Improvements in Alternating Current Electric Motors for Operating Commuting Devices for Converting Alternating into Continuous Currents, and other purposes.
Year: 1896

page_text: Date of Application, 11th Mar., 1896
Complete Specification Left, 11th Dec.. 1896-Accepted, 11th Mar.. 1897
PROVISIONAL SPECIFICATION.
Improvements in Alternating Current Electric Motors for Operating
Commuting Devices for Converting Alternating into Continuous
Currents, and other purposes.
I, ANTHONY STRONG FRAZER of No. 19 Percy Gardens, Tynemouth in the County
of Northumberland Merchant, do hereby declare the nature of this invention to be as
follows:-
My invention relates to certain improvements in the construction of electro motors
to be operated by alternating electric currents, and used for the purpose of driving a
commuting or rectifying device, such for instance as that described in the Specification
of Letters Patent No. 8412 of A.D. 1894, or for other purposes, where absolute
synchronism and instantaneous starting is necessary. In such motors the essential
requirement is the rotation of the commuting device at a rate of speed exactly
corresponding to the periodicity of the primary alternating current.
In carrying my invention into effect, I employ a spindle, freely revolving in suitable
bearings between two standards or brackets, projecting at both ends beyond said
bearings. Upon the spindle, between the standards I fix the armature, preferably of
the ring type, mounted upon a non-magnetic spider wheel, or other suitable mounting.
A drum armature may be substituted if desirable. The ring or drum has projecting
pole pieces, between which the coils are wound. In the example chosen for
illustration there are six such pole pieces, and the arrangement of the winding is such
that, dividing said pole pieces into two groups, the centre one of each has the same
sign poiarity, the two on each side respectively, having the opposite sign, so that
in sequence, taking both sides of the armature the signs would be ++=+=+.
In order to cause the actuating current to flow in one direction through the coils, I
construct a commutator made up of two separate rings, divided laterally so that
(presuming that a field with eight poles is to be used) there are eight segments, four
alternate ones of which are electrically connected, the other four being insulated.
The two rings, similarly constructed are placed side by side upon the spindle, so that a
"live" segment of one ring is opposite an insulated segment of the other, and the
contact plates or brushes are wide enough to cover the surfaces of the segments on
both rings. Thus one brush is in contact with a "live" segment on one ring and
the opposite brush with an insulated segment, and on the other ring the first named
brush makes contact with an insulated segment, and the second brush with a "live"
segment. Thus, when the speed of rotation of the commutator is in unison with the
alternations of the current, a continuous current will flow th ough the armature
coils.
The field is an iron ring, preferably built up of laminæ, and having interior polar
projections, the number of which in the present illustrative example is eight, the
spaces between being alternately wound, and the excitation is arranged so that while
two opposite pairs are active, there is a progressive rotation of polarity (+ or -)
on opposite sides of the ring, when synchronism is attained. In order to attain
this effect, 1 employ a disc of insulating material, fixed to one of the bearing
standards, so that the spindle may revolve freely through the centre thereof. On
the face of said disc I mount two concentric rings, insulated from each other, and

page_text: each divided into eight segments radially. Upon the spindle, and contiguous to said
rings, I fix a cylinder of insulating material, surrounded by a metal band, to which is
attached two arms, extending radially at opposite points of its circumference. Each
arm carries a spring contact plunger, brush, or the like, broad enough to make
electric contact with both rings on the disc, and are so arranged that as said
contacts rotate they make and break contact with opposite pairs of segments
simultaneously. As an alternative, I may arrange the pairs of segments around
the periphery of the disc, and place the contacts aforesaid in a suitable position
relatively thereto as to establish the contact between opposite pairs as hereinbefore
described.
The manner in which the motor according to my invention is actuated may be
described as follows; that is to say; a branch circuit with a suitable resistance
interposed is taken from the main leads of an alternating current system. One
conductor is connected to a brush bearing upon the metal ring carrying the arms
and contacts before described. The segments upon the disc are connected with the
field magnet coils in such a manner that the free end of one coil is connected to a
segment of the outer ring on the said disc, and the free end of the next coil is
connected to the corresponding segment of the inner ring. The opposite pairs of
segments are connected similarly, but it will be evident that the free end of each coil
has two contacts. Therefore the current being thus led into the coils upon opposite
sides of the field, it is conducted to one of the brushes in contact with the arinature
coils, and after traversing these passes back to the main circuit (or return) by means
of the opposite brush on the commutator of the armature. The disc carrying the segments
may be adjusted to a nicety relatively to the armature and its commutator so that the
poles of the field magnet are excited by each successive impulse of the current,
slightly in advance of the armature poles of opposite sign, so that a rotation of
polarity takes place around the inultipolar field, causing the armature to follow in
regular and synchronous progression. It is also evident that a motor constructed
according to my said invention is self starting at any position of rest excepting when
the signs of the field and armature poles coincide, but, in order to prevent the
occurence of said dead point, I may provide a counter weight, an auxiliary, and
temporarily excited magnet, or any equivalent device to produce the desired effect.
When said motor starts, synchronism is attained immediately.
The device for commuting the alternating current and transmuting it into a
continuous current is practically the same as that described as the armature
commutator, but constructed upon suitable lines, and of such calibre as to carry the
required current without becoming unduly heated. Two plain rings, however, have
to be added, with two supplementary brushies for conducting the transmuted current
to its destination. Said commuting device may be constructed according to the
Specification of my Patent No. 8412 of 1894 hereinbefore referred to, and this, or
any other device or apparatus for the same purpose is attached to, or fixed upon the
free end of the spindle of the electro-motor aforesaid.
I do not confine the employment of said motor constructed according to my
invention to driving a commuting device only, but may adapt it to any other purpose
to which a self starting, synchronous motor is applicable in an alternate current
system.
---
FREDK. WALKER,
73 St. Stephen's Road, Upton Park, London, E.,
Agent for the Applicant.

