"Quarter Turn Adapter Connective Outlet Fitting for Liquid Color
Dispensing", published 11 Jun. 2015, issued 2 May 2017 as U.S. Pat.
No. 9,637,283.
[0007] The '911 patent application was also a 35 USC 120
continuation-in-part of U.S. patent application Ser. No.
13/913,375, filed 7 Jun. 2013 in the name of Stephen B. Maguire,
entitled "Injection Molded Diaphragm Pump for Liquid Color with
Quick Release", published 19 Dec. 2013 as US 2013/0334258 A1,
issued 17 Nov. 2015 as U.S. Pat. No. 9,188,118.
[0008] This patent application claims, under 35 USC 120, the
benefit of the priority of the '911 patent application, and through
the '911 application claims the benefit of the priority of the
'731, 921, and '035 applications.
[0009] The '921 and '035 applications claimed, under 35 USC 120,
the benefit of the priority of the '375 application. This patent
application claims, under 35 USC 120, through the '921 and '035
applications, the benefit of the priority of the '375
application.
[0010] The '911 patent application claimed the benefit of the
priority under 35 USC 120 of provisional U.S. patent application
Ser. No. 61/986,293 filed 30 Apr. 2014 in the name of Stephen B.
Maguire, entitled "Volumetric Control of Liquid Color Pumps"; this
application claims the benefit of the priority of the '293
application under 35 USC 120 through the '911 patent
application.
[0011] The '375 application claimed, under 35 USC 120, the benefit
of the priority of provisional U.S. patent application Ser. No.
61/660,326 filed 15 Jun. 2012 in the name of Stephen B. Maguire,
entitled "Molded Diaphragm Pump". This application claims, under 35
USC 120, through the '921, '035 and '375 applications, the benefit
of the priority of the '326 application.
[0012] The disclosures of all of these preceding applications are
hereby incorporated by reference in their entireties, to the extent
permitted under applicable law.
DESCRIPTION OF THE PRIOR ART
[0013] Diaphragm pumps and piston pumps are known. In both
diaphragm pumps and piston pumps, the pump provides a reciprocating
action whereby the pump alternately displaces liquid and then pulls
in additional liquid to be pumped from a pumping chamber. All such
pumps involved two check valves. An inlet check valve allows liquid
to enter the pumping chamber, but prevents liquid from exiting back
out of the pumping chamber through the inlet check valve. An outlet
check valve allows the pumped liquid to exit the pumping chamber
and prevents the liquid from returning to the pumping chamber
through the outlet check valve.
[0014] In a diaphragm pump, the moving diaphragm serves to suck
liquid through the inlet into the pumping chamber and then pumps
the liquid by applying pressure to the liquid to force the liquid
out of the pumping chamber via the liquid outlet.
[0015] Liquid color is used to color granular plastic resin
material as the granular plastic resin material is molded or
extruded into finished or semi-finished parts.
[0016] Liquid color metering is known, as disclosed in U.S. Pat.
No. 7,958,915.
[0017] One approach to providing liquid color to process machines,
namely molding presses and extruders, as the liquid color is
consumed by the molding process or the extrusion process is the
"Pump-in-a-Drum" approach disclosed in U.S. Pat. No. 7,416,096.
[0018] The pump disclosed in the '096 patent and used in the
"Pump-in-a-Drum" approach is a piston pump, which displaces a known
volume of liquid color for each full piston stroke during pump
operation.
[0019] The '096 patent discloses a container of liquid color
material having a diaphragm liquid color pump located in the
container for providing liquid color from the container. The
diaphragm liquid color pump is located in the container at the
container bottom, where the pump can collect liquid color as the
container empties. The pump is driven by a pneumatic
piston-cylinder combination located outside the container, with a
shaft extending downwardly from the pneumatic piston-cylinder
combination to the diaphragm pump, to reciprocate the diaphragm
back and forth to effectuate pumping action.
[0020] The apparatus disclosed in '096 is relatively low in cost.
The apparatus includes a liquid-tight fitting allowing the liquid
color output from the pump to be supplied directly to a plastics
material processing machine, for the liquid color to impart color
directly to plastic parts as they are manufactured.
[0021] The '834 apparatus provides pressure boosting, permitting
liquid color to be injected into an extruder screw or a molding
machine screw barrel at a position downstream from the throat,
closer to the position at which the finished plastic parts are
molded or extruded.
[0022] Published application 2011/0200464 discloses a disposable
low-cost pump in a container for liquid color, where the pump is
fabricated from a plurality of PVC tubular members connected in a
way to provide a pumping chamber. A piston is displaceable into the
pumping chamber. A spring biases the piston outwardly from the
chamber, in opposition to force applied by an air cylinder.
[0023] While these devices have merit and have proved commercially
successful, there is a continuing need for lower cost, higher
reliability apparatus to provide liquid color from liquid color
containers to injection and compression molding machines and to
extruders, to color plastic parts in the course of manufacture
thereof.
