Improvements in and relating to Dynamo-electric Machines or Motors.
Year: 1889

page_text: Date of Application, 9th Aug., 1889-Accepted, 12th Oct., 1889
COMPLETE SPECIFICATION.
Improvements in and relating to Dynamo-electric Machines or
Motors.
I, FRANCIS JARVIS PATTEN, of Burlington Flats, 10 West 30th Street, New York,
United States of America, Electrician, 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:-
My invention consists mainly in a novel method of operating electric motors on
alternating current circuits, by which I secure results not otherwise obtainable, the
principal object being to produce an operative self-starting alternating current motor
by a simple modification of the armature connections of a direct current machine of
the Grammo type.
My invention consists also of a novel construction of dynamo and magneto electric
machine or motor, as hereinafter described.
In the accompanying drawings.
Figure 1 illustrates the method as applied to a machine of the Gramme type.
Figure 2 illustrates the method as applied to a motor having a drum or cylinder
winding.
Figure 3 is an enlarged detail sketch of the system of connecting the two
commutators.
My object is to produce a simple and efficient alternating current motor. It is well
known that such machines have peculiar qualities such as that of being difficult to
start synchronous motion nocessitating high speed at the start, and indifferent direction
of rotation of the moving part; rapid reversals of polarity in the cores inducing heat
with consequent waste of energy and other defects.
The machine which forms the subject of the present invention as will be presently
understood is a positively self-starting machine; further it has but one direction of
rotation and cannot start indifferently in either direction. It is not a synchronous
machine and the reversals of current direction do not produce reversals of polarity of
any iron when the machine is in motion. It is preferably a single field or two pole
machine, instead of being multi-polar, as usual.
In figure 1, R, R, is an ordinary continuous wound Grammo ring revolving between
the two field poles N, N, and S, S and it is proposed to so modify the connections of
this ring as to produce an alternating current motor having the qualities above set
forth. It is well known that a Gramme ring is essentially a direct current apparatus,
and its so called commutator, is actually nothing more than a collector, there being no
rectification of the direction of opposed currents as in other forms of winding and the
ring may be divided into any number of coils, so called depending only upon the
number of bars in the collector.
For convenience the winding of the ring R R is divided into 12 coils numbered 1
to 12 around the ring to the right, and the ordinary collector of twelve bars is shown
inside the ring, connected in the ordinary way to corresponding parts of the ring
winding.
If now a current should be caused to flow in the windings of the ring from the
upper points down to the right and left, to the point n' and so out of the ring, such
current would induce in the core of the ring a south pole and a north pole at n'
and placed in the field as shown rotation would ensue in the direction indicated by the
arrows and, and motion would continue in this direction as long as the current
dowed in the same direction through the ring winding, i.e. from s' downward in the
ight and left hand halves to n'. It is now proposed to bring about this same result
with an alternating current which is rapidly reversed in direction by so connecting
he same ring to another commutator, that the current will still flow continuously in

page_text: the same direction in the ring winding irrespective of its rapid reversal in the external
circuit, in other words it is proposed to maintain a constant unchanged south polarity
in the ring at s¹ and a north polarity at n' by means of an alternating current, and
this without rectifying the alternating current by means of a commutator.
The result rests upon the following fundamental principle, that if a current of one
direction produces a given polarity in a coil then a current of opposite direction can
be made to produce the same polarity in the same coil by sending this reversed
current through the same coil in a direction opposite to that in which the first current
was sent.
Thus for illustration, if say a plus current flowing downward through the coils of
the ring from ¹ to n¹ produce a south pole at s' and a north pole at n¹, then a reversed
or minus current would. produce the same polarity at s' and n¹ if sent through the
ring in the opposite direction, i.e. from the point n' upwards to the right and left
tos. Now the machine has besides the ordinary collector f¹, f etc., a commutator
of an equal number of bars shown outside the ring for convenience at a³, a², a³, to a¹³,
and I call this a commutator because it operates to reverse, not the currents themselves
as usual, but the points at which opposed currents shall enter the ring and it is
actually a brush changer."
In further illustration of the principle used it may be stated that if an alternating
current were sent into a Gramme ring through the brushes bearing on its collector,
and the brushes could be made to change position mechanically at each reversal of
the current, the machine would then be self-starting armature polarity would be
constant, motion would be continuous and it would act precisely as when supplied
with a direct current. The external commutator a¹, a³, etc. has precisely this effect.
For it is so connected to the winding of the Gramme ring R, R, that as the
brushes mb, mb, bearing on it pass successively from one segment or bar to the
next, the current sent to the ring is caused to enter the ring from opposite sides so
that reversed currents sent into ring winding through successive segments would
maintain a permanent south pole at the point s' and a permanent north pole at n¹,
as for the reason before explained opposite currents are caused to flow through the
ring in opposite directions. Examining first the connections of the Gramme ring to
the collector f1, f, f, and to the commutator a', a², a³, &c., we find the former
connected to the ring winding as an ordinary Gramme ring collector; the latter,
however, is not so connected, for the segment a¹ and all the odd numbered segments
are connected direct to the turns of the ring immediately beneath them; segment a¹
to coil of the ring a³ to coil 3 a³ to coil 5 a³ to coil 7 a to coil 9 and a¹¹ to coil 11 ;
but the even numbered segments are not so connected, thus segment a³ is connected
to coil 8 on the opposite side of the ring from this segment; a similarly to coil 10, a
to coil 12, a³ to coil 2, a¹0 to coil 4 and a¹ to coil 6 of the ring; thus all odd.
numbered segments are connected to points of the ring winding immediately beneath
or over them, and all even numbered segments are connected to coils diametrically
opposite in position to these segments. If therefore, positive or plus currents be sent
through the ring when odd numbered coils are in bearing with the brushes, and reversed,
negative or minus currents are sent when even numbered segments are in bearing
with the same brushes, these reversed currents will maintain the polarity of the ring
constant.
Thus let the terminals ± and ± at A be the poles of a source of alternating or
reversed currents of any given periodicity, and let it be assumed that the first say
direct impulse proceeds in the direction shown by the single arrows from through
machine brush mb to the Gramme ring at the point s down both sides of the ring
to n, out machine brush m³, back to source at A. This impulse will make a
south pole in the ring at s' and a north pole at n', at the same time current will
flow through the shunt field circuit, connected to the brushes fb and f³ in the
direction shown by the arrows creating the field N N, S S, as indicated, and under
the action of this direct impulse motion will ensue in the direction indicated by the
arrows, opposite the bands of a clock. If now it be assumed that under this

