Control system for metering pump and method
37 claims: 4 independent, 33 dependent
- 1PATENTKRAV 1. Metod för att till en fördelarpistol tillhandahålla fluid uiidtu. Lxyuk med eu doseringspump ansluten till en motor, vilken fördelarpistol öppnas och stängs 5 för att fördela fluid på ett substrat som framförs av en transportör förbi fördelarpistolen, vilken metod innefattar :att förändra en transportörhastighet med en förändringstakt;10 att detektera ett fluidtryck vid fördelarpistolen när transportörhastigheten förändras och fördelarpistolen fördelar fluid;att detektera transportörhastigheter;att förändra ett fluidtryck vid fördelarpistolen i 15 respons på detektering av nämnda tryck och transportörhastigheter, så att fluidtrycket vid fördelarpistolen förändas med en takt som följer en förändringstakt hos transportörhastigheten;att detektera full transportörhastighet;och 20 att därefter automatiskt styra ett fluidflöde vid fördelarpistolen som en funktion av full hastighet hos transportören.
- 2Metod enligt krav 1, varvid steget att automatiskt styra ett fluidflöde vid fördelarpistolen vidare 25 innefattar att detektera ett önskat driftstryck hos fluiden vid fördelarpistolen vid full hastighet hos transportören.
- 3Metod enligt krav 1 eller 2, varvid steget att förändra ett fluidtryck vid fördelarpistolen vidare inne30 fattar:att generera första motorhastighetssignaler i beroende av nämnda detekterade tryck och hastigheter;att styra motorns hastighet som en funktion av nämnda första motorhastighetssignaler, så att fluidtrycket 35 vid fördelarpistolen förändas med en takt som följer en förändringstakt hos transportörhastigheten;och 523 754 att efter detektering av full transportörhastighet automatiskt växla styrning av motorns hastighet från närraida föxöLa muLoxiiasLighetssignaler till en andra motorhast ighet ssignal som endast representerar full transportörhastighet .
- 4Metod enligt krav 3, vidare innefattande:att tillhandahålla en samplad transportörhastighet;att generera ett måltryck som en funktion av nämnda samplade hastighet;att tillhandahålla ett samplat tryck hos fluiden vid fördelarpistolen: och att bestämma nämnda första motorhastighetssignal som en funktion av måltrycket och det samplade trycket.
- 5Metod enligt krav 4, varvid steget att generera måltrycket vidare innefattar att multiplicera den samplade hastigheten med en lagrad konstant, vilken lagrade konstant representerar en kvot med en tälj are som representerar ett tryck vid fördelarpistolen och en nämnare som representerar en transportörhastighet.
- 6Metod enligt krav 4, varvid steget att generera måltrycket vidare innefattar att multiplicera den samplade hastigheten med en lagrad konstant, vilken lagrade konstant representerar en kvot med en tälj are som representerar ett önskat fördelartryck vid fördelarpistolen under en fördelarmanöver och en nämnare som representerar en full transportörhastighet.
- 7Metod enligt krav 4, varvid steget att generera måltrycket vidare innefattar att multiplicera den samplade hastigheten med en lagrad konstant, vilken lagrade konstant representerar en kvot som har en tälj are som representerar ett fullt tryck vid fördelarpistolen vid full transportörhastighet under en omedelbart föregående fördelarmanöver och en nämnare som representerar en full transportörhastighet under nämnda omedelbart föregående fördelarmanöver.
- 8Metod enligt krav 4, vidare innefattande att bestämma den första motorhastighetssignalen genom att an523 754 vända måltrycket och det samplade trycket i en PIDslinga.
- 9Metod enligt krav 3, varvid transportörens hastighet ökas från vila till en full transportörhastighet med nämnda förändringstakt;varvid nämnda detekterade tryck och hastighet samplas ;och varvid nämnda första motorhastighetssignal genereras i beroende av det samplade trycket och den samplade transportörhastigheten.
- 10Metod enligt krav 9, varvid steget att växla styrning av motorns hastighet vidare innefattar:att detektera ett måltryck hos fluiden vid pistolen vid en full transportörhastighet;och att generera nämnda andra motorhastighetssignal i beroende av detektering av måltrycket hos fluiden vid pistolen vid full transportörhastighet.
- 11Metod enligt krav 10, vidare innefattande att generera ett flertal motorhastighetskommandosignaler som funktion av en kombination av de första och andra motorhast ighetssignalerna, varvid varje successiv motorhastighetskommandosignal genereras med successivt mindre delar av den första motorhastighetssignalen och successivt större delar av den andra motorhastighetssignalen.
- 12Metod enligt krav 11, vidare innefattande:att generera initiala motorhastighetskommandosignaler som en funktion av i princip den första motorhastighetssignalen;att generera följande motorhastighetskommandosignaler som en funktion av successivt mindre delar av den första motorhastighetssignalen och successivt större delar av den andra motorhastighetssignalen;och att generera slutliga motorhastighetskommandosignaler som en funktion av i princip den andra motorhastighetssignalen .
- 13Metod enligt krav 11, vidare innefattande att generera motorhastighetskommandosignaler i enlighet med 523 754 MS = F x MS p + (1 - F) x MS ls , där:MS = en motorhastighetskommandosignal, MS P = den första motorhastighetssignalen, MS L s = den andra motorhastighetssignalen, och F = en faktor som med tiden varierar inkrementellt mellan 0 och 1.
- 14Metod enligt krav 9, vidare innefattande:att generera ett måltryck genom att multiplicera den samplade hastigheten med en lagrad konstant, vilken lagrade konstant representerar en kvot som har en tälj are som representerar ett tryck vid fördelarpistolen och en nämnare som representerar en transportörhastighet;och att bestämma den första motorhastighetssignalen som en funktion av måltrycket och det samplade trycket.
- 15Metod enligt krav 14, varvid steget att generera den andra motorhastighetssignalen vidare innefattar att multiplicera den samplade hastigheten med en lagrad konstant, vilken lagrade konstant representerar en kvot som har en tälj are som representerar en motorhastighet och en nämnare som representerar en transportörhastighet.
