US1431948A - Control system - Google Patents

Description

F. D. HALLOCK.

CONTROL SYSTEM. APPLICATION FILED JAN. 16, I920.

1,431,948, Patented Oct. 17, 1922.

. INVENTOR @{MerD/Va/bd.

Patented Oct. 17, 1922.

UNITED STATES PATENT OFFICE.-

FLETCHER D. HALLOCK, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENN- SYLVANIA.

Application filed January 16, 1920. Serial No. 351,855.

T 0 all whom it may concern:

Be it known that I, FLETCHER D. HALLOCK, a citizen of the United States, and a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Control Systems, of which the following'is a specification.

My invention relates to control systems for electrical motors and particularly to systems that embody starting resistors and controllers having a plurality of positions.

The object of my invention is to provide a control system which shall prevent the continued operation of the motor when the controller is in an intermediate position.

My invention provides a time-element device that interrupts the circuit of the motor if the controller is maintained in an intermediate position for more than a predetermined maximum interval of time.

Figure 1 of the accompanying drawing is a diagrammatic View of a control system, and associated apparatus, constructed in accordance with my invention, and Fig- 2 is a top plan view, partially in section, of the time-element device employed in the system shown in Fig. 1.

The control system illustrated in the drawing comprises a motor 1, having a fieldmagnet winding 2, that is supplied with energy from supply circuit 3, through a starting resistor 4, by means of a plurality of electromagnetic switches 5, 6, 7 and 8. A master controller 9 governs the operation of the various switches.

The line switch 5, which is adapted to connect the motor 1 to the supply circuit 3, has an actuating coil 10 and aninterlock 11. The accelerating switches 6, 7 and 8 respectively have actuating coil 12, 13 and 14 that are energized in accordance with the position of the master controller 9.

The master controller 9 has a plurality of stationary contact fingers 15, 16, 17 and 18 that are adapted to engage an energized control segment 19 and contact fingers 20 and 21 that engage a bridging segment 22. Segments 19 and 22 are mounted on the drum of the controller 9 and are moved into and out of engagement with the stationary contact fingers by means of an operating handle 23. The controller has a position I which corresponds to the oil position, a plurality of intermediate or accelerating positions II, III and IV, and an operating position V.

A cam 24, which is mounted on an extended portion of a controller shaft 25, is provided with a portion 26 that actuates a dashpot device 27, or other time-limiting device, in accordance with the movement of the controller handle 23.

The dashpot device 27 comprises a cylinder 28 that is adapted to receive a plunger 29 which is biased to its outermost position by means of a compressed spring 31. The spring 31 is seated on the cylinder head 32 and engages a seat 33 that is mounted on the shaft .30 of the plunger. A collar member 34 is rigidlysecured to the shaft 30 and is adapted to engage a contact device 35. The outer extremity of the shaft 30 is provided with a roller 36 that engages the cam 24.

The dashpot 27 is so designed that the plunger 29 is freely movable against the compression of the spring 31 but the outpiston 29 and the cylinder 28 when the spring 31 tends to return the piston to the position shown in the drawing.

The contact device 35 comprises a pair of stationary contact members 37 that are bridged by a movable contact member 38 which is pivotally mounted on an arm 39. An engaging arm 40 is pivotally mounted on a stationary pin 41 which also constitutes a pivotal mounting for the arm 39. The arm 40 is provided with a shoulder 42 that engages the arm 39 and restricts the movement-of the arm 40, relative to the arm 39, in one direction but which permits free pivotal movement of the arm 40, relative to the arm 39, in the other direction. A helical spring 43 is mounted concentric with the pin 41 and biases the arm 40 to the position shown in solid lines in the drawings.

The collar member 34 is so designed and positioned, relative to the arm 40, that, when the plunger 29 is moved to its innermost position, the collar member 34 will pass the pivotally-mounted arm 40, as indicated by the dotted outline of. the various members for this position, and will engage the opposite side of the arm 40 on its return stroke.

The collar member 34.- does not inerrupt the circuit established by contact members 37 and 38 during the inward movement of the plunger but will interrupt this circuit when the plunger is returned to its normal position. The interval of time necessary for the plunger to engage the arm 40 and open contact members 37 and 38 depends upon the setting of the dashpot 27.

