US2812553A - Textile machine device - Google Patents

Description

Nov. 12,1957 w J. H. COULLIETTE 72,812,553

TEXTILE MACHINE DEVICE 1 1954 7 Sheets-Shed 1 INVENTOR Nov 12, 1957 J. H. COULLIETTE 2,812,553 v TEXTILE MACHINE DEVICE Filed June 24, 1954 I 7 Sheets-Sheet 2 INVENTOR Nov. 12, 1957 J. H. COULLIETTE TEXTILE MACHINE DEVIC E '7 Sheets-Sheet 5 Filed June 24; 1954 1957 J. H. COULLIETTE TEXTILE MACHINE DEVICE 7 Sheets-Sheet 4 Filed June 24, 1954 CLUTCH EXCITATION AND CONTROL CIRCUIT Q 0 0 i l. 0.

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AUDIO OR LbwfFR'EouENcY AMPLIFIER To CLUTCH CONTROL CIR- sun O CAPACWOR INVENTOR Nov. 12, 1957 J. H. COULLIETTE 2,812,553

TEXTILE MACHINE DEVICE Filed June 24, 1954 7 SheetsSheet 5 LP. Brake Set QR B girlie L) I Set T 5 10 7 T5 P, 12, I 1" AUDIO OR LOW FREQUENCY AMPLIFIER Fl g- 2 TO BRAKE CONTROL b CIRCUITS INVENTOR Nov. 12, 1957 Filed June 24, 1954 J. H. COULLIETTE TEXTILE MACHINE DEVICE 7 Sheets-Sheet 6 6% 67 68 v AuoIo OR LOWPIE- SENSING REFERENCE W ,MPUFIER CAPACITOR CAPACITOR TO cLuTcI-I CON- TROL cIRcuITs RE NULL 74 ''g AND BALANCE R.F. BRIDGE CIRCUIT Z (SEE DETAILnRAw- QUENCY AMPUFIER ING TO BRAKE cou- TROL cIRcuITs 66 RF.- POWER Aumo oscILLAToR s2 63 64 65 66 AMPLIFIER POWER AMPLIFIER (PLATE Monu- LATE BY T0 PLATE MODULATE STANT pu- R. F. POWER AMPU- TUDE A' F. PIER 69 SIGNAL) POWER SUPPLY HIGH- LY STABIUZED 7O SUPPLIES BLOCKS 7 62, 63,64, 65,66,69

70, 7 I, 72. RF. BUFFER AMP- LIFIER STAGE STABLE cRYsTAL OSCILLATOR STAGE 'INVENTOR Nov. 12, 1957 J. H. COULLIETTE 2,812,553

TEXTILE MACHINE DEVICE Filed June 24. 1954 I 7 Sheets-Sheet 7 COAXIAL SWITCH RELAY COIL 76 T0 GRID OF RF. BRIDGE BALANCE TO MODULATOR INVENTOR AMPLIFIER United States Patent TEXTILE MACHINE DEVICE James H. Coulliette, Chattanooga, Tenn., assignor to Industrial Research Institute of the University of Chattanooga, Chattanooga, Tenn.

Application June 24, 1954, Serial No. 438,985

Claims. (Cl. 19-130) This invention relates to textile machine controls and has especial reference to mechanism to provide uniform mass per unit length of slivers, rovings, laps, or the like.

In order to produce a thread or yarn of uniform weight per unit length, it is necessary to have:

(1) A uniform array of fibres, often designated as a sliver, roving, or lap, and

(2) Machines which'will draw and twist the array of fibres fed into the machine.

In various textile operations it is customary to pass slivers or roving between two spaced pairs of rolls, the forward pair rotating faster than the rear pair so that a degree of draw or reduction in cross sectional area of the array of fibres will occur. In the prior art the rate of rotation of the rolls has been adjusted manually at frequent intervals in order to provide draw in proportion to the quantity of material passing through the rolls. This attempt at maintaining uniform cross section or weight per unit length of the fibre array has not been satisfactory, however, since frequent manual adjustments have been necessary and the regulation has not achieved a uniform result.

My method for obtaining a uniform array of fibres involves the setting up of a machine to produce a variable draft, and to control this draft automatically by means of an electronic circuit which will sense any variation in the weight per unit length of the array of fibres, and thereupon alter the draft of the array of fibres to maintain the desired weight per unit length.

