IT8148661A1 - Improvements in the arrangements for controlling the motion of electric motors, particularly for sewing machines - Google Patents

Description

DOCUMENTATION

RELIEF

Improvements in the provisions for the control of the operation of electric motors, in particular for machines

to sew'

ABSTRACT l/i < 2 J_ _Control arrangement for the Ooc process ?i- <i j

?of braking "nature and. the definitive stop in the pre-established position O?C0 I 5 ? 'of an alternating current electric motor - M < c "S ^ -I;ta-for.-sewing-machines-with-presetting-of-al- *0Z CN < aneno-a desired-needle-position?using -- M oc < co -control-system?with-phase-overlap,-in ?> and i

? ;which-a circuit?arrangement?in?series?of-multi-..Monostable?calibrators.??provided,-which-?-suitable-for

? to be started in a controllable way

i

? .an-operation-amplifier-connected--with-the-si-> ?

command-system, phase-overlap, -in manie

j?a?tale?cha-alternatively?are?atti,ad e essere pre

.set...motor_braking?and-motor_starting.depending.on.the.phase-overlap.coincidence.with.from.time.one?of.several.pre-established.positions,.of.a.position.transmitter,

ni connected to the reset input of the monostable multivibrator.

The present invention relates to a control circuit arrangement for the braking process and for the definitive stop in a predetermined position of an AC electric motor for sewing machines with presetting of at least one desired needle position using a phase-superposition control system and to a method for braking and immobilizing the motor in a predetermined manner using this control circuit arrangement.

Generally speaking, three-phase electric motors are generally used for the drive systems of industrial sewing machines. In this case, it is of essential importance for industrial sewing machines and their economical operation that the shutdown process and therefore a required needle end position can be carried out quickly and, where possible, at relatively high speeds, and that an accelerated restart or restart is also possible with little delay.

. For such industrial sewing machines with the necessary three-phase electric motors, the use of phase-overlapping control systems and the definitive stop of the motor is known. ?4

<? tor in the presence of an exact positioning of the a- *2 _ needle can be achieved with satisfactory precision- O ? O

without any slowdown or delay of a certain importance? As advantageous as the use of electric current drive systems may be, < ?7 -N --r v <(J > 7

Z CN ! three-phase alternative electricity in the industrial field,

ce < these however are very little appropriate for the 1*empie ?

O) c go to homes or in smaller companies or small production facilities that do not have a connection system to a three-phase alternative current source.

_ _ In this case, use electrical drive arrangements with motors powered by direct current, for example with a motor having_

a magnetic field with constant flux intensity, as well as with a rotating armature, immersed in the magnetic field, having a low moment of inertia,

which is connected to the input shaft of the sewing machine and is connected to a source.

of electrical voltage as well as with a control part, which is in turn connected

with the engine armature to determine the selective control of the same (E3-0S 1960 788).

Furthermore, there is also a provision of

drive for a motor intended for sewing machines which must be deactivated relatively to.

tA quick mind in a predetermined position in the form

O ili OC

of a DC powered motor, the qua oooc O le after an initial braking with a lower number of revolutions <

Z

\ N< moves in rotation to the position corresponding to the immobilization position and is immobilized Z o < NI OC

bilized through a second frequence operation <

o> born (CH-PS 449750), in which case a series-excited motor of the direct current type is used and the arrangement is essentially characterised by the fact that a control organ is provided

or switching to short-circuit the rotor of the

motor for performing both braking operations twice through.,a resistance

braking and by actuating a control organ in the direction of immobilizing the engine, the first short circuit is first performed and a lower supply voltage is selected, after which the

short circuit and the motor continues to rotate due to this lower supply voltage

with a lower number of revolutions and finally determines the second short circuit through a switching organ which controls the position of the motor which must be deactivated and therefore the position of the needle.

_ _ Current rectifiers used in? ^

q. the known circuit arrangements are used in general as control organs between Q ?. the motor and the supply or power transformer, in which case the different speeds are obtained by the fact that the cycle O 2 C CN is regulated

working cycle of the rectifier elements. It follows from this that whenever the rectifiers CO ?> c become operational or allow current to flow at a time when the voltage of the alternating current is different from zero, high output pulse peaks cannot be avoided, which can lead to very serious disturbances in the motor's electrical circuit. An discontinuous trend in the operation of the motor's power supply circuit leads to frequent interruptions of the overload safety valve, for example.

excessive heating, vibratory phenomena and similar further inconveniences

placed.