[0024] When providing liquid color to a process machine, namely
either an extruder or a molding press, the liquid color must be
metered to the process machine at a rate that is determined by the
rate of operation of the process machine and by the consumption
appetite of the process for liquid color as the process machine
operates.
[0025] The appetite of the process machine for liquid color varies
over a wide range due to changes in speed of operation of the
process machine and other factors. Hence, the speed of
reciprocation of the piston in the pump that meters the liquid
color to the process machine must be accurately controlled. For
accurate control of the operating speed of the pump, which in turn
controls speed of reciprocation of the piston within the pump, it
is desirable to have feedback information as to the location of the
piston within the pump at all times, to assure that the piston and
the pump are metering liquid color to the process machine at the
correct rate. It is also desirable to be able to vary the rate of
operation of the pump and hence the rate of reciprocation of the
piston within the pump, to achieve a correct and optimum metering
rate for liquid color supplied to the process machine.
[0026] One approach to metering and regulating metering of liquid
color to a process machine is to use an air cylinder to move the
piston located within the pump. The air cylinder approach is a
simple, low-cost solution, but in order to function correctly in a
liquid color metering application, feedback information is required
to detect the exact location and rate of movement of the pump
piston as the pump piston is advanced by action of the air cylinder
supplying compressed air.
[0027] Other approaches to metering liquid color are also known,
using less sophisticated devices such as a sensor that detects only
a full stroke of a piston within a pump, with the device then
estimating the location of the piston as it advances during
subsequent strokes based on the previously detected full stroke.
Such an approach, while feasible, has shortcomings for very small
dispenses of liquid color, which may not require a full stroke of
the piston given the small amount of piston displacement required
to dispense a very small amount of liquid color. An additional
disadvantage of this approach is that the initial dispense of
liquid color is generally not linearly related to the length of the
air pulse, since the first air pulse normally must be a longer
pulse to pressurize associated tubing, and to build initial
pressure, before any piston movement will occur. The only way to
automatically adjust the first pulse is to detect the exact moment
of piston movement.
[0028] Air cylinders conventionally move an associated piston a
full stroke within a fraction of a second, with the piston not
stopping between the two extremes of piston travel. Air cylinders
are not conventionally adapted to move their associated piston only
a small or measured amount less than a full stroke of the piston,
between the extremes of piston travel. But such small, measured
movements of a piston are exactly what are required when using a
piston pump to meter liquid color. This is because liquid color is
often required in very small, precise amounts, which are often much
less than the amount of liquid color supplied by a full stroke of
the piston in a piston pump.
[0029] This invention addresses this problem.
SUMMARY OF THE INVENTION
[0030] In one of its aspects, this invention provides a method for
operating a pump having a moveable pumping member within a pumping
chamber, where the method preferably includes positioning a
moveable reciprocable member in contact with a pumping member to
move reciprocally in concert with the pumping member. In this
aspect, the invention preferably proceeds with sensing position of
the reciprocable member, which is indicative of the position of the
pumping member, and producing a signal indicative thereof. The
method then preferably proceeds in this aspect by periodically
applying force to the pumping member to move the pumping member and
thereby effectuate pumping of liquid from the chamber. The method
preferably further involves using the signals to regulate frequency
of force application to the pumping member to achieve a preselected
rate of output from the pump.
[0031] In one application of the invention, addition of color to a
plastic molding or processing operation requires careful metering,
which this invention provides. When such color is added, the rate
of color dispensing must exactly match the rate requirement of the
process machine. Consequently, speed of the liquid color pumping
process must be carefully controlled. In the instant invention,
rate of pumping is controlled and even partial pumping strokes may
be effectuated by the invention preferably pulsing very small
bursts of air to the diaphragm portion of the pump. By regulating
the duration of each air pulse and regulating the time between air
pulses, the invention facilitates metering liquid color at a
desired precisely controlled flow rate.
[0032] In this invention, air pulses are used to push against a
movable pumping diaphragm. A stiff spring is used to urge the
diaphragm to return to a neutral position within the pump when
required after completion of one or more diaphragm full or partial
pumping strokes.
[0033] The invention preferably provides continuous feedback of the
exact position of a liquid color pump diaphragm at all times as air
pushes the diaphragm downward. Such continuous feedback information
regarding the exact position of the diaphragm at all times
preferably allows continuous monitoring and correction of liquid
color flow rate by regulation of the frequency and duration of the
air pulses applied to the diaphragm and also facilitates accurate,
partial strokes of the pumping diaphragm. The invention
accomplishes this by preferably providing a moveable pin that
follows the diaphragm of the liquid color pump as the diaphragm
moves. The invention further accomplishes this by using a linear
potentiometer in a position so that the potentiometer senses
movement of the pin.
