US2837705A

US2837705A - Device to regulate the direct current motors for the coil rolls of a rewinder

Info

Publication number: US2837705A
Application number: US529455A
Authority: US
Inventors: Spuhler Roland
Original assignee: BBC Brown Boveri France SA
Current assignee: BBC Brown Boveri AG Germany; BBC Brown Boveri France SA
Priority date: 1954-08-21
Filing date: 1955-08-19
Publication date: 1958-06-03
Anticipated expiration: 1975-06-03

Description

ne 3, 1958 R. s HLER 2,837,705

DEVICE TO REGULATE T DIRECT CURRENT MOTORS FOR THE COIL ROLLS OF A INDER Filed Aug.

m J 1N VENTOR WW Q W & 1%

ATTORNEYS Unite St tes Patent DEVICE TO REGULATE DIRECT CURRENT MOTORS FQJR THE COIL ROLLS OF A REWINDER Roland Spnhler, Wettingen, Switzerland, assignor to Aktiengesellschatt Brown, Boveri & Cie, Baden, Switzerland, a joint-stock company Application August 19, 1955, Serial No. 529,455

Claims priority, application Switzerland August 21, 1954 4 Claims. (Cl. 318-7) This invention relates to a device to regulate the direct current motors of the coil rolls of a rewinder at constant tension and velocity of the goods. Such re- Winders are e. g. used for the rewinding of fabrics in dye works, as well as for the rewinding of paper, foils; wires, tapes and the like.

With this rewinding it is desirable that the goods move at steady velocity during the entire rewinding process. Besides, the tension to which the goods are exposed during the entire rewinding process must be constant. While the diameter of the batching roll is growing and the diameter of the unwinding roll is diminishing, the circumferential speed of the rolls must be kept constant. Accordingly the R. P. M. of the batching roll progressively increases and that of the unwinding roll diminishes. With increasing diameter of the batchingroll, the winding moment increases while the unwinding moment decreases. Accordingly the rolling momentum of the driving motor must be increased While the braking motor running as generator must obtain a reducing rolling momentum to maintain the constant motion of the goods.

Devices to regulate the direct current motors for such rewinders are known. Yet they require considerable costs. According to the present invention, gas discharge tubes are preferably used as regulating devices. Of course, also other regulating devices, equivalent to said tubes can be used, e. g. high vacuum tubes, magnetic amplifiers, machine intensifiers, etc.

The invention consists in that the rotors of the direct current motors are jointly fed and their induction Winding is fed from the alternating current supply through one gas discharge tube inserted in push-pull for each rotor. In the rotor current circuits one rheostat is inserted for each rotor, and the governing of the tubes is effected in phase opposition through a resultant control voltage which is composed of a predetermined voltage, an effective voltage dependent on the rotor current which was taken oil the rheostats, and a voltage which is a function of the machine speeds so that the tension and the velocity of the goods remain approximately uniform. The invention is explained in detail by way of a preferred embodiment illustrated in electrical schematic diagram in the accompanying drawing.

With reference now to the drawing, 21 and 23 are batching and unwinding rolls for the goods to be rewound, e. g. fabrics when passing through a dye reservoir. The rotors l and 2 of direct current dynamo electric machines are coupled respectively with these rolls. The feeding of the machines is eflected jointly through the direct current generator 3, driven by the alternating cur-.

rent motor 4. The output voltage of the generator is adjustable by the fie d rheostat 9, and the polarity of the output can be reversed by means of the switch 19 to efizect reversal of the direction of rotation when the goods move back. The field coils 5 and 6 of both machines are fed, from an alternating current supply over one gas discharge tube 7 or 8 for each coil and the transformers 25 and 26. The tubes are installed in push-pull so that Patented June 3, 1958 during the increase of the field current in one coil 21 reduction appears in the other coil and vice versa. For this purpose, the regulation of the gas discharge tubes is eflected in phase opposition through pre-amplifiers 27 and 28 by a positive or negative control voltage Vc, acting on the terminals 29a and 30a of the rheostats 29 and 30.

in series with the rotors 1 and 2 there are installed identical shunts 10 and 11. On these shunts there is taken oil over the terminals Ida and 11a a signal voltage which is proportional to the difilerence of the rotor currents When both machines work as motors, respectively to the total when one machine operates as generator and the other Works as motor. This voltage is applied in opposition to a predetermined value of voltage taken oir a control rheostatfl, fed by direct current. Similarly the control voltage can be suitably influenced by a correcting voltage which is dependent on the dilterent rotation speedsof the motors. This voltage is produced by two tachometer dynamos 13 and 1 which are coupled respectively with the motors 1 and 2; said dynamos are engaged in opposition in the regulating circuit over the potentiometer 15. Consequently the control voltage Va is the resultant of the rotor currents of motors 1 and 2 as taken from terminals 16a, 11a, the predetermined value of voltage taken of control rheostat 12, and the correcting voltage which is a function of the rotational speeds of the motors. The resultant control voltage V0 is applied to the terminals 29a, of the pro-amplifier circuit. The proper polarity of the control voltage may be established by means or" the polarity reversal switch 18.

The mode of operation is as follows: During a winding process the driving machine operates as a motor while the braking engine acts as a generator. With constant tension and constant velocity of the goods, the output of the rewinding process is constant for the entire length of the goods. The generator 3 supplies the electric and mechanical power loss of the machines including the rewinder. The rate of revolutions of the machines is fixed on the average by the armature voltage of the generator 3 and can be adjusted by way of the rheostat 9. The currents passing through the rotors 1 and 2 are a measure for the winding tension apart from the friction. The mechanical losses are substantially proportional to the rate of rotations of the motors.

