US1392250A - Control system - Google Patents

Description

R. E. DE CAMP.

CONTROL SYSTEM.

APPLICATION FILED AUG-26, 1918.

1,392,250. PatentedSpt. 27,1921.

2 SHEETSSHEET I.

/5- l4 I5 UUEJIUUUIT'UUU WITNESSES: lNVENTOR R. E. DE CAMP.

CONTROL SYSTEM.

APPLICATION FILED AUG.26, 1918.

PatentedSept. 27, 1921.

2 SHEETS-SHEET 2.

INVENTOR fia y A. fie flaw 0 BY TTOIIQNEY WITNESSES:

UNITED STATES,

PATENT OFFICE.

RAY n. on our, on winxxNsnuac, PENNSYLVANIA, AssIoNon 'ro wnsrrNcnousn nnncrmc a MANUFACTURING COMPANY, A conronnrxon or PENNSYLVANIA.

common srs'rnn.

' Specification of Letters Patent.

Patented Sept. 27, 1921.

Application filed Angst 26, 1918. Serial No. 251,429.

To all whom it may concern:

' Be it known that I, RAY E. DE CAMP, a citizen of the United States, anda resident of Wilkinsbur in the county of Allegheny and State of ennsylvania, have invented a new and useful Improvement in Control Systems, of which the following is a specification.

My invention relates to control systems and particularly to systems such as those forming the subject matter of a copending application, Serial No. 236,937, of H. D. James, May 27, 1918, and assigned to the Westinghouse Electric & Manufacturing Co.

Figures 1 and 2 of the said application represent motor-control systems in which the acceleration of the motor is effected through the short-circuiting of. a resistor by means of a plurality of contactors, the actu-' ating coils of which are energized by the closing of relay members which, in turn,

Fig. 1 is a diagrammatic view of a system arranged according to my invention, and Figs. 2, 3 and'4 are, respectively, a side and an end elevation and a plan view of a preferred relay mechanism employed in connection with the system or Fig.1. This relay mechanism constitutes the subject matter of my copending application, Serial No. 241,259, current-limit relay, filed June 21, 1918.

Referring to Fig. 1, a motor, the armature of which is shown at 1 and the shunt fieldmagnet winding at 2, is connected between line conductors 3v and 4, the motorcircuit being controlled by a line contactor 5, with a. regulating resistor 6 normally in series with the armature 1. A start push-button switch controls the closing of the contactor 5 through an actuating coil 8. The start push-button switch may be shunted by means of a switch 9 mechanically interlocked with the contactor 5. One or more trated) control the shunting of successive portions 13, 14 and 15 of the regulating resistor 6 through the medium of actuating coils 19, 2O and 21. A coil 22 is connected in parallel circuit with the resistor 6, and a second coli 23 1s connected, in circuit with an external resistor 24 of high resistance,'across the line conductors 3 and 4. The energizing of the coil 22, as explained below, causes the successlve closing of relay members 25, 26 and 27, in accordance with the strength of the current passing through the 'coil 22. The relay member 27 controls the closing of the clrcuit of the coil 23. The coil 19 and therelay member 25 are series-connected in a circuit extending from the line conductor 3, through the coil 19, the relay 25 and the. start and stop push-button switches, to the line conductor 4. The coil 20 and the relay member 26, as well as the coil 21 and the relay member 27, are in parallel relation to the coil 19 and the relay member 25. The pressing of the stop push-button will stop the motor.

The preferred form of device for use in the system of Fi 1 is illustrated in Figs. 2, 3 and 4. Brie y, it comprises a coil, the current flowing through which creates a magnetic field which causes an armature to close, thereby releasing a plurality of armatures, each bearing a relay contact. member. These latter armatures are spring operated to closed-circuit positions, but, owing to the magnetic field above mentioned, the power of the springs is temporarily overcome until the magnetic flux, produced by the electric current, falls to predetermined values. The armatures are thus operated in succession, depending for their operation on the period of acceleration of the motor.

