PUMP ACTUATOR AND METHOD FOR PUMP OPERATION

Abstract

Method and apparatus for controlling a moveable pumping diaphragm and a liquid color diaphragm pump, including a housing, a movable pin slidably residing within the housing, a potentiometer connected to and residing within the housing for sensing movement of the pin, riding against the diaphragm of the pump and a spring for biasing the pin against the diaphragm.

Claims

1) A method for operating a pump having a movable pumping member and a pumping chamber, comprising: a) positioning a movable reciprocable member in contact with the pumping member to move reciprocally in concert with the pumping member; b) sensing position of the reciprocable member and producing signals indicative thereof; c) periodically applying force to the pumping member to move the pumping member and thereby effectuate pumping of fluid from the chamber; d) using the signals to regulate frequency of force application to the pumping member to achieve a preselected rate of output from the pump.

2) The method of claim 1 further comprising: a) recording the signals at the extremities of reciprocable member travel; b) using those signals and known length of reciprocable member travel to determine location of the reciproable member based on signal received at a given time; c) adjusting the frequency of application of force to the pumping member according to the location of the reciprocable member to maintain a desired output from the pump.

3) The method of claim 2 wherein the step of using those signals and known length of reciprocable member travel to determine location of the reciproable member based on signal received at a given time further includes determining the relationship between duration of force application to the pumping member and pumping member displacement.

4) The method of claim 1 wherein the pumping member is a diaphragm.

5) The method of claim 1 wherein the sensing is performed by a potentiometer.

6) The method of claim 1 wherein the force is pneumatically applied.

7) The method of claim 1 wherein the pumping chamber is air-tight.

8) The method of claim 5 wherein the potentiometer is within an actuator chamber.

9) The method of claim 8 wherein the actuator chamber is sealed.

10) The method of claim 9 wherein the actuator chamber is within polymer foam.

11) The method of claim 1 further comprising adjusting the frequency of application of force to the pumping member according to the location of the reciprocable member to maintain a desired output from the pump.

12) The method of claim 2 wherein the force is applied to the pumping member by bursts of air.

13) The method of claim 1 further comprising the steps of: a) noting position of the reciprocable member as indicated by a potentiometer signal; b) applying a burst of air to the pumping member; c) recording a second potentiometer signal indicative of reciprocable member position; and d) determining pumping member movement as a function of applied force duration from the movement of the reciprocable member in response to the air burst applied to the pumping member.

14) The method of claim 1 wherein periodically applying force to the pumping member to move the pumping member and thereby effectuate pumping of fluid from the chamber is performed by controlling duration and timing of air bursts applied to the pumping member.

15) A method for operating a liquid color diaphragm pump, comprising controlling duration and sequencing of bursts of air applied to a diaphragm contacting the liquid color being pumped.

16) A method for operating a liquid color pump having a movable pumping member and a sealed pumping chamber, comprising: a) positioning a movable reciprocable member within an actuator chamber in contact with the pumping member to move reciprocally in concert with the pumping member; b) sensing position of the reciprocable member within the actuator chamber and producing signals indicative thereof; c) periodically pneumatic applying force to the movable pumping member to move the pumping member and thereby effectuate pumping of liquid color; d) using the signals to regulate frequency of pneumatic force application to the pumping member to achieve a desired rate of output from the pump.

17) An actuator for controlling a movable pumping member in a pump, comprising: a) a housing; b) a movable pin slidably residing within the housing, having an extremity portion passing through the housing for contacting the movable pumping member and moving unitarily therewith; c) a potentiometer connected to and residing within the housing for sensing movement of the pin and producing a signal indicative thereof; and d) a spring for biasing the pin against the pumping member.

18) Apparatus of claim 17 wherein the housing has a first aperture for connection to a supply of pulsed air, wherein the housing has a sealed chamber within the pin, spring and potentiometer reside.

19) Apparatus of claim 17 wherein the potentiometer has a movable portion positioned between and contacting the spring and the pin, for movement with the pin.

