US1351035A - Dynamo-electric machine - Google Patents

Description

B. E. HELlMUHD.

DYNAMO ELECTRIC MACHINE. APPLICATION FILED DEC. 14, was.

1,351,035. Patented Aug. 31; 1920.-

Trolley m i Mp/ are a I AH F/ 1 APG 4 R/ MP2 WITNESSES: INVENTOR lf 5 He//mu/2 W g 0 WW ATTORNl EY UNITED STATES PATENT OFFICE.

RUDOLF E. HELLMUND, 0F PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTBIC AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- VANIA.

DYNAMIC-ELECTRIC MACHINE.

Application filed December 14, 1915.

To all whom it may concern:

Be it known that I,RUnoLF E. HELLMUND, a subject of the Emperor of Germany, and a resident of Pittsburgh, in the county of 'kllegheny and State of Pennsylvania, have invented a new and useful Improvement in Dynamo-Electric Machines, of which the following is a specification.

My invention relates to dynamo-electric machines and systems of control therefor and especially to machines of the-dynamotor type.

One object of my invention is to provide a achine of the al ove-indicated character which shall be relatively simple and inexpensive in construction and effective and reliable in operation, and which shall embody means for effecting a variation of the voltage ratio between the two commutator cylinders, or the equivalent, of the machine under prcdeterminml conditions, either by simultaneously increasing the voltage of one cylinder and decreasing the voltage of the other or by maintaining the voltage of one cylinder substantially constant and varying the voltage of the other cylinder, as hereinafter more fully set forth.

More specifically stated, it is the object of my invention to provide a dynamo-electric machine having a rotor provided with a plurality of commutator cylinders, a stator frame having a plurality of wound main and auxiliary polar projections, and a plurality of sets of brushes disposed upon the respective cylinders in such manner that the voltage between brushes on one cylinder shall be proportional to the sum of the main and the auxiliary polar fluxes, and the voltage between brushes on the second cylinder shall be proportional to the main flux.

A further object of my invention is to provide a system of control embodying a machine having the above-indicated characteristics, whereby, under regenerative conditions of a plurality of parallel-related main dynamo-electric machines, the excita tion of the lield windings thereof may be automatically varied oppositely to the variations of armature or load current, thus providing a stable regenerative system.

In connection with regenerative systems and in various other cases, it is often desirable to obtain from a relatively high supply-circuit voltage a low excitation volt- Specification of Letters Patent.

Patented Aug. 31, 1920.

Serial No. 66,725.

age, and the well-known type of dynamotor is generally employed for such purposes. The dynamotor has various advantages over an equivalent motor-generator set by reason of its lightness of weight and relatively low cost, and also because it is, at times, desirable to have the secondary voltage, that is, the lower voltage, of the dynamotor respond rapidly to any change in the primary voltage. The desired rapidity is possible only when the field fluxes that induce the primary and the secondary voltages are identical, as is the case in a dynamotor. However, the standard dynamotor has the disadvantage that it does not permit of a change of the ratio of its high and low voltages. In some instances, it may be desirable to provide a rising-voltage characteristic in the output or low-voltage circuit of the dynamotor and, in other cases, to supply a constant-voltage characteristic.

According to my present invention, I provide a novel type of dynamotor or double comn'iutator machine for effecting, in one case, a simultaneous opposite variation of the high and low "oltages of the machine, under predetermined conditions; or, in accordance with another modification, the voltage of the motor or high-voltage commutator cylinder is maintained substantially constant while the voltage of the generator or low-voltage commutator winding is automatically varied in the desired 'manner.

The standard type of dynamotor employs a plurality of main polar projections and a plurality of comm utating polar projections, the sets of brushes on the respective com mutator cylinders being disposed in alinement with the commutating polar fluxes, in accordance with familiar practice. In accordance with certain features of my present invention, I so dispose the main polar projections and a plurality of auxiliary or secondary polar projections that certain of their respective axes are located intermediate spaced pairs of non-corrcsponding brushes; that is, the brushes on the different cylinders.