It appears that a logical place to introduce my device for the evening of the array of fibres is at the picker lap winder, or perhaps at the comber lap winder. In the picker lap winder a continuous web of fibre is fed from the heaters to the winder, while in the comber lap winder a number of slivers are drawn from cans and combined to form the comber lap which is fed into the winder. In each machine the winder provides for taking up the lap between a pair of feed rolls, and supplying it at a uniform rate to a take-up reel which is driven at a constant circumferential speed by an electric motor with appropriate controls. My evener device is designed to insure that the lap supplied to the winder feed rolls has a constant and uniform mass per unit length.

My evener device includes two pairs of fluted rolls of which the forward pair is geared to, or may in factbe, the winder feed rolls. The second pair of rolls-the drafting rollsis driven through a slipping clutch, such as a magnetic or hydraulic clutch, at a circumferential speed somewhatless than that of the winder feed rolls. The pair of drafting rolls carries an electro-magnetic brake which is energized by a variable current. The variable 2,812,553 Patented Nov. 12, 1957 braking current is supplied by an electrical circuit which senses variations in the weight per unit length of the lap and in turn alters the braking and/ or clutching current.

When the drafting rolls are driven through a slipping clutch, the varying braking and clutching action will result in a varying speed of the drafting rolls, and consequently, a varying draft.

For example, if the electronic circuit senses a thin, or light-weight section in the lap, a signal is fed to the amplifier to reduce the braking current and increase the clutch current. creased clutch current allow the drafting rolls to speed up, thereby reducing the draft, and increasing the weight per unit length of the lap.

Conversely, a thick section would supply a signal to the amplifier to increase the braking current and decrease the clutch current. The resulting increased braking current and decreased clutch current will slow down the drafting rolls, thereby increasing the draft, and reducing the weight per' unit length of the lap.

The required electronic control circuits can be arranged in a variety of ways. The most obvious sensing device is a capacitor in which the lap constitutes a constantly changing dielectric. Textile fibres have a greater dielectric constant than air. Hence, the capacitance of the capacitor Will be increased as the weight of fibre between the capacitor plates is increased. If the textile fibre lap is caused to move between the plates of a capacitor which is a component of a balanced A. C. bridge circuit, increasing the amount of fibre in the capacitor will increase the capacitance of this sensing capacitor. The increase in capacitance will cause a proportionate unbalance of the currents in the bridge. Conversely, decreasing the amount of fibre will cause unbalance in the opposite sense. Coupling the A. C. bridge to an amplifier provides a means of obtaining a controlled variable current which is used to energize the magnetic brake and/ or the magnetic clutch. It remains then to adjust the amplification so that the change in draft is sufiicient to re-establish the desired mass per unit length in a specified time interval. This time interval (or amplification) can best be determined by experimental observation of the operation of the device.

The stability of the oscillator frequency and the amplification of the amplifier are of importance. The ideal condition is that a certain capacitance of the sensing capacitor will always correspond to a certain value of control current. It would be desirable, therefore, periodically to introduce in place of the sensing capacitor a reference capacitor corresponding to the desired mass per unit length lap, and have the amplification automatically adjusted to give the standard braking current. This procedure would correct for drift both in the oscillator and in the amplifier simultaneously.

Since the lap winder is stopped at regular intervals to permit removal of the filled reels, it will probably be satisfactory to maintain the calibrating adjustment of the evener manually. It can be so arranged that when the winder is stopped for the removal of a filled reel, a standard capacitor is automatically connected to replace the sensing capacitor, and the operator can adjust a control knob to reset the braking and clutching current (read on an ammeter conveniently located) to the standard value. I

in order to overcome the above-mentioned and other The reduced braking current and in-, V

defects of past practice, it is an object of the present invention to provide an automatic roving control which will automatically vary the degree of draw in accordance with the weight per unit length of the roving.

Another object is to provide means for controlling automatically the relative speeds of rolls feeding material therethrough, the speeds being automatically changed in proportion to mass per unit lengthof material passing between rolls.

A further object is to provide sensing means for determining automatically the density of material being moved by rollers or other mechanism.

Another object is to provide sensing means for determining automatically the density of material being moved by rollers or other means and to provide means for automatically changing the density in accordance with determinations of said sensing means.

An additional object is to provide a textile machine for regulating automatically the draw of slivers, roving, laps, or the like, in order to produce an array of fibres of substantially uniform weight per unit length.

