Improvements in and relating to Electric Motors.
Year: 1891

page_text: Date of Application, 25th Aug., 1891-Accepted, 31st Oct., 1891
COMPLETE SPECIFICATION.
Improvements in and relating to Electric Motors.
A communication from abroad by LUDWIG GUTMANN, of Pittsburgh, Allegheny
County, State of Pennsylvania, United States of America, Electrical Engineer.
I, GEORGE CECIL DYMOND, M. Inst. M.E., of the Agency for Foreign Patent
Solicitors, 6, Lord Street, Liverpool and 6, Bank Street, Manchester both in the
County of Lancaster, & 323 High Holborn in the County of Middlesex, Patent
Agent, do hereby declare the nature of this invention and in what manner the same
is to be performed, to be particularly described and ascertained in and by the
following statement :-.
This invention relates to a means and method of producing rotation of one coil
relatively to another coil placed within inductive relation to the same and connected
in circuit with an alternating, pulsating or intermittent current generator, by
successively short-circuiting more or less of the sub-coils of the first coil.
By this invention there is provided an electric motor that serves as an economic
machine having as high an efficiency as the ordinary type of direct current motor.
By actual experiment it is found that, if an alternating electric current be sent
through the field magnet coils of a motor (with subdivided or laminated iron core),
the armature (whether of the independent coil or open or closed coil type) will
revolve, if some of the armature coils are short circuited. It is this principle that
underlies this motor, and its application thereto is described by reference to the
accompanying drawings.
Figure 1 is a vertical section of the motor at right angles to the axis of the
armature, which, together with the commutator, is not shown in section, but in
end view.
Figure 1 is a view of the top, and Figure 1B a view of the bottom or lower
commutator brush holder, the brushes resting by spring pressure as in every dynamo
upon the commutator.
Figure 2 is a view in elevation of one end of the complete motor, a portion of the
same being shown in section, and the field magnet coil being shown in Figure 3, as
it would cause confusion if entered in Figure 2. In Figure 3, is shown, also, the
earth connection and the field magnet core in part.
Figure 4 represents the application of four motors to work circuits, 3 of which
are shown being differently connected up in the circuit to the fourth one.
Figure 5 is a modification of the construction of the brush, while Figure 7 is
another modification.
Figure 6 illustrates, partly in diagram, one way in which the coils of the
armature may be short circuited by the brushes, and by which figure the reason of
continuous rotation may he understood, and Figure 8 shows means for regulation.
The device consists of the combination of field magnets built up. of superposed
insulated plates a, each of such a shape as to be comparable to a double E connected
by are shaped picces; legs for supporting the said magnets in an insulated
condition from the earth; coils c of electrical conductora, wound upon the said
cores as to the central portion of the double E and having their terminals
connected to the binding posts d which are insulated from the field magnet. cores ;
screw caps e screwed upon the insulators of the said posts, and through which the
said conductors of the coils are continued to the terminals of the alternating
dynamo f; an armature whose commutator is represented by the letter g, located
between the poles of the field magnete, the armature being of any suitable type
mentioned above; brushes or contact pieces k, constructed sufficiently wide as to
short circuit a portion of the winding partly in a strong and partly in a weak