An insulating panel 29 carries two brackets 30 and 31 supporting the coils 22 and 23 which, when energized by current flowing through them, create magnetic fields for atltracting an armature 32 and any desired number of additional armatures 33, 34 and 35. v A compression spring 36 is adjustably ,m0unted upon a non-ma-gnetizable rod 37,

- other ends of the members 41.

piece for the armatures 33, 34 and 35. A bar 40 is rigidly connected to the rod 37 and nor.-

mally engages the armatures 33, 34 and 35.

The spring 36 thus normally maintains the armatures 33, 34 and 35 in open position, with the members 41, which are carried by these armatures, in contact with the pole piece 39. The members 41 are preferably of non-magnetizable material to prevent freezing. The armature 32 is provided with brackets 42, which are pivotally mounted upon the bracket 30, and is normally retained in the broken-line position, (Fig. 2), by a weak spring 43. The bracket 30 supports a non-magnetizable, U-shaped member 44, between the arms of which are pivotally mounted the armatures 3.3, 34 and 35, which carry, respectively, the movable contact members 45, 46 and 47 of the relay members 25, 26 and 27 shown in Figs. 2, 3 and 4 as closed. The stationary contact members 48, 49 and 50 of the relay members 25, 26 and 27 are mounted upon the insulating panel 29. Springs 51 are attached to longltudinally adjustable members 52 and to the The pole piece 39 is provided with longitudinally adjustable members 53 to regulate alr gaps 54 between these members and the corresponding armatures. By means of this adjustment, or by means of the members'52, the action of the magnetic flux produced by the coils 22 and 23 may be so regulated that the armatures 33, 34 and 35 will be operated in roper sequence. I

he operation is as follows: Upon the actuation of the start push-button, the coil 8 is energized by means of a circuit extending from the line conductor 3, through the 0011.8 and the start and sto pushbuttons, to the line conductor 4. he contactor 5 and the switch 9 are thereupon closed, the latter creating a short-circuit for the start push-button, which may thereupon be released, and the former closing the motor circuit. Current then flows from the line conductor 3 through the armature 1, the resistor 6 and the contactor 5, to the line conductor 4. A circuit is also established through the coil 22, in parallel to the resistor 6. The energizing of the coil 22 creates a magnetic field which attracts the armature 32 to the pole piece 38 (Fig. 2). The rod 37 (Fig. 2) is thereupon pressed inwardly in opposition to the force of the spring 36, forcing the bar 40 away from the armatures 33, 34 and 35. The motion of the armature 32 is from the b oken-line to the full-line position of Fig. 2 If the current is above a previously selected safe value, the flux of the magnetic field will overcome the forces of the springs 51, and the armatures will remain with the stops 41 in engagement with the pole piece 39. As the motor accelerates and the current begins to I die down, the magnetic fiux set up by the coil 22 becomes weakened, After a time, when the flux ha decreased to-a predetermined value, the spring 51, attached to one of the armatures, say the armature 33, will overcome the flux of this field, so that the relay member 25 will be closed. The time when this operation occurs depends upon the air gap 54 and the tension of the spring 51. The relay members 26 and 27, however, remain open.

A circuit now exists from the line conductor 3, through the coil 19, the relay member 25, the switch 9, and the stop push-button, to the line conductor 4. The closing of this circuit energizes the coil 19 which causes the closing of the contactor 10 and this, in turn, creates a shunt circuit for the portion 13 of the resistor 6. The motor then further accelerates to decrease the voltage across the-terminals of the coil 22 and thus weaken the magnetic field in the neighborhood of this coil, which permits the closing of the relay member 26. A circuit is then made from the line conductor 3, through the coil 20, the relay member 26, the switch 9, and the stop. push-button, to theline conductor 4. The coil 20, thus becoming energized, causes theclosing of the contactor 11 and the consequent shunting of the resistor 14. Afterthe motor is further accelerated, the magnetic field surrounding the coil 22 is again weakened and the relay member 27 is closed, creating a circuit from the line conductor 3, through the coil 21, the relay member 27 the switch 9 and the stop push-button, to the line conductor 4, thereby causing the energization of the coil 21 and the closing of the contactor 12. The resistor 6 is then entirely shunted from the armature circuit, and the armature 1 is connected directly across the line.