page_text: first impulse the armature turns through the are covered by one single bar of the
collector, and a reverse impulse is sent from the source at A, as indicated by the
double arrows >> in the main circuit, then as the direction of this impulse is opposite
to the former it may be regarded for convenience of analysis as entering the machine
at the lower brush mb, which after the motion assumed to have taken place under
the first impulse will then be bearing upon the segment as of the commutator and
brush mbwill likewise bear upon segment a2 and the current shown by the
double arrows will flow in at brush m² to segment a when it will go through
the auxiliary connection shown around to the opposite side of the ring: Entering
at coil 2 opposite segment as, and from this point of the ring it will flow downwards
on both sides to the right and left in the same direction as before to the point 8 on the
ring, then out the auxiliary connection as shown by the arrows around to segment a³,
and out brush mb back to source at A, thus completing the circuit in a direction
opposite to the former, but still in the same direction in the coils of the ring, and so
maintaining with this reversed impulse a south polarity in the ring at s', and a north
polarity at as before, thus motion will continue in the same direction as before
providing the field poles have not been changed, but the field circuit is connected to
the brushes fbf, which bear upon the ordinary Gramme collector, and as we have
seen, that current must always flow in the same direction through the ring with these
reversed currents, it must likewise flow in the same direction from the brushes fb,fb²,
bearing upon the regular ordinary collector of this ring, therefore, with alternating
currents in the external circuit there will always be currents of one direction in tho
ring itself flowing uniformly and constantly down both sides from s¹ to n¹, and
likewise out the brushes fb, fb, maintaining a constant field N N, S'S, as shown, I
have, therefore, practically a direct current motor on an alternating current circuit
resulting from a system of connections which has practically the effect of shifting the
brushes in position free from one side of the ring to the other at each reversal of the
current and this system of connections constitutes an important modification of the
Gramme machine, for while such a system makes the ring absolutely inoperative with
a direct current it renders it operative with an alternating current.
It will bo observed, however, that if the brushes mb and m 2 be lifted off the com-
mutator a, a, &c. and the terminals of a direct current circuit be connected to the
brushes, and f³ the machine then becomes an ordinary direct current Gramme
motor with the fields in shunt relation to the armature and the machine thus
lessens none of its value as a direct current motor while, by the addition of the
reversely connected brush changer a¹, a' &c., to the ordinary Gramme machine, it
can be used as an ordinary direct current motor or as an alternating current motor
at pleasure. My invention, therefore, consists in adding to an ordinary armature and
collector connected in the usual way, an additional or anxilliary collector having tho
same number of bars as the former, but with successive bars connected to diametrically
opposite points of the continuous ring winding.
Figure 2 shows the application of the system or method to an ordinary direct
current motor, having any form of cylinder or drum armature winding, the Troelich
winding being selected for illustration. The connections are the same as in the figure
previously described except that the ordinary commutator 1, 2, &c., is shown outside
and the other reversely connected commutator is shown inside and this auxilliary
commutator which I designate as a "Brush charger," instead of being connected to
the winding of the armature is connected to corresponding bars of the other collector
which amounts, in fact, to the same thing and the source of alternating current +
and A is shown inside the latter ring. The arrow heads indicate the direction of
current flow throughout the winding.
In Figure 3 is shown an enlarged view of the system of connecting the two
sets of commutators to each other, the outside ring being the ordinary direct current
commutator the inside one being the reversely connected brush changer.
I will now explain why the machine: is a self-starting one with an alternating
current, why it will not turn indifférently in either direction but has a single

