Improvements in Dynamo Electric Generators or Motors.
Year: 1888

page_text: Improvements in Dynamo Electric Generators or Motors.
A communication from abroad by HENRY W. SPANG, of Reading, Pennsylvania,
United States of America.
1, WILLIAM PHILLIPS THOMPSON F.C.S., M.L.M.E. of the Agency for Foreign
Patent Solicitors, 6 Lord Street, Liverpool, and 6 Bank Street, Manchester, both in
the County of Lancaster, and 323 High Holborn, in the County of Middlesex, Civil
Engineer, 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 :-
The invention relates to the construction of electric generators and motors; and it
involves a novel construction of field-magnets and a new plan of mounting the
armature.
It
The field magnet is so constructed that poles of opposite character are presented to
different longitudinal portions of the armature and upon opposite sides thereof.
may be constructed and wound in any convenient manner for securing poles of
opposite character at proper points. The so-called Siemens' consequent pole type of
field-magnet may be adopted, but the position of the two poles are such that they are
not directly opposite each other, but are staggered or in different longitudinal
planes.
The armature is provided with an automatically operating mechanism for increasing
the pressure by which it is bound to its shaft, whenever there is any tendency upon
the part of the former to slip.
For this purpose there is placed within the armature a series of supporting blocks,
which when in position, form a cylindrical casing having a tapering or conical
internal surface. Within these blocks there extends a tapering wedge, the outer
surface of which conforms to the inner surface of the blocks. This wedge screws
upon the armature-shaft and the thread upon the shaft is formed in such direction
that the operation of the machine tends to screw the wedge within the circle of the
blocks and expand them.
In the accompanying drawing, Figure 1 is a side view showing the arrangement of

page_text: the field-magnet pole-pieces. Figure 2 is a section of the armature, and Figure 3 is
an end view. Figure 4 illustrates a slight modification.
Referring to the Figures, B represents a ring armature wound and mounted upon
a shaft A in a manner presently to be described. It will be understood that the
precise form of armature here shown is not always essential, and the type may be
varied as found advantageous. The armature revolves within a field created by the
field-magnet F. This field-magnet is wound with coils n¹, n² and s¹, 2, and it
is provided with polar extensions N and S. These respectively receive north and
south polarity by reason of currents traversing the several coils. The poles N
and S, instead of being diametrically opposite each other as in the usual construction
of electric generators and motors, are here diagonally arranged, so that while the
pole N confronts one end of the armature, the pole S confronts the other end. By
reason of this construction an armature of suitable length may be employed in
connection with field-magnet poles which are narrow and which thus concentrate
their lines of force upon small areas..
It is well known that theoretically an armature should be of as great length as
possible and of small diameter, so that the core and the wire upon it may be in close
proximity to the poles, and the surface of the armature may be as great as possible
for the purpose of radiating heat, and in the case of the Siemens' armature, that the
proportion of idle wire at the ends of the armature shall be as small as possible; but
such construction has been found to be disadvantageous in machines having field-
magnets of the usual form, for the reason that, the pole-pieces of the field-magnets
have been made of a width equal to the length of the armature, and thus the
magnetism is too greatly diffused, and not sufficiently concentrated upon the
armature. By the construction of field-magnet here adopted it will be seen that
the core of a comparatively long armature is placed or revolves in a more intense
field.
The armature is mounted in the following manner: Upon the shaft there is formed
a screw thread a and this turns in a metallic wedge D provided with an internal
screw d. The screw and thread are so formed that the revolution of the shaft will
tend to move the wedge in the direction of its smaller end. The wedge is tapering
in form and fits within a cylindrical series of blocks E of wood or other preferably
non-conducting material E. The inner surfaces of these blocks conform generally to
the outer surface of the wedge, and the outer surfaces of the blocks press against the
inner surface of an armature F of any suitable character. It is designed that the
revolution of the shaft shall tend to press the wedge further within the blocks, thus
expanding them and causing them to press more tightly against the surface of the
armature. The blocks E are preferably separated from each other a slight distance,
but are sufficiently near together to give a firm support to the armature.
For the purpose of causing the blocks to hold tightly to the armature, and at the
same time to prevent them from injuring the wire, they are preferably covered upon
their outer surfaces by paddings of cotton cloth or other suitable material coated with
varnish, shellac, glue or other substance adapted to harden and seal the parts
together.
Upon the shaft A there is formed a collar or shoulder which is designed to
prevent the commutator G and the armature from displacement longitudinally. The
commutator is of any suitable character preferably formed of plates which are held
in position by suitable clamping plates H¹ and H2, which are bound together by
suitable screws k, k. The plate H₁presses against the ends of the blocks E, and the
plate His prevented from slipping by reason of the collar h. Anti-friction
washers preferably intervene between the plates H and the collar h. These allow
all of the parts to turn together in case there is a movement of the armature with
reference to the shaft. It is evident that the entire system will be bound together
firmly by reason of the wedges, and the moment the draft upon the armature exceeds
the friction between the shaft and the armature, the shaft will turn within its bearings
and move the wedges forward, thus expanding the blocks and causing them to press
the armature more firmly.

page_text: If the machine is to be employed as a motor the direction of the screw upon the
shaft should be such that the forward pull of the armature against the resistance
due to the load applied to the shaft, will tend to tighten the parts as before.
In Figure 4, a modification is illustrated in which an additional wedging-nut is
employed. This screws toward the center of the armature from the opposite end of the
commutator. The screw-threads upon the shaft to which the wedges or nuts D
and D are applied are the reverse of each other. The nut D¹ is shown as being
shorter than the nut D.
It is evident that the field-magnet described may be used with armatures mounted
in the usual manner.
Having now particularly described and ascertained the nature of the 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:-
1. The combination with the armature of a dynamo electric machine, of a
consequent-pole field-magnet having its poles presented to different points in the
length of said armature, each convolution of the coils of said armature extending
across the face of each of the field-magnet poles.
2. The combination with the armature of a dynamo electric machine, of a field-
magnet having two poles facing the axis of the armature, and presented to said
armature at points diagonally opposite with reference to its axis, the separate
convolutions of the armature coils extending through the field of each pole.
3. In a dynamo-electric machine, the combination with a ring armature, of pole-
pieces of opposite character presented to the periphery of the armature at different
points in its length, the separate convolutions of the armature coils extending across
the face of each pole-piece.
4. In a dynamo-electric machine, the combination of a single continuous core of
soft-iron, wire wound upon the same forming a cylindrical armnature, and a field-
magnet having consequent poles located in different transverso planes with reference
to the axis of the armature.
5. In an electric machine, the combination of a continuous armature-core, its axis,
wire wound upon said core parallel with said axis, and two field-magnet poles
presented to different points in the length of the armature, and upon opposite sides
thereof.
6. The combination of the armature-shaft of an electric machine, an armature
movable thereon, an automatic tightening device coupling the armature to the shaft,
whereby the normal movement of the shaft during its operation, tends to tighten the
grip of the armature upon the shaft, and a commutator coupled to and moving with
the armature independently of the shaft.
Dabad : 10:1
WM. P. THOMPSON & Co.,
Agents for the Applicant.