DE2415042A1 - CONTROL OF DC MOTORS FOR SEWING MACHINES OR THE LIKE - Google Patents

Description

PATENT LAWYERS

Dipi.-ing. H. Seiler Dipi.-ing. J. Pfenning Dipi.-Phys. KH Meinig CRC 83

1 Berlin 19

Oldenburgallee 1O Tel. O3O / 3O4 55 21/22

Wireword: rope defense patent

Postal checking account: Berlin-West 59 38-1O2

March 26, 1974 Me / an

PHOTOCIRCUITS DIVISION OF KOLLiIORGEH CORPORATION

31 Sea Cliff Avenue Glen Cove, K.Y. 11542, USA

Control of DC motors for sewing machines or

like that

The invention relates to a control of the drive and the running speed of DC motors, in particular such as are used for sewing machines or similar devices.

Strict requirements are placed on the control of sewing machines used on an industrial scale. First of all, the electrical control of the drive of the sewing machine must be designed so that its drive continuously with variable load can be applied while the speed of the sewing machine run from which the machine is operated

409843/0745

the person continuously and preferably within the total ^! th operating range must be pre-selectable and controllable in an infinitely variable manner. In addition to the requirements mentioned first, it must also be possible, secondly, to stop the sewing machine in a controlled manner within a relatively short braking period and with a minimal distance for the movement of the doll. Finally, thirdly, it must be possible to stop the sewing machine in this way.

I pen _r that the needle is either in its upper or in its!

lower position. The control must therefore be designed so that a precise position specification and control and not only accidental stopping of the machine in any needle position can be specified.

In addition to these desirable and necessary requirements, there are! especially for driving sewing machines, yet others, such as those of a fast positive and negative Acceleration, so they are both for a quick start as well as a correspondingly sudden deceleration is advantageously designed. Such requirements are roughly equivalent to: Electric motor with low moment of inertia, which is in direct connection with the needle mechanism. Such an engine! is also an ideal drive when it comes to an undelayed, rapid start-up of the machine and a sudden braking of the same is possible, as it is due to the low inertia

409843/0745

is characterized by a relatively high torque. For the same reason, there is always less for such a drive element

Braking torque required to drive the motor and the one it drives Bring mechanism to a complete standstill.

In general, the drive motor has so far been braked dynamically, to stop the needle mechanism a. However, if the dynamic braking alone will cause the braking process has, then a specific needle position for the standstill cannot be reached because of the initiation of the Braking the engine speed in any of their

countless intermediate positions can be found. In this context, one must also consider the possibility of initiating the braking process in a special section of the movement of the needle mechanism. In order to counteract the problem, a complex motor control has recently been used to drive commercial sewing machines, by means of which the subsequent actuation of the braking process proceeds in such a way that the speed of the motor is first reduced to a predetermined speed level, at least for a short time ^! Time to be stabilized on this. After reaching this speed value of the motor is in the predetermined control sequence \ dynamic braking to a standstill, according to i of a pulse signal which is emitted when the needle mechanism any known in its motion cycle

409843/0745

Position runs through.

For a corresponding sequence control that is precise in its sequence the above technology has been used for motors up to now. However, the people operating the machines have recognized that Such a sequence control is too complex, especially since it requires a corresponding operating sequence, whereby it moreover, it is also very expensive and the operating conditions are difficult to maintain can.

The complexity and the complex structure of the known Einrichtunpn are due to various factors. First of all, it should be noted that such facilities operate photosensitive devices and have circuitry for generating pulses, their repetition rate must be reliably predeterminable and determinable for the actuation of the control device and the motor speed. Even though the pulse train technique eliminates the need for tachometers or other speed indicators can be avoided, they unnecessarily complicate the structure of the control circuit. Others, the structure of the control unit Onerous factors can be traced back to the actual motor drive itself, if this is a rectified alternating current is fed. The pulsating direct current can

409843 / 074S

with variable power components of a silicone rectifier arrangement which is connected to a multiphase power source. Through triggered control of the Rectifier circuit can be the removable phase portion and thus regulate the performance of the engine. In order to achieve a dynamic braking process when using such circuits To effect, special circuits are required to trigger the rectifier circuit during the dynamic Switching off the braking and causing the drive to set a low torque, using the DC motor ι in the mentioned subsequent sequence during the braking time initially received a speed stabilization at low speed must before the final braking is carried out.