page_text: Improvements in Alternating Current Electric Motors for Operating
Commuting Devices for Converting Alternating into Continuous
Currents, and other purposes.
1. ANTHONY STRONG FRAZER of No: 19, Percy Gardens, Tynemouth, in the County
of Northumberland, Merchant, do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement :-
My invention relates to certain improvements in the construction of electro-motors
to be operated by alternating electric currents, and used for the purpose of driving a
commutating, or rectifying device, such for instance as that described in the Specifi-
cation for Letters Patent No. 8412 of A.D. 1894, or for other purposes where
absolute synchronism and instantaneous starting is necessary. In such motors the
essential requirement is the rotation of the commutating device at a rate of speed
exactly corresponding to the periodicity of the primary alternating current.
In order that my invention may be the better understood I have appended the
accompanying two sheets of drawings, in which
Figure 1 represents an elevation of a motor which may be adapted to a commutating
or rectifying device, and Figure 2 an end view thereof.
Figure 3, Sheet 2 is a diagram showing the winding of the field and armature.
Figure 4 is a perspective view of one of the two crown wheels or clutches forming the
commutator of the shunt driven armature.
Figure 5 is a view of the face of the commuting or rectifying device and
Figure 6 is a face view of the revolving contact arm which is adapted thereto.
Similar letters of reference are used to denote corresponding parts throughout the
several views.
In carrying my invention into effect, I employ a spindle A, Figures 1 and 2
Sheet 1, freely revolving in suitable bearings between two standards or brackets B B',
and upon the spindle, and between the standards I mount an armature C, preferably
of the ring type. I may, however, use a drum armature, if desirable. The ring or
drum has projecting radial pole pieces P' between which the coils c are wound. The
arrangement of winding is to divide the armature coils into two parts, so that they
are practically in series round the ring as shown by Figure 3, Sheet 2, and each end
coupled to a crown wheel commutator, one section of which is shown by Figure 4,
Sheet 2. The two sections are placed so that the projections or teeth t engage with
each other separated by insulation or by an air space. In Figure 3 the teeth of the
two crown wheels forming said commutator are distinguished by shade lines. This
allows of the brushes S+ and Sto be placed, or connected as a shunt relatively to
the field magnet coils, so that the commuted or rectified current causes the polarity
of said armature to remain constant.
The field is an iron ring D, preferably built up of laminæ, and having interior
polar projections P corresponding to those of the armature p and the interior spaces
are wound with coils, 1, 2, 3, 4, 5, 6, 7, 8, as shown by Figure 3, the ends of which
are connected in series at 1 2 3 4 5 6 7 8 and the free ends of each
of which are connected to the commuting device shown by Figure 5, which
consists of a "face commutator," the outer ring L being a terminal ring, and the
inner ring L' being the other terminal ring, the whole being mounted upon a slate
or other insulating boss M. The annular space between the terminal rings L and L'
is filled by two sets of segments, respectively numbered from 1 to 8 as shown,
these being insulated from each other, and also from the two rings L L'. This.

