WO2005080654A1

WO2005080654A1 - Electronic positive feedwheel unit

Info

Publication number: WO2005080654A1
Application number: PCT/EP2005/000736
Authority: WO
Inventors: Rolf Huss; Friedrich Dinkelmann; Friedrich Weber
Original assignee: Memminger-Iro Gmbh
Priority date: 2004-02-23
Filing date: 2005-01-26
Publication date: 2005-09-01
Also published as: DE102004009057A1; BRPI0507981A; CN1946890A; US20070272784A1; EP1718792A1

Abstract

The invention relates to a thread feeding device which is provided with a motor-driven feedwheel, whereby the rotational position of the feedwheel is detected by a high precision angle transmitter. Said angle transmitter has a resolution that is greater than the diameter of the feedwheel measured in millimeters. Preferably, resolution is greater than the five times (preferably 5.24 times) the value of the diameter of the feedwheel. The thread is preferably wound around the feedwheel in a plurality of windings (three to twenty).

Description

Electronic positive feeder The invention relates to a thread delivery device, in particular for the positive delivery of threads to knitting machines, e.g. Circular knitting machines is suitable.

In knitting machines as well as circular knitting machines, the stitch size of the stitches to be produced by the individual knitting systems is set by precisely measuring the individual threads running to the knitting points. This principle is well established for knitting smooth goods using mechanically driven suppliers. This was done early on after an electrical or electronic see a replacement for the rigid mechanical coupling between the thread delivery device and the knitting machine.

For example, US Pat. No. 3,858,416 discloses a knitting machine with an electrical supplier, which can alternatively be operated in a tension-controlled manner or in synchronism with the master cylinder of the knitting machine. To carry out the latter operating mode, a magnetic or other sensor is provided on the main drive of the knitting machine, which generates a pulse train whose frequency corresponds to the speed of the knitting machine. A frequency / voltage converter converts these impulses into a voltage, which then characterizes the working speed of the knitting machine.

The motor driving the thread delivery wheel is connected to a tachometer generator, which is also connected to a frequency / voltage converter in order to supply a voltage which characterizes the speed of the motor. A comparison circuit compares the voltages supplied by both frequency / voltage converters and controls the motor of the supplier accordingly.

In such arrangements, there may be temporary deviations between target deliveries and

Actual deliveries come that influence the quality of the knitted fabric.

Attempts have been made in various ways to electrically drive thread delivery wheels. For example, DE 38 24 034 Cl discloses driving a thread delivery wheel with a stepper motor. Stepper motors cannot be switched on and off arbitrarily. Rather, a certain operating regime must be observed when starting up and shutting down so that step errors do not occur.

DE 15 74 430 shows further efforts to deliver strip or strip-shaped material, in particular threads, to a point of consumption at a predetermined speed. For this purpose, an electric drive motor is provided, the shaft of which is connected to a delivery wheel. A coupling device permits the arbitrary coupling and uncoupling of the delivery wheel from the drive motor. The delivery wheel serves as a tachometer. Tension meters are arranged before and after the delivery wheel. In a set-up operating mode, the thread feed wheel is uncoupled from the motor shaft and the speed of the thread feed wheel that is set is registered in order to be used as a basis for later operation of the motor. The clutch must be activated to take up the set-up mode. Resistance in the thread path also acts as a brake on the thread. In the case of knitting machines, the resulting amount of thread is thus influenced by chance. The clutch has a mass moment of inertia that is added to the mass moment of inertia of the thread feed wheel and the motor.

