US832713A - Alternating-current motor. - Google Patents

Description

UNITED STATES PATENT OFFICE.

JOHN B. WIARD, or LYNN, MASSACHUSETTS, ASSIGNOR T GENERAL ELECTRIC COMPANY, ACORPORATION on NEW YORK.

ALTERNATlNG-CURRENT MOTOR.

Patented Oct. 9, 1906.

A li ti fl d February 23, 1904. Serial No. 194,711;

To all whom it may concern:

Be it known that I, J OHN B. WIARD, a citizen of the United States, residing at Lynn, county of Essex, State of Massachusetts,

. have mvented certain new and useful Imrovements in of which the following is a specification.

My invention relates to alternating-current motors, and particularly to automatic means for changing over from starting to fullspeed circuit connections. Heretofore these changes have usually been made manually by hand-operated switches or automatically by centrifugalswitches. The latter, although preferable to the former, are costly and more or less unreliable on account of their large number of parts and complexity and in general constitute one of the weak points in the design of such motors.

It is the principal object of the present ini ecrliti gn to afoid these objections, and this 0 y emp o a ma eticall o erate switch which wil l itomati dhlly ma ke the necessary changes in connections.

It is well understood that when the primary circuit of an alternating-current motor is first closed excessive currents fiow in both field-windings and armature, causing a considerably-distorted magnetic field, a portion of which extends beyond the ends of the motor-armature, and that as the armature speeds up and approaches synchronism the currents in the various windings diminish to their normal values and the field becomes normal.

3 5 take advantage of the external field thus produced to actuate a starting-switch which is so constructed and arranged that it will be drawn over by the external magnetic field to close the starting-circuits and will fall back 0 when said field weakens to establish the fullspeed connections.

My invention also comprises other features and presents other advantages which will more fully appear upon reference to the following detailed description, taken in connection with the accompanying drawings, in which one embodiment of the invention is illiistrafied.

n t e accom an drawin in which like characters are??? like pa r ts, I have illustrated an induction-motor having a main primary winding and a displaced starting-winding provided with an automatic Alternating-Current Motors,

starting-switch constructed in accordance with my invention.

Figure 1 of said drawings is a central ver tical section of said motor, and Fig. 2 is a diagram showing the switch connections.

The field structure 1 of the motor, which is suitably secured within the motor-casing 2, is provided with a main primary winding 3 and a starting-winding 4, which may be of any The motor-armature 5 is a squirrel-cage armature and is mounted upon the shaft 6, which is suitably journaled at its opposite ends in bearings in the motorcasing.

The circuit of the starting-winding, which includes some suitable dephasing means, such as the inductive resistance 7, is completed across the supply- leads 8 and 9 through the enga ing contacts 10 and 11 of the startingswitc These contacts, which are preferably composed of carbon, are mounted in blocks 12 and 13, also of conducting material, and are provided with suitable terminal screws 14 and 15, respectively. The blocks 12 and 13 are fitted within a tube 1.6, of fiber or other non-conducting material, located in one of the heads of the motor-casing 2 adjacent to the armature-shaft 6. This fiber tube completely incloses the contacts 10 and 11, so that all arcing is confined to an almost air-tight space, where it can do no harm. By means of an adjusting-screw 17 and a setscrew 18 the position of this insulating-tube may be definitely fixed.

The block 12, carrying the swith-contact 10, is held in a fixed position, while. the block 13, carrying the contact 11, is movable within the insulating-tube -16,the movement of the latter being limited by slots 19 19, through which the terminal screw 15 passes. A spring 20, coiled about the insulating-tube 16 and bearing at one end against a fixed portion of the casing and at the other against the screw 15, normally holds the contacts 10 and 11 of the switch separated. A slot 21 in the casing, through which the terminal screw 14 passes, makes provision for the movement of said screw resulting from the adjustment of the tube 16 and the inclosed switch-contacts by the screw 17, and suitable insulating-pieces 22 prevent tween said screw and the motor-casing. At the opposite side of the movable armature 5 preferred type.

electrical contact befreely over the spring 24, an

netic material, whi ch passes ub of the armature. This ring is preferably equal in diameter to the diameter of the armature and is adapted to be drawn thereagainst in opposition to the force of a coiled spring 24, surrounding a portion of the hub of the armature 5. Where the motor is to be mounted with its shaft vertical, it is hung so as to bring the ring 23 on the under side and the spring 24 is omitted, the force of gravity alone being sufiicient to draw the ring from the motor-armature when the flux falls off. The ring 23 may also be built up of laminations of iron, if desired; but I have found that for most purposes castiron is satisfactory, for the reason that since the ring rotates at the same speed as the armature the frequency of the flux changes therein is low and the consequent loss due to such a ring is practically negligible. Movement is transmitted from this ring to the movable contact 11 of the startingswitch by means of a plurality of rods or bars 25, which extend throughsuitable apertures in the hub of the armature and are freely movable therein. These rods are. connected at the switch side of the 26, which is located so as to engage a block of insulation 27 secure to the inner end of the movable contact-block 13 of the starting-switch;

As previously indicated, when the motorcircuit is first closed excessive currents flow in the primary Winding 3 and in the armature and considerably distort the normal magnetic field of the motor and produce a stray field adjacent to the motor-armature. This field acts upon the magnetic rin .23 to draw it into engagement with the en of the armature in 0 position to the force of the d thereby forces the ring 26 against the movable element of the startingswitch so as ,to bring the contacts and 11' into engagement. As soon as the startingis a ring 23 of ma circuit is closed by this action, the. armature speed of the will rotate, and as it speeds up and approaches s chronism the stray flux will weaken an the spring 24will radually return the parts to the position s own in Fig. 1 to open the starting-circuit and thereafter allow the motor to run as a straight single-phase motor.