[0034] In the preferred practice of the invention, a series of very
short electrical pulses is applied to a solenoid valve arrangement,
which opens and closes a supply of pressurized air which is applied
to the diaphragm for very short periods, usually about 1/100.sup.th
of a second for each electrical pulse. These short electrical
pulses, when applied to the solenoid valve arrangement, with the
solenoid valve arrangement in turn applying corresponding
individual pulses of air under pressure to a diaphragm within the
pump, results in delivery of just enough air to displace the
diaphragm a small distance, against the force applied by the stiff
spring, with the diaphragm moving preferably about 5/100.sup.th of
an inch (0.050) with each pulse.
[0035] In the most preferred operation of the invention, the
invention utilizes only about one-quarter inch of the diaphragm
movement, which translates into about 300 different position
readings of a moveable potentiometer arm, and hence the position of
a pin riding the diaphragm, and the position of the diaphragm
itself, thereby assuring precise location information at all times
respecting the position of the pumping diaphragm.
[0036] The invention preferably varies the overall metering rate of
liquid color, preferably by changing the time between pulses.
Longer "on" time durations for each pulse result in lower liquid
color metering rates, while shorter "off" time durations between
each pulse result in higher liquid color metering rates.
[0037] The invention further provides a diaphragm pump for liquid
color, where a body portion of the pump is molded and formed of a
single piece of plastic. The molded body portion of the pump is
preferably incorporated into the liquid color container lid as a
part of the container design. The diaphragm portion of the pump,
when in operation moves from an unflexed "rest" or "up" position to
a flexed "down" position, with total movement at the diaphragm
center desirably being in the order of about one-quarter of an
inch.
[0038] In one embodiment manifesting aspects of the invention, the
thickness of a liquid color container lid is used to provide space
for the diaphragm, with the diaphragm being located in space
created by removal of a portion of the container lid. The molded
body portion of the pump and the diaphragm are mounted on the
bottom side of the container lid. The space created by removal of a
portion of the container lid allows the diaphragm to flex into the
space as needed.
[0039] The invention yet further provides a liquid color container
having a pneumatic pump, where the container has a lid with an
aperture therein. An integral molded plastic one-piece pump lower
body portion resides within the container and is connected to the
lid. A diaphragm is sandwiched between the integral molded plastic
one-piece pump lower body portion and the lid, in a location to
overlie the aperture in the lid. The diaphragm is moveable away
from the lid responsively to preferable pneumatic pressure applied
to a side of the diaphragm facing the lid and is moveable towards
the lid and into the aperture in the lid upon relief of such
pneumatic pressure.
[0040] Another aspect of the invention is the provision of a linear
potentiometer as part of the pump by which the pulsed compressed
air is applied to the diaphragm. The linear potentiometer provides
a feedback signal, indicative of position of a light "riding" pin
that is movable in contact with the diaphragm and moves unitarily
therewith, to a microprocessor controlling operation of the pump so
that operational characteristics of the pump including (i) the
effect of air pulse timing; (ii) the instantaneous liquid color
metering rate; (iii) the instantaneous position of the riding pin
and hence of the diaphragm; and (iv) the associated volume of
liquid color metered, can be monitored. This feedback signal
facilitates adjustments to achieve the exact amount and rate of
liquid color required by a process machine, namely a molding press
or an extruder.
[0041] A light spring, above a slide arm of the potentiometer and
biasing the pin downwardly, assures that the potentiometer slide
arm or "T-bar" and the pin contactingly follow the diaphragm as air
pushes the diaphragm down.
[0042] The method aspect of the invention may preferably further
include recording signals at the extremities of pin travel, using
those signals and the known length of pin travel to determine
location of the pin based on signal received at a given time and
adjusting the frequency of application of force to the pumping
diaphragm according to the location of the pin and the
potentiometer slide arm or T-bar, to maintain the desired output
from the pump.
[0043] The method may further involve using the signals and known
length of the pin travel to determine location of the pin based on
signal received at a given time and may further include determining
the relationship between the duration of force application to the
pumping diaphragm and the pumping diaphragm displacement.
[0044] In one of its many aspects, this invention provides a liquid
color pump including a diaphragm displaceable into a chamber to
displace liquid color therefrom; a pair of solenoid valves, with
each valve having an inlet port, an exhaust port, a first supply
port connecting to the inlet port when the valve is energized, and
a second supply port connecting to the inlet port when the valve is
not energized. A first one of the valves has its inlet port
connected to a compressed air supply, its first supply port
connected to the diaphragm, its second supply port blocked and its
exhaust port connected to the inlet port of the second valve. The
second valve has its output port connected to atmosphere.