Proceeding from this, it is an object of the invention to provide a thread delivery device which is particularly suitable for knitting machines, in particular knitting machines with alternating

Thread requirement is suitable, and a high delivery quality allowed. This object is achieved with the thread delivery device according to claim 1:

The yarn delivery device according to the invention has a yarn delivery wheel rigidly connected to an electric motor and having a given diameter. The thread delivery wheel can have both a round and a polygonal cross section. For example, it can be formed by a rod cage. An alternative is a one-piece thread delivery wheel, deep-drawn from sheet metal, the circumference of which is provided with longitudinal ribs, for example, so that it mimics the outer contour of a rod cage. Other thread delivery wheels are also possible. It can be wrapped in a wrap that lies around the entire circumference. The winding can also only touch part of the circumference of the delivery wheel and can be guided, for example, via (fixed or movable) lifting pins. In addition, an angle encoder is provided which is connected to the thread delivery wheel in a rotationally fixed manner and which generates a signal which identifies each rotational position of the thread delivery wheel. What is essential here is a high angular resolution, which is at least so large that the ratio between the number of steps of the angle transmitter and the diameter of the thread feed wheel is greater than three per millimeter. With angular resolutions above this limit, the thread delivery wheel can be positioned so precisely that synchronous running between the thread delivery wheels and the knitting machine is achieved in all essential operating states of the knitting machine. If the angle resolution of the angle encoder is greater than the specified value and if the rotary position of the motor is set accordingly in a position control loop, a knitting machine with an electronic positive feeder can be started up and stopped without the otherwise feared series of stands being formed. Under rows of stands understood the stitches whose stitches have a different size than the other stitches of the knitted fabric.

The angle transmitter is preferably connected to the shaft of the motor, a shaft running through the motor being provided in a preferred embodiment, the thread delivery wheel being arranged at one end and the angle transmitter being arranged at the other end. The angle encoder is preferably an incremental encoder with a high number of increments. With a diameter of 40 mm, the angle encoder has at least 120 steps, i.e. an angular resolution of at least 3 °. Embodiments are preferred in which the ratio s / d (number of steps to delivery wheel diameter) is greater than five. (“Number of steps” is understood to mean the number of steps that can be distinguished in one revolution using the angle encoder.) In such a case, the incremental encoder resolves more than 200 steps per delivery wheel revolution. This corresponds to a resolution of at least 1.8 ° or better, in the preferred case, s / d is greater than 5.24, which means that regardless of the respective thread delivery wheel diameter, the position control loop delivers delivery accuracies with regard to the yarn delivery, in which delivery deviations are less than 0.6 mm when the knitting machine changes its working speed, e.g. stops or starts.

The precise, high-resolution angle encoder thus creates an electronic positive feeder that not only delivers precisely but can also be controlled remotely. For example, it can be specifically switched on and off when creating patterned knitted fabrics. The electronic positive feeder according to the invention thus makes friction feeders previously used for this purpose. unnecessary. It enables better control of the mesh size when producing patterned goods. The electronic positive feeder preferably receives a pulse sequence as the control signal, each pulse corresponding to an angular step of the thread feed wheel. The angular step corresponds, for example, to an angular step corresponding to the angular resolution of the position encoder. It is preferably dimensioned so large that it corresponds to a thread delivery path of 1 mm, preferably 0.6 mm. With each impulse that the thread delivery device receives, it rotates the thread delivery wheel by a thread length of 0.6 mm. In this way, a continuous control of the delivery quantity is possible according to the rotation of the main cylinder of the knitting machine. The position-controlled supplier behaves virtually like a stepper motor-driven supplier, with its position control loop preventing the occurrence of step errors.

The thread delivery device can preferably house a position controller which compares the angular position of the thread delivery wheel precisely detected by the angle transmitter at any time with a target signal and compensates for deviations. In an extended embodiment, the position controller can also be part of a tension controller. In this case, a thread tension sensor is then additionally provided, which detects the actual tension of the thread. If this deviates from a predetermined target voltage value, corresponding positioning signals are generated, which the position controller then implements. The voltage regulator is preferably designed as a PD regulator with feedforward control. This means that the controller has a proportionally amplifying component ("P") and a differentiating component ("D"). From the detected thread tension, the current delivery speed and possibly the motor currents a correction quantity is determined, which is linked to the target voltage value in order to correct it in such a way that permanent control deviations caused by the controller disappear.

