Improvements in Electric Motors.
Year: 1890

page_text: Date of Application, 20th May, 1890-Accepted, 19th July, 1890
Communicated from
No. 27, School
Manufacturers.
COMPLETE SPECIFICATION.
abroad by THE GIANT ELECTRIC MOTOR COMPANY, of
Street, Boston, Massachusetts, United States of America,
Improvements in Electric Motors.
I, HENRY HARRIS LAKE, of the firm of Haseltine Lake & Co. Patent Agents,
45 Southampton Buildings, in the County of Middlesex 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 electric motors of the multiple type by which is meant a
motor provided with a field magnet having a plurality of north poles and a plurality
of south poles presented to the armature, and it consists in certain novel features of
construction, arrangement and combination of parts hereinafter described and shown
in the accompanying drawings in which
Figure 1 is an end elevation of a motor embodying this elevation.
Figure 2 is a vertical longitudinal section on line 1, 1, of fig. 1.
Figure 3 is a vertical, transverse section on line 2, 2, of Fig. 2.
Figure
4 is a vertical section on line 3, 3, of Fig. 2 and looking towards the right
of said Fig. 2.
Figure 5 is a diagram illustrating the manner of connecting the armature
magnets.
Figure 6 is a diagram illustrating the manner of connecting the segments of the
commutator the same being connected to Fig. 5 by dotted lines.
Figure 7 is a side elevation of one of the field magnet pole pieces.
In the drawings A A are the end frames of the motor, which also serve as the yokes
of the field magnet and are bolted to the base plate A¹ at their bases and connected
together at their tops by the tie-bar A2 as clearly shown in Figs. 1 and 2.
The frames or yokes A, A each have formed therein a bearing A³ in which is
mounted the shaft B and is also provided with the inwardly projecting annular rib a
upon which are bolted the field magnet cores (), each composed of a series of thin
flat plates 6 of soft iron placed one upon the other and firmly secured together by
rivets and provided at its inner end with a laterally projecting arm C the working
face or inner surface of which is curved tangentially to a plane at right angles to the
axis of the shaft B all as shown in Figs. 2, 4 and 7.
The plates b, of which said field magnet cores C are composed, may be curved, in
the direction of their widths, to arcs of circles concentric with the axis of the shaft B
as shown, or they may be straight, in the direction named, and be arranged
tangentially to circles concentric to said axis.
There must be four or more of these magnet cores Cattached to each frame A, so
that each field magnet shall comprise a plurality of both north and south poles, the
number of said poles being increased according as it is desired to decrease the speed
of revolution of the motor, as when it is desired to apply the revolving part of the
motor directly to a shaft that requires to be revolved at a comparatively slow speed.
In the machine illustrated in the drawings there are eight cores C attached to each
frame A, and each field magnet has four north and four south poles.
Each of these magnets is wound with a coil C³, of suitable insulated wire held in
place by the fibre insulating plates c, c as shown in Figs. 2 and 4, and said coils on
each frame A are connected together in series by wires c¹ and the two series are
connected together by wire c² so that a current of electricity passing from the binding
post d through the commutator and along the wire d' traverses all of the coils (%, of
one field magnet, and then all the coils of the other field magnet in succession and
Price 8à 1
.

page_text: •
pass off through the binding post d² as shown in the central portion of the diagram
shown in Fig. 5.
The hub of the bearing A³ on one of the frames A has adjustably screwed thereon
the segmental plate D the hub of which is cut open on one side and provided with an
ear e on each side of said cut by means of which and the screw el said plate may be
clamped firmly to the bearing A³ as shown in Figs. 1 and 2.
.
The shaft B has firmly secured thereon just inside the bearing A³ which carries
the plate D, a disc E of suitable insulating material and at a suitable distance therefrom
another disc E of like material said discs having in their faces that are towards each
other annular grooves to receive tongues f formed on the ends of the commutator
segments g and the insulating plates 9' placed between them as shown in Figs. 2
and 4.
The commutator segments 9 correspond in number to the number of armature
segments used which, in the case represented, is forty.
The shaft B also has secured thereon so as to revolve therewith the hub F having
formed in one piece therewith the disc or flange F at one end, and secured to its
other end by the nut h and pins ¹, the disc F2 corresponding in size and shape to the
disc F¹.