In the accompanying drawing, Figure l is a diagrammatic view of a dynamo-electric machine constructed and connected in ac cordance with my invention, the machine being shown in end elevation; and Fig. 2 is a diagrammatic view, in side elevation on a smaller scale and with parts broken away, of the machine shown in Fig. 1.

Referring to Fig. 1 of the drawing, the system shown comprises a plurality oi? suit able supply-circuit conductors respectively marked Trolley and Ground, a variable translating device TD; and a dynamoelectric machine D of the general dynamotor type.

The translating,- device TD may comprise a plurality of lamps or resistors or other devices which. may be connected in or cut out oi circuit, as may be desired, whereby a variable load may be introduced into the circuit of the low-voltage armature winding of the dynamotor, as more fully set forth hereinafter.

The dynamotor D comprises a rotor R that is provided with a motor or high-voltage commutator cylinder M and a generator or low-voltage commutator cylinder G that are preferably disposed at the respective ends "of the rotor and are connected in the usual manner, to a plurality 01"" separate armature windings that are here diagrammatically shown at ANY 1 and AVV2 in Fig. 2. A stator frame SP2 is provided with a plurality of oppositely-disposed main polar projections MP1 and MP2, and a plurality of auxiliary polar projections or secondary projections APaS and APG that are disposed in non-quadrature relation to the main projections MP1 and MP2; and a plurality of suitable field-magnet windings MFl and AFl are disposed upon the main projections and the auxiliary projections, re spectively.

The circuit of the shunt field winding M131 is established from the Trolley through a junction-point 10, the field winding MF1 and a junction-point 11 to the negative supply-circuit conductor Ground. The junction-points 10 and 11 are also directly connected to the brushes 1 and 2, respectively, of the motor commutator cylinder 'll/li.

The auxiliary field winding; A1 1 is connected in series-circuit relation with the brushes 4 and 3 of the generator commutator cylinder G and the variable translating device TD.

The motor commutator cylinder M is provided with a set of suitable brushes 1 and 2, and the generator commutator cylinder Gr is also provided with a set of brushes 3 and t. instead of the brushes being alined with each other, the pairs of non-corresponding brushes are shifted with respect to each other and the main polar projections have their axis lying intermediate such spaced pairs. For example, in. the system shown, the axis of the main polar projections extend through a point intermediate non-corresponding brushes 1 and 4 and a second point intermediate the non-corresponding brushes 2 and 3. However, the auxiliary polar projections have their axis disposed in substantial alinement with the brushes 1 and 2 that are associated with the motor commutator cylinder lri, and thus, the auxiliary polar projections make an angle with the corresponding: main polar projections that is materially less than 9*?) electrical degrees.

The main field winding Ml l is disposed around the main polar projections MP1 and MP2 in such manner as to produce north and south poles of magnetism therein, as indicated by the letters a and s, respectively. The circuit of the auxiliary field winding re -1E1 is disposed upon the auxiliary polar projections A 5 and APtS to create north and south magnetic poles in accordance with the designations a and s, respectively.

It will be observed that, since the polar projections MP1 and APS provide north magnetic poles, the flux threading the armature winding A31 1, that is associated with the motor commutator cylinder M, is proportional to the sum oi the main and auxiliary polar fluxes, while the iiux linking with the armature winding;- jiW2, which is associated with the commutator cylinder G is proportional to the main polar iiux by reason of the fact that the auxiliary polar flux passes parallel to the brushes 3 and 4.

The advantages of the construction just described may be set forth as follows: In other types of' dynamotors the primary armature winding, that is, the armature winding that is associated with the motor commutator cylinder M, is not used to as good advantage as'possible, because the voltage induced between the motor commutator cylinder brushes 1 and 2 is the diiierence be tween certain positive and negative voltages that respectively correspond to the various field fluxes, thereby requiring the use 071 a relatively large number of conductors to produce a certain total voltage. In the structure that is illustrated in F 1, however, the auxiliary polar projections AP and A1 6, by reason of their alinement with the brushes 1 and 2, serve as commutatine; poles therefor. @onsequently, the auxiliary polar projections exert no direct effect upon the voltage between the brushes 1 and 2 but serve to increase the voltage between the other brushes 3 and 4 wlth an increased load current in the translatmgdevice TD.

