Improvements in Dynamo-electric and Electro-dynamic Machines.
Year: 1894

page_text: Date of Application, 17th Feb., 1894
Complete Specification Left, 19th Nov., 1894-Accepted, 16th Feb., 1895
PROVISIONAL SPECIFICATION.
Improvements in Dynamo-electric and Electro-dynamic Machines.
We, PAUL PÖSCHMANN, Electrical Engineer, and RICHARD HANISCH,
Merchant, trading jointly under the style of Poeschmann & Co., of 43, Freiberger-
strasse, Dresden, in the Kingdom of Saxony and German Empire, do hereby
declare the nature of this invention to be as follows:-
--
This invention relates to an improved arrangement and construction of dynamo-
electric and electro-dynamic machines; its primary object being to effect the
better utilization of the lines of force in the magnet holders or fittings of such
machines.
In dynamos as hitherto constructed, magnetic "back-circuits" have been provided
for by fitting the magnets in a yoke of angular, bow or other shape, with the result
that the lines of force concentrated sidewise into the iron or were deflected at an
angle; the resistance thus created, which must be overcome, leading to a very
noticeable dispersion of said lines of force.
To obviate such dispersion, it is proposed to impart to the magnet holder, which
is completely closed in on all sides, a cylindrical or spherical shape, thereby causing
the lines of force to retain the same direction which they first assumed in the wire,
and to close their circuits in circular curves.
For the purpose of avoiding the dispersion of the lines of force in dynamos
having armatures of the "Gramme" ring type, and of causing, in this case also, the
lines of magnetic force to develop in circular curves, in the same direction in which
they were first produced, the magnetic or "back-circuit" cylinder is made open at
one end, while the armature is wound in a peculiar manner, with poles of opposite
signs facing one another radially.
The advantages of the novel magnet-holding structure have been ascertained by
means of various arrangements of magnets made by way of trial in order to
determine the course taken by the lines of force in completing a circuit.
In fitting a magnet according to the present invention, an iron core and an
exciting coil or bobbin are enclosed in an iron cylinder.
In the improved magnet holder, the lines of force form circuits in the identical
direction in which they were generated in the wires, this being the case throughout
the entire magnetic circle, so that the lines of force are neither dispersed nor drawn
out of shape; whereas in the ordinary arrangements with open yokes the lines of
force are unduly stretched out in the direction of the yoke, dispersion of magnetic
force being the result.
A two-pole dynamo constructed in accordance with this invention comprises a
magnet holder consisting of a single cylindrical casting closed at the top and
bottom. This closed cylinder is cast in one piece with its bed or supporting plate
and the magnetic core, which rises from said bed or plate. The wall of the
cylinder is partly cut away or perforated at the points where the armature-spindle
projects; these perforations being, however, as small as possible. There is also
an aperture provided for the insertion of the armature; this aperture, which is Do
larger than necessary, being closed by a plate fitting it exactly. The upper part
of the cylinder is dome-shaped. To the closing plate there may be secured pins
for holding the brushes, in which case the plate should be mounted to rotate in
order to facilitate the adjustment of the brushes. Or, the closing plate may be
provided with a nave or boss adapted to receive a ring carrying the pins for holding
the brushes; the brush-holding ring being made to rotate.

page_text: As the dispersion of the lines of force between the magnet-poles can never be
avoided entirely, an annular bead or shoulder is provided within the cylindrical
casting around the upper pole; the object of such bead or shoulder being to
intercept or absorb any lines of force which may stray upwards, thus neutralizing
part of the downward pressure.of the armature-spindle, or in other words, materially
diminishing that pressure. The lines of force, instead of starting in a direction at
right angles to the direction of motion, and thereby causing sparks, follow a
direction which, in addition to relieving the armature-spindle from some of its
downward strain, brings about a diminution in sparking. The core and the top of
the cylinder may have channels extending through them, which, in conjunction
with the rotating armature, serve to ventilate the interior of the cylindrical casing.
In order to insure in dynamos of large size having numerous poles the favourable
effect of obtaining lines of force which, throughout the circle, retain their original
direction, it is advisable to use magnet holders of spherical shape closed on all
sides. In such case, the magnet fitting or holder may consist of a spherical casing
made in two parts and having inwardly directed radial cores, either round or oval.
