US1343212A - Starting device for electric motors - Google Patents

Description

G. W. HUEY.

STARTING DEVICE FOR ELECTRIC MOTORS. APPLICATION FILEDMAR. B, 1917.

1,343,211 2. Patented June 15, 1920.

WITNESSES: INVENTOR Q 42! 0M. George WHuey ATTORNEY UNITED STATES PATENT OFFICE.

GEORGE W. I-IUEY, OF WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

STARTING DEVICE FOR ELECTRIC MOTORS.

- Application filed March 8,

To all whom it may concern:

Be it known that I, GEORGE W. I-IUEY, 'a citizen of the United States, and a resident of Wilkinsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Starting Devices for Electric Motors, of which the following is a specification,

My invention relates to starting devices for electric motors, and it has for its object to provide a simple and eflicient means for automatically controlling the acceleration of electric motors in accordance with their speeds.

It is well known that, in the acceleration of electric motors, the voltages applied thereto should be increased at rates substantially in accordance with the rates of acceleration of the motors. It is desirable, also, to increase the voltages applied to electric motors gradually and automatically inorder that the motors may reach their normal running speeds without .loss of time or without subjecting them to undue strains;

I provide an arrangement comprising a centrifugal pump for placing a fluid under pressure. The pump, which is operatively connected to the. motor to be controlled, effects the operation of a rheostat arm or equivalent device by-means of a cylinder and a piston that is controlled in accordance with the pressure generated by the pump. Since the pressure generated by a centrifugal pump is proportional to its speed, it will be apparent that a starting device controlled by it operates tocontrol the acceleration of an electric motor in accordance with the speed which the latter has attained.

When an'arrangement of this character is employed, it is only necessary to close a .line switch, whereupon the motor is accelerated automatically to its normal running .speed without the manual manipulation of starting the rheostats or other controlling devices. a i

' In the accompanying drawing, Figure 1 is a diagrammatic view of circuits and apparatus embodying myinvention as applied to an alternating-current motor. Fig. 2 is a view, similar to Fig. 1, illustrating my invention adapted for use in connection with a direct-current motor.

1 Referring particularly to Fig. 1, line conductors 1, 2 and 3, which may be connected to any suitable source of alternating curually shunt the resistors 5 Specification of Letters Patent. PatentedJune 15, 1920-.

1917. Serial No. 153,298.

rent, supply energy to an alternating-current motor 41. Three resistors 5, which are respectively in circuit with the phase windings of the motor l, are controlled by a movable member 6. p

The movable member 6, which may comprise the contact arms of a face-plate controller or rheostat, is controlled by a mechanism comprising a centrifugal pump 7 that has an inlet pipe 8 for connecting it to any suitable source of fluid (not shown).. The fluid employed may be, for example, oil, water or other suitable material. The pump is operatively connected to the motor l by a releasable clutch 9. The pump 7 is connected to a cylinder 10 by means of a pipe 11. A pistonlQ, which is within the cylinderlO, is connected to the movable member 6 bya rod 13. A spring 1-1 normally retains the piston 12 and its connected parts in their respective illustrated positions.

A no-voltage release device 15 comprises a coil 16 and a core member 17 which coacts with the lug 18 on the rod 13. The core member 17 is also connected to the movable member of the clutch 9. When the coil 16 is energized, the core member 17 engages the lug 18 to retain the movable member 6 in its normal running position and eiiec-ts, also, the disengagement of the members of the clutch 9. When the coil 16 is deenergized, the core member falls to its lowerposition to release the member 6 and to effect the engagement of the members of the clutch 9.

tocomplete the circuits of the motor 4 through the resistors 5. The motor 4 drives the pump 7 at a gradually increasing speed and the latter operates to apply a force upon the piston 11 which increases at a corresponding rate.

The member 6 is actuated in a clockwise direction, as viewed in the drawing, to gradp and thus decrease the resistance of the motor circuit. The actuation of the member 6 continues until the resistors 5 are entirely shunted. A contact member 20 carried by the member 6 completes a circuit for the coil 16 when the member 6 is in its normal running position.

The core member 17 is actuated upwardly to engage the lug 18 and to effect the disengagement of the clutch 9. The member 6 is retained in its running position while the pump 7 is permitted to come to rest. The fluid in the cylinder 10 may then leak through the pump to the source from which it was drawn. The motor continues to operate under normal conditions, with the resistors 5 entirely shunted.

In case of "failure ot wiltage, the coil 16 is deenergized and the core member 15 is actuated by force of gravity to its lower position to again effect the engagement of the clutch members. The spring 14- then returns the piston 12 and the member 6 to their respective initial positions in readiness for the succeeding starting operation. In case the line switch 19 remains closed until normal conditions are restored in the main circuit, the motor 4 will be started again automatically in the manner de scribed above. The core member 17 again engages the lug 18 to retain the starting device in its running position.