20) Apparatus of claim 18 wherein a portion of the housing comprising the chamber is polymer foam.

21) Apparatus of claim 17 wherein the signals are electrical signals, the potentiometer has terminals providing the electrical signals indicative of movement of the pin, and the apparatus further comprises: a) signal carriers electrically connected to the terminals and passing through housing; and b) electrical connectors mounted on the housing exterior and being electrically connected to the signal carriers.

22) Apparatus of claim 20 wherein the signals are electrical signals, the potentiometer has terminals providing the electrical signals indicative of movement of the pin, and the apparatus further comprises: a) signal carriers electrically connected to the terminals and passing through the polymer foam; and b) electrical connectors mounted on the chamber exterior and being electrically connected to the signal carriers.

23) Apparatus of claim 17 wherein the pumping member is a diaphragm.

24) An actuator for controlling a movable pumping diaphragm in a liquid color diaphragm pump, comprising: a) a housing; b) a movable pin slidably residing within the housing, having an extremity portion passing through the housing for contacting the movable pumping member and moving unitarily therewith; c) a potentiometer connected to and residing within the housing for sensing movement of the pin and producing a signal indicative thereof; and d) a spring for biasing the pin against the pumping member; wherein the housing comprises a sealed chamber within which the pin, spring and potentiometer reside; the potentiometer comprises a movable portion positioned between and contacting the spring and the pin for movement with the pin; a portion of the housing comprising the chamber is polymer foam; the potentiometer has terminals providing the signals indicative of pin movement; and further comprising e) signal carriers electrically connected to the terminals and passing through the polymer foam.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG. 1 is a front elevation of an actuator embodying aspects of the invention.

[0022] FIG. 2 is a left side elevation of the actuator illustrated in FIG. 1.

[0023] FIG. 3 is a right side elevation of the right side actuator illustrated in FIGS. 1 and 2.

[0024] FIG. 4 is an isometric view of the actuator illustrated in FIGS. 1 through 3 showing the bottom of the actuator and the left quarter of the actuator, namely the side portion of the actuator shown partially in FIG. 1 and partially in FIG. 2.

[0025] FIG. 5 is an isometric view of the actuator illustrated in FIGS. 1 through 4 showing the right quarter of the actuator, namely the side portion of the actuator illustrated in FIGS. 1 and partially in FIG. 3.

[0026] FIG. 6 is an isometric view of the actuator showing the top of the actuator and the front left quarter side portion illustrated in FIG. 4.

[0027] FIG. 7 is an isometric view of the actuator showing the top of the actuator and the front right quarter side portion illustrated in FIG. 5.

[0028] FIG. 8 is a top view of the actuator illustrated in FIGS. 1 through 7.

[0029] FIG. 9 is a sectional view of the actuator illustrated in FIGS. 1 through 8, with the section taken at lines and arrows A-A in FIG. 8.

[0030] FIG. 10 is a sectional view of the actuator illustrated in FIGS. 1 through 9, with the section taken at lines and arrows B-B in FIG. 8.

[0031] FIG. 11 is a schematic view, partially in section, showing the actuator illustrated in FIGS. 1 through 10 together with a connected microprocessor and a connected solenoid valve.

DESCRIPTION OF THE PREFERRED EMBODIMENTS AND BEST MODE KNOWN FOR PRACTICE OF THE INVENTION

[0032] The actuator 43 of this invention has specific applicably to liquid color diaphragm pumps; the actuator may also be used with piston-type pumps.

[0033] In a pump to which the actuator is best adapted for use, such as that disclosed in U.S. Pat. No. 9,188,118, air is applied to the top side of the diaphragm, to press the diaphragm down. This downward movement of the diaphragm defines the pumping stoke. In the pump, a spring on the bottom side of the diaphragm acts against the diaphragm to move the diaphragm up. Upward movement of the diaphragm in response to the spring pressure defines the suction stroke.