The present invention does not now use

. in contrast to this state of the art n? a

three-phase current motor, n? a current motor

~ -continues, but uses a DC motor instead

._ - .directly connectable alternating/two-phase electric power.

_ -to the usual domestic electrical network, in which case_

Q. starting from this "starting point" the <

5 .fundamental problem of being able to preset the deactivation process and therefore one or more posi- _ .

_ well-defined terminal needle positions as far as possible....

hiss in such a satisfying way as, ci?_

_ -?.already possible in general for three-phase current motors. . . . . . _

_ _ The solution to these problems is solved according to the present invention through a

IBAnRBgANO&ZAN,ARDO .. .control circuit layout, how is it?

defined by the characteristics of the _characteristic-_ part

_ .. claim 1._

_ The procedure for braking and deactivating in a pre-established or well-defined manner

with the use of a circuit arrangement_

_of control according to claim 1-? characterized

according to the present invention with characteristics

Liiriven

With the present invention it becomes possible for the first time to obtain a needle position capable of being pre-established with sufficient accuracy starting from any high working speed with a relatively low expenditure of technical circuitry and electromechanical nature, and primarily with the use of a drive system for sewing machines of the starter type Oe= ?>-of small volume and comparatively low weight. O Q ' Od ? so . 5 -< L-_ ? M -The present invention will have to be de- ^ r'

Or written in more detail below with reference to CN CC reference to the attached drawings, which reproduce an advantageous embodiment solely by way of example.

In the drawings:

Figure 1 shows a block circuit schematic view of the control circuit arrangement according to the present invention and Figure 2 shows a schematic illustration for the execution of the braking process according to the method according to the invention using the control circuit arrangement according to Figure 1.

-- ? According to figure 1 the 'circuit control arrangement for the braking process and for

permanent deactivation in pre-established positions?

of an alternative current electric motor for

sewing machines in the embodiment illustrated by way of example consist of a series

of monostable multivibrators from M1 to M6, which are started by an indirect operation amplifier.

?ricato with OP and by a transmitter of positions P and O ? oc which mutually determine a further progressive advancement of the same in the manner of a shift register. L ?

The P position transmitter can be Z OSC

re consisting for example of a perforated disk fis <

CQ

ri> placed above the motor axis, in which case the outputs of the same indicated with 3? 8, 5? 1? 7 are suitable to be started or controlled through diodes

luminescent.

The motor speed regulation is done through a phase overlap control arrangement, which is adjustable when,

coupled with a potentiometer PO, which is incorporated in an operating lever not shown, in

so that when the lever is released the engine is braked until it comes to a complete standstill and in the case of activation

of the same against the action exerted by the spring force of a lever can cause the engine to accelerate continuously up to a maximum speed.

The potentiometer PO is located with its output a on one side applied to an input of the operation amplifier OP and in addition to that, via a diode D4, is applied to an input of a known integrated circuit component designated IC. The output a of the potentiometer PO is located via a compensation resistor RT in application to the reference potential, to which the output 3 of the position transmitter P is also applied. The second input of the operation amplifier PO, namely the positive input, is applied via a resistor-dividing circuit arrangement on one side against the reference potential and therefore to output 3 of the position transmitter P and on the other side to output 5 of the position transmitter P, which in turn is connected to ground.

_ .the output of the operations amplifier. 0P,_ which is reactively coupled with an input . of the same is applied to the first input of a first monostable multivibrator M1. When the voltage drops below a predetermined voltage by the potentiometer PO, the operations amplifier OP

becomes conductive, so that the monostable multivibrator M1 flips into its . conductive state, for which reason a corresponding pulse is again applied to the post-inserted monostable multivibrator, indicated by M2, and precisely to the first input of the same. < d. It should be noted in this regard that only one signal passes from the binary valence "1"

to that "0" determines a passage to the conductive state of the first monostable multivibrator M1, in

so that the control lever is operated and

therefore the potentiometer in the direction of an ever-increasing resistance cannot lead

when the monostable multivibrator M1 switches to the conductive state. Such an operation only causes the superposition control system to .

phase change determines an increase in the number of revolutions.

of the engine controlled through this system, that is, for example, it lets it start slowly

from its resting position.

The integrated circuit IC pre-establishes the system of

phase overlap command, for which ra

The motor is coupled with its input terminals ?h through an electrical resistance inductively by means of the inductance I to the integrated circuit element IG.