- 16Metod enligt krav 9, vidare innefattande:att generera ett måltryck genom att multiplicera den samplade hastigheten med en lagrad konstant, vilken lagrade konstant representerar en kvot som har en tälj are som representerar ett önskat fördelartryck vid fördelarpistolen under en fördelarmanöver och en nämnare som representerar en full transportörhastighet;och att bestämma den första motorhastighetssignalen som en funktion av måltrycket och det samplade trycket.
- 17Metod enligt krav 16, varvid steget att generera den andra motorhastighetssignalen vidare innefattar att multiplicera den samplade hastigheten med en lagrad konstant, vilken lagrade konstant representerar en kvot som har en tälj are som representerar en full motorhastighet 523 754 under en fluidfördelarmanöver och en nämnare som representerar en full transportörhastighet. 13. Metod enliyt krav 9, vidare innefacuande:att generera den samplade hastigheten med en lagrad konstant, vilken lagrade konstant representerar en kvot som har en tälj are som representerar ett fullt tryck vid fördelarpistolen vid full transportörhastighet under en omedelbart föregående fördelarmanöver och en nämnare som representerar en full transportörhastighet under den omedelbart föregående fördelarmanövern;och att bestämma den första motorhastighetssignalen som en funktion av måltrycket och det samplade trycket.
- 1819. Metod enligt krav 18, varvid steget att generera den andra motorhastighetssignalen vidare innefattar att multiplicera den samplade hastigheten med en lagrad konstant, vilken lagrade konstant representerar en kvot som har en tälj are som representerar en full motorhastighet vid full transportörhastighet under en omedelbart föregående fördelarmanöver och en nämnare som representerar en full transportörhastighet under den omedelbart föregående fördelarmanövern.
- 1920. Metod enligt krav 19, vidare innefattande att generera motorhastighetskommandosignaler i enlighet med MS = F x MS P + (1 - F) x MS ls , där:MS = en motorhastighetskommandosignal, MS P = den första motorhastighetssignalen, MS L s = den andra motorhastighetssignalen, och F = en faktor som med tiden varierar inkrementellt mellan 0 och 1.
- 2021. Metod enligt krav 9, vidare innefattande:att minska transportörens hastighet från full transportörhat ighet till vila med en förändringstakt;523 754 att generera den första motorhastighetssignalen i respons på samplat tryck och den samplade transportörhasu 1 y lic t, cΪΪ;att förändra motorns hastighet i respons på den första motorhastighetssignalen när transportörhastigheten minskar och att förändra fluidtrycket vid fördelarpistolen med en takt som väsentligen följer förändringstakten hos transportörens hastighet;att detektera ett tryck som är väsentligen lika med ett återcirkulationstryck;och att därefter automatiskt växla styrning av motorns hastighet från nämnda första motorhastighetssignal till en motorhastighetssignal som representerar ett återcirkulations-läge.
- 2122. Anordning för styrning av en hastighet hos en motor av en doseringspump som tillhandahåller en trycksatt fluid vid en fördelarpistol, vilken fördelarpistol öppnas och stängs för att fördela fluid på ett substrat som framförs av en transportör förbi fördelarpistolen, vilken anordning innefattar:en tryckstyrning som genererar första motorhastighetssignaler som en funktion av varierande hastighet hos transportören och varierande tryck i fluiden i fördelarpistolen när fördelarpistolen är öppen;och en flödesstyrning som genererar andra motorhastighetssignaler som en funktion av transportörens hastighet;en motorstyrning som automatiskt reagerar på antingen nämnda första eller andra motorhastighetssignaler, och genererar hastighetsstyrsignaler till motorn, vilka hastighet skommandos ignal er styr motorn vid hastigheter som orsakar pumpen att tillhandahålla fluid till fördelarpistolen vid tryck som förändras med en takt som följer en förändringstakt hos transportörhastigheten.
- 2223. Anordning för styrning av en hastighet hos en motor av en doseringspump som tillhandahåller en trycksatt fluid vid en fördelarpistol, vilken fördelarpistol 523 754 öppnas och stängs för att fördela fluid från ett munstycke på ett substrat som framförs av en transportör forbi fordelcixpj_tsLolen, viiken anordning innefattar:en motorstyrenhet som är operativt ansluten till doseringspumpens motor och som tillhandahåller endera av första motorhastighetssignaler i respons på avkännande av varierande transportörhastigheter och varierande fluidtryck i fördelarpistolen när fördelarpistolen är öppen, och en andra motorhastighetssignal i respons på avkännande av full transportörhastighet, vilka första och andra motorhastighetssignaler styr motorn vid hastigheter som orsakar pumpen att tillhandahålla fluid till fördelarpistolen vid tryck som förändras med en takt som följer en förändringstakt hos transportörhastigheten.
- 2324. Anordning enligt krav 23, varvid motorstyrenheten innefattar:en första ingång som mottar transportöråterkopplingssignaler som representerar respektive transportörhastighet;och en andra ingång som mottar tryckåterkopplingssignaler som representerar respektive fluidtryck.
- 2425. Anordning enligt krav 24, varvid nämnda tryckåterkopplingssignaler representerar respektive fluidtryck vid en punkt omedelbart uppströms munstycket.
- 2526. Anordningen enligt krav 24 eller 25, varvid nämnda motorstyrenhet genererar måltryck som funktion av transportörhastigheterna och tillhandahåller nämnda första motorhastghetssignaler som funktion av måltrycken och fluidtrycken som representeras av respektive tryckåterkopplingsignaler.
- 2627. Anordning enligt krav 24 eller 25, varvid nämnda motorstyrenhet genererar varje måltryck genom att multiplicera en av transportörhastigheterna med en lagrad konstant, vilken lagrade konstant representerar en kvot som har en nämnare som representerar ett tryck vid fördelarpistolen och en nämnare som representerar en transportörhastighet . 523 754
- 2728. Anordning enligt krav 24 eller 25, varvid nämnda motorstyrenhet genererar varje måltryck genom att multiplicera en av transportörhastigheterna med en lagrad konstant, vilken lagrade konstant representerar en kvot med en tälj are som representerar ett önskat fördelartryck vid fördelarpistolen under en fördelarmanöver och en nämnare som representerar en full transportörhastighet.