In a further development, the thread delivery device according to the invention has a first operating mode in which, depending on the embodiment, it operates as a positive feeder in a tension-controlled or position-controlled manner. In an additional operating mode, which can be referred to as the drag mode, the current of the electric motor is reduced to such an extent that it no longer causes active thread conveying. The motor current is set in such a way that all possible cogging torques of the electric motor are overcome and no drive torque or at most a drive torque is generated which is not sufficient to convey the thread. From the machine's point of view, there is no positive feeder in this operating state. Rather, the thread-consuming machine has to get the thread from a thread source, for example a creel. The drive torque of the electric motor is at most so large that this process is facilitated. The force for pulling the thread from the creel is only partially applied by the supplier. The thread delivery wheel is thus virtually uncoupled from the motor shaft, at least insofar as it does not produce any funding. The thread consuming machine or its knitting system can get the thread with little resistance. A circuit connected to the electric motor or the incremental encoder can precisely detect the amount of thread that has been fetched and use it as a basis for the further operation of the thread delivery device in a positive delivery mode. Details of advantageous embodiments of the invention are the subject of the drawing, the description or the claims. Exemplary embodiments of the invention are illustrated in the drawing. Show it:

FIG. 1 shows a plurality of electronic position-controlled suppliers and their connection to a central control in a schematic representation,

FIG. 2 shows the feeders designed as voltage-controlled feeders, connected to a central control device in a schematic representation,

FIG. 3 shows the feeders according to FIG. 1 with an additional towing mode, connected to a central control in a schematic representation,

FIG. 4 shows an angle encoder of a supplier in a schematic representation,

FIG. 5 output signals of the angle encoder according to FIG. 4,

FIG. 6 shows an alternative embodiment of an angle sensor in a schematic representation,

FIG. 7 shows a voltage-controlled supplier with feedforward control in a schematic representation and

Figure 8 shows a modified angle encoder in a schematic perspective view. FIG. 1 illustrates a group of thread delivery devices 1, 2, 3 which are connected to a central control device 4. The control device 4 can be a central control device, it can belong to a knitting machine, be a separate device or be accommodated in one of the thread delivery devices 1, 2, 3. Three thread delivery devices 1, 2, 3 are illustrated by way of example only. If necessary, however, only a single thread delivery device 1 or a larger group of thread delivery devices can be provided.

The number of thread delivery devices 1, 2, 3 corresponds to the number of threads to be supplied to a thread-consuming machine, such as a circular knitting machine, and thus the number of knitting points. They are essentially the same in structure. The following description of the thread delivery device 1 is therefore representative of the other thread delivery devices 2, 3 and any other thread delivery devices that are not illustrated.

The thread delivery device 1 has a thread delivery wheel 5, which is formed, for example, by a deep-drawn sheet metal part. It can be provided at the top and bottom with a flared edge 6, 7, which form a thread inlet area and a thread outlet area. A thread storage area arranged between them can be provided with ribs 8. In front of and behind the thread delivery wheel 5, thread guide means, such as a thread inlet eyelet, a thread outlet eyelet, a thread brake, a knot catcher and the like are arranged. In addition, if necessary

Thread feeler lever or other thread monitoring devices can be provided. The thread delivery wheel 5 is wrapped by a thread in at least one, preferably a plurality of turns 11. The winding 11 formed in this way comprises at least one, but preferably a plurality of turns 12. When the thread delivery wheel 5 rotates, the thread 9 runs on the upper edge 6 onto the storage area of the thread delivery wheel, forms adjacent turns and thereby pushes the winding 11 axially downwards. The thread delivery wheel 5 can have a slight taper in order to facilitate this process. With the thread delivery wheel 5 running, the winding 11 is thus constantly in motion on the thread delivery wheel 5.