Another complicating feature may be the use of silicone controlled rectifiers to short circuit the DC motor during the dynamic braking process

ι be seen. A specially designed circuit must be included in the Circuit are introduced to overcome the difficulties that arise here, with just the triggering of the

dynamic braking at the end of the first braking period of

This is important because the rectifier arrangement tends to 'i
! Stay connected until the electricity is nearly destroyed

has been.

40 9843/0 745

The invention is therefore based on the object of i Avoid disadvantages of conventional control devices for DC motors while at the same time observing their advantages;

it is particularly important to eliminate the complexity and complexity of control of the above-mentioned type and in this respect to implement a simple, properly functioning, reliable and operationally safe control system, in particular J for sewing machines, at low cost. | The control of the motor and thus of the sewing machine mechanism must be precise, safe and executable in such a way that the ί rectification of a continuously variable alternating current ^; signal predetermined signal of the DC motor drive can be brought into agreement with the control circuit for regulating a sewing machine or the like, with a speed-regulated drive being used in the interposition

thinks, uria gg is a DC voltage at the signal uiri can.

The stated problem is solved by means of a control device, about which a DC motor in accordance with

a deceleration command is braked dynamically, while the dynamic motor energy, which is generated as back EMF by the brake pre-; gang is generated, for specifying a control signal for the i Establishment applies. !

403843/0745

In a preferred embodiment of the invention, the dynamic braking current is used to indicate a predetermined desired motor speed, the motor speed being subsequently regulated by a current regulating device in series with the motor. The engine is in its dynamic braking state by under-; interruption of the variable direct current supply to the connection terminals of the same and connection of these connection terminals with ■ the brake control unit. The current regulation of the motor continues in the following sequence of the deceleration until the needle mechanism reaches a predetermined position and thus external braking devices bring the motor to a stop at a known speed in the prescribed time and length of movement of the needle.

It is for the invention in this connection of importance that the dynamic braking current is used for providing a variable signal which is added to a fixed reference voltage so that the resulting control signal of regulation can serve the engine, while its velocity ¹ ness is stabilized. '

The invention is intended below with reference to the accompanying drawings For example, statements are described in more detail, in which a preferred embodiment is reproduced. It means:

409843/0745

Fig. 1 is a schematic circuit diagram for the inventive Engine control and,

Figure 2 is a series of graphical representations of curves ^; AI ■ I

run from different points of view for

the control unit according to FIG. 1.

The following picture results for the normal motor drive: I The direct current shown on the left-hand side of Fig. 1! Motor 10 has a high torque and a low moment of inertia and is connected to a conventional full-wave rectifier bridge 14 via a switch 12. A variable alternating current is fed to the bridge in the manner shown via the winding of a transformer, for which purpose the transformer 15 is connected on the input side to a corresponding alternating current network. One winding of the transformer
is provided with a sliding contact 16 in the center tap, which is connected to the foot pedal 18 via a suitable mechanical coupling
is in connection, which in turn can be operated by the operator of the sewing machine. The coupling mechanism | between the sliding contact 16 and the foot pedal 18 is in the
Drawing indicated with the dashed lines. To the
Transformer is supplied with an alternating current from the power grid!

which is in the embodiment by 220 volts voltage and | 60 Hz. The input terminals of the
Transformer are terminals 17a and 17b. When the pedal is depressed, the screen will zoom in continuously

409843/07 4 5

Q _

the voltage of the supplied alternating current due to the change in the tap of the sliding contact 16 and thus a
corresponding change in the voltage supply to the two-way | Rectifier 14. The DC voltage supplied to the motor 10 by the rectifier arrangement drives it to the desired level
Direction, referred to as the so-called forward direction;

should, on. ^;

Such a circuit for a motor drive is for example in US application Ser. No. 259 171 of June 2, 1972
has been proposed.