- 2829. Anordning enligt krav 24 eller 25, varvid nämnda motorstyrenhet genererar varje måltryck genom att multiplicera en av transportörhastigheterna med en lagrad konstant, vilken lagrade konstant representerar en kvot som har en tälj are som representerar ett fullt tryck vid fördelarpistolen vid full transportörhastighet under en omedelbart föregående fördelarmanöver och en nämnare som representerar en full transportörhastighet under nämnda omedelbart föregående fördelarmanöver.
- 2930. Anordning enligt krav 24 eller 25, varvid nämnda motorstyrenhet bestämmer nämnda första motorhastighetssignaler genom att använda måltrycken och trycken vid fördelarpistolen i en proportionell, integrerande och deriverande (PID) slinga.
- 3031. Anordning enligt något av kraven 24 - 30, varvid nämnda motorstyrenhet vidare innefattar:en tryckstyrning som reagerar på transportör- och tryckåterkopplingssignaler och genererar nämnda första motorhastighetssignaler som en funktion av varierande transportörhastigheter och varierande fluidtryck i fördelarpistolen när fördelarpistolen är öppen;och en flödesstyming som reagerar på transportöråterkopplingssignaler och genererar nämnda andra motorhastighetssignal som en funktion av full transportörhastighet.
- 3132. Anordning enligt krav 31, varvid nämnda motorstyrenhet vidare innefattar en motorstyrning som bringar nämnda motorstyrenhet att tillhandahålla nämnda första motorstyrsignaler i respons på detektering av en transportörhastighet som är mindre än full transportörhastighet, och 523 754 nämnda andra motorhastighetssignal i respons på detektering av full transportörhastighet.
- 3233. Ainjj-diiiny enligt krav 31 eller varvid namncla motorstyrenhet vidare innefattar:en tryckstyrning som genererar nämnda första motorhastighetssignaler som en funktion av varierande transportörhast igheter och varierande fluidtryck i fördelarpistolen när fördelarpistolen är öppen, och en flödesstyrning som genererar nämnda andra motorhastighetssignal som en funktion av full transportörhastighet .
- 3334. Anordning för styrning av en hastighet hos en motor av en doseringspump som tillhandahåller en trycksatt fluid vid en fördelarpistol, vilken fördelarpistol öppnas och stängs för att fördela fluid på ett substrat som framförs av en transportör förbi fördelarpistolen, vilken anordning innefattar:en motorstyrenhet som är operativt ansluten till doseringspumpens motor och som tillhandahåller första motorhastighetssignaler i respons på detektering av varierande transportörhastigheter och varierande fluidtryck i fördelarpistolen när fördelarpistolen är öppen, och en andra motorhastighetssignal i respons på detektering av en full transportörhastighet, varvid nämnda motorstyrenhet är anordnad att automatiskt växla styrning av motorns hastighet mellan nämnda första motorhastighetssignaler och nämnda andra motorhastighetssignal, vilka första och andra motorhastighetssignaler styr motorn vid hastigheter som orsakar pumpen att tillhandahålla fluid till fördelarpistolen vid tryck som förändras med en takt som följer en förändringstakt hos transportörens hastighet.
- 3435. Anordning enligt krav 34, varvid nämnda motorstyrenhet är anordnad att automatiskt växla styrning av motorns hastighet genom att först detektera ett måltryck 523 754 hos fluiden vid pistolen vid en full transportörhastighet, och sedan att tillhandahålla nämnda andra motorhastxyhetööxyTiäl j. beiuenue av detektering av måltrycket hos fluiden vid pistolen vid full transportörhastighet.
- 3536. Anordning enligt krav 35, varvid nämnda motorstyrenhet genererar ett flertal motorhastighetsstyrsignaler som funktion av en kombination av nämnda första och andra motorhastighetssignaler, varvid varje successiv motorhastighetsstyrsignal genereras med successivt mindre delar av den första motorhastighetssignalen och successivt större delar av den andra motorhastighetssignalen.
- 3637. Anordning enligt krav 36, varvid nämnda motorstyrenhet genererar initiala motorhastighetsstyrsignaler som en funktion av väsentligen den första motorhastighetssignalen, därefter genererar följande motorhastighetsstyrsignaler som en funktion av successivt mindre delar av den första motorhastighetssignalen och successivt större delar av den andra motorhastighetssignalen, och därefter genererar slutliga motorhastighetsstyrsignaler som funktion av väsentligen den andra motorhastighetssignalen.
- 3738. Anordning enligt krav 37, varvid nämnda motorstyrenhet är anordnad att generera motorhastighetsstyrsignaler i enlighet med MS = F x MS P + (1 - F) x MS ls , där:MS = en motorhastighetsstyrsignal, MS P = den första motorhastighetssignalen, MS L s = den andra motorhastighetssignalen, och F = en faktor som med tiden varierar inkrementellt mellan 0 och 1. 523 754 1 MOTOR θ-Μ---I .1 523 754 (°) (c)
Independent claims37
83 paragraphs in 2 sections, as filed
(54) NAME Control system for dosing pump and method (56) PUBLICATIONS QUOTED:
US A 4,530,862 (427: 445) (57) SUMMARY:
An apparatus for controlling the speed of an engine in a metering pump which provides pressurized fluid at a distributor gun. The distributor gun is opened and closed to disperse fluid on a substrate conveyed by a conveyor past the distributor gun. The device has a pressure control which generates first engine speed signals as a function of varying speeds of the conveyor and varying fluid pressure in the distributor gun when the distributor gun is open. A flow control generates other motor speed signals as a function of varying conveyor speeds. During changes in the conveyor speed, an engine speed control provides the first engine speed signal to the putter motor, which drives the engine at speeds causing the pump to supply the fluid to the distributor gun at pressure which changes at a rate that follows a rate of change of the conveyor speed. When full conveyor speed is detected, the motor speed control provides the second motor speed signal to the pump motor, which drives the engine at speeds determined by full conveyor speed. Furthermore, methods are presented for generating pressure-related and conveyor speed-related motor speed signals and to automatically switch between these signals as a function of conveyor speed.