Other objects will appear in the specification.

In the drawings:

Figure 1 is a top plan view of my automatic lap density control device, and associated electrical circuits.

Figure 1a is a fragmentary plan view showing sensing capacitor plates mounted between forward and rear pairs of feed rolls.

Figure 2 is a circuit diagram, partly in block form, illustrating the electrical connections of my automatic lap density control system.

Figures 2a, 2b, and 2c are circuit diagrams showing components and groups of components of my automatic lap density control system.

Figure 3 is a diagram of a radio frequency bridge circuit employing a sensing capacitor, a comparison capacitor, and a relay to switch capacitor.

Figure 4 is a cross sectional end view showing rounded type capacitor plates.

In Figure 1, take-up reel 1 is driven as follows: belt 21 transmits power by means of pulley 10 mounted on drive shaft 11 and by pulley 60 keyed to shaft 58. Shaft 58 rotates in long pedestal bearing 59 which is screwed to base 61. Fluted rolls 2 and 3 are keyed to shafts 4 and 5, respectively. Shaft, 4 rotates in pedestal bearings 6 and 8 screwed to base 61. Shaft rotates in'pedestal bearings 7 and 9 attached to base 61. Gear 56 is keyed to shaft 4. Gear 55 is attached to shaft 5. Gear 57, keyed to shaft 58, meshes with gears 55 and 56. When pulley 60 turns, gears 55 and 56 also rotate. and 55, being meshed with gear 57, turn fluted rolls 2 and 3. Take-up reel 1 is placed to set in the V formed by fluted rolls 2 and 3. When these rolls rotate in the direction indicated, take-up reel 1 rotates in the direction shown, being driven by the surface friction of reel 1 against fluted rolls 2 and 3. As the surface of the material on wind-up or take-up reel 1 is the only contact with 2 and 3, the material will wind up at a constant lineal speed.

Pulley 10 is fastened to principal drive shaft 11 which carries upper feed roll 12 and isrotatable in pedestal bearings 13 and 14 attached to base 61. Shaft 11 is connected. to motor shaft 15 through flexible coupling 16. Shaft 15 of motor 17 carries attached pulley 18 which drives pulley 19 by means of belt 20. Similarly, pulley 10 drives pulley 60 through belt 21. Lower feed roll 22 is mounted on shaft 23 which is rotatable in bearings in pedestals 13 and 14. This roll cooperates with roll 12 to feed lap 52 through the rolls. This lap can be continuous in width rather than in strips. Gear 24 is fastened to the end of shaft 23 and is meshed with gear 25 fastened to shaft 11. These gears are so chosen that the peripheral speeds of both rolls will be approximately equal when shaft 11 is rotated and drives gear 24 through gear 25.

Upperroll 26 is carried by shaft 27 which is rotatable Gears 56 r in bearings in pedestals 28 and 29 fastened to base 61. Lower roll 30 is mounted on shaft 31 which is also rotatable in bearings in pedestals 28 and 29. Gear 32 is attached to the projecting end of shaft 31 and is meshed with gear 33 which drives it and which is fastened to shaft 27. This shaft also carries metal rotor 34 of eddy current brake E, the stator windings 35 of which are fastened rigidly in position by means of attached frame 36 which is bolted to base 61. Conductors 37 and 38 are connected with brake windings 35.

Shaft 27 passes through a bearing in pedestal 39 fastened to base 61 and carries attached metal or other conductive cylindrical shell 40 which surrounds rotor 41 having attached electro-magnets 42, the windings of which are connected with slip rings 43 and 44 carried by shaft 45 which is rotatable in long pedestal bearing 46 which is fastened to base 61. Gear 47a is attached to shaft 27 and is meshed with pinion 48:: on the shaft oftachometer or generator 49 which is screwed to frame 36. The output of instrument or generator 49 is led out by conductors 50 and 51.

Slivers or lap 52 may be pulled out of suitable canisters (not shown), or supplied otherwise, and are fed between rolls 26 and 30, and then between rolls 12 and 22, and are then wound around take-up reel 1. As the lap is wound around take-up reel 1, the lineal velocity remains constant because the surface of the lap itself wound around reel 1 is in contact with fluted rolls 2 and 3, which rotate at constant speed. A normal difference in velocity is predetermined between rolls 2 and 3 and rolls 26 and 30. This introduces a predetermined fixed draw on lap 52. This fixed draw representsthe normal state of the equipment. This draw is caused to vary in accordance with the mass per unit length of roving 52. This will be explained in more detail later.

