US2597133A - Control system - Google Patents

Description

y 1952 F. D. SNYDER 2,597,133

CONTROL SYSTEM Filed May 10, 1946 7Zxfi/g Machinery WITNESSES: INVENTOR Q 7% fiEaBir/cA D jnyder. a. w 61002;. W

ATTORNEY Patented May 20, 1952 UN I TED STATES PATENT OFFICE SYS'I'IM Frederick. 1).. Milton assignur. to

Westinghouse. Electric Corp'orafion Ea'st Pittsliurgh, 12s., a correlation of. Pennsylvania Applieathmi 10;. 1946,. NB, 668394 I I4. Claiinsi' 1, My invention relates tosystems for controlling the performance. of electric motorsi and; inane:- of" its morespecific aspects; to speed.contrellsystems for electric winder drives as: used in connection: with textilezor other strand, web; or'yarnfabricatw ing machinery.

It is an object or. my inventionl to: provider/ system which is. capable. or controlling. cr: negue lating the speed of an electric motor witntheaid of control equipment of especially simple amt inexpensive design. Another object, subsidiary to the one just mentioned, isthe-prcvisicn of: control devices that permit operating; an alternatingcurrent motor at controlled; avemge -spee'dsbelowthe synchronous speedtofi themotor.

Referring to winder drives-,,fcr instancafnrtexe tile machinery, myinvention aimslaalse atzproviding av motor control system which. operates; to maintain. the material to be wound: at at substantially constant travelling; speed, on substan-* tially constant tension and requires atecmsider-- ably reduced amountof, control equipment-than heretofore necessary for systems or comparable; performance.

Another object. in conjunctionwith. any at those mentioned; is to permit the? useaoii alternate ins-current motors-; including: single phase: motors, for speed control: purposes without: quiring the use of variablaveltager generators; or: the likeadditional;equipment.

An object of my inventionissfunthentwdevise: an: escapement type: let-ofi7 control; for; unwinding-i yarn, web, or the like material; from 32811111113 on storagereel; In. weaving: loomsgjnr-instkmaertha unwoven warp is storedwn alargelbeamunlwliich: the wound-up material may] have; a: oft about fivev inches; when the-beamiscempty andea: diameter of about thirty inclres: whem the: heami is full. The'loom. as. it: weavessrequiressthat: warp be held: under tension. and; fed at Just; the: correct speed. This means that the unwinding? speed of the warp has to vary continuously. on the loom Warpbeam as the. diametenotttheire' maining material on the; beanr keeps In conventional equipment. the warp rieaxm is: held from rotating by meanssofa gear trainzwhich. is driven from the: beam and terminates: at. escapementmotionsimilan t'o azcloclimechanisin: A dancer roll is.) placedagainst; the: unwound stretch of thewarp. materialz As theil'oomz cone sumes the Warp; the dancer roll! is: fbrcedi down: and, after a certain movement it releases; a shoe-type brake thatnormallw keeps thespendulum of the escapement motionfrommovingz. The;

time releases; the pendulum to oscillate, thereby allowing a little amount of warp to be released from the beam-,. until the dancer r011 moves up and: again applies the: brake to the escapement pendulum. Such a mechanical escapement motier is. rather critical, considerable-treuble is experi'encecr with. its? proper: maintenance, and" the tension ofthe: warp: material is usually varying to a larger extent than desirable. The lastmentionedobiect of my invention therefore aims at providing. a. let-cit control for spools of. materiaL to beunwound, which avoids the intricacy on theiknown mechanical escapement devicesv andafiorde at higher degree of accuracy in perform- 8,1108

According to enactv the features: of my invention,,L provide: the motoref an electric drive with a. power supply circuit which contains control means. for effectingan. intermittent one-and-oif contnol-iof the power supply, so that the-motor israpidlyr energized and deenergized during intervalsi of-. varying. ratio, with the result thatthe averagemotor speed: is: determined by this ratio. Referring; to winder. drives: for textile machinery and; thelike; yarn, strand, or webfabricating equipment, I provide? the: control systemwith a dancer mil or. othercondition responsive device. which: cooperates: with the: material so -as--to perform an oscillatory. movement which in turn con-- was the above-mentioned on-and-otl control means-cf the. power supply circuit.