The shunting of the entire resistor 6 deenergizes the coil 22 and tends to release the armature 32 (Fig. 2) and open the relay members 25, 26 and 27. This i prevented in In system by the coil 23 the circuit of whic closed by the relay member 27 extends from the line conductor 3, through the coil 23, the resistor 24, the relay member 27 the switch 9 and the stop pushbutton, to the line conductor 4.

To stop the motor, the stop push-button switch is depressed to open the circuit of the coil 23. The spring 36 then actuates the armature members33, 34 and 35 to their respective open positions. Since the armature members correspond to the relay members 25, 26 and 27 of Fig. 1, the relays open the circuits of the corresponding actuating coils of the accelerating switches, and the latter open to insert the resistor 6 in circuit with the motor. The circuit of the actuating coil 8 of line switch 5- is opened, also, by the stop push-button switch.

I claim as my invention:

1. In a motor-control system, the combination with an electric circuit including a resistor, of a circuit comprising a switch for short-circuiting said resistor, and means for maintaining said resistor short-circuited, said means comprising a relay member for controlling said switch and a coil energized in accordance with the position of said relay member.

2. In a motor-control system, the combination with an electric circuit including a resistor, of a circuit comprising a circuitcontrolling device for effecting the shunting of said resistor, an actuating coil for said device in parallel relation to said resistor, and means controlled by the closing of said device for maintaining the latter closed.

3. In a motor-control system, the combi-' nation with an electric circuit including a resistor, of means comprising a relay member for effecting the shunting of said resistor, an actuating coil for said relay member in parallel relation to said resistor, and a coil adapted to be energized upon the closing of said relay member to maintain the latter closed.

4. In a motor-control system, the combination with an electric circuit including a resistor, and means comprising a plurality of' relay members for successively effecting the shunting of portions of said resistor, of means dependent upon the voltage across said resistor for keeping said relay members open, means for successively closing said relay members when the said voltage falls below predetermined values, and a coil energized upon the operation of the last of said relay members to close for maintaining said relay members closed when said resistor has been completely shunted.

5. In a control system, the combination with an electric motor, a resistor in circuit therewith, and means comprising a plurality of switches for successively shunting portions of said resistor, of a coil in parallel relation to said resistor, means dependent upon the value of the current in said 0011 for successively effecting the closing of said switches, and a coil energized substantially simultaneously with the operation of the last of said switches to close for insuring that said switches remain closed during the normal operation of said motor.

6. In a motor-control system, the combination with a motor armature and a resistor in circuit therewith, of means comprising a plurality of switches for shunting said resister, a plurality of relay members for controlling said switches, and a holding coil for said relay members, one of said relay members being adapted to close the circuit of said holding coil.

7. In a motor-control system, the combination with a motor having an armature and a resistor in series therewith, of means comprising a plurality of switches for shortcircuiting said resistor, an actuating coil for each of said switches, a relay member for closing the circuit of each of said coils, a coil in parallel with said resistor for controlling said relay members, and a coil controlled by the last of said relay members to close for controlling said relay members.

8. In a motor-control system, the combination with an electric motor having an armature, and a resistor in series therewith, of'a plurality of switches for controlling said resistor, a plurality of relay members for controlling said switches, and a coil for insuring that said relzy members remain closed after being actuated to such positions, said coil being energized upon the closing of one of said relay members.

9. The combination with an electric motor having an armature, a resistor in circuit therewith and a source of current for said motor, of a switch for short-circuiting said resistor, a coil in parallel relation to said resistor for causing the actuation ofsaid switch, and a coil energized by the voltage of said source for maintaining said switch in its actuated position.

In testimony whereof I have hereunto subscribed my name this 22nd day of August, 1918.

RAY E. DE CAMP.

Images