The conditions present at the connection terminals during normal engine operation are indicated by the graphic representation in FIG
The waveform can be seen in FIG. 2D, where the voltage is plotted against time. The graphic representation is intended to illustrate the conditions that exist when the operator completely releases the pedal. Much more difficult
is that the voltage applied to the terminals of the motor includes the j back EMF which is superimposed on the voltage from the two-way rectifier 14 (see the dashed lines) !.

The following picture emerges for the braking of the motor:
The control system is in the braking state when the

... / 10

403843/0745

the person operating the sewing machine no longer depresses the pedal
occurs. After returning the pedal to its starting position
the sliding contact 16 of the transformer closes the circuit
briefly to terminal 17b, which means that the applied alternating current at the bridge goes back to zero, like that in the field ^!

I "1" can be seen in Fig. 2D. At the same time the moves

Contact 13 of switch 12 from its normally closed-j NEN position in its opposite switching position and come into contact with the contact 20 here. This means that the motor is connected to I.

BreLis- ^:

the / control system for the mowing mechanism of the sewing machine; closed, which is reproduced in the right part of Fig. 1 j

while the needle moving mechanism itself is not ^! is shown. If the switch 12 is in the last-mentioned position, then this means that the motor is both dynamic; is braked and to drive the motor with a correspondingly regulated current applied to it
maintains a controlled predetermined intermediate speed.
The engine speed during the aforementioned actuation conditions is shown in FIG. 2A, where the speed j of the engine is shown as a function of time. Of the
Area (0) shows a slight slowdown in motor speed during the normal drive phase when the pedal is in
returns to its resting position.

... / 11

409843/0745

ί ί

! ί

j The braking is initiated automatically in order to bring the mechanism j for actuating the needle of the sewing machine to a standstill j with the needle in its fully down position. As I said, this applies to the case that the pedal is released. The braking process now takes place in three steps:!

1. First there is a negative acceleration to dynamic! Way of the current speed of the ι motor to a predetermined speed level, where ι For this purpose, the curve section (1) in Fig. 1A is representative.

ι 2. The following is a constant speed for _; i - ι

'■ the motor, which is maintained until the ' needle mechanism has a preselected position in its movement '. cycle has reached. For this, the curve section (2) in FIG. 2A is responsible, to which the section

\ (3) follows, in which a combined dynamic and external + · ne braking takes place, until the motor in the manner shown

J speed has reached zero and the motor has come to a standstill. In the event that the The sewing machine should come to a standstill so that the needle is then in the fully raised position, a corresponding command is given, by means of which it is possible to move the needle from its lower position into the to move desired upper, for which the motor at a speed level corresponding to the curve section (2)

... / 12

409843 / 07A5

is held automatically for a time that corresponds to the desired j needle lift. The relevant process is in; the curve section (4) of Fig. 2A. After the! Needle has reached the raised position, the motor will decelerated dynamically from its constant, relatively low speed level and by external braking; what should be made clear by the curve section (5) * j (rig. 2A). j

The dynamic braking of the motor is predetermined by the resistor 22 in series with it Impedance, which in the manner shown with the emitter j

i collector path of the switching transistor 24 is connected. <During the dynamic braking process, the Transistor 24 in its switched-on position, which is achieved by means of a signal voltage applied to the base of the transistor is achieved via the amplifier 25. The signal voltage is specified via the braking circuit to which the flip-flop pulse generator 27 belongs, which responds completely to signals that are on the one hand representative of the engine speed i

and on the other hand for the position of the needle. J

If the motor 10 is in the state of dynamic braking, then one falls into the mentioned short-circuit circuit Voltage across the resistor 22, which is proportional to the motor speed. This voltage is in a comparator;

... / 13

4 0 9 8 4 3/0 7 L 5

30 compared with a reference voltage that is applied to the amplifier 31 in the form shown. When the voltage across the resistor 22 drops below the predetermined value of the The reference voltage drops, then the output signal goes to the Differentialxalkomparator 30 in the "low" state, and it is shown in FIG. 2E at the output of the negative edge detector 33 Impulse induced. This pulse causes the motor to receive a predetermined selected speed. Output side the detector is connected to an OR gate 35, the output of which in turn is at the input S of the flip-flop 27 for the brake control lies. The said pulse causes the output Q of the flip-flop to go into the "high" state during the Output Q is reset to "low".