Otherwise, when the motor is to be braked, the control lever and thus the potentiometer PO between terminals a and b is activated in the reverse direction, in which case through both dividing resistors, which are connected to the positive input of the control amplifier. OP the latter is pre-stressed or re-stressed by such a fundamental voltage that it inverts L1

< c_ Ni< the output signal of the op-amp? NJ

ni OP only when the control system a -Z CM < Ni phase overlap or phase cut is no longer practically effective, i.e. it goes from "1'c to "0 ". . . ... ... - _ _ _

As a result, the monostable multivibrator M| is again controlled or started -- in such a way that it thereafter becomes conductive for the reversal period associated with it.

The pulse coming from the output side of the first monostable multivibrator is applied ?through'????????????^ to the input 18 of the NAND gate circuit indicated by N1. When, as previously mentioned, the potentiometer PO is operated

then the output of the operation amplifier goes from "V" to "0", so that at point 21,22,23 of

a further circuit leads ???? indicated with N2 yes

finds the information value 'binary "0" equally applied, so that at the inverting output 20

of the same and therefore to the inputs 11, 12 of the NAND gate circuit 4 Q. the information value oi < "V is applied.

oOc (?? < In this way a condition O is reached

? u 5 OS O

< os. which allows the generation of the information value "V Z

K

<-0 at the inputs of the NM D gate circuit indicated by N1, ?a*3

? Z ? CN so that at output 19 of the same the binary value "0" appears, which in turn is 00

?? G

means that a post-inserted transistor T1 becomes

conductive for the reason that its electrode

base is negative with respect to the emitter voltage

applied. In this way, however, the second transistor T2 is also made conductive,

%

the base of which is inserted in the emitter-collector circuit of transistor T1.

The ionization of transistor T2 causes the motor brake to be attracted, which is? Eip_ostq_ai__terminals_ e_k._After_the_multivibrato-._

monostable king M1 ? returned by overturning to its starting position, i.e.

is in the blocked or cut-off state, transistors T1 and 12 also return to their non-ionized position, i.e. the brake located at terminals j. and k is no longer activated.

Simultaneously with the return by overturning

of the monostable multivibrator M1 the monostable multivibrator M2 is turned into the ionizing condition, for which reason the output Q carries the Q ? <

?' a information 1 during the ionization period < ?' or ^ ? of the monostable multivibrator MI at "0", in which . M < co

or case the voltage at the input.51 of the integrated switching circuit IC becomes lower and the motor starts to run again. .. I If, however, during the ionization period of the monostable multivibrator M2 the generator 26VI, position P indicates through input 1, in which case for a needle position the external connections c e. on p side and e and f on the other side are connected to each other, that at the moment of reaching the first position through c, d the reset input Rg of the monostable multivibrator

M2 quickly goes from "1" to "0", the multivibrator

monostable Uz falls into the interdi condition

zxone

Through the multivibrator fallout

monostable M2 the output Q of the same will go from "1"

to "0" and therefore the phase cut control system is re-inserted and at the same time,

the monostable multivibrator is made conductive.

M3. As a consequence of this, the exit is of the same

will go from "0" to "1" and through the diode D2 will be <

d. c/i made conductive the NAND gate circuit indicated by <

O ? N1 . Inputs 11, 12 and 18 of the NAND gate circuit o- (-0 : V O -? ~ are in this case set to "1". Both transistors - O < J. ^ 2 transistors Ti, T2 ionize and the ?? 1 N process takes over.

^ ?S ^ braking. ? -c-?

1 ? ^ The monostable multivibrator M3 ?????- & ? za during its overturning the monostable multivibrator M4 directly following it, for which reason the output Q of the same passes from *'1 " to

"0." and as a result, the phase cut control system is reactivated for the

why does the motor receive voltage again through the terminals h._.11 braking time?^

the monostable multivibrator M3 is chosen in such a way that the motor has reached the condition

of immobility or of stopping with certainty before

this multivibrator returns again for ribai

tation in the off position, which is also true for the monostable multivibrators M1 and M5.

When reaching the position, which is characterized by the output 7 of the position transmitter P, the reset input

of the monostable multivibrator M4 is briefly brought to "0? via the external terminals <

a. short-circuited e and f. The backward tilt c/i < of this monostable multivibrator determines O w OS f? < on the other hand the tilt of the monostable multivibrator M5 and ionizes the latter, so that < c-K NJ CO

? cdS that the output Q of the same passes from "0" to "1", and ,Q o z 'O CN o therefore through the diode D3 the NANO gate circuit indicated with N1 is made conductive, which

?> in turn leads through the transistors T1 and T2 --in the ionized or conductive state to the braking of the motor until it is completely immobilized.-.