[0045] In yet another one of its aspects, this invention provides a
liquid color pump having a diaphragm displaceable into a chamber
for displacing liquid color therefrom; a pair of solenoid valves
each having an inlet port, an exhaust port and an output port
connected to the inlet port when the valve is energized but
connected to the exhaust port when the valve is not energized. A
first one of the valves has its inlet port connected to a
compressed air supply; its output port connected to the diaphragm;
and its exhaust port connected to the inlet port of the second
valve, with the second valve having its output port connected to
atmosphere. In this aspect of the invention, the liquid color pump
further includes a potentiometer sensing displacement position of
the diaphragm and a processor actuating the solenoid valves
responsively to diaphragm position sensed by the potentiometer.
[0046] In still yet another one of its aspects, this invention
provides a liquid color pump comprising a diaphragm displaceable
into a chamber to displace liquid color therefrom, a solenoid valve
for releasing repeated bursts of air to displace the diaphragm into
the chamber, a potentiometer for sensing displacement position of
the diaphragm; and a processor for repeatedly actuating the
solenoid valve to provide the repeated bursts of air responsively
to diaphragm position sensed by the potentiometer. The solenoid
valve preferably has an inlet port connected to a supply of
compressed air and an outlet port that upon valve energization is
connected to the diaphragm for flow of compressed air flow
therethrough from the supply to the diaphragm to displace the
diaphragm for pumping action of liquid color. Upon de-energization
of the solenoid valve, the outlet port connected to the diaphragm
is connected to an exhaust port.
[0047] In another one of its aspects, the invention provides a
liquid color pump having a diaphragm displaceable into a chamber to
displace liquid color therefrom, a first solenoid valve when
energized supplying compressed air from a supply to the diaphragm
and when de-energized connecting the diaphragm to an exhaust port;
a second solenoid valve which when energized connects the exhaust
port of the first solenoid valve to atmosphere; a potentiometer for
sensing displacement position of the diaphragm; and a processor for
actuating the solenoid valve responsively to diaphragm position
sensed by the potentiometer.
[0048] The combination of pulsed air to effectuate movement of a
pumping diaphragm pressing against a spring together with a linear
potentiometer providing feedback signal indicative of diaphragm
position, in order to control diaphragm movement, is new to liquid
color metering.
[0049] The control aspect of this invention preferably incorporates
one or two solenoid valves opening and closing to apply pressurized
air against the diaphragm. When two solenoids are used, one
solenoid is pulsed "on" for a precise short interval, typically 10
microseconds. These pulses are separated by an "off" time that can
be from a very short period up to several seconds. The "off" time
interval controls overall flow rate of liquid color to the process
machine.
[0050] In the invention, a linear potentiometer preferably detects
diaphragm position by preferably detecting the exact position of
the riding piston, from fully retracted to fully extended. By
monitoring this position and using the position feedback
information, a microprocessor controlling the pumping operation can
adjust the pulse "on" time, the pulse "off" time, and the number of
pulses, to achieve the desired metering amount and the desired rate
of delivery of the liquid color to the process machine.
[0051] The microprocessor controller allows input of all process
information required for regulating the process, namely the process
machine rate of consumption of granular plastic resin material in
pounds per hour, the percent of liquid color to be added to the
granular plastic resin material by weight, the weight of the liquid
color pumped in pounds per gallon, and the volume displaced by the
liquid color pump for each application of pressurized air to the
diaphragm.
[0052] Knowing the process rate and the weight or volume percentage
(and density in the case of volume percentage) of color to be added
to the granular plastic resin to be molded or extruded allows
calculation of the amount and rate of liquid color to be supplied
in terms of grams of liquid color per hour. Knowing the weight of
liquid color in pounds per gallon allows for conversion from grams
of liquid color to volume of liquid color in cubic centimeters.
[0053] The following detailed description is merely exemplary in
nature and is not intended to limit the described embodiments of
the invention or uses of the described embodiments. As used herein,
the words "exemplary" and "illustrative" mean "serving as an
example, instance, or for illustration." Any implementation or
embodiment or abstract disclosed herein as being "exemplary" or
"illustrative" is not necessarily to be construed as preferred or
advantageous over other implementations, aspects, or embodiments.
All of the implementations or embodiments described in the detailed
description are exemplary implementations and embodiments provided
to enable persons of skill in the art to make and to use the
implementations and embodiments as disclosed below, to otherwise
practice the invention, and are not intended to limit the scope of
the invention, which is defined by the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0054] FIG. 1 is a schematic view of two solenoid valves connected
together to provide pressurized air to one side of a pumping
diaphragm of a liquid color pump in accordance with the
invention.
[0055] FIG. 2 is a schematic view of the same two solenoid valves
illustrated in FIG. 1, with the valves energized in a manner to
vent the side of the diaphragm to which compressed air had been
supplied to effectuate liquid color pumping in FIG. 1.
[0056] FIG. 3 is a front elevation in section of an injection
molded diaphragm pump for liquid color with quick release in
accordance with the invention, with the pump mounted on the lid of
a liquid color container and the liquid color container lid shown
fragmentally.