According to another feature of my invention, an; alternating-current motor, for. instance of: the singles phase type, is connected with a trans-- former or.- 'other alternatingrcurrent supply'means through. twm rectifying deviceswhich: are: connected in parallel and inverse relation to each other so! thatthe motor is energized by. alternating. cur-rent when both rectifying devices: arein conductive condition-.. 0110 ofv the rectifying. deVicesis-Ot the" controllable type; It may: con.- sist at a g-ridcontrolled gaseous.- discharge tube on the; type. knownr as thyratron; The: abovementioned conditiomresponsive; control devlceris connected with the control or gridrl circuit of the controllablea rectifying; device, in order to render iaintermittentlw conductive" and non conductive; thereby: causing: the: motor! to: receive measured impulseaof: alternating;- current energizatiom.

These-l and .further objects: and features: of my." invention: will: be apper'entrfrom: the: followingdescription; of? the? embodiment shown in: the: dmwing; which." illustrates diagrammatically a wlinder rdriveifontextile machinery-in contension on the travelling stretch .ofi'warpfimateriab junction with. controlequipment d s e and? operative in accordance with the principles of my invention.

In the drawing, a roll of yarn material is denoted by I. The material 2 withdrawn from the roll I travels into a loom, or other fabricating machinery shown schematically at 3. The beam or shaft carrying the roll I of material is provided with two series-arranged worm gears 4 and 5, of which the latter is connected to an electric drive motor 6. The worm gearing between the beam and the motor 6 represents a reduction gear of a high reduction ratio and is of the selflocking type. That is, unless the motor 6 is driven, the worm gearing will prevent the roll from paying out material. The motor 6 consists preferably of a single phase capacitor motor. The motor terminals are denoted by TI, T2 and T3, and the appertaining capacitor by C. A transformer I with primary terminals 8 and 9 and two secondary windings I and II provides the necessary power supply. The terminal TI of motor 6 is directly connected to one terminal of the secondary winding ID. A thyratron I2 has the heater I3 for its cathode I4 energized from the transformer secondary II. The anode l5 of tube I2 is connected to motor terminal T3 through an auxiliary resistor IS, a capacitor I1 and a switch contact I8. The contact I8 is normally closed. The tube [2 operates as a controllable rectifier. Its control grid I9 is connected through resistors and 2 I, to a voltage dividing arrangement of resistors 22 and 23 which is series connected with a rectifier 24 across the secondary winding III of transformer I. The rectifier 24 may consist of a dry junction type unit for halfwave rectification. A capacitor 25 connected across the series connected resistors 22 and 23 serves to smooth the current rectified by the unit 24. Consequently, the voltage dividing resistors 22 and 23 are traversed by a substantially continuous direct current when the transformer I is energized. As a result, a potential is normally imposed on the tube control grid l9 which is sufiiciently negative with respect to the tube cathode M to maintain the tube in non-conductive condition. A point between resistors 20 and 21 is connected through a normally open control contact 26 with the cathode I4 of the tube. Consequently, when contact 26 is closed, the negative potential on grid I9 is reduced to nearly that of the cathode I4 in order to fire the tube I2.

A second half-wave rectifier 21 is connected in parallel and inverse relation to the tube I2. This second rectifier may consist of a dry junction type unit, although an electronic tube may be employed instead.

The terminal T2 of the capacitor motor 6 is connected to the cathode I4 of tube [2 under control by a normally open switch contact 28. The contacts I8, 26 and 28 are controlled by a tension responsive device which has a dancer roll 29 biased by a spring 30 so as to be held against the travelling stretch 2 of the material fed from the roll I into the textile machinery 3. The contacts I8 and 28 form together a reversing switch for the motor 6. Small oscillatory movements of the dancer roll 29, sutficient to close and open the control contact 26, do not affect the contact condition of switch contacts I8 and 28. However, when the material 2 slackens or reduces its tension to such an extent that the dancer roll 29 moves upwardly beyond a given maximum limit, the switch contact I8 is opened and the contact 28 closed. The motor terminals TI and T2 are then directly connected across the transformer secondary [0 so that the motor is caused to run in opposition to its normal direction of operation. As a result, the material 2 is wound back onto the roll I, until the slack is reduced and the dancer roll 29 forced to reestablish the illustrated normal condition of switch contacts I6 and 28.

The operation of the control system as a whole is as follows.