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The numbers in brackets indicate international identification code, INID code. Letters in clamps indicate international document code.
523 754
SUMMARY
An apparatus for controlling the speed of an engine in a metering pump which provides pressurized fluid at a distributor gun. The distributor gun is opened and closed to disperse fluid on a substrate conveyed by a conveyor past the distributor gun. The device has a pressure control which generates first engine speed signals as a function of varying speeds of the conveyor and varying fluid pressure in the distributor gun when the distributor gun is open. A flow control generates other engine speed signals as a function of varying conveyor speeds. During changes in the conveyor speed, an engine speed controller provides the first engine speed signal to the pump motor, which drives the engine at speeds causing the pump to supply the fluid to the distributor gun at pressure which changes at a rate that follows a rate of change of the conveyor speed. When full conveyor speed is detected, the motor speed control provides the second motor speed signal to the pump motor, which drives the motor at speeds determined by full conveyor speed. Further, methods are presented for generating pressure-related and conveyor speed-related engine speed signals and to automatically switch between these signals as a function of conveyor speed.
* 523 754
Technical area
The present invention relates generally to a device for distributing viscous fluids and in particular to a device and method for providing a distributor gun with molten adhesives.
Technical background
The ability to accurately distribute viscous industrial materials, such as melt adhesives, is a necessity for manufacturers active in the packaging and plastics industries. Inconsistent application of adhesive to a substrate results in useless and discarded products and increased costs. The process of feeding adhesively to a fluid distributing applicator or gun must therefore be carefully controlled
A typical fluid distribution operation utilizes a distributor gun to apply a fluid, for example an adhesive, to a substrate which is moved past the distributor gun by a conveyor. The speed of the conveyor, or line speed, is determined according to such factors as the complexity of the distributor pattern and the configuration of the gun. Fluid adhesives are usually fed to the distributor gun via flexible hoses. Adhesive is pumped from a container of a metering pump, for example, a motor driven positive displacement pump. A metering pump for the purposes herein is a pump in which the discharge volume is proportional to the action or displacement of the pump, depending on the viscosity of the fluid, in addition to fluid leakage into the pump. With a metering pump, therefore, the flow rate of adhesive distributed from the gun is a function of the speed of the motor driving the pump.
Proper application of fluid or adhesive to a substrate requires that the flow rate of the fluid from
523 The 754 distributor gun remains as constant as possible through the fluid distribution process. Variations in flow rate result in different quantities or volumes of fluid applied at different locations along the substrate. Therefore, with too little adhesive, a desired thickness is not achieved and the quality of the adhesive capacity is reduced. Similarly, when an excess quantity is distributed, the adhesive can subsequently be distributed to areas of the substrate where it is not desired, and again the quality of the substrate product is reduced. In both cases, the result is usually a discarded product.
In many applications, the speed of the carrier carrying the substrate is adjustable, and changes according to the production line's ability to produce a high quality product. In the first run of a product, for example, a production line can be controlled at a slower rate to ensure a high quality product. Over time, as the product line is adapted, it can run at higher conveyor speeds and still produce a high quality product. Assume that the fluid distributor system is operated correctly when the conveyor is operated at a first constant speed. If the velocity of the conveyor and substrate is increased to a higher constant velocity, the flow rate of fluid dispensed by the gun must also be increased to maintain a consistent high-quality coating of fluid on the substrate. It is known to use a signal associated with the higher constant speed so that the speed of the pump motor can be increased and the flow of fluid to the gun increased, causing the pressure in the gun to increase. The increased gun pressure causes the flow rate of fluid from the gun to increase and the flow rate of fluid distributed to change as a function of the conveyor speed.
The above-mentioned flow control system works relatively well when the conveyor is operated at a constant speed, but the flow control system does not function properly during the period.
523 754 when the conveyor accelerates or decelerates. Such changes in the speed of the conveyor occur, for example, when the conveyor is initially booted from rest. Known systems lack the ability to maintain the desired flow rate of fluid through the distributor gun during periods when the conveyor accelerates or accelerates.
Fig. 5A shows how the flow pressure in the distributor gun changes with respect to acceleration and deceleration of the conveyor. With some systems, such as those using a pressure relief recirculation valve, the recirculation pressure when the conveyor is operated at a rate of zero 504 is higher 502 than a desired operating pressure 504 of the distributor gun. Therefore, when the conveyor line is initially launched 506 and accelerated, fluid distribution occurs at too high a pressure, leading to deposition of excessive amounts of fluid and production of discarded products. Production of discarded product will continue as the pressure increases 508 and the conveyor accelerates until both the conveyor speed and the operating pressure reach their desired value 509. For illustrative purposes, the desired values of conveyor speed and operating pressure are shown as common line 504. When a deceleration command is given 530, conveyor speed 532 decreases to zero 534. However, when the distributor gun closes, pressure 536 increases until the pressure drop valve opens. In other recirculation systems, a solenoid operated pressure relief valve is provided in series with a restricted aperture, and when the recirculation valve opens, recirculation pressure 510 is maintained at a lower level than the desired operating pressure. As the conveyor accelerates 506, the gun pressure first drops to an even lower level 512 faster than the metering pump can increase the pressure. Therefore, for a short period of time after the conveyor line begins to start, an excessive amount of fluid is distributed, resulting in the production of discard products. As the conveyor line accelerates, one is distributed
523 754 current conveyor speed, at any position 514, the right amount of fluid, but continued acceleration 516 of the conveyor with layic pressure. q ± ie ± ± L t i i i i are an an an an an an an an an an an an an an the desired flow rate of fluid through the distributor gun. Therefore, discard products continue to be produced until the conveyor speed and operating pressure both reach their desired values 40. As the conveyor begins a deceleration, the recirculation valve opens and the pressure decreases until it stabilizes at a value determined by the restricted opening.
