US666255A - Electric switch and resistance. - Google Patents

Description

No. 666,255. Patented Ian. 22, IQOI.

C. W. ATKINSON. ELECTRIC SWITCH AND RESISTANCE.

(Application filed June 2, 1900.)

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(Application am June 2, 1900.

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No. 666,255. v Patented Ian. 22, I961. C. W. ATKINSON.

ELECTRIC SWITCH AND RESISTANCE. (Application filed use 2, 1900. (No llodal.) a Sheets-Shoat .3.

WITNESSES.

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- UNITED STATES PATENT OFFICE.

CLAUDE WILLIAM ATKINSON, OF CARDIFF, ENGLAND.

ELECTRIC SWITCH AND RESISTANCE.

SPECIFICATION forming part of Letters Patent No. 666,255, dated January 22, 1901.

Application tiled June 2,1900. Serial No. 18,867. (No model.)

To all whom, it may concern;

Be it known that I, CLAUDE WILLIAM AT- KINSON, a subject of lhe Queenof Great Britain and Ireland, residing at Cardiff, in the county of Glamorgan, England,haveinvented a new and useful Improvement in Electric Switches and Resistauces, (for which I have made application for Letters Patent in Great Britain, under No. 6,261, bearing date April 3, 1900,) of which the following is a specification.

My invention relates to electric switches and resistances, and more particularly those classes of switches and resistances which are used for the purpose of starting or regulating continuous-current shunt-wound motors, and has forits object the construction and arrangement of such apparatus whereby the cost of manufacture may be reduced. The object of a switch of this class is to prevent a sudden rush of the electric current through the armature of the motor while it is at rest by causing the current in the first instance to pass through a series of resistances, which are gradually out out of the circuit by the continued movement of the switch. Provision should also be made to prevent the operation of the switch until such time as the magnets of the motor have been magnetized by the electric current and to cut olf the current from the motor should this magnetizing-current fail. In additionit is advisable to automatically disconnect the motor from the source of supply in the event of the current exceeding a certain predetermined maximum value.

In order that myinvention may be the better understood, I will now proceed to describe the same in relation to the accompanying drawings, reference being had to the letters and figures marked thereon.

Like characters refer to like parts in the various figures.

, Figure 1 is a sectional elevation of a switch made according to my invention. Fig. 2 is a plan of the same with the cover and handle removed. Fig. 3 is an elevation, partly in section, of a resistance made according to my invention. Fig. 4 is a plan of one of the armatures of the control-electromagnets. Fig. 5 is a sectional view of the contact-arm, one electromagnet, the two armatures, and the casting carrying them, all of which being mounted on a sleeve as a whole form the rotating elementof the switch. Fig. 6 is a plan of the casting O,'showing the detent Q engaged therewith. Fig. 7 shows, diagrammatically, the various elements of the device with the electrical circuits. Fig. 8 shows the adjusting device for the armature G Figs. 9, 10, and 11 are modified detail views illustrating different modes of reducing friction between pins D and P.

In order to carry my invention into efiect, I wind resistance-coils of wire a upon a metal rod 13, insulated with suitable insulating-coatings 0, having at one end metal contactplates d. I attach one end of the resistance- Wire a to the contact-plate d by soldering or other means, and the other end I attach by soldering or other suitable method to a cop-' per strip e, which is bent around the insulated rod and has one end projecting so that it may be attached to the end of the rod Z), upon which the next resistance coil is wound. When the resistance-coil has been wound, I cover it by means of a layer of insulating material f, which I make cylindrical in section, by preference, or of other suitable section, if desirable. I place several such resistance-plugs in a holder g, made of metal,either castings having cylindrical holes formed therein or of thin metal folded in a corrugated manner forming pockets, and connecting the copper strip e, attached to one end of a resistance-coil in one plug, to the central rod 19, connected to the other end of the resistance-coil in the next plug, I form as'eries of resistances through which the current may be made to pass and which may severally be cut out of circuit by means of a switch (in the usual way) making contact with the contactplates d.

I attach the'wire bringing the supply of electricity to the terminal plug 9, which is connected to the contactplate 01, so that when the switch is in the position shown in Fig. 2 the whole of the resistance is cut out of circuit and the current passes to the switchcontact h and thence to h and from here to the contact-plate d to the terminal plug 9 which is connected with one terminal of the motor. When the switch is moved so that the contacts h and h arein contact with the contact-plates d and d, respectively, the current has to pass through the resistances on all the plugs, and by continuing the move ment of the switch in the direction (1 d (Z (Z the circuit will be broken altogether.