In Figure 1, sensing capacitor 67 comprises lower condenser plate 67a screwed to insulating block 67c which is attached to pedestal 13, and upper plate 67b screwed to insulating block 67d which is fastened to pedestal 14. Lap 52 passes between these condenser plates which may be relatively long or short to suit conditions. An alternate arrangement for the sensing condenser, located be tween the feed rolls, is shown in Figure la. This arrangement is preferred when the lap is moving at a slow lineal speed as in the case of the picker lap. The arrangement shown in Figure l is preferred when the lap is moving at a relatively high speed as in the comber lap winder.

In Figure 2 the complete schematic diagram of the control circuits is shown. In Figure 2a the portion of the circuit designed to control the excitation of eddy current clutch 40-41-42 shown. In Figure 2b the portion of the circuit designed to control the excitation of electromagnetic brake 3435-36 is shown.

Figure 2c, in block diagram form, shows the power supply and other units which supply signals to the clutch control and brake control circuits. In Figure 3 the circuit for the radio frequency bridge which contains the sensing element is shown. Other types of brake and clutch may be used, if desired.

In Figure 2c, the radio frequency circuits and audio circuits which precede the clutch control circuit Figure 2a, and brake control circuit Figure 2b, are as follows: block diagram 73 contains voltage regulated power supplies supplying circuits 62 through 72. Block 72 is a stable crystal oscillator supplying a constant frequency radio frequency signal to buffer amplifier 71. Buffer amplifier 71 in turn feeds a radio frequency signal to power amplifier stage 69. Block diagram contains a stable audio oscillator feeding a power audio amplifier which is used to modulate the amplitude of radio frequency stage 6 at a fixed percentage. i

The amplitude modulated radio frequency energy from amplifier stage 69 is suitably coupled into a radio frequency bridge circuit 66. In Figure 3, sensing capacitor 67 is a capacitor in one arm of radio frequency bridge circuit 66. Reference capacitor 68 is switched in and out of the radio frequency bridge circuit in place of sensing capacitor 67 by coaxial switch 74 for purposes of comparison and adjustment of the bridge circuit 66. Switch coil 76, when energized, switches contact arm 74a from sensing capacitor 67 to reference capacitor 68 whenever the machine is stopped for unloading. Switch 74 is of the low capacitance coaxial type and is normally closed in the position leaving sensing capacitor 67 in the circuit. Reference capactor 68 serves to standardize lap size by simultating the reactance of capacitor 67 when element 67 has the proper mass per unit length of lap passing through it. Thus, when the machine is stopped for removal of a full reel, theoperator can, from visual indicator 75,- Figure 2a, see if the equipment is in proper operating condition. Switch coil 76 is automatcally energized by the same switch used to stop processing of lap andthus affords a convenient way to keep check on the quality of the processed material. Visual indicator 75 is a standard D. C. indicating instrument placed across load resistor R9 in Figure 2a. It indicates the value of rectified signal fed to the clutch control circuit. Potentiometer 19 is used to calibrate meter 75.

In Figure 2 two-stage radio frequency amplifier 65 is used to amplify the bridge error signal from bridge circuit 66. Amplifier 65 is followed by a linear radio frequency detector stage 64 feeding two identical signals to audio amplifiers 62 and 63. The error signal fed to audio amplifier 62 from detector stage 64 is amplified and fed to bridge rectifier D. R. 34-56. This signal then is used in controlling the clutch 4041--42 by the circuits shown in Figure 2a. Amplifier 63 in like manner amplifies the error signal from detector 64 and applies it to the bridge rectifier D. R. 910-11-12. This, in turn, controls the braking current in brake 34 through 38, Figure 2b.

The circuit of Figure 3 operates as follows: an amplitude modulated radio signal from power amplifier stage 69 is fed into bridge circuit 66 by means of the combination of transformer and switch components 80, 81, 82, 83. Coil 80 is mutually coupled to inductors 78 and 79, being supplied R. F. energy from winding 83 of transformer T9. Provision is made for adjustment of the level of R. F. energy fed to the bridge by means of tap switch 81 which, through selection of the proper tap on resistor 82, sets the level for the bridge 66.