In this instance, the arrangement is such that all the N. poles are situated in the
upper part, and all the S. poles in the lower part, of the machine, or vice versú; the
N. poles and S. poles, being, moreover, connected by different junction-pieces.
The spherical magnet holder may, however, have two N. poles located in
the upper half, and one S. pole in the lower half of the sphere; the object and the
effect produced being the same as in the arrangement previously described.
Where it is desired to apply the improved principle of construction to a dynamo
having more than one pair of poles and a "Gramme" ring armature, the magnet
holder should be in the form of two cylinders, one fitted within the other; the
whole, including the rear plate, being preferably cast in one piece. The exciting
coil is mounted on the inner cylinder; the armature rotating between the two
cylinders. The outer cylinder is formed with gaps; the inner one having gaps to
correspond. The ribs or parts between the gaps face one another and constitute
poles of opposite signs. The armature-coil is so wound in this machine that, while
the induced current travels between the pole-ribs in one direction, the generating
current flows between the poles proper in the opposite direction.
It will be understood that the lines of force cannot form as complete circuits in
those parts of the cylinders in which the gaps are as they do at the closed and solid
rear portion of the cylinders and at the back plate.
Dated the 17th day of February 1894.
G. G. M. HARDINGHAM,
191, Fleet Street, London, E.C., Chartered Patent Agent.
COMPLETE SPECIFICATION.
Improvements in Dynamo-electric and Electro-dynamic Machines.
We, PAUL PÖSCHMANN, Electrical Engineer, and RICHARD HANISCH,
Merchant, trading jointly under the style of Poeschmann & Co., of 43, Freiberger-
strasse, Dresden, in the Kindom of Saxony and German Empire, 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 an improved arrangement and construction of dynamo-
electric and electro-dynamic machines; its primary object being to effect the better
utilization of the lines of force in the magnet holders or fittings of such machines.
In dynamos as hitherto constructed, magnetic "back-circuits" have been provided
for by fitting the magnets in a yoke of angular, bow or other shape, with the result

page_text: that the lines of force concentrated sidewise into the iron or were deflected at an
angle; the resistance thus created, which must be overcome, leading to a very
noticeable dispersion of said lines of force..
To obviate such dispersion, it is proposed to impart to the magnet holder, which
is completely closed in on all sides, a cylindrical or spherical shape, thereby causing
the lines of force to retain the same direction which they first assumed in the wire,
and to close their circuits in circular curves.
For the purpose of avoiding the dispersion of the lines of force in dynamos
having armatures of the "Gramme" ring type, and of causing, in this case also,
the lines of magnetic force to develop in circular curves, in the same direction in
which they were first produced, the magnetic or "back-circuit" cylinder is made
open at one end, while the armature is wound in a peculiar manner, with poles of
opposite signs facing one another radially.
The advantages of the novel magnet holding structure have been ascertained by
means of various arrangements of magnets made by way of trial in order
determine the course taken by the lines of force in completing a circuit.
In the accompanying drawings,
Figs. 1, 2, 2 and 3 illustrate a two-pole dynamo constructed in accordance with
the present invention; Fig. 1 being a side elevation, Fig. 2 a longitudinal section,
Fig. 2 a transverse section and Fig. 3 a plan, partly in horizontal section,
corresponding with Fig. 1.
Figs. 44, 4B, 6A, 6B, 74, 7B are diagrams illustrating various arrangements of
magnet holding structures. Figs. 4 and 4" being respectively a side elevation and
a transverse section and Figs. 64 and 6B respectively a side elevation and an end
view of arrangements hitherto in use, and Figs. 74 and 7" vertical and horizontal
sections respectively of the improved arrangement.
Fig. 8 illustrates in transverse section and Fig. 9 in longitudinal section a dynamo
having a number of poles, and Fig. 10 is a side elevation thereof.
93
Figs. 11, 12 and 13 represent the construction of magnet holder adapted for use
in dynamos having more than one pair of poles and provided with a
ring armature.
66 Gramme
Fig. 14 illustrates a modified arrangement of magnet-holder in which two N. poles
and one S. pole are employed.