The thread feed wheel 5 is connected to a shaft 13 which belongs to an electric motor 14. The connection is non-rotatable and is preferably not resolvable by means that can be controlled during operation, such as couplings or the like. The electric motor 14 is preferably a brushless DC motor with a low moment of inertia, such as, for example, a bell-type rotor motor, a disc rotor motor or the like. With lower dynamic requirements, another motor, such as a brushless DC motor, a synchronous motor or the like, can also be used. In the case of a brushless DC motor, the electric motor contains 14 Hall sensors for detecting the position of its armature, e.g. 8 and corresponding electronic switches for energizing the stator windings according to the angle of rotation of e.g. permanent magnet excited rotor. In such a motor, the torque generated by the electric motor 14 on the shaft 13 corresponds to that supplied via a feed line 15

Operating current.

The shaft 13 is either in the area between the electric motor 14 and the thread feed wheel 5 or alternatively Its end 16, which is remote from the thread delivery wheel 5 and protrudes out of the electric motor 14, is connected to an angle encoder 17, which is preferably designed as an incremental encoder or as an analog encoder with high resolution. Its step number s is the number of steps that result in a single full rotation of the shaft 13. The angle transmitter 17 preferably has at least such a number of steps s that the ratio between the number of steps s and the diameter d of the windings 12 is greater than three, preferably greater than five. Thus, the error that occurs when the rotational position of the thread delivery wheel 5 is detected is below a limit, which could cause traces in the knitted fabric even with particularly hard (inelastic) threads.

The structure of the angle encoder 17 is shown by way of example in FIG. 4. It is formed here by a resolver which has an armature with an armature coil 18, the longitudinal axis of which is transverse to its axis of rotation. The axis of rotation is perpendicular to the drawing plane in FIG. The armature coil 18 is connected to a feed coil 19, which is axially oriented and receives an AC excitation signal via a stationary outer coil, which is not further illustrated. Two stator coils 21, 22 radially oriented with their coil axes and offset by 90 ° detect the alternating field generated by the armature coil 18. The signal curves illustrated in FIG. 5 result. According to the position of the armature coil 8, the amplitudes of the voltages generated in the stator coils 21, 22 increase or decrease sinusoidally or cosinusoidally. For example, one

Angle of rotation P induces a positive voltage U _x in the stator coil 21 and a negative voltage U ₂ in the stator coil 22. Via the arc sine or arc cosine function can be deduced from the tensions on the angle of rotation P.

An alternative embodiment of an angle encoder is illustrated in FIG. 6. This works optically and has a first stationary disc 23 and a second disc 24 connected to the shaft 13. Both disks are each provided with a pattern of lines 25, 26 oriented in the radial direction. These form a light-dark pattern. The spaces between the lines 25 and 26 are preferably transparent. In a preferred embodiment, the width of bars and gaps between them approximately match. The lines 25, 26 can also be slightly wider than the gaps. They also coincide in number. If the angle encoder is to record not only the speed but also the direction of rotation, they preferably differ in number by one. A light source 27, for example in the form of a light-emitting diode, is provided for step counting and is arranged on one side of the disks 23, 24. A photosensitive element 28, for example a photoresistor, a phototransistor or the like, is provided on the opposite other side. If the direction of rotation is to be detected, one or two further light barriers of this type are provided which illuminate the pair of disks at another point. Figure 8 illustrates another modified

Embodiment of an angle encoder with a rotatable permanent magnet M and four Hall sensors 21a, 21b, 22a, 22b arranged in the same field. These are connected together as a bridge, for example. Such angle encoders are for example installed in some brushless electric motors anyway to control electronic switches that serve to control the motor winding. If, by evaluating the voltages occurring at the Hall sensors 21a, 21b, 22a, 22b, such an angle encoder 17 permits the resolution of one revolution in a step number s which is equal to or greater than the number of steps defined by the conditions discussed above, this internal motor angle can be Serve as a position transmitter for the connected control loop. The brushless DC motor thus becomes a virtual stepper motor which, unlike known stepper motors, does not make any step errors, even if no special consideration is given to changes in speed. Such a virtual stepper motor can be operated in start / stop mode without observing special start-up regimes or shutdown regimes.