.. In this regard it is necessary to point out that as a consequence of the inertia mass r

- the residual movement of the motor rotor due to inertia is greater the higher the speed of the motor, i.e. at the first braking operation through the monostatic multivibrator M1 this residual movement is substantially

less defined than at the moment of the second braking operation through the monostatic multivibrator T.I3 and this last movement is in turn?

less defined than what you have during the third

braking through the M5 monostatic multi-speed controller.

The M6 monostatic multivitreator is used only

for the precise setting of the initial position ? or the initial conditions of the ?/9>* jf < * the above-mentioned electronic components. ?O ? f e; h ^ O ~: C The reference voltage z -N t o to is applied to input 1' of the integrated switching circuit IC ?. Via the connecting elements ?0

? ?o ;2;' o 21 e 6' ? a ramp generator is applied for the generation of a triangular voltage to the circuit in c<o

ccn control integrated IC, in which case this voltage

Does sawtooth act in relation to the 5' input?

so that the phase cut adjustment

can be chosen correspondingly between 0 and.

180?..

Previously, the situation in which the AGP must remain still has been described.

in the lowered state. In the following, reference will be made briefly to the placement in position

opposite. _

In this position between exits 1 and 7

of the position transmitter P are not externally connected to each other c and d and f, but c and d and f are. When during the braking process described above the potentiometer

PO is activated in the opposite or reverse direction, i.e. the engine must start again before it can reach the ^O condition again.

c/S of immobility, then through the circuit leads <

Or LJ NAND indicated by N1 the ** ?r stage is interrupted.

O

Q ?j activated from time to time of the braking process oc < Z

and the IC control circuit brings the motor to the ver- < r?.

N

?? rotation speed corresponding to the setting ? or CN or < of the potentiometer, inputs 3, 8, 5 of the transmitter-^

< m tore of positions P represent the power system?>

c voltage measurement of the transmitter

of positions.

Figure 2 shows the procedure for the permanent immobilization of an AC motor.

for sewing machines using a control circuit system, such as has already been described above by way of example with reference to figure 1, in the form of a block diagram.

Accordingly, the speed regulator, which according to the embodiment

given as an example in figure 1? consists of

from the potentiometer PO, acts directly on the system.

but of command for cutting or phase overlap and on the first braking process, in which case,

the first braking leads to immobilization of the engine and after that, the phase cut control system causes the engine to start again. < o? ? " oc . . The position transmitter causes the <

Z r < ? ra, when reaching position 1, NI -oes-.the second braking operation, which in turn ? ?,o z ^?o < NI

_ta leads to the motor's immobilization, in which OH < CO

.this time however the residual motion due to the inertia of the engine and therefore the definitive immobilization is already precise as in the case of the first

braking process. After this has elapsed

braking period the engine will be started, again-:

mind through the cutting control system

phase until the moment in which the transmitter of_po-_

sizioni reaches position 2, for which reason the third braking process is triggered,

which now definitively immobilizes the engine, without any further movement being observed.

Claims (2)

1. Control arrangement for the braking process and the final stop in a preset position of an AC motor for sewing machines with presetting of at least one desired needle position using < ization of a phase-cutting superposition control system O Ul yo, characterized by the fact that one o ?L1 Q? Series circuit arrangement of monostable multivibrators ? IX Ni - N _ (M1 to M6) is foreseen, which can be^ > ? ? * or ~ rs?) or re regulated through an opera- ? amplifier ?K zioni (OP) connected with a cutting system of ? cn c phase (IC) such that in alternating order ~ motor braking operations and motor starting operations dependent on phase cutting can be preset in accordance with each time one of several preset positions of a position transmitter (P) connected to the reset input of the monostable multivibrator. 2. Method for braking and predetermined immobilization of an AC motor for sewing machines using a control circuit arrangement according to claim 1, characterized in that ? CSJ ? a) the engine is brought _into_a first process of braking starting from a working speed that is arbitrary to the idle condition in the presence of an undefined needle position, condition- born__from_the_motp__residue__by inertia, which_ __ ti) after which the motor is restarted up to a first pre-established position in the form of a specific angular position of rotation, which I < cj a new braking of the motor occurs, which O u-l pc ? ; O ,d) the motor is now excited in starting fi- Q ? Ci z up to a second position, and which _ _ <r --h'i --oi : _e) a third braking immobilizes the motor definitively and in the pre-established position.