The current curve through resistor 22 for dynamic braking is shown in FIG. 2C, with the associated Switching states of the switch 12 can be seen from FIG. 2B. The rapid deceleration of the engine as a result of the dynamic Braking process can be seen clearly from the curve area (1) of the graph in Fig. 2A.

In the normally present initial position of the flip-flop 27, the output Q is "high". While In this state, a signal is fed to the amplifier 25, i.e. a voltage is applied to it which

... / 14

409843/0745

th of the transistor 24 causes. However, in the event that the operator of the sewing machine releases the pedal, results First, a dynamic braking of the motor via the short circuit, which is caused by the low resistance 22 represents. I.

The dynamic braking is continued until the voltage which drops across the resistor 22 is equal to the reference voltage at the comparator 31, so that the pulse shown in FIG. 2E! falls back to zero at this point. The negative ' edge of the pulse, which is then also applied to the detector 33, produces a pulse (34 in FIG. 1) which sets the flip-flop 27 accordingly. The consequence of this is that the output Q of the flip-flop 27 is at the "high" level, whereby the device regulating the speed control is enabled to take over its control function, while at the same time the switching transistor 24 is in the blocking position via -j goes. As can be seen, the output Q is connected via the amplifier 38 to the base of a current regulating transistor 40, the collector of which is connected to a suitable direct current source + V. In the operational sequence, the Br? Ems circuit now changes over to the actuation run of the area (2f of FIG. 2A, that is to say in an area in which the motor speed is kept constant until a pulse responsible for the needle position is present.

... / 15

409843/0745

The speed regulation works as follows: The speed setting, as found in areas (2) and (4) of FIG. 2A, is carried out by the feeder a correspondingly regulated current to the motor

^! through the transistor 40. Reinforced in the areas mentioned

the amplifier 42 voltage drop across the resistor 22 chip \. The gain of the amplifier 42 is selected so that the voltage applied to the anode of the Zener diode 44 is equal to the voltage drop across the motor, ie

the value i_R_ of the valve. The one lying on the engine, about a a

The voltage signal carried by the transistor 40 and the diode 45 is in this respect predetermined by the Zener diode, the variable i R falling in the motor.
aa

In the DC motor operating sequence, any I 'change in torque causes a corresponding change in motor J speed, which, as can be seen from the circuit,

! is perceived by the amplifier 42, which in turn the

Zener diode 44 as a variable size of a speed control and control signal controls. Any voltage changes in this signal then also have corresponding repercussions to the base of the transistor 40, which is connected to the sum voltage of the Zener diode 44 and the variable voltage i R

el el

is applied whenever the amplifier 38 receives a voltage signal from the output Q of the flip-Fbps 27. In accordance with

... / 16

4098 A 3/0745

changes with the signal change at the base of the transistor this the voltage at the diode 45, which leads to the setting of the value i R falling across the motor circuit, namely

a a j

in such a way that the engine speed remains constant will. The terminal voltage of the motor is essentially equal to the sum of the back EMF of the motor and the

the voltage i R. Thus, in the areas mentioned, the a a

Motor speed always towards a constant I.

Value by changing the terminal voltage towards the sustainer: direction of the back EMF are regulated, determined by the Zener voltage, with the size R in the result ι the change in the back EMF changes.

The absolute amount of the motor speed is determined by the Zener voltage set. About the resistors 47, 48 is the transistor 40 has a low bias value applied to it.

The transistor 40 remains in its conductive state until the flip-flop 27 is reset to the initial position. Above the entire time, the motor 10 is driven with a torque which is necessary to maintain the constant speed to maintain until the needle mechanism has arrived at the known position.

