IMPROVEMENTS IN DYNAMÓ-ELECTRIC AND ELECTRO-MOTIVE MACHINES
Year: 1884

page_text: I, EDWARD BRAILSFORD BRIGHT of 31 Golden Square in the County of
Middlesex, Civil Engineer do hereby declare the nature of my invention for
IMPROVEMENTS IN DYNAMÓ-ELECTRIC AND ELECTRO-MOTIVE MACHINES and in
what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :—
In Dynamo-electric or Electro-motive machines as at present constructed in
which continuous electric currents are generated or employed there are neutral
parts of the magnetic field between the opposite poles of the exciting magnets,
amounting on the average to about a fourth of the whole.
The armature coils passing through these neutral spaces are not only useless
but mischievous, inasmuch as they add to the resistance of the working circuit.
without contributing electro-motive force to the general current, besides occasioning
other electrical disadvantages.
An example of these non productive spaces is shown at a and b in Figure 1 of
the sheet of drawings annexed. hereto which represents the poles of the field
magnets and the armature of an ordinary form of Gramme machine, in which
c c and d d are the poles and e the shaft carrying the revolving ring armature
and commutator.
In some Dynamo-electric apparatus as at present constructed, for instance the
Brush machine, this evil has been partly mitigated by cutting the idle armature
coils out of circuit while passing through the. neutral portions of the magnetic field."
In my invention the magnetic field is complete throughout an entire. circle
divided in two parts hy a sharply defined line, the whole of the armature coils
being thus rendered productive.
The application of my invention to the Ring type of Dynamo machines will be
understood by a reference to Figures 2, 3, 4, 5, and 6 in the accompanying
drawings.
.
The armature is caused to rotate between a pair or more of field magnets having
iron flanges or pole-pieces, and so fixed in relation to each other that when one of
the coils of the rotating armature is passing from the end of the pole piece of one
polarity of the field magnet on one side of it, it is at the same time coming before
the pole piece of opposite polarity of the field magnet on the opposite side.
The arrangement of the field magnets with their flanges or pole pieces is shown
in Figures 2, 3, and 4, where the zero line a, b indicates the position in the circle
of rotation where the opposite poles end on one side and commence on the other.
In Figure 2 the poles are shown at c c, d d. Any form of coil may be used; as
for example cylindrical or oval in section, but I prefer to employ coils shaped in
section in the form of a D or bent bow as shown by the straight plain and curved
broken lines surrounding the letters e and ƒ in Figure 2, and¸é e¹ and ƒ ƒ¹ in
Figure 4.
A section of the shaft of the revolving ring, armature is shown at in Figures 2

page_text: and 4, the armature itself being omitted in order to show the inclined position of
the pole pieces of the field magnets.
Figure 3 represents the arrangement of the field magnets and their pole pieces in
plan, in which ef and e¹ f¹ represent the field magnets of which the respective
poles are shown in front view at Figure 4. The centre of the armature shaft.
coincides with the dotted line a b, but the shaft and armature are not shown in
order to render the arrangement of the field magnets more clear.
The ends of the cores of the field magnets are recessed as shown by the curved
broken lines surrounding h h¹ and i ¹, in order to concentrate the magnetism on
the faces of the pole pieces which are adjacent to the armature.
jj are iron yokes uniting each pair of field magnets and secured to or forming
part of the bed plate k k k k.
I do not confine myself to this form of arrangement of my invention, as the field
magnets may be placed in a vertical or other position and may be adapted to other
types of continuous current Dynamo-electric machines or Electro-motors.
Figure 5 shows in section a suitable form of flat ring armature adapted to
Figure 3 g g being part of the shaft, m m the core of the armature, and n n the
surrounding coils of wire.
Το
At Figure 6 is shown a ring armature with coils circular in section, in which
part of the shaft is lettered ġ g, and the core of the coils of the armature m m.
this form of armature I have applied a special shape of pole pieces of the field
magnets shown in section at N, N, S, S, by which the magnetism is intensified
upon the exposed portion of the armature coils and which is one part of my
improvements.
The insulated wire of the armature coils may be wound upon a core consisting of
a bundle of soft iron wires, or hoops, or on a solid iron ring, or on iron segments
separated by thin non-magnetic divisions; and for some special purposes
wound altogether upon a non-magnetic core.
it
may
be
I prefer to make the shaft g of gun metal or phosphor bronze if the size of the
machine is such that the field magnets are near to each other, for in such case if
iron is used it will to some extent divert polarity.
At Figure 7 my system is shown as applied to an armature of the Wylde or
Wallace Farmer type carrying a series of electro magnetic coils, the axes of which
are at right angles to the plane of rotation of the armature, the coils of which are
indicated by the letters m. It will be observed that in this case the pole pieces of
the field magnets which face each other on the opposite sides are of differing
polarities as shown at N, S, and S, N.
When incandescent lamps are used an alternating current machine possesses
some advantages owing to the change of direction of current; but if this is done
occasionally by an ordinary reversing switch in connexion with continuous current
'Dynamo-electric machines such as I have described, it answers the same purpose;
and the reversal may be made automatically by a ratchet wheel and pawl upon
every occasion of turning on the current.
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,
.
(1) The construction and use as described of Field magnets with pole pieces so
arranged as to produce a continuous magnetic field in a rotating armature.
(2) The construction of the coils of field magnets with sections as described.
D
gord 1
- Tasatra 1001
E. B. BRIGHT.