As can be seen from Fig. 5A, with the lower recirculation pressure just described, the conveyor accelerates to its desired speed well in advance of the distributor gun pressure reaching its desired operating pressure. A major contributing factor to this extended pressure recovery time is the use of flexible hoses connecting the pump to the distributor gun. At the desired operating pressure, the hoses expand somewhat and the amount of fluid distributed is small relative to the volume of the hoses. In fact, often the amount of fluid dispensed is no more, and often less than, the expansion of, or increased the volume of, the hose at the desired operating pressure. Therefore, it takes longer for the pump to regain the desired gun pressure since the pumped fluid must again exhale the hose with fluid to achieve the desired operating pressure. It will be appreciated that the graphical representations of print and line speeds in Fig. 5 are exemplary only. The acceleration and deceleration of the conveyor often vary non-linearly and are usually not linear as shown. Furthermore, the carrier's acceleration and deceleration may vary from day to day and may be different with different systems. Furthermore, the exact profile of pressure with respect to time often varies substantially at a moment and is in no way as35 associated with the speed of the conveyor.
Therefore, there is a need for a fluid distributor system which maintains a desired fluid flow rate
523 754 through the distributor gun when the speed of the conveyor carrying the substrate changes, for example when the conveyor accelerates the funnel to rest to its desired conveyor speed.
Summary of the Invention
The fluid distributor system of the present invention addresses the above and other problems associated with known systems by providing a system for pumping a fluid into a distributor gun. The fluid distributor system of the present invention minimizes the production of discarding products during periods when the conveyor speed changes. The fluid distributor system of the present invention is particularly useful at the beginning of a production series when the conveyor accelerates from rest to a desired full production rate. In addition, the fluid distributor system provides the same benefits at the end of a production series as the conveyor decelerates from full production speed to rest. Thus, by reducing cassette production, the fluid distributor system of the present invention reduces the cost of cassette production, maintenance and the unit price of the product.
In accordance with the principles of the present invention and the described embodiments, the invention provides, in one embodiment, a device for controlling the speed of a motor in a metering pump supplying a pressurized fluid dispensing gun. The distributor gun is opened and closed to disperse fluid on a substrate conveyed by a conveyor past the distributor gun. The device has a pressure control that generates first engine speed signals as a function of changes in the conveyor speed and fluid pressure in the distributor gun when the distributor gun is open. A flow control generates other engine speed signals as a function of changes in the conveyor speed.
An engine controller automatically responds to the first and second
523 754 engine speed signals to generate speed command signals for the engine. The speed command signals control the engine at speeds causing the pump to supply fluid to the distributor gun at pressure which changes at a rate that follows a rate of change of the conveyor speed.
The first motor speed signal from the pressure control controls the pump motor according to both the conveyor speed and the fluid pressure at the distributor gun during an acceleration and deceleration of the conveyor. Thus, the pressure at the distributor gun changes at a rate that follows the acceleration and deceleration of the conveyor, and the flow of fluid from the distributor also follows the acceleration and deceleration of the conveyor to disperse the correct amount of fluid onto the substrate. When the conveyor reaches constant full speed, the motor control supplies the pump motor with the second motor speed signal, which regulates the flow of fluid according to constant full conveyor speed.
According to a second embodiment, the invention comprises a method of supplying a pressurized fluid distributor gun by means of a metering pump connected to a motor. The distributor gun is opened and closed to disperse fluid onto a substrate conveyed by a conveyor for the distributor gun. First, a speed of the conveyor is changed. Then the fluid pressure is sensed at the distributor gun while the speed of the conveyor changes and the distributor gun distributes fluid. Furthermore, the conveyor speed is detected as the conveyor speed changes. In accordance with sensed pressures and velocities, the fluid pressure in the distributor gun changes at a rate substantially following a rate of change of the conveyor speed. Thereafter, the fluid flow is automatically controlled as a function of detecting the full speed of the conveyor.
According to one aspect of the invention, first motor speed signals are generated in accordance with the sensed fluid 5223 754 pressures and conveyor speeds, and a second motor speed signal is generated in accordance with sensed full conveyor speeds. the motor speed control is automatically switched from the first motor speed signals to the second motor speed signal as the conveyor has full conveyor speed.
According to a further aspect of the invention, the control of the engine speed is gradually switched from the first engine speed signals to the second engine speed signal by different proportions of first and second engine speed signals.
The foregoing and other objects and advantages of the present invention will become more apparent from the accompanying drawings and the description thereof.
Brief description of the drawings
The accompanying drawing, which is included and forms part of this description, illustrates embodiments of the invention and aims, together with a general description of the invention given above and the detailed description of embodiments given below, to describe the invention.
Fig. 1 is an overall schematic block diagram of a fluid distributor system in accordance with the principles of the invention.
Figures 2A-2B are flow charts showing one embodiment of a process for controlling the pump motor speed of the fluid distributor system of Figure 1.
Figures 3A-3C are flow charts showing a further embodiment of a process for controlling the pump motor speed in the fluid distributor system of Figure 1.
Fig. 4 is a flow chart showing a cycle for obtaining values of parameters used in the processes for controlling the pump motor speed in the fluid distributor system of Fig. 1.
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Fig. 5A is a graphical illustration of known relationships between conveyor speed and fluid distributor pressure with respect to time.
Fig. 5B is a graphical illustration of a new fluid distributor pressure coefficient with respect to time when the fluid distributor system of Fig. 1 is used.
Detailed description of the invention
With reference to Figure 1, a fluid distribution system comprises a fluid distributor gun 22 with a nozzle 24 for distributing a fluid 26, for example an adhesive, on a substrate 28. The substrate 28 is advanced by a conveyor 30 past the distributor gun 22. The conveyor 30 is mechanically coupled to a conveyor drive having a conveyor motor 32. The speed of the conveyor is sensed by a conveyor feedback device 34, for example, an encoder mechanically coupled to the conveyor 30. The feedback device 34 has an output 36 connected to a control unit 38 of the distributor gun, and the feedback device 34 generates a feedback signal which changes as a function of changes in the conveyor speed.