Bridge arms of unit 66 are non-resonant to the input radio frequency signal. Windings 78 and 79 are identical. When radio frequency energy is coupled into the bridge circuit by winding 80, then equal non-resonant voltages of opposite phase are induced in arms AC and AD. When variable capacitor 77 is adjusted to have a reactance equal to that of sensing capacitor 67, equal circulating currents flow in the paths labeled ADBA and ACBA. These equal currents are 180 out of phase, oppose each other in primary winding 86 of transformer T9 and cancel out, causing no signal to be developed in winding 86 if the bridge is in proper balance. The bridge will be in proper balance if the reactance of sensing capacitor 67 is identical to that of variable capacitor 77. If then, after a balance has been obtained by adjustment of capacitor 77, roving, sliver, lap or another material is introduced into the gap between the plates forming sensing capacitor 67, a change in capacitance of capacitor 67 occurs because of the change in dielectric material. This change in capacitance of capacitor 67 causes the bridge circuit to be in an unbalanced condition. A current will be developed in winding 86 of transformer T9 (Figure 3) which will be proportional to the capacitance difference between capacitor 77 and sensing capacitor 67. This current will be due to the phase voltage difference caused by a different voltage drop across the reactance of sensing capacitor 67. The voltage drop across path ADB then does not equal the voltage drop across ACB. Defining Co as the capacitance of capacitor 67 with the desired mass per unit length of textile fibre array between its plates, and C9 as the capacitance of component 67 when the device is in operation, the output current Io will be proportion to Ct-Co. The difference in capacitance has a direct relationship to the output current flowing in winding 86 of transformer T9. The unbalance current in the bridge is coupled through the windings of transformer T9 to the grid circuit of the R. F. bridge balance amplifier 65. This error voltage as fed to bridge balance amplifier 65 is utilized as previously described.

The sensing capacitor 67, Figure 4, is of special design. The adjacent surfaces of the condenser plates 67a and 67b are segments of cylinders. This arrangment provides an increase in smoothness of control of the uniformity of the array of textile fibres. The electrostatic lines of force between the condenser will be somewhat as shown in Figure 4, so that a dense section in fibre array entering the electrostatic field will produce a gradually increasing rate of change in capacitance until it reaches the center of the field, and thence a decreasing rate of change of capacitance until it leaves the field. Hence, the signal resulting from a change in fibre density will result in a gradual change in draw of the lap, and a greater evenness of the array of fibres will be obtained.

The following describes the excitation circuits necessary to control the eddy current clutch and eddy current brake used with this invention. In order to develop torque, all eddy current equipment requires slip between input and output members. The term torque represents the turning effect of a force applied at a specified distance from the axis of rotation. The normal units for torque are in foot pounds. The ability of an eddy current device to deliver a specified torque on the output shaft depends not only on the size of unit but on the difference in speed between input and output members. The discussion which follows explains how by a change in excitation, the amount of slip, or torque, can be made to suit load speeds and thus vary the draft on an array of textile fibres.

Referring to Figure l, the clutch input member 41 is driven by a constant speed motor 17. Input shaft 45 and drum 40 have no mechanical connection, the magnetic field set up between elements 40 and 42 being the only means of torque transfer. Field coil 42 is energized preferably by direct current fed through slip rings 43 and 44 and brushes 47 and 48. No useful torque is available until a difference in speed exists between output and input shafts 27 and 45. The speed of input shaft 45 and degree of excitation of field coil 42 both affect the torque delivered by output shaft 27. Hence, adjustment of the current in field coil 42 controls the speed of output shaft 27. A small speed-indicating generator 49 driven from output shaft 27 is used as a speed governor. The voltage generated .by generator 49 is directly proportional to its speed of rotation. This voltage is used to modulate the electronic control circuit and to cause it to furnish current to field coil 42 proportioned to loading conditions on output shaft 27, tending to maintain a predetermined speed. As the speed of output shaft 27 tends to change with load change, the excitation to field coil 42 is altered to re-establish the proper operating point. The eddy current brake cooperates in a similar manner.

A description of the electronic means of controlling the current supplied to the clutch field coil 42 follows: Figure 2a shows the clutch excitation circuit and Figure 2b shows the brake excitation circuit. Clutch circuit 2a is broken down into five smaller circuits according to function as follows:

Section I.Main rectifier power source comprising components T1, V1, D. R. 1.

