USRE12595E - Robert lundell - Google Patents

Description

REISSUED JAN. 15, 1907.

R. LUNDELL. ALTERNATING CURRENT MOTOR.

APPLICATION FILED SEPT. 29,1906.

' Am WW 4L 0 P3 0 1 WENEZSE: INVENTOR 5 r By his Atlomey, I

PATENT oEEIo ROBERTLUNDELL, on NEW YORK, N. Y.

, ALTIERNATING-CURRENT MOTOR.

Specification of Reissued Letters Patent.

Reissued Jan. 15, 1907.

Original No. 782,8B3, dated February 21, 1905. Application for reissue filed September 29, 1906. Serial No. 337,812.

To all whom zit-may concern} Be it known that 1, ROBERT LUNDELL, a

citizen of the United States, residing at New York, borough ofManhattan, county and State of New York, have made a new and useful Invention in Alternating-Current Motors, of which the following is specification,

reference being made to the accompanying drawings, forming a part of the same.

My invention relates particularly to that class of alternating-current motors which are furnished with a commutator and which may be operated from a -two-wire circuit; and it .has for its objects, first, the construction of a motor which will give agreat starting torque and a high efficiency; second, the construction of a motor Wl11Cl1 will operate without injurious sparking at the commutator under various loads and speeds; third, the construction of a motor which may quickly be reversed from adistance 'without undue complication.

I accomplish the aforesaid objects with the aid of the improved apparatus and by the methods hereinafter described, and fully illustrated in theaccompanying drawings.

It is a well-known fact that if a laminated field-magnet is used in connection with an ordinary series-wound motor the same may be made to run on a single-phase alternat ing-current circuit. It is also well known that an armature having'a commutator can be made to run in an. alternating-current field if certain coils in thesaid armature are sh'ort-circu'ited upon themselves, though wholly disconnected from the primary circuit. An alternating-current commutatormotorhas also been constructed prior to my invention (see British Patent No. 564, of

1887) in which the field-windings were con nected series with certam torque-produc ing portions of the armature winding, while duced currents in the short-circuited coils.

and I combine the torqueefl'ects of the applied currents and the induced currents in the armature-winding in such a manner that idle armature-coils or false currents in said coils (not producing torque) are avoided.

With the aid of my im roved apparatus I cause the currents in" t ose' annaturecoils which are located at ornear the leaving edges of the brushes to flow in the same di rection, and I avoid also any great change in the current strength at these points in order to effectively prevent' sparking at the brushes. r

Referring now to the drawings, Figures 1 and 2 are both diagrammatic views of the apparatus. Fig. 2 is similar to Fig. I, the only difference being that which results from reversing the direction of rotation of the rotary orrnovable part.

Referring to Fig. 1 in detail, L L represent I the two wires or mains of an alternating-current supply. M represents the laminated field-magnet of a two-pole motor having poles P P and field-windings F F, as clearly shown in the drawings. A represents the armature-core of a rotating armature having a Grarmne or ring winding, as clearly 'shown, the coils of which are in turn connected to a commutator C 1n the usual man ner. B B; represent contact-blocks or brushes which are insulated from one another andwhich are wide enough to straddle or to connect a number of commutator bars and coils. D represents a rocker-arm or lever designed to move or regulate the position i of the contact-blocks B B. E is a rod which connects the said rocker-ar1nD to a core or plunger P, which in turn is designed .to be moved by the solenoid'coils C C The said coils C (1 are operated by a small switch 0. which may be located far from the apparatus. This switch is designed to short-circuit one or the other of thecoils and to put both coils in circuit by opening the said switch. The coils C C are for convenienceshown connected to the alternating-current mains L L, though it would be preferable to connect the same to a source of direct-current supply such as a battery, for instance. R represents a suitable starting and regulating box for regulating the current-potential supplied to the motor. w w w to w represent wires for connecting together electrically the various parts of the apparatus in the manner shown in the drawings: Wires 10 and of, which lead to the contact-blocks B B, are supposed to be flexible in order not to interfere with the movement of the saidblocks.

In order to fully explain the combined action of the primary and the induced currents in the armature-windings, the direction of the current at. one particular moment has been indicated upon the drawings by arrows which are shown in full if they pertain to the rimary circuit and which are shown dotted if they pertain othe induced currents The olarities are ewise indicated by letters S shown in full when the pertain to-the primary currents anddotte when they per- I combined polarities due to both-primary and the induced currents. i

tain to the induced currents. The polarities S N shown in full within the'small circles on the armature-core indicate the resul'tant or Looking 'now upon Fig. 1 as a plain serieswound motor, it will be understood by any one familiar with the art that'if the direction the armature-core.

' indicated b of the current at one particular moment is as the arrows (shown infull) the olarities 0' the fieldrmagnet-poles will be as indicated by letters S N on the drawings. It

will also be understood by following the arrowsv shown in full) on the a'rmaturecore that, t e polarities from the primary current will be located opposite the center line of the brushesthat is, forty-five degrees from the line Y Y, as shown by letters S N (in full) on It follows from the location of these polarities that the rotation of the armature would be from'right to left that is, countercl0ckWiseS' on the fieldthe action of the primary current in the arwill 'be secondar wide contact blocks or brushes B B by rea.

. flow through the armature 'from the fieldmature-windings, 1t will also be understood by any one familiar with the art that there currents induced in the ar mature-coils which are shbrt-circuited the son of the lines of force which are caused to magnet poles N to S. The directionof these induced currents will be such that they will op ose the flow of lines of force-that 1's, they wi be in op osite direction to Uhe'current which flows t rough the field-windings F and F".