page_text: magnetic field, and connected in, an insulated. manner to the motor by suitable
supports and armature coils whose terminals are indicated in Figure 6 by
numerals plus 1, minus 1,, plus 2, minus 2, etcetera, and which are shown électrically
connected to commutator plates in such a manner that the brushes embrace a
number nearly equal to or larger than the number of, armature coils not embraced
by the field poles a good conducting spiral of copper surrounding the poles of
the field magnets and located within the magnet coils, the said spiral being
connected to earth 'by the conductor; and a second earth connection between
the field magnet cores and represented by the letter l.
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In Figures 1, 14, 18 and 2, the brushes are each shown as connected to a piece
of insulating material m, which passes through holes in supporting pièces, n.
The
contact between the brushes and commutator is established in a well known manner,
the brushes shown here, to establish connection, by the spring o which forces the
brush or brushes against the commutator. In Figure 5 the brush.is. shown resting
upon the commutator (shown in outline) and supported in a frame n', in which is a
slide p, adapted to be pressed, against the brush by means of screws 9, passing
through the said frame, the said frame being attached to an insulator mi, provided
with
a slot to be able to short circuit more or less commutator "sections, by placing
the brush nearer to or farther away from the commutator.
"When the binding posts, d'are, connected to the poles of the dynamo fan
alternating cu
current traverses the coils C. Experiments show that, if a number of
armature coils diametrically opposite each other be short circuited and these short
circuited coils be placed either equally distant from both the field magnet poles or
else just
opposite the poles, there will be no rotation as there is équilibrium, but if
these short circuited coils are placed nearer to one field pole than to the other, the
equilibriumi is disturbed. There will be a difference of potential at the ends of the
short circuiting wires and a current will flow from the point lying in the stronger
magnetic field to the point in the weaker position causing a very powerful repulsion
and rotation. If these coils are permanently short-circuited, they would come to
rest when arriving at the point of equal minimum position, as equilibrium 18 again
established. It is therefore necessary to effect a short circuit which remains
stationary and is prevented from rotating with the armature. If this be obtained,
the equilibrium will be constantly disturbed, resulting in constant rotation. This
is effected by the use of "very wide stationary brushes, covering a number of
successive segments like Figure 1, or else' close circuiting a part of the winding
upon itself. It is preferable to use double tangential brushes, each side of the brush
forming, with the periphery, of the commutator, an equal or nearly equal angle.
The v
width of the brush for short circuiting the number of sections depends on the
distance of the pole pieces from one another. If there is a large distance between
the field n
magnet poles, then it is preferred to have wide brushes, but if the distance
from one pole to the other or the gap be small, then the brushes have to embrace
but a comparatively, small number of commutator
mutator sections. It is preferred to
make the brushes embrace a number of coils e
equal to all or nearly all the coils
lying in the neutral or weak position. The reason is that, as soon as the brushes
are moved in one or the other direction, one end of the brush is put in maximum
position. "A powerful repulsion and rotation take place when the brushes are in
position indicated by the arrows, Figure 6, the dotted lines indicating the
position of
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TEST the brushes causing that rotation, while, in the position in which the
brushes are drawn in of equal potential. If the brushes be moved in the
ends, are cu
coils
no rotation takes place, in this latter case both the brush
5.11
direction, the motor reverses its direction because the current enters in the
opposite direction into
to the brush and armature coils.
Th
(141)
it is only required to disturb the equilibrium in the armature to obtain
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rotation, no outside connections are required from the brushes to any circuit nor to
FOTO 1
one another, but they may also be connected to one another... The potential of the
FOR
SUM

page_text: brushes being high, there is no need for insulating the brushes, but it is preferred
to separate them from the field magnets to prevent any strain and the entering
of the primary current into the armature coils. The double tangential
brush has been designed for the reason to permit the use of the same brush for
either direction of rotation, backwards and forwards. More or less of the coils in.
a weak magnetic position can be cut out by fixing the brush (Figure 7) nearer to
the commutator or farther away from it; the farther the brush being removed
the more the ends of the brush will close up, but the nearer it is moved towards the
commutator the more the ends will spread. The amount of current circulating
through the armature can be regulated by the position of the brushes.
As these brushes are independent of the remaining part of the motor and very
little or no sparking is observed, it is convenient to enclose them by means of
plates S, Figure 2, through which the armature shaft & passes.
Referring to Figure 4, the motor A, motor B, and motor C are represented as
connected in multiple arc, and each in series with a suitable rheostat by means of
which a variable number of resistance coils can be introduced into the circuit with
the field magnet coils of the motors. This rheostat, preferably an electro magnetic
rheostat in each case, is represented by the letter u. The length of the conductor
of the field magnet coils and that of the rheostat combined, is so chosen that, when
the brushes are removed from the commutator the counter electromotive force,
which the field maguet coils and those of the rheostat can together produce, should:
permit of but an extremely small current to flow through its winding. The current
in the field magnet coils is increased by reducing the resistance in the exciting
circuit, and as that of the motor is a fixed one, the variable resistance is the rheostat,
the resistance of which can be altered in different ways, by varying the amount of
iron influenced by decreasing the capacity of the iron, influencing it by another
conductor, or by reducing the number of coils of the rheostat in circuit with the
motor field coils.
The weaker the rheostat is made, the less opposing resistance is in the exciting
circuit and the larger can be, in consequence, the current flowing. In the case of
small motors, they may be connected and run economically in secondary electric
circuits, as shown by motor D in Figure 4. The converter is v, connected to the
generator, and the field magnet coils are shown.connected in the secondary circuit
of the converter.
The object of connecting the conductors or the core of the field magnet to
ground is to afford greater safety to those who attend the machine.
Referring to Figure 8, there are additional coils c and e" independent of each
other next to the coils c, upon the field magnet core, these coils forming secondary
conductors for carrying currents induced by the current in the coils c. The coils o
and c" are shown open and independent of one another, one terminal of coil c¹ is
connected to the half circle F, one terminal of coil e" is connected to the second
half circle marked F. The coils c¹ and e" are subdivided and the subdivisions are
connected to the arc shaped contact blocks of B and B. Those of coil care
connected to the contact blocks numbered 1, 2, 3 and 4, and those of coil "
are connected to the terminal blocks marked 5, 6, 7 and 8: If the handle or
switch H H', formed either of a single piece or of two insulated contact pieces,
rotates to the right, the half circles F and F are respectively connected with the
other terminal of the sub-coil connected to block 1 and 5 respectively.
It will be noticed that an equal number of reacting coils are switched on by
lever H H so as to maintain the pole strength of either pole D equal. In the
position given in the drawings, both reacting coils c¹ and c are open; as the
lever H H turns to the right or left it inserts one, two, three, four, etcetera,
subdivisions of each of the said reacting coils in series with the former
subdivisions.
In the above Specification, a special form of field magnet has been referred to,
but it is evident that the form bas little to do with the principle of this invention,

