US716504A - Electric switch. - Google Patents

Description

Patnted- Dec. 23, |902.l

3 Sheets-Sheet Illlllll s. H. wHnTINGHAM.

ELECTRIC SWITCH.

(Application tiled Jan 21, 1902.)

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a716-,504. Patented Dec. 23,v |902.

G. H. WHITTINGHAM.

ELECTRIC SWITCH.

(Application Bled-Jan. 21. 1902.)

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UNITED STnTEs PATENT OFFICE.

GEORGE H. WHITTINGHAM, OF NEW YORK, N. Y.

ELECTRIC SWITCH.

SPECIFICATION forming part of Letters Patent No. 716,504, dated December 23, 1902.

Application tiled January 2l, 1902. Serial No. 90,617. (No model.)

To all whom. it mja/y concern:

Be it known that I, GEORGE H. WHITTING- HAM, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented certain new and usefulImprovementsinElectricSwitches, of which the following is a specification.

This invention relates to improvements in electric switches for reversing the current in electric motors, and is especially applicable for use in connection with electric elevators.

One of the objects of the invention is to provide in a construction of switch of this character such an arrangement of parts that when the connection with the main or supply circuit is broken at one side of the switch for the purpose of stopping or reversing the motor the armature and field circuits will remain closed and will not be opened except when the motor-circuit contact-blades are just about to enter the Vsupply-circuit terminals on the opposite side of the switch. This arrangement aifords the armature time to slow down and stop and exhaust its electromagnetic current before the armature and field circuits are broken preparatory to the reversal of the current in the armature, thereby avoiding the destructive arcing of the terminals and contact blades, which results when the armature and field circuits are broken while the armature is rotating.

Another object of the invention is to provide an electrodynamic brake-circuit for the armature,whereby a suitable resistance is automatically introduced into the armature-circuit immediately after the supply-circuit has been broken, thereby tending to overcome the momentum of the armature and assisting in quickly stopping the same. `This provision of an electrodynamic brake-circuit is rendered possible by the fact that the eld and armature circuits remain closed or unbroken after the supply-circuit is disconnected; and another object of the invention is to provide improved means for effecting a quick or snap break between the contact blades and terminals of the supply-circuit.

W'ith these and other objects in view the invention consists in certain electrical and mechanicalfeatures of construction, arrangements, and combinations of the parts hereinafter fully described and claimed.

Reference is to be had to the accompanying drawings, in which- Figure lis a top plan View of my improved electric reversing-switch. Fig. 2 is a side elevation thereof with the main shaft sectioned approximately on the line 2 2 of Fig. 1. Fig. 3 is a similar view with the section taken approximately on the line 3 3 of Fig. l. Fig. 4 is a side elevation of a portion of the switch, illustrating the mechanical devices adapted to close and open the electrodynamic brakecircuit for the armature. Fig. 5 is a detail View of one of the main or supply circuit contact-bars. Fig. 6 is a detail View illustrating the pivotal mounting of said bars. Fig. 7 is a diagrammatic top plan view illustrating the switch in an electric-elevator system.

Referring to the drawings, the letter A designates the switch-base, of slate or any suitableinsulating material, to which are secured two opposite shaft-bearings a, in which is journaled a main shaft b, provided at one end with a sprocket-wheel B, by which the shaft may be rocked or partially rotated in the usual manner to operate the switch. The said shaft-b is electrically divided into two parts by insulation b', as shown in Fig. l, and rigidly secured to said shaft on opposite sides of said insulation are two radiallyextending inflexible or unyielding contactblades C C', adapted to be swung into contact with either of the two pairs of spring-clip terminals c d, located on the base A at opposite sides of the said shaft b. These terminals c CZ are of the pen or spring-jaw variety and are rigidly secured on the ends of bars e, which in this instance are pivotally mounted at one end in bearings g on the base A underneath the main shaft b and extend from said bearings in opposite directions, as shown in Fig. l, with their free ends e forked and straddling headed vertical posts f, whereby they are permitted to havealimited yielding movement away from the base for a purpose hereinafter described. The said bars are also provided near their pivoted ends with lugs e2, pressed upon by springs h, tending to move the bars c, with their terminals c d, toward the base A, as indicated in the drawings. The terminals of one pair form with the complementary terminals of the other pair the two sides of the line or supply circuit of IOO the switch, and for this purpose said complementary terminals are connected by means of wires t', as illustrated in the drawings.