In this way, I provide a dynamotor 1n which the motor voltage is maintained substantially constant, while the generator voltage is varied in accordance with predetermined'conditions to thus vary the voltage ratio of the two commutator cylinders.

in Fig. 1, clockwise rotation was assumed, as indicated by the arrows, and the disposition of the main and auxiliary field windings withrespect to the sets of brushes was determined in accordance with such direction. If rotation in the counterclock-wise direction is assumed, in general, the polarity of the auxiliary polar projections must be reversed or the relative locations of the various sets of brushes must be interchanged. It is believed that the foregoing statement will be evident to those skilled in the art without requiring any further illustration or description.

It should be noted that, although I have shown and described a machine having two commutator cylinders, my invention is capable of wider application; and a machine having a single armature winding and a single commutator cylinder with a double set of brushes, or the equivalent, may be utilized.

Moreover, if desired, field-magnet windings of the familiar distributed type may be employed instead of the concentrated or polar field-magnet windings that are illustrated, as will be understood.

I do not wish to be restricted to the specific circuit connections or structural details and arrangement of parts herein set forth, as various modifications thereof may be made without departing from the spirit and scope of my invention. I desire, therefore, that only such limitations shall be imposed as are indicated in the appended claims.

I claim as my invention:

1.. In a dynamo-electric machine, the combination with a rotor having a plurality of windings and commutators therefor, of a plurality of spaced sets of brushes for said commutators, and a stator frame having a plurality of main and auxiliary polar projections, the axes of all the main projections lying intermediate the commutating zones of spaced pairs of non-corresponding brushes and the axes of said auxiliary projections substantially coinciding with the commutating zone of one set of said brushes.

2. In a dynamo-electric machine, the combination with a rotor having a motor and a generator winding and commutators therefor, of a plurality of spaced sets of brushes for said commutators, a plurality of main polar projections having their axes lying intermediate the commutating zones of a spaced pair of non-corresponding brushes, and a plurality of auxiliary polar projections having their axes substantially coinciding with the commutating zone of one set of said brushes and respectively intersecting the axes of the corresponding main polar projection at an angle materially less than ninety electrical degrees.

3. In a dynamo-electric machlne, the combination with a rotor having a motor and a generator winding and commutators therefor, of a plurality of spaced sets of brushes for said commutators, and a stator frame having a plurality of main polar projections having their axes lying intermediate the commutating zones of spaced pairs of non-corresponding brushes, and a plurality of auxiliary polar projections mechanically and electrically related to said brushes in such manner as to perform the double function of aiding to vary the ratio of the volt ages appearing at said sets of brushes and to act as commutating polar projections for the respective brushes on the motor commutator cylinder.

4. In a dynamo-electric machine,the combination with a rotor having a high-voltage and a low-voltage winding and a commutator for each of these windings, of a plurality of spaced sets of brushes for said commutators, a stator frame having a plurality of polar projections and a plurality of sets of field windings to excite said. projections and the rotor, means whereby the excitation of one of the sets of field windings is changed so as to increase the total voltage induced in the low-voltage winding without substantially changing the total field flux between the commutating coils of the high-voltage winding.

5. In a dynamo-electric machine,the combination with a rotor having coils located on a single core, and commutating means, of a plurality of spaced sets of brushes for said commutatin means,one of said sets of brushes acting as a motor brush set, and another set acting as a generator brush set, a stator core, a plurality of main polar projections and a plurality of materially smaller auxiliary polar projections, and a plurality of sets of field-magnet windings located on said projections and respectively load-current-excited and shunt excited. only, said windings being mechanically and electrically related to said brushes in such a manner as to induce fluxes of the same polarity only between the eonnnutating zones of one set of brushes and a flux from only the main projections between the commutating zone of the other set of brushes, whereby the excitation of only the auxiliary poles is inherently varied with the load of the machine.

In testimony whereof, I have hereunto subscribed my name this 10th day of Dec., 1915.

RUDOLF E. HELLMUND.

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