page_text: this form has been chosen as being the most effective and simple, but any other
form may be used.
Again, the principle holds good in a multipolar motor or if the whole conditions
are reversed as can be done by all similar machines. Instead of using stationary
field magnets, stationary brushes and a movable armature, the armature may be
made stationary and the field magnets movable and the short circuiting brushes
may be made to revolve so that the same efficient working apparatus is obtained.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, as communicated to me
by my foreign correspondent, I declare that what I claim is :-
1. An arrangement of the coils of armature and field magnet in a motor whose
field coils are in circuit with an alternating current generator, and whose armature
coils form secondary conductors to the field coils; whereby the motive force for
propelling the armature consists of the reaction between a given number of poles in
the field and a different number of poles in the armature.
2. The hereinbefore described apparatus for producing rotation of coils placed in
inductive proximity to independent coils, which are included in circuit with an
alternating, pulsating or intermittent current generator.
3. In an electric motor, the combination of a field magnet having two
independent sets of coils; the first coils being included in circuit with an alternating
current generator; the second set being in circuit with commutator plates insulated
from the armature of the motor; and a contact strip for the commutator, mounted
upon and insulated from the armature shaft; the said contact strip being in contact
with pairs of commutators diametrically opposite-cach other.
4. In an electric motor, the combination of exciting coils, in circuit with an
electric genorator of alternating currents; secondary coils mounted upon a
common core with the said exciting coils; armature coils provided with conductors
short circuiting the armature coils in groups; the said secondary coils being
normally open; and means for intermittently closing said secondary coils.
5. In an electric motor, the combination of an armature; a field magnet; coils
upon the armature, and having conductors connecting the same in groups; exciting
coils upon the field magnets; and secondary coils within inductive distance of the
exciting coils and mounted upon the core of the field magnets; and a contact strip
connecting the ends of each pair of diametrically opposite secondary coils, the
contact strip being mounted upon the shaft of said armature.
6. In an electric motor, secondary coils mounted upon the core of the field
magnet of the motor; and conductors connecting the coils of the armature into
groups; each pair of the secondary coils being in turn normally closed, and the
remaining secondary coils being normally open.
7. In an electric motor, the combination of multiple secondary coils mounted
upon the field magnet core; and a contact slide in contact in turn with the
terminals of the coils, the exciting coils of the field magnets being included in
circuit with an alternating current dynamo.
8. In an alternating current motor, the combination of coils in a single exciting
circuit; a stationary commutator; and a contact strip for the commutator and
mounted upon and insulated from the armature shaft; the commutator plates being
insulated from the motor's armature, and connected electrically with the ends, in
order, of secondary coils mounted upon the core of the field magnet.
9. In an alternating current motor, the combination of a single exciting coil, a
stationary armature mounted on a common core with the exciting coils, and a
commutatorless armature mounted upon a shaft and adapted to rotate between said
field magnet poles.
10. In an electric motor, the combination of a field magnet core provided with
polar projections, an exciting circuit wound on the said field magnet core and
connected to a suitable generator, a second and independent winding mounted on

page_text: the same field magnet core subdivided into several coils, conuected like an armature
to a commutator; and an armature independent of a commutator mounted upon a
shaft and adapted to rotate between said field magnet poles.
The outh day of Ano 1901
WM. P. THOMPSON & Co.,
Agents for the Applicant.