When the textile machinery 3 is running and the transformer I energized with the dancer roll and contacts in the position shown in the drawing, the tube I2 is non-conductive, while the noncontrollable rectifier 21 is in condition to conduct current, this current charges the capacitor II.

As soon as the charge reaches full capacity, the further fiow of current is stopped so that the motor 6 remains at rest. The self-locking worm gearing will then prevent the roll I from delivering material. Consequently, the slack portion of material contacted by the dancer roll 29 is gradu ally reduced by the fabricating machinery, and the dancer roll is forced against the biasing force of spring 30 to close the contact 26. At the closing moment, the grid potential of tube I2 is changed and causes the tube to fire. Now, both rectifying devices [2 and 21 are in operation, so that the motor 6 is supplied with almost full alternatingcurrent voltage with one rectifier conducting during half of each cycle and the other rectifier during the other half of the cycle. The capacitor I! does not offer an appreciable impedance to the fiow of alternating current. Consequently, the motor will now rotate in the direction required to release material from the roll I. As soon as a slight amount of material is released, the dancer roll 29 is lifted and the contact 26 opened, with the result of stopping the flow of current through the tube I2. Consequently, the motor is again stopped. The contact 26 is of such design that a movement of the dancer roll of a few thousandths of an inch will suffice to start and stop the motor. The contact 26 may consist of an open metallic contact which does not have to be kept clean because the tube will fire with a resistance up to the order of 100,000 ohms across the control contact 26. Under such conditions, the dancer roll 29 oscillates up and down many times per second so that the motor is intermittently energized and deenergized in rapid succession. Consequently, the motor operates virtually at a controlled average speed just sufficient to unwind the correct amount of material. If, for some reason, the tension of the material becomes excessively low, for instance when the material is permitted to slacken extensively during adjustments of the machine, the reversing switch contacts 18 and 28 become operative, as explained previously, and adjust the slackness or tension of the material 2 between the proper operating limits of the control contact 26.

The capacitor I I may be of the electrolytic type, a rating of about 500 Mfd. being, as a rule, sufiicient for single phase capacitor motors of up to about 1 hp. to operate under a secondary transformer voltage of about to about 220 volts. When using an electrolytic capacitor, the voltage drop through the tube l2 should be slightly larger than the drop through the parallel connected rectifier 21, in order to insure that the capacitor II will remain slightly charged at all times in the proper direction. To this end, some circuits may require the insertion of a resistor, such as the one denoted by I6, in series with the anode of the tube.

If desired, a separate c ectroniaenctic contector may be used oi th i n-re ns: swi c icon tac ors t8; d; 18;. and the coil at the concrete r v rsina ccntactor then be ontr l-led a n le. annilia r ontact; oi. th dancer roll de ice.

While I have illustrated 1 scrib d. the p icati n of; s nvention to a winder dri e t wi l e nnde stoo t at the n cck ontrol: mbodied in th example may also h us d or elec ri i eescr na nn oscs. ot er ant ecn one. n d. Hermannp lica ons. the. reversin switch eature na-r be h l y omitted. des red the intermit en on ansi o i control o the power the may be eiiected by mea s other tnana -ioncr sl ck? css: responsive. evice- It: w ll; f nether b under-- stood by those skil ed n he art: that he intone tion s likew s applica ctc c cctr nc cr h r than, capacitor type motors; it an adran a hat-.brfl itxic o t cap citor motor or other t ncof; s n le-phase nc..- tor can. be made to. operat ;ataccntmllahlesah synchronous speed with the aidof; extremely p e Control devices. such andothcrmcdificatio s and. alterationsbascd ont c; alccreediscloccd chair cristies of my invention or tcndcd; to be Hik cluded in the essential team; or the. inyention setiorth. in the claims; attached hereto.

Iclaim asmyinyention;

1. A control: system, ompris n anal-tornad current motor, means. for supplying. alternatina current, two. halfewaye rectifiers connected: in parallel. relation. and opposing polarities. to each; otherbetween said, currencsupplymeansand said; motor so, that said motor, is. energized; by alternating current when both, rectifiers are in. operation, a. capacitor SBIYiBSeCOIH'iGGlZQIL with said mos. tor for preventing the flow oi currentwhenz only one of: said rectifiers is in operation, and inter--, mittently operable control meansconnected with. one of said rectifiers for controlling its operation. to thereby control the speedof said: motor.