The signals emitted by the resolver according to FIG. 4 or the optical sensor according to FIG. 6 are fed as an actual position signal to a control loop 29 (FIG. 1). This includes a comparator 31, which compares the actual position signals of the angle encoder 17 with the set position signals of a specification unit 32. Any existing deviation between the target position signal and the actual position signal is passed on as an angle error signal via a branch 33 to a control circuit 34, which controls the electric motor 14 accordingly in order to bring the target position signal and the actual position signal into agreement.

Optionally, the actual position signals of all the thread delivery devices 1 to 3 can be passed to the control device 4 via corresponding lines 35. The lines 35 can directly transmit the signals from the angle transmitters 17. derivate by connecting the angle encoder 17 to the control device 4. It is also possible to design the lines 35 as a data bus which is connected to the angle encoder 17 via corresponding interfaces. All existing data buses, including single-wire buses, are included.

The control device 4 sends control pulses to the specification unit 32 via a line 36. The thread delivery devices 1, 2, 3 to be operated in parallel can be controlled in parallel to this extent. In the present exemplary embodiment, the control unit 4 emits individual pulses, each individual pulse corresponding to the rotation of the electric motor 14 by one step of the angular resolution of the angle transmitter 17. If, for example, the angle transmitter 17 is constructed according to FIG. 4 and it contains an evaluation circuit connected to the stator coils 21, 22, which converts the signals derived from the stator coils 21, 22 into a signal of an analog or digital nature which uniquely identifies the angle of rotation, this is also Specification unit 32 is designed accordingly. It then has, for example, a counter, which counts from zero to the maximum number of steps of the angle encoder 17, in order then to start again. The single-step pulses supplied via line 36 thus become an analog or digital step-shaped signal with a corresponding number of steps. As soon as 36 pulses are supplied via the line, the electric motor 14 rotates. If there are no pulses, it stops. In this respect, the electric motors 14 behave from the outside like stepper motors, which perform an angular step for each pulse delivered via the line 36. As a result of the internal position control, however, they are not subject to step errors, so that they can be started and stopped unlike conventional stepper motors. The thread delivery devices 1 to 3 supplied so far work as follows:

It is assumed that the thread delivery devices 1 to 3 are provided on a knitting machine which is designed, for example, as a jacquard knitting machine or as a knitting machine with a streamer. Each thread delivery device 1, 2, 3 supplies a knitting point with a respective thread 9. If the relevant knitting points are to be supplied with thread, the control device 4 delivers

Pulses to the corresponding specification units 32, whereupon the thread delivery wheels 5 rotate accordingly. In doing so, they follow the specified signal at the correct angle, with any angular deviations in relation to the circumference of the thread delivery wheel being less than 1 mm, but preferably less than 0.6 mm. This results from the condition that the ratio s / d is greater than three, preferably greater than five per millimeter. This ensures that any angular errors decrease under other error influences. Such error influences can include, in particular, the sliding movement of the winding 11 on the thread delivery wheel 5. As long as the thread delivery wheel 5 rotates, the winding 11 is continuously displaced axially downward in the direction of the unwinding thread by the incoming thread 9. The existing axial sliding movement naturally also results in a certain slippage of the winding 11 in the circumferential direction. This means that there is a certain slippage of the thread on the thread delivery wheel 5. It is preferred if the quotient of the circumference of the thread delivery wheel and the angle resolution s is less than this slip, for example less than 1 mm, preferably less than 0.6 mm. A knitting machine equipped with such thread delivery devices 1 to 3 can be started up and switched off again and again can be approached without generating rows of stalls, ie rows of stitches of different sizes.