[0057] FIG. 4 is a schematic rear elevation of the injection molded
diaphragm pump illustrated in FIG. 3.
[0058] In FIGS. 1 and 2 schematically illustrating solenoid valves
700, 702, lines and arrows have been provided within the
rectangular boxes schematically denoting solenoid valves 700, 702.
These lines denote the positioning of the valve internals as
respecting connection of the inlet port, the exhaust port, the
valve energized supply port and the valve non-energized supply
port, according to the state of energization of the valve. For
example, in FIG. 1 valve 700 has diagonal arrow from inlet port
700IN leading to valve energized supply port 700S-E, and a second
diagonal arrow leading from valve non-energized supply port 700S-NE
to valve exhaust port 700EX. These diagonal arrows indicate that
when solenoid valve 700 is energized, which is the condition
illustrated in FIG. 1, inlet port 700IN is connected to valve
energized supply port 700S-E and non-energized valve supply port
700S-NE is connected to valve exhaust port 700EX. Still referring
to FIG. 1, the arrows for solenoid valve 702 indicate that in this
state, when solenoid valve 702 is not energized, inlet port 702IN
is connected to valve non-energized supply port 702S-NE, and valve
energized supply port 702S-E is connected to exhaust port
702EX.
[0059] In FIG. 2, the arrows indicating connection or lack of
connection between the various ports of solenoid valves 700, 702
are reversed from that illustrated in FIG. 1, since in FIG. 2
solenoid valve 702 is energized and solenoid valve 700 is not
energized.
Description of the Preferred Embodiments and Best Mode Known for
Practice of the Invention
[0060] Referring to the drawings, in the pump of the invention air
(or another pumping fluid) under pressure is applied to an upper
side 24U of a diaphragm 24, to press diaphragm 24 downwards. This
downward movement of diaphragm 24 defines the "pumping stoke". In
the pump, a spring 106 on bottom side 24L of the diaphragm acts to
urge diaphragm 24 up. Upward movement of diaphragm 24 in response
to the force of spring 106 defines the "suction stroke".
[0061] Moving the diaphragm downward through part of all of the
full range of motion is preferably accomplished by operation of
solenoid actuated air valves 700, 702 and applying air pressure, as
described in more detail below, to move the diaphragm optionally
all the way to the bottom of its range of motion, which may be to
the bottom of the pumping cavity 98 or to move the diaphragm
through less than its full range of motion.
[0062] Referring to FIGS. 1 and 2, solenoid valves 700, 702 provide
pressurized air to diaphragm 24, specifically to the upper surface
24U of diaphragm 24, which is the upper side of diaphragm 24
illustrated in FIG. 3 and is the surface of diaphragm 24 that is
contacted by pin 42 as pin 42 rides diaphragm 24 to provide
positional data respecting the position of diaphragm 24 via signals
generated by potentiometer 36 as slide bar 40 moves with pin
42.
[0063] Solenoid valves 700, 702 are mounted on the rear of liquid
color pump inlet section 22 as illustrated in FIG. 4. Solenoid
valves 700, 702 are controlled by microprocessor 68 and are
connected thereto desirably by electric lines 603, 604. Of course,
wireless connection is also feasible and desirable in connection
with the practice of this invention.
[0064] Compressed air is supplied to first solenoid valve 700 by a
house air line 602 as illustrated in FIG. 4.
[0065] When liquid color is used to color plastic parts during
fabrication, careful metering of liquid color consumption is
required as the liquid color is added while the plastic resin is
melted and processed by a process machine. The rate the liquid
color is dispensed by the pump must exactly match the rate at which
the liquid color is consumed by the process machine. Hence, rate or
speed of the liquid color pumping process must be precisely
controlled. In some applications only require partial pump strokes
are required. The rate at which liquid color is supplied by the
pump is controlled by carefully pulsing only very small bursts of
air into the pump, into the space above the diaphragm. Regulating
the duration of each air pulse and regulating the time between
pulses results in metering the liquid color to the process machine
at exactly the desired flow rate so that the process machine
receives precisely the amount of liquid color the process requires,
at exactly the right rate of supply of liquid color.
[0066] Critical to the success of this process for supplying liquid
color is having continuous feedback of the exact position of the
diaphragm at all times as compressed air released by solenoid valve
700 pushes the diaphragm downward. Knowing the exact position of
the diaphragm at all times allows accurate continuous monitoring
and correction of the liquid color flow rate by regulation of the
solenoid valves 700, 702 by the potentiometer 36 and microprocessor
68, and also allows accurate metering of partial stokes of
diaphragm 24.
[0067] The invention accomplishes this by providing a pin 42 that
lightly rides the upper surface 24U of diaphragm 24, following the
diaphragm as the diaphragm moves down and up. The invention further
involves positioning potentiometer 36, most desirably a linear
slide potentiometer, so that potentiometer 36 is actuated by
movement of pin 42.