A system controller 42 generally functions to coordinate the operation of the overall fluid distributor system. For example, the system controller 42 usually provides a user interface for the system and controls the operation of the conveyor motor 32 via a signal line 43. Within the system controller 42 there is furthermore a pattern control unit 44 which controls the operation of the fluid distributor seat 22 as a function of the specific application being run. The pattern control unit 44 receives, at input 40, a part-present signal, or trigger signal, which provides a synchronization with the movement of the substrate 28 on the movable conveyor 30. In response to the trigger 35 signal at the input 40 of the system controller 42, the system controller provides a first signal to the gun control unit 38 via an input 45, and requests that the pi523 754 gun control unit close a recirculation valve 56. The recirculation valve 56 is used to shunt fluid from the metering pump 52 around the distributor valve 50 and back to the reservoir 54 during passive periods, for example between parts. Further, in response to the trigger signal, the pattern control unit 44 provides a sequence of ON / OFF signals to the gun, usually in the form of pulses to the gun control unit 38 via an input 47.
In response to the positive flank of the ON / OFF pulse, the gun control unit 38 provides an on command on output 46 which actuates a solenoid 48 in the distributor gun 22. The solenoid 48 is mechanically coupled to a distributor valve 50 which is fluidly connected to a metering pump 52 which , in turn, receives fluid from a fluid reservoir 54. Upon receiving a signal at output 46 from gun control unit 38, coil 48 opens distributor valve 50. The pressurized adhesive in the distributor gun passes through the nozzle 24 and is deposited on the substrate 28. The distributor valve remains open for the time that
The ON / OFF pulse lasts, and in response to the negative edge of the ON / OFF pulse, the gun control unit changes the state of the solenoid 48 to close the distributor valve 50. In most applications, a plurality of ON / OFF pulses cause the gun control unit to quickly open and close the distributor valve. distributing the fluid at different locations on the substrate as the substrate 28 moves past the distributor gun 22.
The pump 52 is a positive displacement pump, and the volume of fluid supplied to the distributor valve 50 and distributed through the nozzle 24 is therefore, for a distributor period, directly proportional to the speed of the pump motor 58. An engine speed control unit 57 in gun control unit 38 responds to conveyor feedback device 34 and a pressure feedback device 62 to provide engine speed command signals at an output 61 to pump motor 58. A flow control 60 in the motor speed controller 57 responds to the feedback signal from the feedback device 34 to provide a motor speed signal in the form of motor speed dependent on line speed (MS<sub>L</sub>s) · This MS<sub>LS</sub>signal is provided by motor speed control 68 via a signal line 61 to pump motor 58. This MS<sub>LS</sub>signal changes as a function of line speed of conveyor 30; and thus the pump motor 58 is controlled to have a speed related to the speed of the conveyor 30. Accordingly, the fluid flow through the distributor valve 50 changes as a function of changes in the conveyor speed.
As previously described, such a line speed control system has certain disadvantages during periods of acceleration and deceleration of the conveyor. The present invention therefore uses a pressure transducer 62 which senses pressure at a point immediately upstream of the distributor nozzle 24. The pressure control 66 provides an engine speed signal in the form of engine speed due to pressure (MS<sub>P</sub>) in response to the feedback signal from feedback device 34 and a pressure feedback signal on an output 64. Motor speed control 68 switches control of pump motor 58 between MS<sub>L</sub>s signal at an input 70 and MS<sub>p</sub>signal at an input 72. At the beginning of an acceleration or deacceleration period, the mo25 torque selector 68 essentially selects the pump motor 58 as a function of the distributor gun fluid pressure, i.e., MS<sub>p</sub>signal from the pressure control 66. When the pressure of the distributor gun equals the desired operating pressure with the conveyor at full line speed, the motor speed selector 68 switches control of the pump motor 58 from a pressure control to flow control using MS.<sub>LS</sub>signal from control 60.
One embodiment of such operation of the gun control unit 38 is illustrated by the flow chart of Fig. 2A and
2B. When a flow distributor system shown in Fig. 1 is started, pump motor 58 is started before conveyor motor 32 to initially stabilize and pressurize the fluid system
523 754 t
included in pump 52, recirculation valve 56 and fluid reservoir 54. Engine 58 is operated at a constant ether circulation rate such that a known pressure is generated at the output of pump 52. Pressure can be created by recirculation valve 56 which is a pressure relief valve.
Alternatively, the recirculation valve 56 may be a solenoid valve having a serially connected restricted aperture which provides the desired pressure relief. The pressure at the output of pump 52 may be higher or lower than normal operating pressure sensed by sensor 62 immediately upstream of nozzle 24.
By providing better control of pump motor 58 speed, gun control unit 38 first determines, at 202 in FIG. 2A, whether a conveyor start command has been issued by system controller 42 to conveyor motor 32. A signal represents system controller 42. Gun control unit 38 switches, at 204, to pressure control of pump motor 58 and terminates the recirculation control. To end the recirculation check, the control unit 38 provides a signal over an input 59 causing the recirculation valve 56 to close, which terminates the recirculation position. This step is necessary if the recirculation path includes a solenoid valve. If the recirculation valve is a pressure relief valve, the recirculation position is closed by a lower pressure differential across the pressure relief valve caused by the distributor valve being opened. Then, at 206, the gun control unit 38 samples the feedback signal from the conveyor encoder 34 which represents the speed of the conveyor. The control unit 38 then multiplies, at 208, the newly sampled conveyor speed by a stored pressure conversion constant to determine a target pressure value or setpoint. The stored pressure conversion constant is a ratio having a counter equal to the desired distributor pressure and a denominator equal to full line speed. Then, at 210, the control unit 38 determines if the target pressure value is greater than a maximum pressure limit, ex523,754, for example 1500 psi, and if so, the target pressure, at 212, is set equal to the maximum pressure limit. The control unit 38 then determines that the fluid surface area is less than a minimum pressure limit, for example 25 psi; and if this fails, the target pressure, at 216, is set to a value equal to the minimum pressure limit.
The control unit then samples, at 218, a pressure feedback signal provided from the output 64 of the pressure transducer 62. The pressure control 66 in the control unit 38 determines, at 22 0, a value for the MS.<sub>P</sub> using the target pressure and the gun's sampled operating pressure in a PID process of known kind with acceleration PID constants. The PID process is determined by proportional and / or integrated and / or derivative terms depending on the application and desired response, and each term has a gain or multiplier that is in the range of zero to a value determined empirically to provide the desired response and stable operation. of the motor 52 of the pump 52. At the start of an acceleration cycle of the conveyor, the engine speed selector applies 68 MS<sub>p</sub>signal to the pump motor 58.