Section Il.Reference voltage source having components V2, Re, C7, and T281.

Section [IL-Generator rectifier section components R5, R6, R7, C5, 06, V3, T3 (all).

Section IV.Rider wave or phase shift section with components T182, R2, C15.

Section V.-Grid bias section with components Ra, D. R. 2, C3,R-1,C4.

SECTION I Thyratron V1 in cooperationwith transformer T1 rectifies the A. C. current from lines 55. D. R. 1 is a selenium rectifier used, because of the high inductance of field coil 42, to provide a directional discharge path to maintain smooth coil current during the half cycle tube V1, is nonconducting. The magnitude of current flowing in field coil 42 is a function of the potential existing between grid G and cathode K of tube V1. Making grid G more positive with respect to cathode K increases current in clutch winding 42. The converse is also true. The volt age existing between grid G and cathode K of tube V1 is the resultant of that supplied by Reference Voltage Section II and Generator Rectifier Section III; also, Grid Bias Section V and rider wave from Section IV contribute. In addition, a voltage is inserted in series with the resultant of the above voltages. This comes from the voltage across resistor R9, which voltage is a function of the error voltage from preceding circuits as applied to Bridge Rectifier D. R. 3, 4, 5, 6. It is this voltage across resistor R9 that provides the continuous and automatic control of the clutch current as determined by the mass per unit length of lap 52.

SECTION II Section II provides a stable reference voltage for the purpose of setting the steady state speed of output shaft 27. The setting of potentiometer Ra determines this point of operation.

SECTION HI Section III is the generator rectifier section, the rectified output of which is available across potentiometer R5. It will be noticed that this voltage is in series with the reference voltage across element R8, its point of takeoff being from the movable arm on component R5. As previously mentioned, the output voltage, of generator 49 is directly proportional to the speed of rotation of output shaft 27. This means that any change in output speed of shaft 27 as preset by the reference voltage across potentiometer R8 causes a proportionate change in voltage to be developed across potentiometer R5. Since this voltage is in series with the grid bias voltage from Section V, any change in this voltage will cause a corresponding change in current in clutch field 42, thereby restoring the output shaft 27 to its intended speed of rotation.

SECTION IV Section IV is the phase shift or Rider Wave Section in which an A. C. signal is superimposed on the normal grid bias voltage. The phase relationship between plate voltage and grid voltage is made variable by means of potentiometer R2 and capacitor C15. A D. C. grid bias which would normally prevent conduction of tube V1 is applied between grid G and cathode K. When an A. C. rider wave is superimposed upon this negative D. C. bias, the positive A. C. peaks will then exceed the minimum negative bias necessary to prevent conduction, provided the proper phase relationship exists between the A. C. plate voltage and the A. C. rider wave. The plate voltage must be in its positive phase, and the grid must also be in positive phase with the phase angle such that the peak of the positive half cycle in the plate circuit falls within the positive half cycle in the grid circuit. The period of plate conduction depends on how soon in the plate current positive half cycle the grid is able to overcome the normal negative grid bias. The shorter the period of conduction, the lower the average clutch .current, the converse being also 'true.

.8 sncrrou v Grid bias Section V rectifies the voltage applied by means of secondary S2 of transformer T1 and serves to set up initial operation of the circuit so far discussed.

The following controls are used in the setting up op' eration. Potentiometer R2 is a sensitivity control, determining how small a variation in control signal will change the output speed of shaft 27. Potentiometer R4 is a control for setting the slowest speed. Potentiometer R5 is used to manually pre-set speed between the range determined by resistor Ra and potentiometer R4.

The Brake Circuit The brake circuit in Figure 2b is essentially the same as clutch circuit Figure 2a. The main differences are that no tachometer generator is used, and rectifier D. R. 13 replaces the vacurn rectifier tube Vs of circuit Figure 2a. Potentiometer R12 is the brake sensitivity control. Potentiometer R11 sets the minimum constant drag on output shaft 27 by eddy current brake 40-41-42. Po tentiometer R17 sets the maximum braking current. Secondary S1 of transformer T5 feeds bridge rectifier D. R. 91011-12 with an A. C. signal varying in strength with the mass per unit length of the textile fibre array passing through sensing capacitor 67. The rectified D. C. output from this bridge rectifier appears across the terminals of resistor R18. This voltage is inserted in series with the reference voltage developed across potentiometer R11. This varying D. C. signal or error voltage in cooperation with the bias across potentiometer R14 and the stable reference voltage across potentiometer R17 varies the current flow in magnetic eddy current brake field 35, which is connected to terminals 37 and 38.