[0068] In one preferred embodiment, total diaphragm movement may be
about 0.25 inch. The potentiometer T-bar arm 40 and pin 42 may move
about 0.75 inch or more, but in the preferred embodiment, the
invention typically uses only 0.25 inch of that stroke.
[0069] Initially, microprocessor 68 preferably records the upper
and lower extreme positions of the linear potentiometer slider arm
40, corresponding to the upper and lower limits of diaphragm
travel. The microprocessor 68 then uses the readings of
potentiometer 36 that are between the corresponding upper and lower
limits of diaphragm travel to determine the exact location of
diaphragm 24 as diaphragm 24 moves up and down and pumps liquid
color. A 0.25 inch maximum travel stroke of diaphragm 24 translates
into about 300 different position readings of the pin 42 and
potentiometer 36, which may be stored and used by microprocessor
68, assuring precise readout of diaphragm location at any time.
[0070] Referring to FIG. 3, liquid color pump 14 is mounted on a
lid 16 of a liquid color container and secured thereto by nut and
bolt combinations 88, as illustrated in FIG. 3. Each nut and bolt
combination 88 includes a nut 90 and a bolt 92, with the head of a
bolt 92 being exterior of the liquid color drum lid 16 and a
corresponding nut 90 being within the drum below drum lid 16.
[0071] Referring still to FIG. 3 and to FIG. 4, pump 14 includes a
pump inlet section 22, a pump outlet section 23 defined generally
by a quarter turn adaptor outlet fitting, and a molded one piece
lower body portion 20.
[0072] As illustrated in FIG. 3, bolts 92 pass through a collection
63 of sandwiched plates 65, 66, 67 that provide a quick release for
both pump inlet section 22 and pump outlet section 23, with bolts
92 further passing through an aperture in drum lid 16 and suitable
holes formed in molded one piece lower body portion 20 of pump 14.
These holes are formed in bosses resulting as one piece lower body
portion 20 is molded.
[0073] One piece lower body portion 20 is a single molded piece of
plastic of integral construction. There is no assembly or
fabrication activity involved as respecting finishing one piece
lower body portion 20 and making it ready for incorporation into
pump 14 once one piece lower body portion 20 is ejected from the
mold of an injection molding machine. The only finishing that may
occasionally be necessary is removal of any flash resulting from
the molding process.
[0074] A liquid color inlet conduit 26 extends downwardly from
molded one piece lower body portion 20 and communicates with
pumping chamber 98 of molded one piece lower body portion 20 via a
liquid color inlet aperture 100 formed in molded one piece lower
body portion 20. A liquid color inlet check valve, located at
liquid color inlet aperture 100 to molded lower body portion 20, is
designated generally 28 in FIG. 3 and includes a liquid color inlet
check valve ball 30, which is biased against a liquid color inlet
check valve seat 34, which seat is preferably defined by an O-ring.
Closure bias for liquid color inlet check valve ball 30 is provided
by liquid color inlet check valve bias spring 102.
[0075] Liquid color inlet check valve ball 30 resides within and is
movable freely with respect to a diaphragm return spring designated
32 in FIG. 3. Diaphragm return spring 32 is positioned to rest on a
shoulder 104 of a cylindrically shaped portion 106 formed in the
open interior of one piece lower body portion 20. Diaphragm return
spring 32 is constrained at its upper end by contact with the
underside of a diaphragm support cup 62. An upper surface of
diaphragm support cup 62 facingly contacts the lower surface 24L of
diaphragm 24. Diaphragm support cup 62 includes a horizontal planar
portion 108 and an annular portion 110 extending downwardly from
portion 108. Annular portion 110 separates diaphragm return spring
32 from inlet check valve bias spring 102, as illustrated in FIG.
3.
[0076] As illustrated in FIG. 3, the injection molded diaphragm
pump with liquid color for quick release further includes slide
potentiometer 36, with the potentiometer having a T-bar 40 for
detecting the position of diaphragm position sensing pin 42. An
optional spring 38 provides slight bias via T-bar 40 to assure
position sensing pin 42 remains in light, riding contact with
diaphragm 24. Gravity may be relied on in lieu of spring 38.
[0077] A pumped color liquid outlet from pump outlet section 23 is
designated 46. The bottom interior surface of liquid container lid
16 is designated 48 and the top exterior surface of liquid
container lid 16 is designated 50. O-rings 52 are provided to seal
the quick disconnect inlet section 22 and the quick disconnect
liquid color outlet assembly 23 relative to an uppermost plate 65
of quick disconnect sandwich 63 consisting of plates 65, 66, 67,
which are bolted to drum lid 16 by nut-bolt combinations 88 as
described.