A. magnetically-operated switch such as I have disclosed is very simple in construction and reliable in pendent in its operation of the frequency of the current-supply is also independent of the motor.

I do not wish to be limited to the specific construction herein disclosed, since it is clear that my invention may be embodied in many different forms; but I desire my invention to receive a broad interpretation, since I believe I am the first to rovide a magnetically-operated switch or automatically armature to a ring mary winding operation and being indechanging over from starting to full-speed connections in an electric motor.

What I claim as new, and desire to secure by Letters Patent of the United States, is

1. The combination with an alternatingcurrent motor having different starting and. full-speed circuit connections, of a magnetically-operated switch comprising a member adapted to be moved toward the motor-armature under the influence of the strong magnetic field produced in the armature at starting to establish one of said circult connections and to be moved away from said armature to break said circuit connections.

2. The combination with a single-phase induction-motor having a primary winding and astarting-Winding, of a switch in circuit with said starting-winding, ed to be moved toward the motor-armature by the magnetic field of the armature to move said switch to one position, and means for moving said switch from said position.

3. The combination with a single-phase inductionm'otor having and a starting-winding, of a switch in circu t with said starting-windin means for malntaining said switch norma ly in its open position, and a member ada ted to be operated by the strong magnetic eld produced in the armature at starting for closing said switch.

4. The combination with a single-phase induction-motor ha g a primary winding and a starting-winding, of a switch comprising fixed and movable contacts included in the circuit of said starting-winding, an in closing casing for said switch-contacts,

means for holding the switch-contacts nor-' mally out of engagement, and a member adapted to be operated by the strong magnetic field of the motor at-starting for closing said switch.

5. The combination with a single-phase.

induction-motor having an armature, a priand a starting-Winding, of a magnetically-o erated switch comprising-a member mova le under magnetic influence toward said armature to close a circuit through said starting-winding when the primary circuit of the motor is closed, and means for, moving said'member in the opposite direction to open said circuit. r

6. In an electric mot-or, the combination with the motor-armature, of a ma neticallythe influence of the magnetic field produced a member adapt-.

operated switch comprising a member adapted to be moved toward said armature under 1n the armature at starting to move said switch to one positionfand means for'mov ing said switch from said position.

7. In an electric motor, the combination with the motor-armature, of a switch located adjacent to one end thereof, and a magnetic ally-actuated member for switch located at the opposite end of said armature.

operating said 1 full-s eed circuit connections,

8. .In an electric motor, the combination with the motor casing and armature, of a switch carried by said casing, and means carried by said armature and rotatable therewith for operating said switch. I

9. In an electric motor, the combination with the motor casing and armature, of a switch carried by said casin and magnetically-actuated means carrie b said armature and rotatable therewith or operating said switch.

10. In an electric motor, the combinationwith the motor casing and armature, of a switch carried by the casing adjacent to one end of said armature, and a magneticallyactuated member for operating said switch carried by said armature at, its opposite end.

11. In an electric motor, the combination with the motor casing and armature, of a switch carried by the motor-casing and comprising an insulating-tube, contacts therein, and means carried by the armature for moving said contacts into engagement.

12. In an electric motor, the combination with the motor casing and armature, of a switch carried by the motor-casing and comprising an insulating-tube, contacts therein, and magnetically-actuated means carried by the armature for moving said contacts into engagement.

13. The combination with an alternatingcurrent motor having different starting and of a magnetic to be moved toward the mem er adapted by the strong magnetic motor-armature field produced in the armature at starting, and a switch controlled by the said member adapted by its movement to change the motor connections from starting to running conditions.

14. The combination with an alternatingcurrent motor having a short-circuited secondary winding and a primary winding arranged for different starting and full-speed circuit connections, of a ma etic member adapted to be moved towar the armature by the strong magnetic field produced in the armature at starting, and a switch controlled by said member adapted by its movement to change the connections of the armaturewindm from starting to running conditions.

15; he combination of a single-phase induction-motor having a main winding and a starting-winding on its primary member, and a short-circuited secondary winding, of a switch in circuit with said starting-windin means for maintaining said switch normal y in its open position, and a member adapted to be operated b the strong magnetic field of the motor pro uced at starting for closing said switch.

16. In an induction-motor, tion with a motor-casing, short-circuited carried by the armature, a switch carrie by the casin and magnetically-actuated means carried I y the armature and rotatable therewith for operating said switch.

In witness whereof I have hereunto set my l hand this 18th day of February, 1904.

JOHN B. WIARD.

Witnesses:

DUGALD MoK. MoKrLLoP, JOHN J. WALKER.

an armature, a

the combina-

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