... / 17

409843/0745

The control for the stopping process when or after reaching the known needle position is as follows:

It will be in accordance with the specification of a reference position for the initiation of the final braking step, which is shown in Fig. 2A with the area (3), predetermined position pulses. For this purpose, the needle mechanism rotates a non-uniformly formed in its contour ferromagnetic cam disk 50, which interacts with a

this opposite wire coil 52 is in the corresponding walking past contours at different distances, voltage pulses are induced in the cam disk, the alternating polarities of which are shown in FIG. 2F are. This pulse sequence is input to the amplifiers 54 and 55. The outputs of the amplifiers are in the one shown Way to AND gates 57 and 58, the second inputs of which are signal

follow the flip-flop 60 for position selection. The outputs of the AND gates are connected to the two inputs of an i OR gate 62, the output of which in turn connects to the input (R) for

the zeroing of the flip-flop 27 is connected, which is used for brake control.

Normally, when the sewing machine is stopped, that needle position is considered for the final one at which the Needle is down. Such a position means that the output Q of the flip-flop 60 is in its basic position

... / 18

409843/0745

Level "high", so that the pulses exclusively through the AND gate 57 are passed and the brake control circuit of the flip-flop 27 are supplied. Accordingly, regardless of Starting situation when the operator of the sewing machine initiates the braking process, the needle is inevitably in brought their lowered position zura hold, which results from the operation of the flip-flop 60, which is normally is in the basic position.

This normally occurs under the condition of zeroing resp. in the deleted or reset state located flip-flop 27, which as a pulse-generating unit, the brake control defaults, is switched during normal operation of the motor, if the motor speed drops below a preselected value. As long as the motor is running at a speed that is above this value, there is a voltage comparator output 30, as can be seen from Fig. 2E, the level "high" on, i.e. that a pulse at the input S of the flip-flop 27 only is present when the signal level is "high" at the output of the! Comparator 30 is omitted. On the output side, the flip-flop 27 regulates the motor speed (compare output Q and FIG. 2G) in area (2) until the needle mechanism and thus the needle itself has reached a predetermined position. Through this a position pulse is generated, which is applied to the zero or reset ZB input R of the flip-flop 27 lying against the previously for the speed

... / 19th

409843/0745

! - 19 -

turning on the motor deletes the existing impulse and thus
again dynamic braking in area (3) of FIG. 2a
initiates.

At this point the braking is carried out by means of an external
Braking device, for example an electromechanical brake, made up of the amplifier 70, the brake coil 72 and the brake armature 73. Of course, other braking organs can also be used in this context, so in the case of

for example an eddy current brake, magnetic brakes and the like ^!

j chen more. The brake unit 70 to 73 is through the backward; ge edge of the pulse at the output Q of the flip-flop 27 brought into operative position. A corresponding edge detector 75 for the rear edge, which can be, for example, a differentiating element, is connected to the output
Q of the flip-flop 27. The detector output triggers alternately
the pulse generator 76 so that that shown in FIG. 2H
Pulse sequence arises. While this pulse sequence is fixed; is, the external braking device is in the operative position

In the event that it is desired, the needle is in its uppermost position
To stop the position, a corresponding command is given via the movement of a control element of the sewing machine, which is usually triggered by a lever 77 which can be operated with the knee. This command means that a

... / 20

409843/0745

Signal (see Fig. 21) at the input of the flip-flop 60, which is responsible for the needle position, is supplied! will. In FIG. 1, the selection switch for the upper position of the needle is shown schematically by the switch 78. That The above command is likewise fed to the amplifier 80 and from this directly to one of the inputs of the OR gate 35 and to the input of the flip-flop 27. The flip-flop is thus set immediately and the drive of the motor with it the reduced speed initiated, like that out; the curve section (4) of Fig. 2a can be seen. The Moton

has been running until the needle from the fully extended down position in the fully raised upper position brought '.