The delivery speed of the threads 9 can be increased, decreased or set to zero by targeted delivery of pulses via the line 36. It is therefore possible to deliver thread to jacquard knitting machines.

In an extension of the embodiment described so far, the thread delivery devices 1 to 3 can be provided with thread tension sensors 37 which monitor the tension of the thread running off. The tension sensors can be connected to the specification unit 32, for example, in order to influence the thread specification. Otherwise the above description applies accordingly. The same reference symbols are used. In this embodiment, the thread delivery devices 1, 2, 3 can also be operated in a tension-controlled operating mode, if necessary. For example, a thread tension signal is supplied via line 36. The specification unit 32 compares them

Tension with the actual tension detected by the thread tension sensor 37 and generates a corresponding target position signal therefrom. This is in turn implemented by the control loop 29 in rotations of the yarn feed wheel 5.

Such a thread delivery device 1 to 3 can alternatively work as a positive feeder or as a voltage-fed feeder, i.e. Deliver thread with constant delivery rate or with constant thread quantity.

FIG. 7 illustrates a supplement for the thread delivery device 1 to 3 according to FIG. 2. The specification unit 32 and the control circuit 34 are combined here to form a position controller 38. This receives at an entrance 39 a voltage command signal. It receives an actual tension signal from the thread tension sensor 37. The angle encoder 17 supplies an actual position signal at a further input. The moment driving and accelerating the thread delivery wheel 5 is detected by means of a current sensor 41 and reported back at an input 42 of the voltage regulator 38. The tension regulator 38 thus receives signals about the speed of the running thread, the accelerating or braking torque acting on the armature of the motor, and the thread tension. It is designed as a PD controller. An error signal is generated from the thread speed, the thread tension and the motor current, which is applied to the PD controller as a disturbance variable. A robust controller is thus created, the control deviation of which is small for almost all yarns occurring, regardless of their elasticity, and follows the changes in the input signal at input 39 very quickly.

FIG. 3 illustrates a further development of the thread delivery devices 1 to 3 based on the embodiment in accordance with FIG. 1. Reference is first made to the description of the embodiment in accordance with FIG. 1 including FIGS. 4 to 6. The following also applies: The control circuit 34 has an additional one

Control input at which it can be deactivated as a control circuit and converted into a towing mode. This control input is connected to the control device 4 via lines 43 or a corresponding bus. As soon as the control circuit 34 receives a corresponding signal via the lines 43, it goes into a towing mode. In this, the electric motor 14 is subjected to a small current, which is at least sufficient to overcome any cogging moments of the electric motor 14. Then this is from the point of view of the thread feed wheel 5 “invisible”, ie it does not hinder a rotation of the thread feed wheel 5 as a result of pull on the thread 9. This corresponds to a virtual uncoupling of the electric motor 14 from the thread feed wheel 5. In this state, the individual thread consumption can - Set (knitting systems) fetch thread without being prevented by the electric motors 14. The control device 4 registers the fetched thread quantities via the lines 35. A preset value can be determined from the detected values, which in later positive operation via the line 36 in Form of corresponding control pulses is supplied.

In the drag mode, a slightly driving torque can also be generated to make it easier for the knitting points to fetch thread. However, the moment or the control currents of the electric motors 14 are so small that there is no independent thread conveyance as a result of the electric motors 14 being energized.

The high resolutions of the angle transmitters 17, which are present in addition to any transmitters present on the electric motors, such as Hall transmitters, for example, also have a positive effect on the detection of the thread quantities obtained from the knitting points. With regard to the measurement of the natural thread consumption in the drag mode, it is possible to achieve a complete detent torque, which is hardly possible with conventional stepper motors. A thread delivery device is provided with a motor-driven thread delivery wheel, the rotational position of the thread delivery wheel being detected with high precision by an angle encoder. The angle encoder has at least a resolution s which is greater than the circumference of the thread delivery wheel 5 in millimeters. The resolution s is preferably greater than five times (preferably 5.24 times) the value of the diameter of a turn of the thread delivery wheel. The thread delivery wheel is preferably wrapped in several (three to twenty) turns.