[0078] The pump assembly further includes a liquid color outlet
shutoff valve designated generally 54, a liquid color outlet
shutoff valve ball designated 56, and a liquid color outlet shutoff
valve spring designated 58. The sandwich-like quick disconnect
plate assembly provided as 63 includes quick disconnect retainer
plate 65, quick disconnect spacer plate 66, and quick disconnect
base plate 67. An optional gasket 600 may be interposed between
upper surface 50 of drum lid 16 and a lower, unnumbered surface of
quick disconnect base plate 67, which faces drum lid 16.
[0079] Microprocessor 68 actuates and operates solenoid valves 700,
702, which supply air as needed to the upper side of diaphragm 24
from a house air line 602, as illustrated in FIG. 4. A voltage
potential outlet signal line 76 from potentiometer 36 works in
conjunction with microprocessor 68 to effectuate effective control
of valves 700, 702.
[0080] A recess 84 formed in the upper surface of pump molded
one-piece lower body portion 20 defines a channel designated by
arrow 86, which shows the direction of flow of liquid color from a
pumping section of the pump, defined generally by the structure
underlying quick disconnect inlet section 22, to an outlet section
of the pump defined generally quarter turn quick disconnect liquid
color outlet assembly 23.
[0081] When pump outlet section 23, defined generally by the
quarter turn adapter outlet fitting, is not present (as having been
removed by rotating it a quarter turn so that the unnumbered feet
of that fitting do not engage channels in spacer plate 66), ball 56
of liquid color shut off valve 54 pops up due to the force applied
to it by liquid color shut off valve spring 58, which is
immediately below ball 56 and in contact therewith. As ball 56
rises, ball 56 encounters a hole in plate 16, or optionally a hole
in gasket 24 underlying plate 16 (if gasket 24 is configured to
extend that far to the left in FIG. 3), and ball 56 seals the hole
due to the spring force exerted by liquid color shut off valve
spring 58 on ball 56. Hence with ball 56 sealing the hole no liquid
color can escape from the pump and the pump has been "shut
off."
[0082] When pump outlet section 23 is put into position with a
quarter turn so that the unnumbered feet thereof engage the
unnumbered channels defined by retainer plate 65 and spacer plate
66 and are retained in place thereby, the unnumbered lower
extremity of a downwardly extending annular channel in pump outlet
section 23 contacts ball 56 and pushes ball 56 down against the
force of liquid color shut off valve spring 58, thereby allowing
liquid color pumped by action of diaphragm 24 to flow to the left
in FIG. 3 and from there to flow upwardly through the channel and
associated passageway in pump outlet section 23, and out of the
pump through the pump liquid color outlet 46.
[0083] Referring to the schematic drawings presented as FIGS. 1 and
2 showing the operation of first and second solenoid valves 700,
702, each of the first and second solenoid valves 700, 702 have an
inlet port, an exhaust port, a valve energized supply port, and a
valve non-energized supply port. The inlet port, exhaust port,
valve energized supply port, and valve non-energized supply port
are respectively indicated by "IN" for "inlet port", "EX" for
"exhaust port", "S-E" for "valve energized supply port" and "S-NE"
for "valve non-energized supply port." Each of first and second
solenoid valves 700, 702 have their respective inlet ports, exhaust
ports, valve energized supply ports and valve non-energized supply
ports indicated by the corresponding appropriate alphabetic
combinations in FIGS. 1 and 2.
[0084] As shown in FIG. 1, when compressed air (or some other
pumping fluid) in pulses is to be provided to the upper side of
diaphragm 24, with upper side of diaphragm 24 denoted 24U, air from
the house air line 602 is supplied to inlet port 700IN of first
solenoid valve 700. Upon energization of first solenoid valve 700,
inlet port 700IN is connected to valve energized supply port
700S-E, which connects to the unnumbered open interior of pump
inlet section 22 and a compressed air pulse is resultingly applied
to upper side 24U of diaphragm 24.
[0085] As soon as the required pulse has been applied for the
required duration, as controlled by microprocessor 68 monitoring
displacement of diaphragm 24 as sensed by slide potentiometer 36,
valve 700 is de-energized. However, upon de-energization of valve
700 the compressed air applied to the diaphragm upper surface 24U
remains present and cannot escape, since the inlet port 7001N of
first solenoid valve 700 is connected to exhaust port 700EX, and
exhaust port 700EX is in turn connected to the inlet port 7021N of
solenoid valve 702. Since solenoid valve 702 is not energized, air
entering inlet port 7021N of solenoid valve 702 attempts to go to
valve non-energized supply port 702S-NE.