I support the holder 9 on the case of the switch j, which Iform of a casting or thin metal tube having its top edge turned inward at y, so that a flange 9 formed in the holder g, can rest on it, and I fix the holder gin position by means of the casting or stamping it, which, having openings formed in it through which the contact-plates (Z project, presses down on the flanges g of the holders 9 and fixes them in position. On a central bolt A, I fit a tube B, which is free to revolve on A, and I arrange a handle or gear for revolving this tube B when it is desired to operate the switch. Onto the tube B, I fix, by means of a key or other suitable means, a casting O, carrying the sliding pin D, so that when the tube B is revolved the casting O revolves with it about the central bolt A. The position of the sliding pin D is controlled by the links E, E and E Hinged to the casting O at F is the thin circular iron plate G, which forms the armature of the electric magnet H, having poles K and K and magnetizing-coil M, so that when the magnet H is magnetized by a current passing through the coil M the armature G is drawn up against the poles K and K into the position shown in Fig. l and held there. The thin circular iron plate G is also hinged to the casting O at F and forms the armature of the electric magnet H having poles K and K and magnetizing-coil M, and may also be drawn up against the poles K and K when an electric current is passed through the coil M The links E and E are hinged at one end to the armatures G and G respectively. At the other ends they are hinged to one end of the link E which in turn is hinged to the sliding pin D, thus forming a compound toggle.

One end of the coil M is attached to the terminal g, which is in connection with the source of electric supply, and the other end of the coil M is attached to the terminal g, which is in connection with the field-magnet coils of the motor, so that as soon as a current is sent through the field-magnets of the motor this current passing through the coil M magnetizes the magnet H and causes the armature G to be drawn against the poles K and K thus causing the sliding pin D to move outward into the position shown in Fig. 1. If this current fails, the armature G is no longer held against the poles K and K and moves, owing to the pressure of a spring, away from these poles and acting on the links E E E draws the pin D inward.

One end of the coil M is connected with the switch-contact 7i and the other end to the contact 7L2, and these two contacts are insulated from one another in other respects, so that the current passing from the source of supply in connection with the terminal g to the armature of the motor in connection with the terminal passes through the coil M The motion of the armature G of the electric magnet H is controlled by means of a spring Y, so arranged that when the current passing through the coil M reaches a certain predetermined amount the armature G is moved up against the poles K and K of the electric magnet H against the action of this spring Y.

If when the armature G is held in the position shown in Fig. 1 against the poles K.

and K of the magnet H by the action of the current passing to the field-magnets of the motor the armature G is drawn up against the poles K and K ol' the magnet H owing to the current passing through the coil M to the armature of the motor becoming greater than the predetermined value, the link E is drawn up with the armature G and this acting on the links E and E draws the pin D inward. The value of this predetermined maximum current at which G is moved may be varied by altering the normal position of the armature G by means of a screw Z, Fig. 8.

The action of the switch may now be described. The current having been turned onto the magnets of the motor by some means beyond the switch here described, this current energizes the magnet H and, drawing over the armature G, pushes outward the pin D, which new projects sulficiently to engage with the pin P or P attached to the switcharm having contacts 7t and 72. The handle of the switch being now operated revolves the tube B, carrying with it the casting C until the pin D engages with one of the pins P or P The motion being continued, the switchcontacts 7L and 71 are caused to revolve about the central bolt A, making contact successively with the contact-plates (Z and d and continuing until they reach the plates (1 and (Z first turningon the current to the armature of the motor through all the resistances I), wound on the rods a, and then gradually cutting out these resistances until when the contacts 7L and 7L2 of the switch rest on the contact-plates d and (Z all the resistances are cut out and the armature of the motor is in direct connection with the source of supply. hen this position is reached, the casting O engages with the pawl Q and is held in that position. It will be observed that until there is a current passing through the coil M-that is, until the field-magnets of the motor are magnetizedthe switch cannot be operated, since the pin D will not then engage with the pins P or P Attached to the pin P is the spiral spring S, attached at the other end S to the frame or case of the apparatus, so that if the handle is released or the release mechanisms become free the switch is moved by the spring S over the contacts (Z until the armature-circuit is broken, and the switch cannot be left in any position between the fullon and full-off positions. If now while the switch is in the position shown in Fig. 1 the pawl Q is drawn outward, the spring instantly IIO switches oif, or when in this position if the current through the coil M exceeds the predetermined limit the armature G of the magnet H moves upward, draws in the pin D, and the spring moves the switch in to the off position. Similarly if when in this position the electric supply fails or the current through the motor field-magnets ceases the current will cease to magnetize the magnet H, and the armature G moving upward draws in the pin D it no longer engages with P or P and the spring S acting switches 0%.

I provide spring-stops T and T which engage with the pins P and P to catch the switch when it switches off and prevent it moving too far, and I sometimes insert a rubber or other spring buffer between the springs T and T and the pins P and P The whole of the mechanism is inclosed by the metal or other cover U engaging with a flange in the castings or stamping 7t, and I usually prefer to retain it there by means of a bayonet attachment.

To insure insulation, I sometimes prefer to enamel the holders g, the casej, the inner casting or stamping 7t, and the cover U.