When the command for the rest position of the needle in its raised position is applied to the flip-flop 60, the changes Signal level at the outputs Q and Q so that in conjunction with j

the AND gate 57 and the AND gate 58 have conditions that! the passage of the pulses responsible for stopping the needles in their raised position through the OR gate 62 enable (compare here the negative pulses in Fig. 2H). The pulses passed by the OR gate 6 2 are present then automatically at the input R of the flip-flop 27. The motor now turns until the needle turns sufficiently has moved far to its upper rest position, whereupon the

... / 21

409843/0745

Pulse at the output Q of the flip-flop 27 is omitted and a braking pulse is generated at the output of the one-shot pulse generator 76 The curve area (5) of the external braking according to FIG. 2A thus begins in the control sequence.

From the above, in conjunction with the accompanying drawings, it can be clearly seen that dynamic braking only exists as long as the transistor 24 is in its conductive state, which is the case when it is applied with a voltage signal from the flop-flop 27 for the brake control. Because the voltage signal is the braking process Direct controls are additional circuits, as previously in control circuits, which are silicon rectifier assemblies conditional, were necessary, no longer necessary. Since the voltage signal dropped across the resistor 22 for both

the speed of the motor as well as / falling over it

Voltage i R is representative, both values can be used for the Vora u.

would give a level of engine speed and thus also for the correction of speed changes compared to the specified speed level. The for this Complicated circuits for pulse counting and the like that were previously required can be dispensed with. So is achieved a considerable simplification of comparable known devices.

... / 22

409843/0745

Another essential advantage of the switching j according to the invention

I arrangement results from the functionality of the switch 12, I. which interrupts the normal voltage supply to the motor for a certain time sequence during the braking process. This makes it possible to have a separate current regulation circuit to use, which is particularly characterized by the tran-! sistor 40 identifies. The energy supply that still takes place for the remaining drive from the normal drive circuit in its double function i offers a further simplification of the control circuit.

Modifications and developments of the circuit described and illustrated, for example, which are part of the present-j The invention are, for example, that the positive and negative pulses of the logic circuit of a variety of different Logical switching elements can be fed if a pulse train is ultimately obtained by this that leads to the application of external braking forces. The invention is of course not restricted in the same way to the use of a certain type of DC motor; rather, for the present purpose, all are DC motors Suitable for low torque and high demands (this also includes the ü 12 M4H motor, for example of the PMI Division of Kollmorgen Corporation, Glen Cove, New York).

... / 23

409843/0745

Claims (21)