Fig. 15 is a diagram illustrating the different curves of the lines of force.
In fitting a magnet according to the present invention, an iron core A and an
exciting coil or bobbin Spare enclosed in an iron cylinder B. C is the armature
interposed between the pole pieces. The cores in the various arrangements are
wound with the same number of convolutions.
In the improved maguet holder (Fig. 7B) the lines of force form circuits in the
identical direction in which they were generated in the wires, this being the case
throughout the entire magnetic circle as indicated at a, a, a, a, a, a,
that the lines of force are neither dispersed nor drawn out of shape; whereas in th
ordinary arrangements (Figs. 4 and 6) where open yokes are employed the lines
of force are unduly stretched out in the direction of the yoke B (a' a" a¹¹),
dispersion of magnetic force being the result.
Referring to Figs. 1, 2, 2 and 3, a two-pole dynamo constructed in accordance
with this invention, comprises a magnet holder such as that illustrated in Figs. 7
and 7, which consists of a single cylindrical casting closed at the top and botton.
This closed cylinder B is cast in one piece with its bed or supporting plate G an
the magnetic core A, which rises from said bed or plate; the back or reverse
circuit not being liable to interruption. The wall of the cylinder is partly cut
away or perforated at the points where the armature-spindle projects; these per-
forations being, however, as small as possible. There is also an aperture provide
for the insertion of the armature; this aperture, which is no larger than necessary,
being closed by a plate D fitting it exactly. The upper part E of the cylinder is
dome-shaped. To the closing plate D there inay be secured pins for holding the
brushes, in which case the plate should be mounted to rotate in order to facilitate

page_text: the adjustment of the brushes. Or, the closing plate D may be provided with a
nave or boss F adapted to receive a ring carrying the pins for holding the brushes.
In this latter case, the brush-holding ring is made to rotate.
As the dispersion of the lines of force between the magnet-poles can never be
avoided entirely, an annular bead or shoulder H is provided within the cylindrical
casting around the upper pole; the object of such bead or shoulder being to
intercept or absorb any lines of force which may stray upwards, thus neutralizing
part of the downward pressure of the armature-spindle, or in other words,
materially diminishing that pressure. The lines of force, instead of starting in a
direction at right angles to the direction of motion, as indicated at K' (Fig. 24),
and thereby causing sparks, follow a direction indicated by the line K, which, in
addition to relieving the armature-spindle from some of its downward strain, brings
about a diminution in sparking. The core A and the top of the cylinder B, which
serve to complete the back-circuits, may have channels m m¹n n' extending through
them, which, in conjunction with the rotating armature, serve to ventilate the
interior of the cylindrical casing.
In order to insure in dynamos of large size having numerous poles the favourable
effect of obtaining lines of force which, throughout the circle, retain their original
direction, it is advisable to use magnet holders of spherical shape closed on all sides
as shown in Figs. 8, 9 and 10. In such case the magnet fitting or holder may
consist of a spherical casing B made in two parts and having inwardly directed
radial cores A either round or oval. In this instance, the arrangement is such that
all the N. poles are situated in the upper part, and all the S. poles in the lower
part, of the machine, or vice versa; the N. poles being connected by a junction-
piece c and the S. poles being connected by a junction-piece d. The lines of force
instead of following the direction indicated by the dotted line in Fig. 9 as they are
generated retain their original course and describe proper circles in accordance with
the arrangement of machine represented in that figure.
The spherical magnet holder B may, be formed as a split closed sphere, as
represented in Fig. 14 in which two N. poles are located in the upper half, and one
S. pole in the lower half of the sphere; the object and the effect produced being
the same as in the arrangement previously described.
Where it is desired to apply the improved principle of construction hereinbefore
described to a dynamo having more than one pair of poles and a "Gramme" ring
armature, the magnet holder should be in the form shown in Figs. 11, 12 and 13,
same consisting of two cylinders, one fitted within the other; the whole, including
the rear plate E', being preferably cast in one piece. The exciting coil Sp is
mounted on the inner cylinder A'; the armature C rotating between the two
cylinders. The outer cylinder B is formed with gaps D'; the inner cylinder A¹
having gaps H to correspond. The ribs or parts G' and F between the gaps in
the respective cylinders face one another and constitute poles of opposite sign.