page_text: "face commuting device is preferably mounted upon one of the two bearing
brackets B, so as to he rigidly held thereupon by the boss M, and each segment
coupled to the free end of the field magnet coil bearing a similar number. The
terminal rings L L are connected by suitable binding screws u u, Figures 1 and 2
to the exterior circuit and also (as a shunt) to the armature brushes S+S-
Against the face of the commuting device comprised by L L' in Figure 1, is
pressed a double arm, R, fitted upon the spindle A and keyed or otherwise affixed as
to rotate with it, but insulated therefrom. This arm is shown more particularly by
the elevation Figure 6, in its exact relation to the commuting disc. The contact is
provided by a pair of contact shoes or pieces, H H', fitting freely within slots in the
insulating arms R and caused to press against the surface of the commuting disc by
springs or the like sufficiently to ensure electrical contact, with the minimum of
friction. The radial distances of the contact surfaces of eich shoe H H₁ from the
centre of rotation are different, so that H makes contact with the outer ring L and
the two sets of segments, and H' with the inner ring L' and said segment. Now
the cycle of contact and rotation is as follows:-If the position of the arms R, said
arms being always understood as being in contact with the face commutator shown by
Figure 5 although for purposes of clearness, shown separately by Figure 6, are such as to
allow of H making contact with the segmental faces 1 and 2 and also the outer ring L,
then H' will also establish electric contact between the segmental faces 5 and 6, and the
inner ring L. Presuming also, that poles px of the armature are mid way between the
poles Px of the field, and the poles immediately preceding them, these being either
oppositely wound or oppositely connected will be of opposite magnetic signs as shown.
A current of electricity entering on the terminal ring L, through the contact of the
shoe H will pass through coils 1, 2 and 5, 6 of the field, and thence through contact
shoe H' to and through the contact ring L'. Thus the armature C will commence to
revolve, because the brushes S + and Sare connected as a shunt to the terminal
rings L L', and maintain its polarity. But the revolution is continued by reason of
the advance of the arms R in the direction of rotation, cutting out the field coils in
opposite sets, and at the same time actuating those in advance.
Thus a concentrated polarity is maintained on both field and armature at the poles
marked Px and px on each, the intense poles being flanked in each case by similar
poles of less intensity and the poles marked O or zero being neutral. The armature
therefore is analogous to two oppositely wound magnets with like poles opposing
each other. The rectified alternations maintain this polarity constant, whilst in the
case of the field each succeeding phase traverses sets of coils alternately wound thus
maintaining also a constant polarity, which travels around the ring, that is to say,
rotating similar polarity is produced, which the armature must follow.
I may employ any kind of brush or spring contact in substitution for the shoes H H',
and may as an alternative device or method, cause the arms R to be rigidly attached,
and the brushes, shoes, plungers or other contacts to impinge upon the face or
periphery of a divided disc or cylinder, with segments corresponding to the field
magnet coils and two continuous terminal contacts, as aforesaid.
It is evident that a motor constructed according to my said invention may be self
starting in any position, and by suitably balancing the moving parts, I may prevent
the occurence of a dead point (when the corresponding pole pieces p and P of the
armature and field magnet respectively, coincide) by a system of balancing, or by the
use of an extra or auxiliary magnet temporarily excited or any equivalent method of,
or means for attaining this purpose. Directly the motor starts, its rotation becomes
synchronous.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
First. In an alternating electric motor for operating commuting devices for
converting alternating electric currents into continuous currents, and for other
purposes, the arrangement and winding of a magnetic field possessing a progressive

page_text: polarity relatively to the constant polarity of the armature substantially as herein
described with reference to the drawings.
Second. In an alternating electric motor for operating commuting devices for
converting alternating electric currents into continuous currents, and for other
purposes, the combination of a multipolar ring or drum armature C and a multipolar
field D, with a commuting device consisting of two terminal rings L L and two sets
of segmental contacts arranged concentrically there between and separately insulated,.
with double radial contacts H H', arranged and connected with the field and
armature coils substantially as and for the purposes herein described with reference to
the drawings.
Third. In an alternating electric motor for operating commuting devices for
converting alternating electric currents into continuous currents, and for other
purposes, the method of, and means for arranging and operating the fixed and
working electrical connections, substantially as and for the purposes herein described,
with reference to the appended drawings.
Fourth. In an alternating electric motor for operating commuting devices for
converting alternating electric currents into continuous currents, and for other
purposes, the construction and employment of two rings L L, as terminal rings, with
segmental contact pieces arranged concentrically there between and connected to the
armature and field coils of a motor as shown by Figures 3 and 5 in combination
with spring contacts H H¹ so that either may be stationary relatively to the other,
and the cycle of operation thereof substantially as herein described and shown.
Dated this 7th day of December 1896
FREDK. WALKER,
73 St. Stephen's Road, Upton Park, London, E.,
Agent for the Applicant.
FREDK. WALKER,
73 St. Stephen's Road, Upton Park, London, E.,
Agent for the Applicant.