Mounted in suitable bearingsj, underneath and independent of the main shaft b, are two oscillating arms D, which are entirely separate from the said main shaft and have movev ment independent of the swinging contactbladesCC',eXcept as hereinafterstated. Each of said arms is provided with two oppositelyextending blades 7c Z, adapted to contact alternately with either of the two pairs of armature-circuit terminals m n, rigidly secured on the base A to close the armature-circuit, with the current flowing either in one direction or the opposite direction. The armature-circuit terminal of one pair is electrically connected to the diagonally opposite terminal of the other pair, as illustrated in Fig. 7. To automatically move said oscillating arms D in either direction in order to close the armaturecircuit, the main contact-blades are provided with lugs o p, as shown best in Fig. 1, extending toward each other over the two oscillating arms D and adapted to strike said arms and force their blades into contact with a pair of armature-circuit terminals on either side of the shaft ct before the contact-blades themselves contact with those supply-circuit terminals on the same side of said shaft to close the supply-circuit. Moreover, it is to be especially noted by this arrangement of the armature-circuit arms D, they being movable independently of the supply-circuit contactblades C C', the latter can be moved out of contact with the supply-circuit terminals at -one side of the switch, past the vertical center, (which is the stop position in elevator systems,) and almost into contact with the supply-circuit terminals on the other side of the switch before the lugs 0 p cause the oscillating armature-circuit arms D to entirely withdraw from their respective terminals. This is an important feature of my invention, for by this arrangement the destructive arcing and burning of the contacts ot' the armature-circuit is avoided.

To those versed in the art of electric reversing-switches, as applied particularly to electric-elevator systems, it is well known that after the supply-circuitis disconnected for the purpose of stopping or reversing the elevator-driving motor the armature of the motor will continue to rotate by its own momentum even after the armature and eld circuits have been broken or opened. It has heretofore been customary to offset the current generated by the armature under these conditions to provide a mechanical brake which is automatically brought into play so soon as the supply-current is disconnected. With the switch of my invention the arrangement heretofore described of keeping the armature and iield circuits always closed, except when the supply-circuit contact-blades are just about to enter the supply-circuit terminals on that side of the switch opposite to the terminals from which theyhave been retracted, enables me to introduce into the armaturecircuit an electrodynamic brake-circuit, the mechanical circuit-closing land circuit-opening features of which are best seen iu Figs. l and 4. Said features comprise a rocking tensioned terminal q, mounted on the base A adjacent one end of the shaft b, and a segmental contact-surface r, rigidly secured on said end of the shaft, as best shown in Fig. 4, preferably by a set-screw s, so that it may be adjusted axially to contact with the said terminal immediately after the supply-circuit has been disconnected. One pole of a rheostat or armature resistance-coil is connected to the said terminal q, and the other pole of said rheostat is connected to the bearingj on the opposite side of the line or field circuit, as iudicated iu Fig. 7, so that just so soon as the supply-circuit is disconnected the rheostat is introduced into the armature-circuit,and thus acts as an electrodynamic brake-circuit to quickly stop the free rotation of the armature. The said brake-circuit is of course disconnected from the armature-circuit before the supply-circuit is again closed, and said brakecircuit, as is evident', is effective whenever the supply-circuit is disconnected whether the armature-circuit is reversed or not.

In describing the operation of my improved reversing-switch reference is to be had particularly to Figs. l and 7 of the accompanying drawings, which latter is a diagrammatic top plan view of said switch in an electric-elevator system. The line or supply circuit is connected to the switch at the terminals at one IOO side of the switch c, (see Fig. 7,) and the iieldshunt therefor is connected to the terminals tt on the other side of the switch and also leads to the two journal-bearings a, of the shaft b. One of said shaft-bearings d is connected by Wire, as shown by the dotted line u, to one of the bearings j for the oscillating arms D, and the other of said shaft-bearings a is connected, as shown by the dotted lines fu, to one pole of the automatic rheostat or starting-controller, and the other bearingyl for the oscillating arms D is connected, as shown by the dotted line w, to the other pole of said automatic rheostat. When the switch contact-blades C C make contact with either pair of terminals c or d, the current will be introduced into the armature-circuit from one of the shaft-bearings a through the wire u, and thereby start the motor. When the switch is inthe oft position, contact will be maintained beween the segmental contact-piece r and terminal q, and then the current from the armature will flow in the direction of the darts, Fig. 7, to one of the bearingsj, whence a portion of it will tlow through the brake-rheostat and back through the other bearingj to the armature, thereby introducing the brake-rheostat into the armature-circuit just so soon as the supply-circuit is disconnected and quickly stop-v ping the free rotation of the motor-armature. The freely-rotating armature generates a cur- IIO rent, because the field-circuit is maintained and remains closed after the supply-circuit is disconnected, the said field-circuit being completed through the starting resistance, (automatic rheostat but this starting-resistance is so slight in proportion to the resistance of the field as to interfere in no wise with its proper action for the dynamic brake e-ect. To trace the current energizing the eld when the switch is in off position, reference is to be had to Fig. 7. Starting at the armature, the current will flow in the direction of the darts to one of the bearings j, whence a portion of it will flow through the brake-rheostat, as before described; but the other portion will How from said bearing to the binding-post t', thence through the fieldshunt to the opposite binding-post t, thence to the adjacent shaft-bearing a., thence through the automatic rheostat or startingresistance, then back again into the switch to the other bearingj, and finally back to the armature.