The following describes the interaction and cooperation of both brake and clutch as a combined unit. In observing the polarities of signal from rectifier bridges D. R. 345--6 (Figure 2a) and D. R. 9-10-1112 (Figure 2b) it will be noticed that the former applies the positive end of the circuit to cathode K, the other end or negative terminal going to the movable arm on potentiometer Rs. Rectifier D. R. 9--10-11-12 is oppositely poled, the negative end of this bridge rectifier going to the midpoint of transformer filament winding T653, thus placing the negative end at the cathode K of thyratron V4. The other or positive end connects to the movable arm on potentiometer R17. With the polarity of the circuits as indicated, it is apparent that, with equal signal inputs to the bridge rectifier circuits, current in the clutch winding will increase when current in the brake Winding decreases, and vice versa.

For an increase in signal to bridge rectifier D. R. 345-6 for the eddy current clutch, the grid of tube V1 will be made less negative and the conduction period of tube V1 will increase. This will cause increased current flow in clutch field 42. The result will be that of increasing the output speed of shaft 27 by reducing the amount of rotational slip between input and output members.

At the same moment that the clutch current increases, the negatively poled signal from the brake bridge rectifier D. R. 9-101112 will apply a negative signal to the grid G of tube V4. This limits the conduction time of tube V4 with a resulting decrease in braking current in winding 35. By causing a certain amount of normal braking (by adjustment of potentiometer R14), the action of brake and clutch can be made a push'pull operation. When a decrease in R. P. M. is called for by the preceding error signal circuits, a reduced positive voltage appears on grid G of tube V1, allowing the normal negative bias to reduce the clutch current and, therefore, output torque and speed of shaft 27. While this is happening to the clutch, a decreasing negative or increasing net .positive voltage appears on grid .G of tube V 1. This increases the brake field current in winding 35 with increased braking on output shaft 27. By cooperating in this way, a smooth positive control is obtained over'the speed of shaft 27 and thefeed rolls 26 and 30 (Figure l) geared thereto. If the speed of shaft 27 is slowed down, more draw for the lap is provided; and if shaft 27 is speeded up, there is proportionally less draw. Therefore, the draw is automatically adjusted by the clutch and brake, under control of the sensing capacitor so that the mass per unit length of the fibre array is substantially constant. This automatic operation is far superior to manually controlled machines.

In the arrangement described above, a capacitative means of sensing variations in the mass per unit length of the array of fibres has been described. Other means of sensing these variations may be used such as the variation in transmission of light through the fibre array into a photoelectric cell. In using this sensing means a photoelectric cell receiving light transmitted through the fibre array would replace capacitor 67, and a similar cell receiving light directly from a constant source would replace capacitor 77. Other sensing means may also be used.

What I claim is:

1. In a textile machine, means including two pairs of rolls for moving and stretching an array of textile fibres, cooperating brake and clutch means for controlling the rate of rotation of at least one pair of said rolls to cause varying draw of said array, means for electrically sensing variations in said array, and means associating said sensing means with said brake and clutch means to vary the draw of said array in accordance with determinations of said sensing means, said brake and clutch means being connected with one pair of said rolls to cause increased speed thereof when the clutch efiect is increased and to cause decreased speed of said one pair of rolls when the brake eifect is increased, and said associating means including electrical circuit means responsive to variations in electrical currents in said electrical sensing means and connected with said brake and clutch means to cause increased effectiveness of said brake means simultaneously with decreased effectiveness of said clutch means.

2. In a textile machine, means including two pairs of rolls for moving and stretching an array of textile fibres, cooperating electrically operated brake and clutch means for controlling the rate of rotation of at least one pair of said rolls to cause varying draw of said array, said brake means reducing the rate of rotation of said one pair of rolls on increased brake effectiveness and said clutch means increasing the rate of rotation of said one pair of rolls on increased clutch efiectiveness, means connecting said brake and clutch means to cause one to increase in effectiveness when the other is decreased in effectiveness, means including a capacitance for sensing variations in properties of said array, and electrical circuit means associating said sensing means with said brake and clutch means to cause variation of the draw of said array in accordance with determinations of said sensing means, said variation of draw being caused by variation of the rate of rotation of said one pair of rolls as a result of variable currents in said electrically operated brake and clutch means produced by variations in said array affecting said capacitance.

