US1245701A - Short-circuiting device for motors. - Google Patents

Description

M. I. GINSBURG.

SH ORT CIRCUITING DEVICE FOR MOTORS.

APPLICATION FILED A UILZ I. 19W.

Patented Nov. ('3, 1917.

2 3HEETS-SHEET l.

J WITNESSES .4 TI'ORIVEYS M. I. GINSBURG.

SHORT cmculrme DEVICE FOR MOTORS.

Patented Nov. 6, 1917.

2 SHEETST-SHEET 2- 7 2' -5. 1a

APPLICATION HLED AUG.24, \9I6.

q and short-circuiting devi lowing is a full, clear,

of the armature UNITED STATES PATENT OFFICE.

MICHAEL I. cmanm, 01 BALTIMORE, MARYLAND.

snon'r-omotmmo DEVICE FOR MOTOR Appliciition filed August 24,

To all whom it may concern:

Be it known that I, MICHAEL I. Gnvsnuuc, a citizen of the United'States,' and a resident of Baltimore, in the county of Baltimore City and State of Maryland, have invented'a new and Improved Short-Circuiting Device 'for'Motors, of, which the foland exact description.

This-invention relates to electric achines and deals particularly with short-circu'iting devices.

The invention has for its general objects to improve and simplify the construction and operation of apparatus ofthis character so as to be reliable and efficient-in use, and com aratively inexpensive I to "manufacture eep-in operative condition,

A more specific'object of; the invention is the provision of an improved short-circuiting device which automatically comes into play when the armature attains predetermined rotative speed, whereby the windings are short-circnited.

ith such objects in view, and others which will appear as the description proceeds, the invention comprises various novel features of construction and arrangement of parts which will be set forthwithparticu: larity in the following, description and claims-appenilcdhereto.

In the accompanying drawings. which illustrate one embodiment of the-invention and wherein similar characters of reference indicate corresponding parts in all the views, Fignre'l is a side view of a motor with a portion of the frame broken away to illustrate the automatic short-circuiting device;

Fig. 2 is a diagrammatic view showiiig the ce, connected'with the windings of the armature;

Fig. 3 is an enlarged view of that side of the short-circuiting device having the centrifugal weights;

Fig. 4 is a View of the opposite side of the short-circuiting device;

"ig. 5 is an edge view of Fig. 4;

ig. 6 isasectional view on the 'line 6-6, Fig. 4; and i Fig. 7 is a detail sectional view on the line -7, Fig. 3.

Referring to the drawing, A designates the frame of the motor, which contains the usual field poles (not shown), and arranged in cotiperative relation with the field poles is the armature B having-a commutator C on which bears the brushes D.. On

he Shaft 1 specification of Letter! Pltnnt.

191a. Serial a... uasaz.

of the armature is mounted the automatic short-circuiting device E. The motor shown is of the four-polar type, but any number of poles may be em loyed.

It will be undiarstood that normally the short-circuiting device E is inoperative andthe motor starts on single-phase alternating current on the repulsion prmoiplc, "by means of the current passing through the field windings, inducing currents in the armature windings, which currents circulate in the armature between points connected by the brushes, bearing on the commutator, but

wheat-he armature attains a predetermined speed, the windings thereof. are short-air cuited by the device E, so that the motor op crates as an induction motor. It has been found in actual practice that the windings of the'armature, can be effectively short. circuited' without providing a contact device groundin or short-circuiting the commutator bars, at the short-circulting effect can be accomplished by connecting the .armature windings together at certain equidistant hits, as, for instance, in a four-pole machine with a series wound armature the armature windings can be connected toget-her at points approximately one hundred-and twenty degrees apart.

The short circuitmg device comprises a disk 2 having a hub 3 which is clamped to the armature shaft by a set-screw 4 screwed into the opening 5 of the hub. Fulcrumed at diametrically o posite points 6 on the disk2 are weights i which swing outwardly from the hub in a plane transverse to the xis of rotation when the armature. rotates.

aoh weight 7 has connected therewith at 8 a link 9, and passing through each link is a bolt 10, which also passes through a slot 1b in the disk 2. These bolts'are connected with a short-circuiting element in the form of a disk 12 provided with radially extending knife switches 13. This disk 12 is held on the c'arryin disk 2 by means of screws or pins 14 whic pass throu h slots 15 in the disk 12 and screw intot e disk 2. The switch bladesare held in open circuit position, as shown in Fig. 4, by helical extension springs 16 fastened at 17 to the switch blades and at 18-to the disk 2. Coiiperating with each switch blade'is a air of contacts 19 and 20 between which e associated knife blade engages. These contacts 19 and 20 are separated from each other and from the disk 2 y insulation'Zl, and they are fastened to Patented Nov. 6, 1917.

- the by screws 22. The wntactsl-Q and 20 have ears or extensions 19 and 20" which have binding screws 23 for securing circuitwires'thereto. As shown in Fig.2, the wind-'1' ing 11: of the armature has wires 24 connectedgtherewith at threepoints approximittely one. hundred and twentydegrees apart, and these wires in turnleadto the contacts 19 and 20,;so. that when the shortcircuiting velement 12 isshifted from the position shown injFig. v4 to thatshoivn' in Fig 2 "by: the" centrifugal :foree acting, on the weights 33, the coilsof the armature will be. short-circuited; It has been found that in a j founpole motor threespoints of connection" are sufficient, and alsowithany other multimlarjnmchines there should be an odd-num- *r of connections. between the' armature windi'nghnd the contacts of the: short-eirv cuiting device. "Twogwlres' are me from a place near to each point on the ar-l nurture Winding to the short-cireu iting device, increasing thefefliciency' and, for extra.

reliabil'iW, so that if one wire should become brolcen the other ire will serve the in-' tended purpose." It will be noted from'Fig.

1 that the short-ciwniting' device-is jet the end of the armature op osite "from the] co m'utator; and it lies'vvit in the casing .of the motor;' The contiiets of-theshoft-circuiting device-can be connected ,With the armature winding at either cndlofethearinaturet From thefore'going description taken onnection with 'f the accompanying drawings, Tthe advantages oi.- the construction and method of operation will 'madily under-- stood-thy those skilledfinjthe' art to which} the invention appertains and while I have -elaim as new and'desire to .t wi' n described the pr nc ple of 0 eration, tovgether with the apparatus .whie I new; con

sider bethe best embodiment thereof, I

. desire to have it understood that the apparatus shown is merely illustrative and that such changes may be made when desired as fall within the scope of the appended claims. Having thus described my invention, I Secure by Letters Patent: a '1. A short-cireuitingdevice of the ,class described, comprising a" carrier, contacts fixedly mounted on the carrier, an'elemen't movably mounted on the carrier and having members forming contacts movable nto and out of engagement with the fixed contacts,

spring means tending to hold said member in a position with the contacts thereof out of engagement with the fixed contacts, cen tri ugalweight's mounted on the carrier at the side opposite from the said member and movable in a plane parallel with the 'plane in which the member has rotary movement,

land means extending-from one side of the- -ca-rrier to :the' other for, connecting the weights with the said member- 2. A short circuiting device comprising a carrier, fixed contacts thereon, a member movably mounted on thecarrier at one side and having 'allimited rotaryinovement, said member being a conductor and having members forming contacts for engaging the first mentioned contacts,; centrifugal weights mounted-on the carrier at the side opposite ,from the mem'benfsaid carrier having slots, links connected withthe weights; and con motions-between the links and-member and extending throu h the slnts of the carrier. 4 MI HAEL I. GINSBURG.

WM. Wnmmmrr, Louis Fnrns'mm. V

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