The results of using pressure as a pump motor control signal are shown in Fig. 5B. As can be seen from this embodiment, the recirculation pressure 550 is less than in previous systems. Further, when the line velocity provides a target pressure value equal to the recirculation pressure 552, the control unit 38 provides a signal at the output 59 to close the recirculation valve 56. At the same time, the control unit 38 provides a signal at the output 46 to cause the solenoid 48 to open the distributor valve.
A signal to the pump motor 58 so that changes in distributor gun pressure 554 follow changes in conveyor speed 516 with respect to time. To produce a desired response, the PID constants are set such that pressure 558 easily exceeds full line speed 504. It should be noted that the desired response will differ between different applications and constructors. The pressure curve in Fig. 5B at
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558 appears as somewhat subdued. However, it will be appreciated that the PID process can be adjusted to provide a more critically attenuated pressure function or even an attenuated pressure function.
The control unit 38 then determines at 222 (Fig. 2B) if the operating gun pressure is equal to the target pressure at full line speed. The point at which the pressure intersects the constant line speed at 555 is theoretically the ideal pressure to be sensed. However, for several reasons, for example that the target pressure is determined from a conversion constant based on non-current values, sensing the pressure at 555 is very difficult. The applicant therefore senses the pressure when the pressure has stabilized and therefore the slope has substantially close to zero for a period of time. It will be appreciated that other methods of pressure sensing at full line speed can be utilized. Upon sensing the target pressure at full line speed (562 in Fig. 5B), the motor speed controller 57 at 224 switches to flow control of the pump motor 58. The motor speed control 68 of the motor speed controller unit 57 thus switches control of the motor 58 from the MS.<sub>P</sub> the engine speed signal to MS<sub>L</sub>s engine speed signal. In this position, 564 transfers control of the pressure in distributor gun 22 from switching point 562 to a flow control 566 which is determined by the full line speed of the conveyor.
While the conveyor is operating at full line speed, the speed of the pump motor 58 is controlled by the gun control unit 38 as a function of the conveyor feedback signal in a known manner. In 226 (Fig. 2B), it is determined whether a stop command to the conveyor has been issued by the system controller 42. As in the acceleration mode, the control of the speed of the pump motor 58 by means of the conveyor feedback signal does not take into account variations in pressure arising from the fluid distribution process in the acceleration mode. Therefore, the motor speed selector in gun control unit 38 switches control of pump motor 58 from flow control 60 to pressure control 66. Again
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In sampling a conveyor speed at 228 and a target pressure is determined, at 230, in the same way as previously described, as well as previous eye squats, the target pressure is checked against maximum and minimum limits in 232 to 238. The gun pressure is again sampled at 240. An engine speed value MS<sub>P </sub>is determined, at 242, by the control unit 38 using the target pressure and the sampled pressure in a PID loop with deceleration PID constants, and MS<sub>p</sub>The value is applied to the pump motor 58. The gun control unit 38 then detects at 244 from the pressure feedback signal on line 64 when the distributor gun pressure is equal to the desired recirculation pressure. When the recirculation pressure is reached, the gun control unit 38, at 246, switches to recirculation control of the pump motor 58. The control unit 38 provides a first signal on line 61 instructing pump motor 58 to operate at a recirculation rate and a second signal on line 59 instructing recirculation valve to open. Thereafter, the system controller 42 stops the operation of the conveyor engine at the end of the acceleration cycle.
Again with reference to Fig. 5B, the pressure results
576 from switching the pump motor 58 to pressure control 66 upon initiation of a deceleration 574. Changes in the distributor gun pressure 580 normally follow changes in the stopped conveyor line speed 532 such that the correct amount of fluid is supplied by the pump 52 to the distributor gun 22 and distributed on the substrate 28. Upon reaching the recirculation pressure, the recirculation valve 56 is opened and the pump motor operates at the recirculation speed, which stabilizes the recirculation pressure. The conveyor stops at zero 534.
The above system provides a substantially improved ratio of distributor gun pressure to conveyor line speed during periods of acceleration and deceleration of conveyor 30. With the above system, as the conveyor accelerates or decelerates,
523 754, a pressure control system is active, in which the engine pump speed is under the control of a pressure loop which causes a rate of change in the flow pressure at the gun to follow or track a rate of change in the conveyor speed. However, when the conveyor reaches full speed, regulation of the pump motor is switched from a pressure control system to a flow control system, in which the speed of the pump motor is controlled solely as a function of the conveyor line speed. Such a system is effective in different applications and on different systems where the acceleration and deceleration of the conveyor will vary. Further, with the distributor system of the present invention, the distribution of fluid on the substrate 28 is maintained for periods of acceleration and deceleration within the specification, and disposal of products can be eliminated.
However, there is a disadvantage to the process described with reference to Figures 2A and 2B. With reference to Fig. 5B, control of the pump motor 58 is switched from pressure control 66 to flow control 60 at a time 562. However, at the shift, the engine speed resulting from pressure control differs from the engine speed resulting from operation with flow control 60. The system therefore attempts to effect an instantaneous engine speed change with this difference. Such a sudden change in engine speed can result in shock or jerk operation of the pump motor 58, which creates mechanical strain on the motor and the pump, as well as pressure irregularities and irregular fluid distribution in the distributor gun 22.
Figures 3A-3C illustrate an alternative embodiment of the invention in which the transition between pressure control of pump motor 58 and line speed control of pump motor 58 is gradual and controlled. In this embodiment, the function of pressing steps 302-320 is identical to the operation of process steps 202-220 previously described with respect to Figures 2A-2B. Referring to Fig. 3B, 523,754 more control unit 38, at 321, also determines a target line speed threshold or setpoint by multiplying the current values of the conveyor speed by an engine speed conversion constant. The engine speed conversion constant is a ratio having a counter equal to the full speed of pump motor 58 and a denominator equal to the full line speed of conveyor 30. The product of the last sampled conveyor line speed times the engine speed conversion constant is stored by the controller
38 as an MS<sub>LS</sub>-value.
