US870892A - Alternating-current motor. - Google Patents

Description

PATENTED NOV. 12, 1907 R. LUNDELL. ALTERNATING CURRENT MOTOR.

APPLICATION FILED SEPT. 28, 1906.

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witness as MEET UNITED STATES RQBERT LUNDELL, OF-NEW YORK, N. Y.

ALTERNATING-CURRENT MOTOR.

Specification of Letters Patent.

Patented Nov. 12, 1907.

Application filed September 26. 1905- Serial No. 280il18.

To all whom it may concern:

Be it known that I, ROBERT LUNDELL, a citizen of the United States, residing at New York, borough of Manhattan, county and State of New-York, have made a new and useful Invention in Alternating-Current Motors, of which the following is a specification.

My invention relates to that class of alternating current motors which are furnished with a commutator and which may be operated by a single or uni-phase current. The invention relates particularly to the class of alternating current motors described by rue in a prior U. S. Patent No. 782,863, dated February 21st, 1905. In the abovementioned patent I have shown and described the manner in which a singlephase alternating current motor may be started from rest with or without load and which may be reversed at will by changing the position of the brushes.

The object of the present invention is to devise new and improved means for reversing the direction of rotation of the armature or the rotary part-said new means being more conveniently employed in connection with certain types of motors, than the corresponding means for reversing described in the patent above referred to.

In order to effect a change in the direction of rotation I employ in the present invention stationary brushes in combination with a current-or polechanging controller, instead of the movable brushes with'their brush shifting mechanism described in the above-mentioned patent.

Referring now to the drawings, Figures 1, 2 and 3 are 7 all diagrammatic views of the apparatus. Figs. 2 and 3 pertain to Fig. 1, being merely explanatory diagrams showing the current connections of Fig. 1 in a simple manner.

. Referring now to Fig. 1 in detail, 1 represents the stationary field magnet, (two-pole in this illustration) 2 the armature and 3 the commutator of an alternating f current motor.

4, 5, 6, and 7 represent brushes which bear upon the commutator as indicated. 8, 9, 10 and 11 represent wires or connections from the said brushes to stationary contact pieces 12, 13, 14 and 15 of a pole changing and current regulating controller having movable contact pieces 20, 21, 22 and 23, as shown developed in the diagram. 16, 17, 18 and 19 represent other stationary contact pieces of the said controller, connecting, as shown, the'four starting and regulating resistances, 24, 25, 26 and 27.

aa to e e and aa to ee represent the different positions of the controller.

28 and 29 represent the current mains or line Wires of an alternating current supply circuit and 30, 31 and 32 represent branch mains or wires, as clearly understood from the diagram.

' The field windings are preferably of the kind known as distributed windings-a Gramme ring winding being shown in Fig. 1 because of simplicity of illuscoils not short circuited, the arrangement being such that resultant polarities are created in the armature, substantially-in accordance with the principle described in the patent hereinbefore referred to.

sets in the two-pole machine shown. Two of these brushes 4 and 7 connect directly with the armature coils which are under the field poles, whereas the other two brushes 5 and 6 connect directly with the arma ture coils which are about midway between the field poles. A similar disposition of the brushes would naturally apply to a multipolar design, that is to say, there will be two sets of brushes, one set being located as would the brushes in a direct current machine, while the other set of brushes will be placed about midway between the first mentioned brushes.

Arrows are shown for the purpose of illustrating at a given moment the direction of the currents in the various circuits, said arrows being shown in full lines when they pertain to the primary currents and in dotted lines when they pertain to the induced or short-cir cuited currents in the armature coils.

The operation is substantially as followsThe priwire 31 into the field windings of the field magnet 1 wherein, at a certain moment, it flows as indicated by the arrows, producing in turn the polarities S and N, as shown on the drawing. From the field windings it flows by wire 32 to brush 4 where it divides itself, one part flowing through one section (or group of coils) of the armature winding to brush 6, as indicated by the arrows, and the other part flowing by wire 8 to contact pieces 12, 20, and 13 to wire 9 and brush 5; then through another section of the armature winding to brush 7. The current flows finally from the brushes 6 and 7 by wires 10 and 11, contact pieces 14, 15, 21 and 19 to wire 30 and to the other line wire 28, as clearly shown on the drawing.

It will be noticed that the brushes 4 and 5, as well as the opposite brushes 6 and 7, are connected together or short circuited by the controller contacts. The two sections of armature coils whichare included in the local circuits of the brushes are thus short circuited, the

effect being somewhat similar to the effect produced It will be noticed that there are four brushes'or two outside source) to flow through the other armature mary current enters from the line wire 29, by branch I by the wide short circuiting bruishes described in the patent above referred to. That is to say, induced currents are produced in the short circuited armature coils as indicated by the dotted arrows. The resultant polarities from the primary and the induced currents in the armature will be located about as indicated by the letters S and N in Fig. 1, the rotation being in the direction of the hands of a clock.

