US1606746A - Control device - Google Patents

Description

Nov. 16 1926. 1,606,746

A. H. CANDEE CONTROL DEVICE Filed Dec. 10, 1919 WITNESSES; INVENTOR flammw Andrew/7. C0002? 4W BY TToNEY Patented Nov. 16, 1926.

UNITED STATES 1 PATENT OFFICE.

ANDREW H. CANDEE, 0F PITTSBURGH, PENNSYL VLANIA, ASSIGNOR T0 WESTING- HOUSE ELECTRIC &. MANUFACTURING VANIA.

COMANY, A CORPORATION OF PENNSYL- CONTROL nnv cnl Application filed DecemberIlO, 1919. Serial No. 343,986.

My invention relates to control devices More specifically stated, it is the object,

of my invention to rovide a continuously rotatable cam of difterent transverse crosssections for actuating a switch member into its closed or resistor-short-circuiting position, the relative periods of actuation to, or

retention in, the closed position being varied by longitudinal shifting of the cam.

Other objectsof my invention will become evident from the following detailed description taken in conjunction with the accompanying drawing, wherein- Figure 1 is a diagrammatic view of a control system embodying my present invention; and

- Fig. 2 is a view showing another elevation of my control apparatus and certain operating electrical connections therefor.

' Referring to the drawings, the system here shown comprises'suitable supply-circuit conductors trolley and ground; a dynamo-electric machine, such as a car-propelling motor, having a commutator-type arnected in series relation with the dynamo electric machine to be intermittently shortcircuited by a control device 3 that is operated by a small electric motor 4.

The control device 3 comprises a station- I ary contact tip or terminal 5 that is mounted upon a support or bracket 5a, and a cooperating movable contact tip or terminal 6 that is secured to one end of an oscillatable arm or lever 7, the other end of the lever being biased toward the illustrated position by means of a helical spring 8, and the lever being pivotally mounted at an incontact members. rocker arm 10 is pivotally mounted upon termediate'point 9 upon a rocker arm or lever/10. Preferably a magnetic blowout coil of a familiar type (not shown) is provided in'connection with the co-operating The outer end 11 of the a second support or bracket12. A roller 13,01? the like, is pivotally mounted near 'the lowermost point of the rocker arm 10 to engage a cam 14, the operating shaft 15-.

of which. is driven by a smallelectric motor 4 having a commutatontype armature 16 and a shunt field winding 17, the degree of ,energization of which may be varied by a resistor 18. I

The brackets or contact supports 5a and 12 are connected to the respective terminals of the accelerating resistor 2 by conductors 19 and 20, y

In addition to the rotative movement of the cam 14 that may be produced through theagency of the electric motor 4, the cam is'adapted forbodily longitudinal shifting or actuation and this result may be accomplished, as -illustrated in Fig. 2, by means of an actuating coil 21 which encloses a portion of a sleeve 22 that is rigidly secured to the cam body 14 and is adapted to loosely slidealong the cam shaft 15, although the rotative movement of the cam with the shaft is insured by the provision of a key 23 that is inserted in the shaft. For the purpose of energizing the actuat- 1ng coil 21, a battery 24 may be connected in circuit with the coil through a'hand-operated switch 25, which also closes the circuit of the auxiliary motor 4- through the battery. To prevent too rapid longitudinal actuation of the cam 14, a dash-pot 26 is suitably connected with the s'lidable sleeve 22, whereby a relatively slow longitudinal movement of the cam 14 and, therefore, a desirably smooth acceleration of the main motor is insured. Return movement of the cam 14 to the illustrated normal position is ensured by a biasing spring 27.

As indicated by the various section lines AA to EE, inclusive, the contour of the cam 14 gradually increases in size from one end to the other of the cam, a comparatively sharp point or narrow ridge 14a extending to the peripheral bounding line of the cam at one end thereof, while this ridge gradually increases in size or, in other words,

therefore, the rocker arm occupies its lowermost position corresponding to the full I open position of the movable contact tip 6.

Upon rotative movement of the cam 14, the roller 13 will ride along the periphery thereof and,'when the ridge 14a passes under the roller 13', a contact of short duration will be effected between the stationary and movable contact tips 5 and 6, respectively. A continuous rotation of the cam 14 by the electrioinotor Will effect. periodical shortcircuits of the accelerating resistor 2, of short duration, so that the effect of a comparatively great resistance is produced in the circuit of the main or car-propelling motor.

By longitudinally shifting the cam 14 towards its positions of greaten cross-section, the duration of the individual short-circuits, which continue to occur periodically, is gradually increased until, when the other end of the cam 14 en ages the roller 13, a permanent short-circuit of the resistor 2 is produced. In other words, by continuously rotating the cam 14 and shifting it longitudlnally during such rotative movement, the

effective or active circuit value of the accelcrating resistor 2 is gradually-decreased to substantially zero, and thus a smooth acceleration of the main motor may be automatically effected without requiring the use of current relays or the likef The operation of my system and apparatus may beset forth as follows. roller 13 occupying its normal position at the end of the cam 14 of smaller cross-section, as indicated in solid lines in Fig. 2, the switch 25 may be closed to concurrently energize the auxiliary motor 4 and the actuat ng coil 21. In this way, the movable contact tip 6 is intermittently brought into engagement with the stationary contact tip 5, as previously'described, by. reasonof the rotative movement that is imparted to the cam 1&1 by the auxiliarymotor 4, while the energization' of the actuating coil 21 serves to effect a longitudinal shifting of the cam 14 towards the position wherein the greatest transverse cross-section thereof is brought into engagement with the roller 13. Consequently, the duration of the individual With the I tioned, or of sufficient inductive characteristics in the motors and other circuits, will serve'to smooth out the pulsations.

It will be appreciated that other means of providing simultaneous movements of translation and rotation, such as the screwthreaded shaft and traveling nut that is used in limit switches for elevator control, may

be employed, if desired. Consequently, I do not wish to be restricted to the specific circuit connections, structural details or arrangement of parts herein set forth, as various modifications thereof may be made withoutdeparting from the spirit and scope of my invention. I desire, therefore, that only such limitations shall be imposed as are in dicatcd in the appended claims.

I claim as my invention:

1. A control system comprising a movable switch member, a resistor adapted to be short-circuited by said switch member, an axially tapering cam for actuating said member, and electrical means for concurrently rotating and longitudinally shifting said cam.

2. In a system "of acceleration, the combination with an electric motorand a resistor, of electrically controlled cam means for intermittently modifying the circuit connections of said resistor and for varying the periods of intermittence.

3. In a system of acceleration, the combination with an electric motor a source of energy and a resistor, of continuously rotatable means for periodically shunting said resister and means electrically governed by said source for varying thetime between such shunting actions.

In testimony whereof, I have hereunto AN RE 'H. oiii innn

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