As previously described with reference to Fig. 2, the engine speed selector 68 again determines in the engine speed controller 57, at 322, whether the current distributor gun pressure is equal to the target pressure at full line speed 15. When this selector point is detected, the motor speed selector 68 gradually changes the control of the speed of the pump motor 58 from pressure control 66 to flow control 60. The change in control can be performed linearly or non-linearly with time. Further, the incremental resolution of each step of the transition can be selected according to a particular application, user preferences, etc. Motor speed selector 68 first sets, at 324, a transition constant F equal to 1. Then, at 326, motor speed selector 68 determines a first increase of the transition in accordance with the following:
MS = F x MS<sub>P</sub> + (1-F) x MS<sub>ls</sub>, and this value of MS is applied to the pump motor 58. Then 30, at 328, the engine speed selector decreases the value of F, and determines, at 330, if the value F equals zero. The process in steps 324-330 is iterated until the value of F equals zero. With each iteration through steps 324-330, F can be fractionally reduced in equal or different steps. Furthermore, any number of steps can be used. When F equals zero, the full value of MS is applied<sub>LS</sub> the engine speed signal to pump motor 58, and, at 331,
523 754, the motor speed control unit 57 switches to flow control of motor 58. The control of pump motor 58 is thus gradually shifted from crank stirring 66 to flow control 60. Such a gradual change of control helps to minimize sudden changes in motor speed commands of pump motor pauses that can result in pump motor 58 in the distributor gun 22, leading to sudden changes in the fluid being distributed.
At 332, then gun control unit 38 is provided with an input from system controller 42, indicating that conveyor 30 has been instructed to stop. In an identical manner as previously described with respect to steps 306-321, the conveyor speed is sampled.
334, a target pressure is determined and checked against maximum and minimum limits at 336-344. The gun pressure is then sampled at 346, and one MS<sub>p</sub>value is determined at 348 and applied to the pump motor. The recirculation pressure is detected at 250, and if the pressure is greater than the recirculation pressure, the process is iterated in steps 334-350. The operation of the pump motor 58 remains controlled by pressure control 66 until the recirculation pressure is reached. Then, as previously described, gun control unit 38 switches the system back to recirculation control at 352.
5 In the embodiments illustrated in Figures 2 and 3, various conversion constants are used which are based on full distributor pressure, full line speed and full engine speed. These values can be determined in advance and manually entered into the system controller 42 and sent to the gun control unit 38 for storage. Alternatively, these values may be continuously determined and stored by the gun control unit 38. For example, with reference to Fig. 4, at 402, the control unit 38 first determines when the conveyor has reached its full line speed. When full line speed has been detected, gun control unit 38 samples at 404 pressure feedback signal, determines average distributor pressure and stores
523 754 this value. Then, at 406, the control unit 38 samples the conveyor feedback signal, determines the average flow line velocity value and stores this value. At 408, the controller 38 samples a pump motor5 feedback signal on line 63, determines an average motor speed value and stores it. The process of Fig. 4 can be performed continuously while the conveyor is operating at full line speed, so stored values always represent the latest full-scale values of pre-gun pressure, conveyor line speed, and pump motor speed. Alternatively, the process of Fig. 4 can be run at selected times during operation of the conveyor, for example immediately before the conveyor is instructed to stop.
The fluid distributor system described above allows for accurate distribution of fluid on a substrate during periods when the conveyor accelerates and decelerates, allowing the production of good products throughout the conveyor's operating time. Thus, the flow distributor system is
While the present invention has been illustrated by a description of various embodiments and while these embodiments have been described in great detail, it is not the applicant's intention to limit or in any way limit the scope of the appended claims to that detail. Further advantages and modifications will be more apparent to the individual skilled in the art. For example, in the described embodiments, during periods when the conveyor speed changes, a pressure feedback signal is used with a target pressure in a PID process to provide engine speed signals which drive the engine at speeds causing fluid pressure changes in the distributor gun to track changes in the conveyor speed. It will be appreciated that fuzzy logic, neural networks, model-based systems, or other processes and systems can be used to provide an engine speed signal as a function of fluid pressure at the distributor gun.
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The invention, in its broader perspective, is therefore not limited to the specific details which represent device and method, and illustrative examples which are shown and described. Accordingly, deviations from such details can be made without departing from the scope of the applicant's general inventive concept.
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Contents2
10 sheets
Sheet 1 Sheet 2 Sheet 3 Sheet 4 Sheet 5 Sheet 6 Sheet 7 Sheet 8 Sheet 9 Sheet 10
8 members in 4 offices
Priority claims4
| Document | Office | Kind | Date |
|---|---|---|---|
| 70242700 | United States of America | A | |
| 70242700 | United States of America | A | |
| 702427 | – | – | – |
| US20000702427 | – | – | – |
Members8
| Document | Office | Kind | |
|---|---|---|---|
| SE0103429D0 | Sweden | D0 | |
| SE0103429L | Sweden | L | |
| JP2002200445A | Japan | A | |
| DE10150230A1 | Germany | A1 | |
| US6517891B1 | United States of America | B1 | |
| US2003101931A1 | United States of America | A1 | |
| US6712906B2 | United States of America | B2 | |
| SE523754C2This record | Sweden | C2 |
1 legal event, as the office reported them to INPADOC
Events
| Event | Code | |
|---|---|---|
| Patent has lapsedLapsedNUG | NUG |
Numbers
- Publication, DOCDB
- 523754
- Publication, EPODOC
- SE523754
- Application
- 103429
- Application, DOCDB
- 0103429
- Application, EPODOC
- SE20010003429
Titles2
- Swedish
- Styrsystem för doseringspump och metod
- English
- Control system for metering pump and method
Classification
- CPC, 4
- F04B49/20
- B05B12/085
- F04B13/00
- Y10T156/1798
- IPC, 9
- F04C14 24
- B05B12 08
- B05B12 12
- B05C5 04
- B05D3 00
- F04B13 00
- F04B49 06
- F04B49 20
- F04C14 08