2; A control system, comprising. ana-lternating-r current motor, means for supplying alternating current, two halt-wave rectifiers connected inv parallel relation and opposin polarities toeach other between said current supply means and said motor sothat said motor isenergized: by alternating current when both rectifier-s are. inopera-- tion, at least one oi-said= rectifiers' consisting of; a controllable electronic discharge device and: having acontrol circuit, and condition-responsivenecillatory control meansconnected with said grid circuit for on and-ofi: control of said device, whereby the speed of said motor is controlled in dependence upon the condition responded to by sa d c nt ol mea s-u 3. A control system, comprising analternatingcurrent motor, means. for supplying. alternating current, a grid controlled discharge tube disposed between said current supply means and saidmotorfor half-wave rectification of the current; another half-waverectifier connected in: parallel and opposing polerelationto saidtube so: that said motor is energized by: alternating current when said tubeis conductive, a capacitonseriesconnected with-said motor for preventing the flow of current throughsaid; motorwhen only said other rectifieris conductive, said: tube having a grid circuit forrenderingitnon-conductive; and condition responsive control means connected with said grid circuit for intermittently causing the latter to impose an on-and-off control on said tube.

4. A control system, comprising a transformer,

a sin le. phase mo or norms two termina s oi h ch. o is. c nn cted o said transformer two a f-wove r otificrs connected in parallel and in-. v r relationto. a h other betwe n sa d her mo o rm nal nd said. ransformer So: that sai o or is energized yalternatineg current when both rcct ficre are: conduc ive, a capacitor series. c n cte betw en sa d mo or. and said trans: fo mer for locking h fiowf current. on y ne of" said; rcctin r is: conductive, and. in ermittentlycpcrating contr l means. onnected with ne-of. s id r c ifiors for aus ng. i to becomeimrmi cntly n n-conductiveo hereby con rol the speed of said motor in accordance with the. variations in the intervals; of conductiyity' 01, said latter; rectifier-..

-v A control ystem, comprising. means for supplying alternating current, a capacitor motor. connected to. said current supply means, a controllablehali-ware rectifier and a. nonecontrollable half-wave. rectifier connected in par llel.

and; inverse relation to each other between said.

motor. and sa currcnt upply meansso that. said motor is energized by alternating current when both rectifiers are conductive, a, capacitor series connected; between, said motor and, said. transformer for; blocking the; low of current. whenonly one or? said rectifiers is, condi-icti-v.e, and

oscillatory contact, means,- connectedL with said controllable rectifier for. rendering; it. intermit tently conductiye; and non-conductiveduring variable intervals; Of tim to. thereby control: the speed of ofsaid, motor.

6; A let-off control for unwinding material.

from a roll, comprising a roll aha-fit, a, salt-locking; goat connected with. said shat-fit for locking the: .1, an. alternating curr nt induction motor? i driv ng nn c ion with. said scar tor causing t to. r tat th ro l n the unw nd ng direction,

altc a nge urzr nt s pplamean connec ed. o

said motor for supplying. pow r, hereto and-havns sc llatory on-and-oif on r l m ans. fon ontr llin th p w r. supply, and; c ndition: rcspom i c. m ans for ntcrmittently actuating; said c n-- t oi. mean in: respon acondition of. th ma.-

t a so; ac rco tro a dimotor-to. runiat so erinc ron us; p e for m in a ning; said ondition substantially within given. limits;

LA. let-0. c ntrolfpr u winding, material; from a; oll, omprising a selfe o kinez ear: dispos d o c nn ct to: ho- 201 a: inslcrnhasa m to v dririn connec onwith; sa d. scan mean: f r upp yin a ternating u -r nt con; e e t aid. motc t, two.- half-wav c nn ct n. parallel; ndin crsc rela ion. o; e ch,

oth r h tw cnl aid mo ornd said: c r ent, v 9 3?. means; s t at said? mo ors; nerg zed. y alterna n c rrent wncnt tn. rectifiera are on;- uc ivci. e; of: said: rcctifi ra b ing; controllable ndzh rine acontrol circuitzfonon-andwfi Open-c a icn, onditio re ponsir on rol: means: co.- operative with the material, and; connected. with said control circuit fon'causingiit tointermittentlyrender. said onerectifier conductive and: nonconductive in responsetoa. conditioni of'the ma terial' inorderto. control said motor so; an to: maintain: said condition substantiall y within,