[0086] However, in the implementation of the invention illustrated
in FIGS. 1 and 2, the non-energized supply port 702S-NE of valve
702 is permanently blocked. Hence, as first solenoid valve 700 is
cycled on and off, with each "on" cycle of first solenoid valve
700, air pressure builds against the upper side 24U of diaphragm
24, thereby further displacing diaphragm 24 downwardly in FIG. 3
and effectively pumping liquid color present in pumping chamber 98
in FIG. 3 out of that chamber, with the liquid color moving to the
left in FIG. 3 through channel 84 as indicated by arrow 86 and
upwardly through pump outlet section 23 defined generally by a
quarter turn adapter outlet fitting, as illustrated.
[0087] As first solenoid valve 700 continues to cycle on and off
and continues thereby to force additional air pressure against
upper side 24U of diaphragm 24, diaphragm 24 continues to deflect
downwardly considering FIG. 3, thereby forcing additional liquid
color out of pumping chamber 98 through channel 84 and out of pump
14 as explained above.
[0088] Once the slide potentiometer 36 indicates that the diaphragm
24 has reached its maximum displacement and has pumped the maximum,
or a desired, amount of liquid color at a desired rate, first
solenoid valve 700 is de-energized and second solenoid valve 702 is
energized. This opens a passageway for escape of the air that had
been pressing against upper surface 24U of diaphragm 24 with that
air flowing out of de-energized first solenoid valve 700 by passing
through port 700S-E and then port 700EX and on to now energized
second solenoid valve 702 entering valve 702 through inlet port
7021N and then venting to atmosphere through solenoid valve 702 by
exiting that valve via energized supply port 702S-E.
[0089] While operation and the structure of the invention as
disclosed has shown first and second solenoid valves 700, 702 as
four-port valves, three-port valves could equally well be used,
whereupon energization of such a three-port valve, the inlet port
is connected to a single supply port, and upon de-energization of
the valve, the single supply port is connected to the valve exhaust
port.
[0090] Three-port and four-port solenoid valves suitable for use in
practice of the invention are available from MAC Valves located at
30569 Beck Road, Wixom, Mich.
[0091] Use of the four-port solenoid valve in the preferred
embodiment of the invention facilitates the delivery of air in
extremely small amounts to provide fine, very precise control of
movement of diaphragm 24. First solenoid valve 700 is turned on and
off for very short "on" times, such as ten milliseconds, namely
1/100.sup.th of a second. This provides a very short pulse of air
against the upper side of the diaphragm 24. When first solenoid
valve 700 is turned off, the air just delivered against the upper
side 24U of diaphragm 24 would normally escape by flowing back
through the solenoid valve and exiting exhaust port 700EX. However,
this is not the way the invention in its preferable mode works, as
the invention does not want this air to be exhausted until
diaphragm 24 has completed its full pumping displacement as
controlled by the microprocessor for the particular liquid color
being supplied and the particular process machine being serviced
thereby. Accordingly, a second solenoid valve, solenoid valve 702,
is connected to the exhaust port of first solenoid valve 700 and is
used to keep exhaust port 700EX closed until venting is
required.
[0092] When it is time to relieve the pressure on diaphragm 24 to
allow diaphragm 24 to return to its neutral position and to allow
liquid color to flow upwardly into pumping chamber 98 that has been
pumped free of liquid color, air must be exhausted from the upper
side 24U of the diaphragm, so second solenoid valve 702 is
energized and the air is vented to atmosphere as indicted by arrow
606 in FIG. 2. Presence of second solenoid valve 702 maintaining
air pressure in the system as air pressure is incrementally applied
to the diaphragm surface 24U by the on and off action of first
solenoid valve 700 facilitates the ultrafine control of the feeding
of liquid color that is effectuated by the instant invention.
[0093] Note that in the four port solenoid valve implementation of
the invention ports 700S-NE and 702S-NE preferably are permanently
sealed.
[0094] Although schematic implementations of present invention and
at least some of its advantages are described in detail
hereinabove, it should be understood that various changes,
substitutions and alterations may be made to the apparatus and
methods disclosed herein without departing from the spirit and
scope of the invention as defined by the appended claims. Moreover,
the scope of this patent application is not intended to be limited
to the particular implementations of apparatus and methods
described in the specification, nor to any methods that may be
described or inferentially understood by those skilled in the art
to be present as described in this specification.
[0095] As one of skill in the art will readily appreciate from the
disclosure of the invention as set forth hereinabove, apparatus,
methods, and steps presently existing or later developed, which
perform substantially the same function or achieve substantially
the same result as the corresponding embodiments described and
disclosed hereinabove, may be utilized according to the description
of the invention and the claims appended hereto. Accordingly, the
appended claims are intended to include within their scope such
apparatus, methods, and processes that provide the same result or
which are, as a matter of law, embraced by the doctrine of the
equivalents respecting the claims of this application.
[0096] As respecting the claims appended hereto, the term
"comprising" means "including but not limited to", whereas the term
"consisting of" means "having only and no more", and the term
"consisting essentially of" means "having only and no more except
for minor additions which would be known to one of skill in the art
as possibly needed for operation of the invention."
* * * * *