It will be seen from the drawing (Fig. 1), that the movable contacts 21 and 23 of the controller are arranged .to regulate the current flowing in the primary circuit by means of the resistances 24 to 27 which servethe purpose of reducing the voltage at the terminals of the motor. These resistances may be inductive or non-inductive according to requirements. They may even be omitted entirely by connecting the motor and the controller to the line through an auto transformer which would give the required regulation of voltage supply in a well known manner. Line XX indicates,- of course, the open'circuit position of the controller. In order to reverse the direction of rotation contacts 22 and 23 are made to engage with the stationary contacts 12, 13, 14 and 15 of the controller. It will be seen that, in this position of the controller, the brushes 4 and 6 become connected together instead of the brushes 4 and 5 and also that the brushes 7 and 5 become connected instead of the brushes 7 and 6 which were connected before.

Figs. 2 and 3 serve to indicate in a simple manner the change in the connections when the controller has been moved from the forward to the reversing position. It should be pointed out, that the connections or the polz "it; of one set of the brushes, viz: the brushes which nnect directly with the armature coils under 35 the field poles remain unchanged, whereas the connections or polarities of the other set of brushes become reversed by the movement of the reversing switch or controller.

I do not limit my invention to the specific constructional arrangement shown and described, as I believe it is broadly new with me to combine with an alternating current'motor of the type described and claimed in my prior patent No. 782,863, a controller which is independent of the motor proper and adapted to be located at any point, the same being provided with the necessary circuit connections in the nature of conductors and contacts for effecting the control thereof at relatively distant points and to combine therewith a reverser for effecting the reversal of rotation of the rotor or armature thereof, and the present invention is an improvement upon that disclosed the before-mentioned patent to the extent that the means of control and reversal are not limited to any definite or fixed distance between the controller and the motor or the reverser and the motor.

Having thus described my invention what I claim and desire to secure by Letters Patent of the United States is 1. An alternating current motor comprising the combination of a field-magnet connected to a source or alternating current supply, an armature having coils connected to a commutator, two sets or stationary brushes bearing upon the commutator and placed 90 electrical degrees apart; means for connecting said brushes in pairs to an outside circuit for the purpose 0! short circuiting certain groups of armature coilsand for introducing outside cur rents into the other armature coils not short-circ'uited and additional means for changing the positions of the short-circuited groups of armature coils relative to the axis of the field flux, tor the purpose of reversing the direction of rotation.

2. An alternating current motor comprising the combi nation of a field-magnet connected to a source or alternating current supply, an armature having coils connected to mutator, one set being placed at points corresponding to the neutral points of a direct current machine, while the other set of brushes is displaced electrical degrees from the first mentioned set; means for connecting the brushes which are 90 electrical degrees apart together in pairs, either in a right-hand or in a left-hand direction according to the desired direction of rotation, and additional means for connecting one of the above mentioned sets or brushes to an outside circuit.

3. A single phase alternating current motor comprising the combination of a field-magnet having an energizing winding, an armature the coils of which are connected to a commutator; two sets of brushes upon the commutator, one set being placed at points corresponding to the neutral points of a direct current machine while the other set of brushes is displaced 90 electrical degrees from the first mentioned set; means for connecting said sets of brushes together in pairs to an outside circuit for the purpose of short-circuiting certain groups of armature coils and for introducing outside currents into the other armature coils not shortcircuited, and additional means for interchanging the positions or the short-circuited and the non-shortcircuited groups of armature coils, for the purpose or reversingthe direction of rotation.

4. A single phase alternating current motor comprising a stationary field magnet having an energizing winding, an armature the coils of which are connected to a commutator with two sets of brushes bearing upon said commutator, one set of brushes connecting with the armature coils which are directly under the field poles and the other set connecting with the armature coils which are about midway between the field poles; incombination with a controller having means for connecting one set of brushes tov an outside circuit and additional means for connecting the two difierent sets of brushes together in pairseither in a right-hand or a left-hand directionfor the purpose of short-circuiting certain groups or armature coils and for reversing the direction of rotation.

5. A single phase alternating current motor comprising a stationary field-magnet connected to a source of alternating current supply, an armature having coils connected to a commutator, two sets of brushes bearing upon the commutator, one set of brushes connecting with the armature coils which are directly under the field poles and the other set connecting with the armature coils which are about midway between the field poles; in combination with a controller having means for connecting one set of brushes in series with the field winding, and additional means for connecting the two different sets of brushes together in palrseither in a right-hand or in a letthand directionfor the purpose of short-circuiting certain groups oi. armature coils and for reversing the direction 0! rotation.

In testimony whereot I have signed my name to this specification in the presence of two subscribing witnesses.

ROBERT LUNDELL.

Witnesses C. J. KINTNEB, M. F. Kns'rrsc.

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