If traced on the drawings, they will be found to'be in the direction shown by 'the dotted arrows when induced by a current in the field-windings, which flows as indicated in Fig. 1. Thepolarities on the armature-core from these seconda currents will be as indi-' cated by the dotte letters S and N, and it follows that 'the direction of rotation will be from ri ht to left, or same asbefore, as S on imagnet will repel dotted S "on' the armatureoo're and N on the field-magnet will repel dotted N on the armature-core. .At the next moment, when the currents aretreversed, the polarities will likew se be re' 'seen that't e combined consequentl versed and the direction of rotation remains as before. Examining now the resultant action of both the primary and thesecondary currents u n the armature-core, itwill be olarities will be located on line Y Y, as indlcated by the letters S and N within the small-circles. This is exactly where'the olarities should be located in order to pro uoe the best torque effectsand the best, efficiency.v In fact, 1f the motor were tobe operated as a plain serieswound motor the ordinary narrow brushes would in this case be located at or near the 'line Y Y. Such a motor would, however, cause difliculties from sparking, due to the large secondary current in the armaturecoil, which is directly short-circuited by the brush.

'By my invention I propose to reduce the secondary or the induced current in any one coil to a normal amount by short-circuitin such a number of coils that the combined ampere-turns from the"shortcircuited portions of the armature will nearly e ual the ampere-turns on the other portions 0 the armature, which are due to the primary currents. I p

It will be seen on the drawings that the induced and the primary currents in the armature-windings are in the same direction at the leaving edges of the contactrblocks B and B-that is, at line X X onFig. 1. If these currents are nearly alike in amperes, it fol- I lows that there will be" no sparking as the commutator-segments leave t e brushes, because of the fact that there will be no reversal or change in the current in the armature Windings at these particular points.

The position of the contact-blocks B B is directly governed by the position'of the core P, as clearly shown in'the drawings, and indirectly by the switch 0, which, as stated before, may be at a considerable distance from the apparatus. The core P may preferabl be supplied. with suitable stops for IIO limiting the extreme positions, or similar sto s may be caused to limit the movement of t e rocker-arm D. i

Fig, 2 shows the direction of the primary and the induced currents reversed in the an mature-windings, owing to a change in the osition of the contact-blocks B and B.

he resultant or combined polarities will i be reversed, as shown b letters N and within the small dotted circles,

and the direction of rotation will be from left to right, or in the direction of the hands on a clock. It may be interestin to n te that the crushes or contact-blocks only beenmoved ninety electrical degrees,

whereas the resultant 'po rities of the armature have been shifted: one hundred and eighty dc ees. The same'ratio will apply to a mu tipo ardesign.

I have illustrated a smooth-core ringwound armature for the sole purpose of plainly indicating the direction of thecurrent in the coils. This form of armature is now obsolete, and I would. naturally employ a slotted drum-Wound armature, as Well as a multipolar design, in a Working machine. I have also shown and described a motor having certain, coils in its armaturawindings in series with its field-windings, and I do not limit my invention to this particular ar rangement, as it is but a simple modification to so connect the circuits that the abovementioned coils of the armature would be connected in parallel with the fieldwindings. Having thus described my invention, What I claim, and desire to secure by Letters P atent' of the United States, is"

1. An alternating-current motor having a stationary field-magnet and an armature of the ring or drum type, the coils of which are connected to a commutator, means for causing saidarmature to rotate from the propelling efl'ect (torq ue effect) of short-circuited induced currents in certain groups of armaturecoils; in combination with additional means for combiningth'erewith the propelling eiiect (torque efiect) of outside currents introduced intothe other groups of armature-coils not short-circuited. i

2. An alternating-current motor comprising the combination of a stationar fieldmagnet connected with a source of a ternating-current supply, an armature having a winding the coils of which are connected to a' commutator and means for causing a united propelling efiect of the applied currents and the induced currents in the said armaturewinding. I

3. An alternating current commutatormotor having a field-magnet connected With a source of alternating-current supply, an

armature of the ringor drum type provided with means for causing a united propelling effect of the applied currents and the in duced currents therein;- in combination with additional means for reversing the'di, rection of rotation.

4. A single-phase alternating-current ma chine comprising the combination of a stationary field-magnet having an energizingwinding, an armature havmg 1ts coils connected to a commutator, wide brushes eX- tending about ninety electrical degrees for short-circuiting certain groups of armaturecoils at an angle of about forty-five electrical degrees to the field flux (field-magnet poles), with means for including the other armature coils not short-circuited in an outside circuit.

5. A single-phase alternating-current motor comprising the combination of a stationary field-magnet having an energizing-wmding, an armature having its coils connected to a commutator, brushes for short-circuiting of about forty-five electrical degrees to the field-magngt poles, means for including the 'other armature-coils not short-circuited in an outside circuit, and additional means for reversing the direction of rotation.

6. An alternating-current machine having a stationary field-magnet with an energizing- Winding therefor, an armature havingits winding or coils connected to a commutator, wide brushes extending about ninety electrical degrees for causing induced currents to flow through certain groups of armaturecoils in combination with means for causing the currents in those armature-coils which are located at or near the leaving edges of the.

brushes to flow in the same direction.

7. An alternating-current motor having a field-magnetconnected with a source of current-supply and an armature with a commutator and brushes for short-circuiting two or more groups of armature-coils While the remaining armature-coils are included in an alternating-currenbsupply circuit; in combination with means for changing the position of the brushes and thereby the direction of rotation. v

' In testimony ivhereof I, have signed my certain groups of armature-coils-at an'angle name to this specification in'the presence of two subscribing Witnesses.-

ROBERT LUNDELL.

Witnesses:

G. J. KINTNER, M. F. KEATING.

Images