The outer yokes of the magnets II and H terminating in the poles K and K I usually make of thin iron stampings, and to insure insulation I frequently enamel the outside of the yoke of the magnet H I sometimes prefer to cover the rods 1) and the resistance Ct with an insulating compound composed of clay admixed with a small percentage of fine asbestos fiber, which gives the clay suiiicient tenacity to hold together when wetwhile it is being applied, and when the covering f has been dried I press it in a small mold with considerable pressure, which has the effect of making the outside very hard and true to size and shape and at the same time forces the material in between the wires forming the resistance Ct and prevents adjacent coils of the wire touching one another when they become expanded by getting heated by the current.

I hold the switch-contacts h and k in position by coating part of them with the same compound of clay and asbestos, and I clamp them between the plate V and the yoke of the magnet H and each of these latter I form with projections by stamping or other means,which engage in corresponding depressions in the ends of the contacts h and 71 as shown in Fig. 1.

VVheu itis desired thatit should be impossible to switch on too rapidly, I connect the handle 1 with the tube B by means of an epicyolic gear, in which the wheel 2 is fixed stationary on the central bolt A. The wheel 3 is keyed or otherwise attached to the tube B, while the wheels 4 and 5, revolving together, are centered on a spindle attached to the handle l in the epicyclic gear. The wheels 2 and 5 have more teeth than the wheels 3 and 4- say, for instance, 2 and 5 have one hundred teeth each and 3 and 4 have ninety-nine teeth each-which gives a fractional motion from the total motion of the handle. This is a very common form of speed or reducing gear.

In order that the switch may be switched off without driving the epicyclic gear as a whole when the pawl Q is released, I mount the handle 1. so as to slide on its spindle parallel to its axis, and I provide one or more pins '7, which pass through-the boss 8 and bear against the handle 1 at one end and the wheel 4 at the other end. The Wheel at is also adapted to slide endwise a small distance and is kept normally away from the wheel 5 by means of a spiral spring 9, situated between them. The wheel 4 is provided with pins or projections 10, which are adapted to engage with holes or recessesll in the wheel 5 when the said wheels are pushed toward one another by means of the handle 1 and pins 10. As the wheels 4 and 5 are placed normally out of engagement automatically, the epicyclic gear is not driven as a whole when the pawl Q is released.

To reduce the friction on the spring S, I sometimes insert the cylindrical guard S which is free to revolve on the outside of the yoke-magnet H, so that the springs wraps onto this as the switch is revolved, and in this case instead of attaching one end of the spring S to the pin P, I attach it direct to this guard S and I form a projection in this guard which engages in the pin P.

I sometimes prefer to close the bottom of the case j with a plate 7' through which alone the terminals g, g and 9 project, and I provide bolts g and g which hold the whole together.

In order to reduce the friction between the pin D and the pins P or P and to make the action more certain, I bevel the end of the pin D, and I carefully polish this surface, or in some cases I replace this form of contact by means of small rollers revolving on the pins P and P or a single roller inserted in the end of the pin D, with its plane of revolution perpendicular to the pins P and P Having now described this invention, what I claim, and desire to secure by Letters Patent, is

1. In a switch for starting or regulating electric motors, a magnetic controller consisting of an electromagnet controlled by the field-magnet circuit of the motor, another electromagnet in the armature-circuit to the motor; a movable armature to each electromagnet; a compound toggle-lever connected to the said two armatures, a sliding pin or detent adapted to be operated by the said compound toggle-lever; a frame pivotally mounted on the main frame of the switch; means for operating said frame; a movable contact-arm adapted to make and break contact with the terminals of the main circuit, an abutment upon the said contact arm adapted to coact with the said sliding pin or detent when the electromagnet controlled by the field-magnet circuit is energized, means too for automatically bringing the contact-arm into the switched-off position, and a detent on the main frame adapted to coact with the pivoted frame, substantially as described.

2. In a switch for starting or regulating electric motors in combination a magnetic controller adapted to automatically prevent the switching on of the current to the motor until the field-magnets of said motor are energized and to switch off the current from the motor on overload a series of contacts, a movable switch-arm, a series of resistances arranged in series with the said contacts and a contact-arm adapted to make contact with the said contacts and to be controlled by the said magnetic controller, substantially as described.

3. In a switch for starting and regulating electric motors in combination a double-pole contact-arm, a series of resistances a series of contacts interspersed among the resistances, an electromagnet connected in series with and between the two poles of the contact-arm, and means operated by the said electromagnet for automatically maintaining the switch in the on position so long as the field-magnets of the motorare energized, substantially as described.

at. In a switch for starting and regulating electric motors, in combination, a movable contact-arm, a series of resistances, a series of contacts interspersed among the said resistances arranged to make contact with the said contactarm, an operating-handle, a speed-reducing gear connecting the said handle with the movable contact-arm, and means for automatically disconnecting the handle fromthe contact-arm to permit the quick return of the latter, to the switchedbft position substantially as described.

In witness whereof I have hereunto set my hand in presence of two witnesses.

CLAUDE \VILLIAM ATKINSON. Witnesses:

WILLIAM HENRY IlIERCHANT, WILLIAM WATKINS.

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