To stop the motor when the various parts are in their respective running positions, it is only necessary to open the main switch 19, whereupon the coil 16 is deenergized and the several devices return to their respective initial positions in readiness for the succeeding starting operation.

By means of the arrangement described above, it is only necessary to complete the circuit of the motor, whereupon it is gradually accelerated to its normal speed and the starting device is retained in the running position. In case of failure of line voltage, the starting device is automatically returned to its initial position and the motor is automatically started when normal conditions again obtain.

lVhile I have shown and described a system in which resistors are in circuit with the primary windings of an alternatingcurrent motor which may be, for example, of the squirrel-cage induction type, it will be understood that the mechanism is adapted equally well for use in connection with motors having phase Nound secondary members and resistors in circuit therewith.

Reference may now be had. to Fig. 2, in which a substantially similar arrangement is provided for controlling direct-current motors. Line conductors 29 and 23, which may be connected to any suitable source of direct current, supply energy to a directcurrent motor 21'. A starting resistor 25,

that is in series withthe armature of the motor 24, is controlled by a movable arm 26 which may be, for example, the movable contact arm of a rheostat or similar starting device. The arm 26 is controlled in a manner similar to that described in connection with the movable member 6 in the systrolled in accordance with V operatively tem illustrated in Fig. 1 and similar reference numerals have been applied to corresponding parts.

To start the motor, a main switch 27 is closed to complete the armature circuit of the motor through the resistor 25. The pump 7 is driven at a gradually increasing speed and the piston 12 actuates the arm 26 to shunt the resistor 25 at a rate correspond ing to the rate of acceleration of the motor. The operation of the starting device and the automatic controlling means therefor is substantially identical with that described in connection with the system shown in Fig. 1, and a detailed description of the same is accordingly omitted.

It will be noted that I provide an arrangement whereby the gradual starting and the stopping of electric motors may be controlled simply by the operation of a single switch. In case an electromagnetic line switch is employed, the manually operable switch may take the form of the usual push button switch.

I claim as my invention: a

1. In a motor-control system, the .combination with an electric motor and a re sistor in circuit therewith, of means for controlling said resistor in accordance with the speed of said motor, said means comprising a movable member and a fluid-pressure device for controlling said member, and means for rendering said controlling means inefiective when said motor attains a pre determined speed.

2. In a motor-control system, the combination with an electric motor and a resistor in circuit therewith, of means for controlling said resistor in accordance with the speed of said motor, said means comprising a centrifugal pump operatively connected to said motor and a movable member conthe pressure gen erated by said pump, and means for stopping the operation ofsaid pump after said motor attains a predetermined speed.

3. In a motor-control system, the combination with an electric motor and a starting device therefor, of means for actuatin l I I o u b said startmg devlce in accordance with the degree of acceleration of said motor, said means comprising a fluid-pressure device connected to said motor, a spring for yieldingly retaining said starting device in its normal position, and a lowvoltage release device for retaining said starting device in its running position.

4. In a motor-control system, the combination with an electric motor and a starting device therefor, of means for actuating said starting device in accordance with the de gree of acceleration of said motor, said means comprising a fluid-pressure device, a releasable clutch for operatively connecting said motor to said fluid pressure device, and

a low-voltage release device for retaining said starting device in its running position and for controlling said clutch.

5. In a motor-control system, the combination with an electric motor and a starting device therefor, of means for actuating said starting device in accordance with the degree of acceleration of said motor, said means comprising a fiuidn'essure device, a releasable clutch for operatively connecting said motor to said fluid-pressure device, and a low-voltage release device which operates, whenenergized above a predetermined degree, to retain the starting device in its running position and to effect the release of said clutch.

6. In a motor-control system, the combination with an electric motor and a resistor in circuit therewith, 01 means for controlling said resistor in accordance with the speed of said motor, said means comprising a power device, a low-voltage release de-' vice for retaining a portion of said controlling means in position to shunt said resistor and for controlling the operative connection of said power device to said motor.

7. In a motor-control system, the combination with an electric motor and a resistor in circuit therewith, of a fluid-pressure device, a clutch for connecting said motor to said fluid-pressure device, means for shortcircuiting said resistor, means for operatively connecting said fluid-pressure device to said short-circuiting means, and means for rendering said clutch effective during the starting of said motor and for rendering said clutch ineffective and for maintaining said short-circuiting means in operative position when said motor isoperating at full speed.

8. In a motor-control system, the combination with an electric motor and a resistor in circuit therewith, of means for short-circuiting said resistor and biased to maintain said resistor in circuit with said motor,

means connected to, and operated by, said motor for actuating said short-circuitin means to short-circuit said resistor, anc common means for disconnecting said actuating means from said motor and for maintaining said short-circuiting means in actuated position.

In testimony whereof, I have hereunto subscribed my name this 27th day of Feb,

GEORGE W. HUEY.

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