[0034] In the preferred pump, normally the diaphragm is operated in full strokes, moving through the full range of motion for which the diaphragm is designed in the pump. Moving the diaphragm downward through the full range of motion is preferably accomplished by opening a solenoid actuated air valve 70 and applying air pressure to move the diaphragm preferably all the way to the bottom of its range of motion, which may be to the bottom of the pumping cavity.

[0035] 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.

[0036] The 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.

[0037] 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 70 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 valve by the potentiometer and microprocessor, and also allows accurate metering of partial stokes of the diaphragm.

[0038] The actuator of this invention accomplishes this by providing a pin 42 that lightly rides the surface of the diaphragm, following the diaphragm as the diaphragm moves down and up. The actuator 43 of this invention further involves positioning a potentiometer 36, most desirably a linear potentiometer, so that potentiometer 36 is actuated by movement of pin 42. In one preferred embodiment, total diaphragm movement in the invention may be about 0.25 inch. The potentiometer 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.

[0039] Initially, a microprocessor 68 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 the potentiometer slider arm 40 that are between the corresponding upper and lower limits of diaphragm travel to determine the exact location of the diaphragm as the diaphragm moves up and down and pumps liquid color. The 0.25 inch of stroke of the diaphragm translates into about 300 different position readings of the pin 42 and potentiometer slider arm 40, which may be stored and used by the microprocessor, assuring precise readout of diaphragm location at any time.

[0040] The invention provides pin 42 for physical connection of potentiometer 36 with the top side of a diaphragm. This is to sense the movement of the diaphragm. Using a moving pin passing through an air pressure seal would risk leaking air around the seal. Any such air leak, even the slightest air leak, would compromise metering accuracy.

[0041] The invention has no parts moving through a seal. The potentiometer and pin are enclosed entirely within an actuator internal chamber 274 that is pressurized.

[0042] Electrical signals from the potentiometer are brought out of the pressurized volume of actuator internal chamber 274 through screws 257 making contact with potentiometer electrical leads 268, which in turn connect with the potentiometer electrical leads 270 inside the pressurized volume; the screws themselves are sealed against air leakage where they enter the pressurized chamber. Absence of any moving or sliding seals assures correct operation for many years with no wear points to fail.

[0043] A light spring 38, above slide portion 40 of potentiometer 36 and bearing on pin 42, assures that pin 42 follows the diaphragm down as the air pushes the diaphragm down. Preferably a heavy pump spring, inside a preferred pump, pushes the diaphragm up at the end of a pump stoke, and the diaphragm then pushes pin 42 and potentiometer slide portion 40 up against the bias of light spring 38.

[0044] The actuator 43 is removable from the pump. Preferably a one-quarter turn locking system with an O-ring base seal allows the actuator to be installed or removed easily while effectively sealing against the pump surface.

[0045] In the drawings it can be seen that that actuator 43 is generally cylindrical in form, with an air inlet 44 at the top thereof being fed by an air supply line 45, which supplies air indirectly with the air being controlled by solenoid valve 70 preferably operating off of a house air line 74. A microprocessor 68 receives signals from the slide potentiometer designated generally 36 which is resident within actuator 43. Also resident within actuator 43 is light biasing spring 38 which works to bias actuator pin 42 and intervening T-bar portion 40 of slide potentiometer 36 downwardly. This downward bias of actuator pin 42 assures that the end of actuator pin 42 is always riding on the diaphragm of a pump being controlled by actuator 40.

[0046] The diaphragm of the pump does the actual pumping. Spring 38, slide potentiometer 36 and actuator pin 42 monitor the position of the diaphragm in the pumping chamber as the diaphragm moves in response to air pressure, most desirably bursts of air pressure, applied to the top side of the diaphragm as air passes downwardly around the edges of actuator pin 42, as the air is released by intermittent operation of solenoid valve 70 when triggered by microprocessor 68. The air maintains a pressurized condition within actuator internal chamber 274.

[0047] Actuator 43 has an upper portion 250 and a lower portion 252 which are connected and held together by hold down bolts 256. An actuator internal gasket 254 resides between actuator upper portion 250 and actuator lower portion 252.