Reference list:

1, 2, 3 thread delivery devices

4 control device 5 thread delivery wheel

6, 7 edge

8 ribs

9 threads 11 windings 12 turns

13 wave

14 electric motor

15 supply line

16 end 17 angle encoder

18 armature coil

19 feed coil 21, 22 stator coils 21a, 21b, 22a, 22b Hall sensors 23, 24 disks

25, 26 strokes

27 light source

28 element

29 control loop 31 comparator

32 default unit

33 branch

34 control circuit

35 lines 36 lines

37 Thread tension sensors 38 tension regulators

39 entrance

41 current sensors 42 entrance

43 lines

P rotation angle d diameter s number of steps

M permanent magnets J ₁ , U ₂ voltage

Claims

Claims:

1. Thread delivery device (1), in particular for knitting machines, with a thread delivery wheel (5) which is wrapped by the thread (9) to be supplied in at least one turn (12) in order to convey the thread (9), with an electric motor ( 14), which has a shaft (13) which is non-rotatably connected to the thread delivery wheel (5), with an angle sensor (17) for detecting the rotational position of the thread delivery wheel (5), the angle sensor (17) providing an angular resolution (see FIG ) which is at least so large that the ratio (s / d) between the angular resolution (s) and the diameter (d) of the thread feed wheel (5) is greater than 3 mm ^"1 .

2. Thread delivery device according to claim 1, characterized in that the angle encoder (17) is connected to the shaft (13).

3. Thread delivery device according to claim 1, characterized in that the shaft (13) is a through the electric motor (14) continuous shaft, at one end of the thread delivery wheel (5) and at the other end (16) of the angle encoder (17) are.

Thread delivery device according to claim 1, characterized in that the angle encoder (17) is an incremental encoder.

5. Thread delivery device according to claim 1, characterized in that the angle encoder (17) is an encoder.

6. Thread delivery device according to claim 1, characterized in that the angle encoder (17) is an optical step sensor.

7. Thread delivery device according to claim 1, characterized in that the angular encoder (17) has an angular resolution (s) which is at least so large that the ratio (s / d) between the angular resolution (s) and the diameter (d ) of the thread delivery wheel is greater than 5 mm ^"1 .

8. Thread delivery device according to claim 1, characterized in that the angle encoder (17) is connected to an actual value input of a control loop (29).

9. Thread delivery device according to claim 8, characterized in that the control loop (29) has a setpoint input, which is set up to receive external setpoint signals.

10. Thread delivery device according to claim 8, characterized in that the control loop (29) is a PD controller.

11. Thread delivery device according to claim 8, characterized in that the control loop (29) is connected to a voltage regulator (38) with a device for applying disturbance variables.

12. Thread delivery device according to claim 8, characterized in that the control loop (29) with a thread the tension sensor (37) is connected to detect the thread tension.

13. Thread delivery device according to claim 12, characterized in that a comparator circuit (32) is connected to the thread tension sensor (37), which compares the detected thread tension with a target thread tension and determines a target position signal from the comparison.

14. Thread delivery device according to claim 1, characterized in that the electric motor (14) is connected to a control circuit (34) which is set up for a towing mode in which the flow through the electric motor (14) is not sufficient torque for independent thread conveying causes.

15. Thread delivery device according to claim 14, characterized in that a control circuit (34) is provided which registers the rotation of the electric motor (14) in the towing mode by means of the angle encoder (17).

16. Thread delivery device according to claim 15, characterized in that a specification for the positive delivery mode is obtained from the registered rotation.

17. Thread delivery device according to claim 16, characterized in that the specification is obtained from the registered rotations of a plurality of thread delivery devices (1, 2, 3).