page_text: direction of rotation with such a current why there is never with the machine in
motion any reversal of the polarity of the iron cores and why the machine is not a
synchronous motor.
It is well known that any such form of direct current motor will start when
actuated by an alternating current for if a plus impulse induces the polarities
shown N N, S´S in the field and s, n in the armature ring and the machine remains
motionless until a reversed current is sent, then both the field and armature polarities
are reversed simultaneously and the tendency to motion is still in the same direction
as indicated by the arrows. The tendency to motion is therefore continuous and in
the same direction polarities of the iron masses being reversed at each reversal of
current until the machine starts, but once started these polarities are all constant
the machine therefore starts as an ordinary direct current machine connected in an
alternating current circuit.
The reasons just given explain also why the machine cannot move indifferently
in either direction, they also explain why there is no change of magnetic polarity
in the iron cores after the machine has moved through the are covered by one
collector bar. It remains to show why the machine is not synchronous with the
generator and does not have to start at the same speed as the generator.
From the analyses given it is evident that when in motion, as contemplated one
bar of the collector must pass under the brushes at each reversal of current. The
number of collector bars, therefore, represents the number of current reversals that
correspond to a single completo revolution of the motor armature.
Thus let it be supposed for illustration that the source of alternating current at A
is an alternating current dynamo having 10 field poles and a speed of 1500 revolutions
per minute. There will be 10 reversals of current produced in each revolution of the
dynamo armature; if therefore the Gramme ring be provided with a collector having
30 bars it will make one revolution for thirty reversals of current and will therefore
make one revolution in the same period of time that the dynamo armature makes
three revolutions, and if the dynamo spoed is assumed to be 1500 per minute the
motor speed will be 500 per minute and constant, and the speed of the motor will
always be defined by the ratio of the number curront reversals produced in a singlo
revolution of the dynamo to the number of collector bars connected to the ring.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is :-
First The method described of operating electric motors on alternating current
circuits which consists in providing such machines with commutators so connected to
the armature winding that currents of opposite direction in the external circuit are
caused to traverse the armature winding in opposite directions.
Second-The method described of operating electric motors on alternating current
circuits which consists in providing such machines with two sets of commutators or
collectors. The odd numbered segments of one set being connected to the odd
numbered segments of the other set in rotation and the even numbered segments of
one set connected to the diametrically opposite even numbered segments of the other
set in rotation substantially as described.
Third The method described of operating electric motors on alternating current
circuits which consists in providing such machines with two commutators or collectors
having a like number of segments the corresponding alternate segments in each being
connected to the same points of the armature winding in rotation the other corre-
sponding alternate segments of the two commutators being connected to diametrically
opposite points of the armature winding substantially as described.
Fourth In a dynamo electric machine, or motor, a Gramme ring armature provided
with a collector, the adjacent bars of which are connected to the ring winding at
points respectively contiguous to and opposite to the said adjacent segments in
rotation around the ring.

page_text: Fifth-In a dynamo electric machine or motor, a Gramine ring provided with two
sets of collector bars, the bars of one set connected to successive coils of the ring in
rotation and the other set having adjacent bars connected to the ring winding at
points respectively contiguous to and opposite to the said adjacent segments in
rotation around the ring.
Sixth In a dynamo electric machine or motor an armature provided with a
commutator or collector the adjacent bars of which are connected to the winding at
points respectively contiguous to and opposite to the said adjacent segments in
rotation around the ring.
Seventh A dynamo electric machine, or motor provided with two sets of collector
bars one set having adjacent bars connected to successive points of the armature
winding in rotation, the other set having adjacent bars connected alternately to points
of the ring winding contiguous to and opposite to the said adjacent bars in rotation
around the ring.
Eighth A dynamo electric machine or motor having an armature provided with
two sets of collector bars and two pairs of brushes one collector having successive
bars connected in rotation to successive points of the armature winding in rotation
and the brushes bearing thereon connected to a field circuit. The adjacent bars of
the other collector connected in succession to points of the winding respectively
contiguous to and opposite to the said adjacent segments in rotation around the ring
and the brushes bearing on this collector connected to a source of alternating
current.
Dated this 9th day of August 1889
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, Agents for the Applicant.