[0048] Actuator upper portion 250, within which actuator chamber 274 is located, is preferably insulative, air tight polymer foam.

[0049] Actuator 43 further includes actuator signal connection external terminals designated 258 in the drawings which have associated therewith tubular connection covers 260, so that suitable wire connections can be made to actuator signal connection external terminals 258, with the wire connections desirably passing through tubular connection covers 260.

[0050] Actuator 43 further includes a pair of lugs 262 which form the male potion of a preferable quarter turn quick disconnect assembly which allows actuator 43 to be quickly removed from the liquid color pump and replaced if need be. A handle 264 is provided as part of actuator 43 to assist in manual, preferably quarter turn, rotational movement of actuator 43 to remove it from the liquid color pump.

[0051] An abutment plug is provided at the top of pin biasing spring 38, as illustrated in FIG. 11, with a tiny passageway optionally being provided through abutment plug 266 to facilitate air passage from the solenoid valve downwardly through actuator 43 into contact with the upper service of a diaphragm portion of a liquid color pump to which actuator 43 is connected. Alternatively, air from solenoid valve 70 may pass around the sides of a solid abutment plug 266, between abutment plug 266 and the annular interior surface of actuator upper portion 250, to reach the pumping diaphragm.

[0052] Electrical leads from slide potentiometer 36 that are internal to actuator 43 are designated generally 268. These leads extend from potentiometer electrical terminals 270 that are shown in FIG. 11. An actuator chamber 274 is present within upper portion 250 of actuator 43 with slide potentiometer 36, pin biasing spring 38, and the upper portion of actuator pin 42 all being resident therewithin, as illustrated in FIGS. 10 and 11. The actuator chamber 274 present within upper portion 250 of actuator 43 houses slide potentiometer 36, pin biasing spring 38 and the upper portion of actuator pin 42. Upon microprocessor 68 actuating solenoid valve 70 to provide a pulse of air via air inlet 44, the air passes downwardly through inlet 44 into actuator chamber 274 and around and between pin 42 and the surrounding lower portion 252 of actuator 43 to escape at the bottom of pin 42 into the pumping chamber where the air is on the upper side of the pumping diaphragm of the diaphragm pump.

[0053] O-rings 52 are provided so that in combination with the quarter turn release mechanism of which lugs 262 are a part, the actuator upon a quarter turn thereof is in tight facing connection with the frame portion of the associated pump such that an air tight seal is created between the lower planar surface 276 of actuator lower portion 252 and the pumping chamber in which the diaphragm resides. Once the air applied to the diaphragm has pushed the diaphragm downwardly, thereby forcing liquid color below the diaphragm out through the outlet portion of the associated pump, a strong spring also located in the associated pump pushes the diaphragm upwardly, back into the neutral position, whereupon another pulse of air, signaled by the microprocessor and released by action of the solenoid valve, passes downwardly through actuator chamber 274 as described above and applies force in the form of air pressure to the upper side of the pumping diaphragm.

[0054] Actuator chamber 274 is sealed such that air cannot enter actuator chamber 274 other than through the action of microprocessor actuating the solenoid valve and providing air in pulses via air inlet 44. All electrical connections to potentiometer 36 are provided by potentiometer electrical leads 268, typical ones of which have been illustrated in the drawings. These potentiometer electrical leads pass through the polymer foam body of actuator upper portion 250 and are sealed within that polymer foam body so that no air can enter into actuator chamber 274 other than the air provided by solenoid valve 70.

[0055] While the actuator of the invention has been illustrated in generally cylindrical form, the actuator may be in any other form such as with a triangular horizontal cross-section, a rectangular horizontal cross-section, a hexagonal horizontal cross-section, and an octagonal horizontal cross-section, etc.

[0056] Gasket 254 provides a tight seal between the upper portion 250 and lower portion 252 of actuator 43. The presence of air pressure within actuator chamber 274 assures that air will not flow into chamber 274 other than through air inlet 44 as air provided by inlet 44 is on its way to the top surface of the pumping diaphragm.