3. In a textile machine, means including two pairs of rolls for moving and stretching an array of textile fibres, means including power means and electromagnetic clutch means for driving one said pair of rolls, means for rotating the other said pair of rolls, a generator associated with said means for driving said one pair of rolls and producing current in proportion to the speed of said one pair of rolls, electromagnetic brake means associated with :said driving means to reduce the speed of rotation of said one pair of rolls, sensing means for determining variations in properties of said array, said sensing means including electrical means producing current in proportion to said variations, and control circuit means including a 1"0 said generator associating said sensing means with said electromagnetic brake and clutch means for automatically causing the speed of said one pair of rolls to vary in accordance with determinations of said array variations by said sensing means.

4. The device of claim 3, said brake and clutch means comprising an electro-magnetic brake and an electromagnetic clutch, and means associating said brake and clutch to cause one to become more effective as the other becomes less efiective.

5. The device of claim 3, said brake and clutch means comprising an eddy current type brake and an eddy current type clutch.

6. The device of claim 3, said sensing means including a sensing capacitor, a reference capacitor, a radio frequency bridge circuit'associated with said capacitors, and relay means for connecting either capacitor into circuit.

7. In a textile machine, means including two pairs of rolls for imparting draw to an array of textile fibres, power means for rotating one pair of said rolls at predetermined speed and for rotating the other pair of said rolls at slower speed to produce draw in said array of fibres, electromagnetic clutch means for connecting said power means to drive one pair of said rolls, electromagnetic brake means for slowing the rate of rotation of said one pair of rolls, electrical means for sensing variations in properties of said array of fibres, and electrical circuit means connecting said electromagnetic clutch means and said electromagnetic brake means with said sensing means to make said clutch and brake means responsive in operation to variations in properties of said array of fibres, said variations causing varied current through said sensing means.

8. The device of claim 7, said clutch being connected to disengage when said brake is engaged.

9. The device of claim 7, said clutch being connected to engage when said brake becomes disengaged.

10. In a textile machine, means including two pairs of rolls for imparting draw to an array of textile fibres, ,power means for rotating one pair of said rolls at predetermined speed and for rotating the other pair of said rolls at slower speed to produce draw in said array of fibres, a shaft for imparting rotation to one pair of said rolls, an electromagnetic brake associated with said shaft to reduce the rate of rotation thereof, an electromagnetic clutch for effectively connecting and disconnecting said power means and said shaft, electrical means including capacitance means for sensing variations in dielectric properties of said array of fibres, and electrical circuit means connecting said clutch and brake with said sensing means to make said clutch connect the shaft and power means when the brake is ineffective and to disconnect the shaft and power means when the brake is applied, said sensing means and electrical circuit means being arranged to cause said brake to be increased in effectiveness when the sensing means detects a density of said array greater than a predetermined value and to cause said clutch to be increased in effectiveness when said density is less than a predetermined value.

11. The device of claim 10, said sensing means including an elongated pair of metal plates between which said array of fibres is passed.

12. The device of claim 10, said sensing means including an elongated pair of metal plates ahead of the forward pair of rolls, said array of fibres passing between said plates.

13. The device of claim 10, said sensing means includ ing electronic circuit means and an elongated pair of metal plates ahead of the forward pair of rolls, said array of fibres passing between said plates.

14. The device of claim 7, said sensing means including a capacitor having a pair of plates of variable spacing to provide a non-uniform field therebetween through which the array of textile fibres passes.

1 11 15. The device of claim 7, said sensing means including a capacitor having a pair of plates between which the array of textile fibres is moved, the entrance and exit edges of said plates having greater space therebetween than an intermediate location between the entrance and exit of said capacitor.

References Cited in the file of this patent UNITED STATES PATENTS T'-' "'t 7' f Riq a dsqv +---,-,-V----- S p 3, 9 Grqb et a1 July 25', 1950 Andersen Dec. 26, 1950 Anderson Dec. 26, 1950 Hiensch n Feb. 20, 1951 Ingham Aug. 28, 1951 Busby June 9, 1953 Tuek Octv 6, 1953 Tr u itt Mar. 2, 1954 Hare June 29, 1954

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