The inner or adjacent faces of the discs F1 and F2 have formed therein peripheral
rabbets h² to receive the inner end of the radially projecting arms h³ made of some
strong insulating material preferably vulcanized fibre which are secured in position
on said discs by screws i as shown in Figs. 1, 2, and 3.
Each of these arms h³ has formed therein near its outer end a rectangular slot to
receive the end of an armature core G, composed preferably of a plurality of, thin
flat soft iron plates fastened together by rivets, and secured in position by the set
screws as shown in Figs. 1, 2 and 3.
Each of these armature cores G has wound thereon, between the arms h³, a coil h*
of suitably insulated wire. In the motor illustrated in the drawings there are forty
armature magnets, so arranged that their end surfaces, instead of their sides, are
presented to the action of the two field magnets between which they are placed and
revolve about the axis of the shaft B.
It is a well known fact that in an electric motor a greater power can be obtained
by the use of a great number of small magnets than from a smaller number of large
magnets with the same aggregate weight or mass of metal used in each case,
and
also that the power capacity of an electro motor is proportioned to the number of
changes of polarity which take place in a given time.
In consequence of the above facts electric motors as heretofore constructed have to
be run at very high speeds in order to transmit any considerable power, and as the
speed of the motor is very much higher than it is desirable to run most machinery
that is to be operated thereby, resort is had to gearing to reduce the speed to the
desired number of revolutions per minute.
This in many cases is objectionable on account of the additional weight of the
apparatus and the extra cost of the same.
I overcome this objection by using an increased number of magnet poles in either
or both the field and armature magnets and connecting the armature in a novel way
which I will now proceed to describe.
The usual manner of connecting a series of armature coils with each other is to
join the outside end of the first coil to the inside end of the next or second coil, the
outside end of the second coil to the inside end of the next or third coil and so on
around the circle to the last coil and the outside end of the last coil to the inside end
of the first coil, each of the junctions between said coils being connected by a suitable
wire with a corresponding segment of the commutator, and brushes or contact pins
touch the commutator at intervals equal in angular space to the distance apart of two
field poles from each other, as many brushes or contact pins being used as there are
pole ends in the field magnet.
In my improved motor, the forty armature coils are arranged equidistant from each
other in a circle concentric with the axis of the shaft B, ten in each quarter of the

page_text: circle, and those in each quarter are numbered from 1 to 10 as shown in Figs. 3
and 5.
Commencing with armature coil No. 1 at the top of the motor I connect the inner
end of said coil by the wires k with the outer end of No. 1 coil at the right side of
the motor, the inner end of that coil by wire k¹ to the outer end of coil No. 1 at the
bottom, the inner end of the last mentioned coil by wire k to the outer end of
coil No. 1 at the left side of the motor, these four coils forming a group of magnets
connected together as one magnet, in such a manner that whenever a current of
electricity is traversing them and one is reversed all of the four will be reversed at
the same instant.
There are ten groups each comprising four magnets each magnet in a group having
a like number, and connected together in the same manner as group No. 1.
The coil No. 1 at the left side of the motor has its inner end connected to the outer
end of coil No. 2 of the right hand upper quarter by the wire and the coil No. 2 in
the left hand upper quarter of the circle has its inner end connected by the wire l' to
the outer end of coil No. 3 in the right hand upper quarter of the circle and so on
until coils 3, 4, 5, 6, 7, 8 and 9 in the left hand upper quarter of the circle are in like
manner connected respectively to coils 4, 5, 6, 7, 8, 9, and 10 in the right hand upper
quarter of the circle by the wires 12, 13, 14, 15, 16, 17, and 18.
'
The inner end of the coil No. 10 in the left hand upper quarter of the circle is then
connected to the outer end of coil No. 1 in the right hand upper quarter of the circle
as shown at m Fig. 5.
The segments of the commutator are numbered to correspond to the numbers of the
armature magnets in four sets of ten each as shown in Fig. 6.
These segments are connected together in ten groups of four each as follows:
All of the segments numbered 1 are connected by wire n; those numbered 2 by
wire n', 3 by wire n², 4 by wire n³, 5 by wire n', by wire n³, 7 by wire n°, 8 by
wire n'. 9 by wire n8 and 10 by wire n' as shown in Fig. 6.