It is to be noted that both pairs of supplycircuit terminals c d normally rest on the su rface of the base A, and are therefore held from movement when the contact-blades are moved into contact with said terminals, and that as the contact-blades C C are unyielding and rigid on the shaft b a more effective contact will be made than if the contactblades were capable of yielding; but, on the other hand, when the shaft Z) is turned to withdraw said contact-blades from the terminals the terminals themselves will yield in an upward direction, as indicated in Fig. 2, and will snap down with aquick break when the springs h have reached a certain tension. Thus it will be seen that the contact-blades C C/ have a positive and unyielding action when making contact with the terminals, thereby avoiding theblistering or burning which results from a slow contact, and also have a quick snap break when they are withdrawn from the terminals.

Reversing-switches of the character herein described are usually used on elevator-motors which require heavy torque or starting-power. To secure this, the motor is provided with one or more series coils, and it has heretofore been customary to carry the current through these series coils before entering the switch, so that the direction of the current in both series and shunt fields shall be the same. This arrangement resulted in keeping one side of the supply or main line always connected to the motor; but with my arrangement of switch, as will be seen best by the diagram of wiring, Fig. 7, both sides of the main or line circuit are opened when the main-line switch is in olf position, and the armature-circuit reversing part of the switch is connected to the line-circuit switch through the series coils instead of theseries coils being connected directly to one side of the line. Hence my reversing-switch is a double-pole switch, which is arranged to open both sides of the line, and this, together with the arrangement of series coils, provides that when the line-circuit is open both sides thereof are entirely disconnected from the motor, and the latter will be entirely dead It is to be understood that various changes may be made in the detail mechanical features of construction without departing from the scope of the invention as defined in the appended claims.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is-

1. In an electric-elevator system, the cornbination with a motor-supply circuit and contact-blades and terminals for closing and opening the same, of an armature-circuit arranged to remain closed until after said contact-blades have been brought to and past the stop7 position.

2. In an electricelevator system, a motorreversing switch, comprising supply-circuit terminals and contactblades; armature-circuit terminals; arniature circuit contactblades having a limited movement independent of said first-named contact-blades but also movable therebyinto and out of contact with said armature-circuit terminals; and means whereby said firstnamed contactblades may moveto and beyond the stop position without moving the armature-circuit contact-blades out of contact with the terminals of the latter.

3. In an electric-elevator system, the combination of a supply-circuit; an armature-circuit; a switch adapted to close and open said supply-circuit and reverse said armature-circuit, and arranged to leave said armaturecircuit closed after opening the supply-circuit; and a brake-resistance circuit adapted to be automatically introduced into the armature-circuit after the supply-circuit has been opened.

4. An electric re versing-switch, comprising a base; a partially-rotatable shaft mounted in bearings on said base; two contact-blades carried by said shaft and provided with lugs, o, p; two pairs of supply-circuit terminals located on said base at opposite sides of said shaft in alinement with said blades; two pairs ofarmature-circuit terminals; and oscillating arms, D, mounted in bearings, j, on the base independent of the bearings for the said shaft and in alinement with the said lugs, o, p, whereby said arms may be moved by said lugs into contact with either pair of armature circuit terminals, as set forth.

5. An electric reversing-switch, comprising a base; a partially-rotatable shaft mounted in bearings on said base; contact-blades secured to said shaft; two pairs of supply-circuit terminals mounted on said base at opposite sides of said shaft in alinement with said contact-blades; two pairs of armature-circuit terminals mounted on said base nearer the shaft than the supply-circuit terminals; bearings,j, on said base underneath the said shaft IOO ICS

IIO

and independent of the bearings for said shaft; and oscillating arms, D, mounted in said bearings, j, and adapted to be moved by said contact-blades into contact with either pair of armature-contact terminals, as set forth.

6. An electric reversing-switch, comprising a base; supply-circuit terminals mounted on said base; a partially-rotatable shaft mounted on said base and provided with contactblades adapted to make and break contact With said terminals; an armature circuit adapted to be automatically reversed by said contact-blades; and a make-and-break device for a brake-resistance circuit provided with a segmental contact-piece, r, held on said shaft, and a tensioned terminal, q, mounted on said base, as set forth.

7. An electric reversing-switch, comprising a base; a partially-rotatable shaft mounted 011 said base and provided with contactblades; terminal bars, e, pivotally mounted at one end underneath said shaft and having their other ends forked; headed posts,f, straddled by said forked ends whereby to limit the movement of said bars; supply-circuit terminals secured to the said bars in alinement with said contact-blades; armaturecircuit terminals mounted on said base; and oscillating arms adapted to be moved by said confact-blades into and out of contact with said last-named terminals, as set forth.

8. In an electric-switch system for reversing motors that employ series coils, the combination of a supply or line circuit.; asvvitch mechanism adapted to open both sides of said line-circuit; and an armature-circuit-reversing switch arranged to be connected to the line-circuit switch by means of the series coils, whereby when the line-circuit is open, both sides of the motor-circuit, together with the series coils,are entirely disconnected from the line-circuit.

In testimony whereof` I affix my signature in the presence of two witnesses.

GEORGE H. WHITTINGrI-IAM.

Witnesses:

FREDERICK S. STITT, CHARLES L. VIETscH.

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