Supposing that the goods pass in the direction of the arrow. Thus the machine 2 operates as a motor and the machine 1 acts as a generator. Across the erminals Ida and 11a, there appears a voltage corresponding to the total of the motor current and the generator current. The currents are, apart from the friction, a measure for the rotational moments of both machines. The voltage appearing on the terminals Fla/11a is a measure of the winding tension. This voltage is compared with the me determined voltage o the potentiometer i2 and their difference is applied e r as a positive or negative signal on the driving tubes 27, 28 connected in phase opposition. In interrelation to the size and the polarity of this control voltage Vc, the field current of coils and 6 is amplified or diminished respectively or vice versa. The gain amplification is selected so that with increasing load rotation momentum the E. M. F. of the motor grows at the appropriate rate even at a relatively slight increase in the rotor current. The inverse process takes place with the generator. The machine currents change to a relatively minor extent than do the induction currents and thus the magnetic field of the machines. The rate of rotation itself is adapted to the respective rewinding state by the simultaneous amplification or r duction respectively of the relative fields in usual way.

The additional voltage on the potentiometer 15 corrects approximately the mismatching influences of "the mechanical friction. That is necessary because the currents combine through the shunts and 11 of the tension-proportional current and a current to overcome the friction force. The friction power and thus its friction currents are in first approximation proportional to the rate of motor revolutions. The resulting mismatching additional voltage reduction on the shunts 1G and 11 can be compensated by both tachometer-dynamos 13 and 34 whose voltage is proportional to the rate of rotation. The difference in voltage, between effective and theoretical value which finally regulates the tubes is, in this way, free of mismatching friction influences.

Alternately connected in parallel with the input resistances 29, by means of switches controlled by relay 17 are

resistances

16 and 16a which serve to achieve a certain non-symmetry in the control of the modulation currents. In this manner it may be achieved that the velocity of the goods remains constant during the entire winding process. Apart from nonlinearity and saturation influences, the velocity of the goods would somewhat fall by the end of the winding process. By the asymmetric insertion of the

parallel resistances

16 or 16a at the moment of equal winding diameter, this decrease in the velocity of goods can be corrected. It may occur that by the influence of the nonlinearity of the regulation and iron saturation the relay 17 must also be switched at another period than c. g. at the moment of the reversing. The switching of the relay 17 can, in this case, be made dependent on the difference voltage of the tachometer-dynamos 13 and 14 on or from the activity of the reversing switch.

The use of two equal shunts 14 and 11 in each rotor circuit according to the switch indicated above, shows the further advantage that the mismatching influences of copper and iron losses are eliminated in advance, since the mismatching volta e components originating from the electric losses are approximately ofi-setin'the resulting actual value voltage.

The device according to the invention is characterized by a high accuracy of the regulation at relatively inexpensive cost. The invention is particularly suitable for modern dye rewinders in the textile industry. Special meters of speed and protecting equipment, e. g. pendulurn rollers; scanning rollers etc. are not needed. The device allows, above all, with a small pressure of goods, where the influence of the friction is especially strong, still an accurate regulation. A further advantage consists in that apart from the motors, there do not exist any mechanically driven components such as belts,

1 claim:

1. Aspeed regulating system comprising adirect. current motor and a direct current generator having their armature circuits connected in parallel with a direct current source; means providing a direct current signal voltage which is a function of the difference of the armature currents of said direct current machines; means providing a direct current correcting voltage which is a function of the difference of the rate of revolutions of said direct current mach nes; means for comparing said signal voltand sait correcting voltage with a predetermined direct current voltage to produce a resultant direct current control voltage; a pair of electron tubes connected in push-pull relationship, the field winding of 'said'direct current motor being connected in parallel across-one of said electron tubes and the field winding of said direct current generator being connected in parallel across the other of said electron tubes; means for applying alternating current voltages upon the field windings or" said motor and said generator respectively; and means for applying said direct current control voltage upon the control grids of said electron tubes so that during the increase of the field current in the field Winding of one of the direct current machines a reduction in field current will be efiected in the field winding of the other direct current machine.

2. A speedregulating device as defined in claim 1 wherein said means for providing said correcting voltage comprises a first tachometer mechanically connected to the motor shaft and a second tachometer mechanically connected to the generator shaft, said tachometers being connected in series opposition.

3. A speed regulating system as defined in claim 1 and further including means for adjusting the degree of regulation of the field windings of the direct current machines comprising switch-controlled resistor means connected in parallel with said electron tubes.

4. A speed regulating system as defined in claim 3 wherein goods are unwound from a supply reel mechanically connected to the shaft of the direct current generator and said goods are Wound upon a take-up reel mechanically connected to the shaft of the direct current clutches, cog-wheels, etc. so that the wear is reduced to a minimum.

motor, and wherein said switch-controlled resistor means are actuated when the diameters of the goods on the reels are momentarily equal so that'constan't linear velocity of the goods will be maintained.

References (Jilted in the file of this patent UNITED STATES PATENTS 1,991,088 Forbes -Q Feb. 12, 1935 2,060,672 Heymann Nov. 10, 1936 2,168,777 McCreary Aug. 8, 1939