This construction has the advantage that electro-motive forces are induced on both
the outer and inner sides of the coils, or winding, on the armature ring; all the
conductors or wires being cut by all lines of force and all in the same direction.
According to the " Gramme mode of coiling, the outer side of each coil lies
parallel radially with the inner side belonging thereto.
"
In order that the electro-
inotive forces induced in the outer and inner sides of the coil or conductor shall not
neutralize each other, the mode of coiling or winding illustrated in Fig. 124 (in
which fig. it is shown, by way of example, as applicable to a machine having two
pairs of poles) is employed. The armature ring (C) is indicated by dotted lines,
one full winding being indicated by the full lines. The winding commences at
and ends at . The direction of the winding is shown by the arrows. On the
outer and inner surface of the ring, the wire is parallel with the axis of the ring;
but, at the front and rear of the ring, the portions of the wire are so directed
that while the outer wire is opposite one of the free spaces (D¹) in the cylinder,
between two outer pole-ribs, the corresponding inner wire will be opposite one of
the inner pole-ribs (G'). Each outer side of the coil encloses or forms, with the

page_text: inner side of the coil belonging thereto, an angle, the magnitude of which will
depend upon the number of pairs of pole-ribs facing each other. Of each of the
outer and of the inner sides of the coils, one will always be in the powerful field,
between two pole-ribs of different polarity, while the other will be in the
gaps (H' D').
It will be understood that in connection with the arrangement last described, the
lines of force cannot form as complete circuits in those parts of the cylinders in
which the gaps D' and H₁ occur as they do at the closed and solid rear portion of
the cylinders A' and B' and at the back plate E'.
In the diagram, Fig. 15, is illustrated the difference in the curves of the lines
of force resulting from the employment of dynamos furnished with magnet holding
devices constructed in accordance with this invention. The numbers applicable to
the vertical column indicate the inductive force, and those applicable to the
horizontal line the magnetizing force. The curve I is illustrative of the force
obtained by the use of such an arrangement as is described with reference to
Figs. 74 and 7; the curve II being illustrative of the force obtainable from the
use of the arrangement shown in Figs. 4A, 4B, 6* and 6B in which the lines of force
become dispersed or drawn out in the direction of the yoke.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, we claim :-
1. A two-pole dynamo in which the magnet holder or support consists of an
upright undivided cylinder closed on all sides, from the centre of the bed plate
whereof there rises a core of N. polarity, while to the top of said cylinder is secured
an attachment or pole-piece of S. polarity; the arrangement being such that the
lines of magnetic force form circular curves or circuits, and retain the direction
imparted to them on their being generated in the coiled wire.
2. A dynamo comprising more than two poles, designed to work in the manner
referred in the preceding claiming clause but so modified in construction that the
closed cylindrical or spherical magnet holder or support employed is split or divided
in the horizontal plane, each pair or series of poles of the same sign being located
in the same half of the cylinder or sphere and connected by a suitable junction-
piece or pieces.
3. A dynamo comprising more than two poles designed to work in the manner
referred to in the first claiming clause, and comprising a hollow cylindrical armature
revolving between pole-ribs formed on two rings, projecting from a cylindrical
shaped magnet, whereby the poles of opposite sign face each other, and the coiling
or winding on the armature ensures that of the outer and inner sides of the coils,
the corresponding outer and inner sides of the coils are in an angular distance from
each other, the magnitude of such angle being determined by the number of pairs
of the inducing poles, substantially as specified.
4. In a two-pole dynamo of the kind referred to in the first claiming clause,
cutting away or perforating one side of the wall of the cylindrical magnet holder
(which is closed on all sides) for the insertion of the armature, the aperture being
closed by means of a fixed or rotating plate either carrying a rotating bridge or
brush holder or having the brushes attached to it directly.
5. In a two-pole dynamo of the kind referred to in the first claiming clause,
providing the upper pole-piece or attachment with an annular bead or shoulder
such as H, which bead, by absorbing or intercepting dispersed lines of force, reduces
the downward pressure of the armature spindle.
Dated the 19th day of November 1894.