PATENT & CLAIMS ί 1. ^ Control device for the braking process of direct current motors in sewing machines or the like rait external energy supply, characterized by the motor with deceleration and braking forces acting braking elements / on the back EMF of the motor when the motor is no longer directly from the external energy source is supplied, responsive organs which specify a signal corresponding to the engine speed and finally by means of control means which react to the signal corresponding to the respective engine speed and bring the braking elements into the actuation position at the time in which the engine has reached a predetermined speed level. 2. Control device according to claim 1, characterized in that that means responsive to the separation of the motor from the external energy source for dynamic braking of the same and decelerating the motor to a predetermined speed and means for driving the motor at and with this speed setting for at least a limited time prior to actuation of the braking elements are. -24- 409843/0745 3. Steuerexnrxchtung according to claim 1, wherein the direct current motor drives the hammering mechanism of a mower, characterized by means for applying a direct current signal voltage during the normal operation of the sewing machine to the motor, a braking circuit with means for connecting the motor in series with one provided for this purpose Power line during the braking process, further by a position signal depending on the position of the needle mechanism dispensing means, by means of the reel mechanism with a braking force, and finally through a brake control circuit, which jointly responds to the position signal and the motor current in series with the said Power line for the excitation of the braking mechanism can respond, so that the needle mechanism in a predetermined position is stopped by the control circuit during the braking process. 4. Control device according to claim 3, characterized in that the power line lying in series with the motor is a has only a low DC impedance, and that the brake control circuit partially responds to the voltage signal which drops above this impedance. 5. Control device according to claim 3, characterized in that that the brake circuit is provided with a switch that operates during normal operation of the sewing machine 409843/0745 '-25- j ί a corresponding direct voltage j to the direct current motor applies and the interruption of the supply of the outer I. DC voltage to the motor by turning the switch contact j a connection of the motor with the series current. line during the braking process. 6. Control device according to claim 3, characterized in that
that the brake control circuit has a switching means, which in
Row with said power line and on the brake; control circuit reacts so that a dynamic braking of the Engine only during selected time segments of the overall i i braking takes place. I. 7. Control device according to claim 6, characterized in that j that a speed controlling circuit, by means of! which on the motor for selected time periods during the! i braking a predetermined DC voltage is applied, j is provided. ι 8. Control device according to claim 7, characterized in that j that the circuit controlling the speed by means of! the brake control is controllable so that it is then in j its acting function is when the engine speed has reached a specified value. -26- 409843/0745 9. Control device according to claim 8, characterized in that The circuit controlling the speed drives the motor with a predetermined torque. 10. Control device according to claim 9, characterized in that the speed controlling circuit consists of one Regulator organ for applying a variable direct current to the liotor in accordance with a variable control signal and from funds for the production of a variable j borrowed control signal or a corresponding control panel | ming exists, this signal being a first, in übeieinstira-; The solution changes with the change in the rotor speed borrowed signal component and a second signal component with an essentially constant current or voltage value i owns. I. 11. Control device according to claim 10, characterized in that that the intended generator is responsive to the current of the motor, the first signal component generating means, means for a reference potential between the on the Voltage responsive means and the control element for specifying a second signal component are, and means for Application of a signal or a voltage from the brake control circuit to the regulator member, the potential of this voltage signal being greater than the reference potential is. -27- 409843/0745 12. Control device according to claim 8, characterized in that that the speed control circuit responds to the position signal and in its switched through State remains when the motor has reached the predetermined speed level and the needle mechanism reaches a selected position during its movement. 13. Control device according to claim 12, characterized in that that the brake control circuit via the interruption of the actuation of the speed control circuit the Brake system switches on. 14. Control device according to claim 13, characterized in that that the braking elements respond to an electrical signal and the brake control circuit generates an electrical signal having a predetermined duration so that the actuation of the braking elements in accordance with the this can take place predetermined time period. 15. Control device according to claim 8, characterized in that that the brake control circuit includes a pulse generator which generates an electrical control signal when the engine exceeds a predetermined speed level, and that the switching means of the brake circuit respond to the control pulse -28-409843 / 0745 speak and thus a dynamic one for this duration Braking is carried out. 16. Control device according to claim 15, characterized in that that the position signal is at least one signal which .wird generated when the needle mechanism a reached predetermined position in its movement cycle, and that the pulse generator of the brake control circuit a control signal for which the constant specified speed controlling circuit, where the generator is the gene \ The called pulse signal initiates or receives after the electrical control pulse has been interrupted, and the control pulse is deleted after a position pulse has occurred. 17. Control device according to claim 16, characterized by Means that react to a needle position command and suppress or override the response of the pulse generator to the engine speed and the control signal trigger for the speed control circuit after such a command, 18. Control device according to claim 17, characterized in that that to the position signal at least one additional Signal which is temporal from the first position signal 409843/0745 separates, may include that the pulse generator on a j such other position signal responds, and the control! signal that was triggered by the Iladel Konsaando den is, with the stop of the Hade lmechani sinus in a second predetermined position takes place. 19. Control for DC motors, consisting of tools, which respond to a Breras command for a short circuit of the
Motor respond, which is lower by a power line
Impedance is given, means for determining the Stror.es
in this line and specification of a control signal for the
In the event that the current amplitude has reached a predetermined amount, and the means which respond to the control signal for the controllably changing impedance in this current line. j 20. DC motor control according to claim 19, characterized in that \ draws that at least one of the named Jüttel Ililfs-; Raittel to regulate the speed of the Ilotor be j sits. j 21. Control device for DC motors according to claim 20, characterized in that the means for regulating the speed from a power source, a device for
Current regulation, which is in series with the Ilotor, and 409843/0745 A variable voltage for the motor from a direct current source in over once iranung with a signal or a voltage of the variable speed control and consists of means that respond to the control signal and to the current common through the
Low impedance power line is given, this being the speed regulating signal
or generate a corresponding voltage. 409843/0745 Blank page