given limits 8. A left-ctr control: for unwinding material from a: roll; comprising asel'f -lookinggear disposed for connection to the roll, a single-phase motor in driving connection with said gear, means for supplying alternating current connected to said motor, two half-wave rectifiers connected in parallel and inverse relation to each other between said motor and said current supply means so that said motor is energized by alternating current when both rectifiers are conductive, a capacitor series connected with said motor to prevent the flow of current when only one of said rectifiers is conductive, one of said rectifiers having a control circuit and being onand-off controllable thereby, tension-responsive control means connected with said control circuit to intermittently control said latter rectifier in response to variations in the tension of the material in order to control the speed of said motor so as to maintain said tension substantially within given limits.

9. A system for controlling the winding performance of a roll of material, comprising a reversible electric motor, means for supplying power to said motor, reversing switch means disposed between said power supply means and said motor so as to connect said motor normally for operation in a given running direction, on-and-off control means disposed between said power supply means and said motor for controlling the supply of power when said motor is connected by said switch means to run in said given direction, a tension-responsive device arranged to engage the material so as to perform oscillatory movements in dependence of variation in slackness of the material, said device being connected with said control means for causing the latter to control the speed of said motor so as to maintain the slackness normally within given limits, and said device being also connected with said switch means for temporarily reversing said motor when the slackness exceeds a given value.

10. A system for controlling the winding performance of a roll of material, comprising a reversible electric motor, means for supplying power to said motor, reversing switch means disposed between said power supply means and said motor so as to connect said motor normally for operation in a given running direction, a discharge tube disposed between said current supply means and said motor so as to control the power supply to said motor when said motor is connected by said switch means for running in said given direction, said tube having a control circuit having a movable control contact for rendering said tube conductive and non-conductive depending upon the position of said contact,

a tension-responsive device having a movable member disposed for engaging the material so as to perform oscillatory movements in dependence upon the tension in the material being wound, said member being connected with said contact for causing it to control said tube so as to vary the speed of said motor for maintaining said tension normally within given limit values, and said member being also connected with said switch mean for causing the latter to temporarily reverse said motor when said tension drops below a given value.

11. A control system, comprising alternating current apparatus to be controlled, means for supplying alternating current, two half-wave rectifiers connected in parallel relation and opposing polarities to each other between said current supply means and said apparatus so that said apparatus is energized by alternating current when both rectifiers are in operation, a capacitor series-connected with said apparatus for preventing the flow of current when only one of said rectifiers is in operation, and control means connected with one of said rectifiers for controlling its operation to thereby control the energization of said apparatus.

12. A system for controlling the winding performance of a reel of material comprising an electric reel drive motor of the induction type,

alternating-current supply means connected to said contact means in response to variations in tension of the material. 1

13. A let-oil control for unwinding a reel of material, comprising a reel shaft, an induction motor connected with said shaft for turning aid shaft in the let-01f direction when said motor is energized, alternating-current supply means for said motor, a gaseous discharge tube connected between said power supply means and said motor for energizing said motor when said tube is conductive, said tube having a control circuit, oscillatory on-and-off contact means connected in said control circuit for controlling said tube to be conductive and non-conductive respectively depending upon the position of said contact means, and a tension-responsive device engaging the let-ofi material and connected with said contact means for moving said contact means so as to cause said tube to intermittently energize said motor.

14. In a reel let-oil control for connection to oscillatory tension feeler means, the combination of a single-phase induction motor, alternatingcurrent supply means connected with said motor to provide energizatio therefore, an electronic tube having a plate circuit connected with said supply means for controlling said energization and having a grid circuit, said grid circuit having bias voltage means attachable to the feeler means and having a cut-ofl voltage value and a firing voltage value, respectively, depending upon the condition of the feeler means.

FREDERICK D. SNYDER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,265,329 Henderson May 7, 1918 1,304,565 Henderson May 27, 1919 1,828,506 Morse Oct. 20, 1931 1,857,817 McCann May 10, 1932 1,912,892 Eitzen June 6, 1933 2,275,192 Bailey Mar. 3, 1942 2,285,654 Hanna et a1. June 9, 1942 2,314,070 Bogoslowsky Mar. 16, 1943 2,419,070 Grunke et al Apr. 15, 1947

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