The control segment 19 is energized, from one side of the supply circuit 3, through the contact members 37 and 38.

The operation of the system illustrated in the drawing is initiated by moving the controller drum to the first operative position, designated position 11 in the drawing, to close line switch 5 by energizing coil 10 from the control segment 19. A holding circuit for the switch 5 is established, by the inter-- lock 11, through contact members 37 and 38.

The movement of the controller handle from the ofi to the first operative position causes the portion 26 of the cam 24 to engage the roller 36 and force the plunger 29 of the dashpot to its innermost position. The collar member 34; passes beyond the pivotally mounted arm 40 when the controller is moved from position I to position Ill, as shown in dotted outline in the drawing.

If the controller drum be moved successfully through positions Ill and IV before the return of the collar member 3 by the action of the dashpot 27, switches 6 and 7 will be successively closed by the energizetion of their respective coils l2 and 13, through the corresponding control fingers 16 and 17, from the energized control segment 19.

If, however, the operation of the controller drum is delayed a sufficient interval of time to permit the collar member 3a to engage the arm 40 of the'contact device 35, on its return stroke, the holding circuit for coil 10 of line switch 5 will be interrupted by the switching device 35 to de-energize the control system. The time interval that is required for the return of the collar member 34 to engagement with the depending arm ll) is determined by the setting of the dashpot,

The subsequent operation of'the system requires that the controller be re turned to its initial position I beforeswitch 10 can again be closed.

lf, however, the controller 9 is moved, within the specified period of time, to position V, corresponding to the final operative position of the controller drum, the contact segments 22 bridge the contact members 20 and 21 to maintain the holding circuit for the coil 10 of line switch 5 before the dashpot 27 will have effected the interruption of the holding circuit at the contact members 37.

The application of my invention to control systems permits of the use of a starting resistor of minimum capacity, since the dashpot device ensures the opening of the motor circuit a predetermined interval of time after the motor is connected'to the supply circuit. The starting resistor is, therefore, protected from continued use during the operation of the motor which might otherwise overheat and destroy the resistor. It will, therefore, be understood that a resistor of much lighter weight'than those heretofore employed may 1. In a control system, the combination with a dynamo-electric machine, of means for controlling the operation thereof including a normally closed switch, and means for opening said switch in a predetermined period of time unless the machine operation has reached acertain stage. i

2; Ina control. system, the combination with a dynamo-electricmachine, of rotatable means for controlling the operation thereof and a timeelement device initially occupying its normal position and subsequently operated by predetermined rotation of said means and adapted to interrupt the circuit of said machine if more than a given time interval is consumed in actuating said rotatable means from one position to another.

3. In a control system, the combination with a dynamo-electric machine, of means for controlling the operation thereof including a, normally closed switch having a pivotally mounted member, and means operable by said controlling means for passing said member in the one direction and for engaging it when returning to open said switch unless the machine operation has reached a certain stage in a given period of time.

l. in a control system,*the combination with a dynamo-electric machine, of rotatable means for controlling the operation thereof including a normally closed switch having a pivotally mounted member, and spring-controlled means initially actuated by said rotatable means to pass said pivotally mounted member and subsequently adapted to return and engage said member to open said switch in a predetermined time.

5.110 a control system, the combination with a dynamo-electric machine, of means for controlling the operation thereof, rotatable cam means operated by said controlling means, and a spring-controlled time-element device adapted to be initially actuated by said cam means to a certain position and to subsequently interrupt the machine circuit unless movement of said controlling means to a iven position has been effected.

6. n a control system, the combination With an electric-motor, of a rotatable controller for governing the operation thereof, a switch in the motor circuit and having a pivotally mounted arm, cam means operable with said controller and a time-element device adapted to be actuated by said cam 10 means past said arm and to engage it upon a return movement to open said switch if said controller remains in an intermediate position more than a given interval of time.

In testimony whereof, I have hereunto 15 subscribed my name this 30th day of December 1919.

FLETCHER D. HALLOCK.

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