One half of the segments in the upper and lower quarters of the circle are provided
with binding screws o, o said screws on one side of the commutator cylinder being set
in the segments having odd numbers as 1, 3, 5, and on the opposite side in the segments
having even numbers as 2, 4, 6.
The binding screws in the segments 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 are respectively
connected by correspondingly numbered wires to the correspondingly numbered
armature coils in the upper left hand quarter of the circle of armature magnets as
shown in Figs. 5 and 6, said wires being shown partly in full lines in said figures and
partly by dotted lines connecting said figures.
By this method of connecting the armature magnets together in groups of equal
number and of the same phase, and connecting the several groups together in series,
and connecting the segments of the commutator together in groups and said groups
of commutator segments to corresponding groups of armature inagnets I am enabled
to very largely increase the number of magnets, both field and armature, without
increasing the number of commutator brushes or contact pins, only two being necessary
whatever the number of the field and armature magnets provided that the number of
the armature magnets shall be some multiple of the number of poles in the field
magnet.
What is meant by magnets having the same phase is: armature magnets that, at
the same instant, bear the same relation to a field magnet pole, that is are at the same
distance from and on the same side of a field magnet pole, with reference to the
direction of the revolution.
The segmental plate D has set therein two inwardly projecting studs p and p¹ on
which are mounted respectively the brush holder blocks q and q provided with suitable
slots to receive the commutator brushes r and which are secured therein in their
proper positions by the set screws and respectively.
The brushes are pressed into contact with the peripheral surface of the commutator
cylinder by the tension of coiled springs & surrounding the studs p and p' one end of

page_text: each of which is made fast to the adjustable collar on its stud and the other end to
the brush holder one only of said springs being shown in Fig. 2.
"
The brushes are so arranged and adjusted that their points of contact with the
peripheral surface of the commutator cylinder are at the same angular distance from
each other as the pole ends of the field magnets are apart.
-
The frames A A are made of iron and form the yokes for the field magnet cores.
By forming the lateral extensions C on the field magnet cores C and curving their
active faces as hereinbefore described a great advantage is obtained in an increased
effectiveness of the motor due to the fact that several armature magnets are within the
influence of each field magnet pole at the same time and is being acted upon thereby
with a greater or less degree of force according to the distance between said armature
magnets and said curved surface.
In the case of field magnets not having said extension and curved surface each
armature pole is within the influence of the field magnet pole only for a very short
space of time, and only one of the armature poles are within the influence of said field
magnet pole at the same time.
Another important feature of this invention is making the supports of the armature
cores of vulcanized fibre or other strong insulating material whereby a defect in the
insulation of the wire of one armature coil is prevented from affecting either of the
other coils.
Another important feature of this invention is the ability to use a large number of
poles in either or both the field and armature magnets with only two commutator
brushes or contact pins, whereby a considerable saving is made in the first cost of the
commutator, and a great saving in time in fitting and adjusting said brushes as well
as expense in repairs caused by replacing so many brushes when they wear out and
repairing the damage done to the commutator cylinder by the wear of a large number
of brushes.
.
Having now particularly described and ascertained the nature of my said inven-
tion, 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 :-
1st. In a multipolar motor the combination of a plurality of groups of equal number
of armature magnets arranged in a circle about a common centre, the magnets in each
group being located equidistant from each other about said circle and connected
permanently together as one magnet and the several groups being connected to each
other in succession; a commutator having as many segments as there are armature
magnets and arranged in corresponding groups, the segments in each group being
connected together as one and each group of segments being connected with corre-
sponding points of junction of the several groups of armature magnets, and a field
magnet composed of a series of electric helices and having a plurality of both north
and south pole ends, the cores and pole ends of said helices being each made up of a
series of plates which extend the whole length of the core to the pole end and having
its pole end expanded laterally and curved tangentially to a plane at right angles to
the axis of the revoluble portion of the motor.
2nd. In an electric motor an armature having a series of magnet cores arranged
with their magnetic axes parallel to the axis of revolution of the revoluble portion of
the motor and mounted in supports made of vulcanized fibre or other suitable insulating
material, whereby the several cores are insulated from each other, so that if the
insulation of the wire of one coil is defective it shall not affect the other coils.
D
1 LOL
M
1000
1
HASELTINE, LAKE & Co.,
4, Southampton Buildings, London, Agents for the Applicant.