Improvements in Electro-motors and Dynamo Machines.
Year: 1885

page_text: PROVISIONAL SPECIFICATION.
Improvements in Electro-motors and Dynamo Machines.
I, MORITZ IMMISCH, of 119 Torriano Avenue, Camden Town, London, in the
County of Middlesex, Electrician, do hereby declare the nature of my invention
for "IMPROVEMENTS IN ELECTRO-MOTORS AND DYNAMO MACHINES" to be as
follows:-
This invention relates to improvements in electro-motors and dynamo machines
where two field magnet poles and two brushes are employed, with three armature
coils wound on an iron core, such coils being either single coils proper, or they may
be subdivided into a greater number which shall always be the product of three
and any even number, for instance, there may be 3, 6, 12, 24 and so on.
The commutator is divided into a number of segments, altogether of double the
number of coils used, which segments are divided into two series bridged over by
the brushes, that is to say, each brush shall rest on both series at the same time.
The commutator segments are equally divided between the two series, and have
an angular displacement with regard to each other such that the line of division
between two adjacent segments in one series shall be opposite the middle of a
segment belonging to the other series. Under these circumstances it is evident
that each brush can only bridge over two segments at a time, and as there are
three coils in the system (no matter into how many sub-coils each may be divided)
the third coil is cut out, except for the moment when in the act of changing each
brush bridges over the coil which is at the point of being cut out and the one
which is at the point of coming into action; this overbridging of consecutive
segments is similar to that which takes place in most forms of dynamo machines
and electro-motors, and as it is of only momentary duration it will not be taken
into account in describing the working of my system.
In the case where only three coils are employed each coil is cut out twice in a
revolution, making six pulsations during such revolution; when six coils are used,
each coil is cut out four times making twelve pulsations in one revolution; it being
remembered that no matter what the number of sub-coils may be, they in reality
form only three coils proper. It may be generally stated that the number of
pulsations in each revolution is double the number of coils or sub-coils employed.
The object of cutting out a coil during part of a revolution is to give a certain
time to each coil before the direction of the current is changed. While one of the
three coils proper is cut out the remaining, active, coils produce polarity at opposite
points of the armature.

page_text: As each of the brushes rests simultaneously on two segments belonging to
different coils, it follows that the coils affected are connected in what is called
multiple arc.
When the three coils proper are subdivided into a greater number, the sub-coils
forming one coil proper are connected together partly in multiple arc and partly
in series.
In the case of motors I sometimes use an armature with radial pole extensions,
the recesses between which extensions serve to receive the insulated wire; in the
case of dynamo machines the wire may be wound upon a plain iron core without
pole extensions, in the manner of the ordinary "drum" armature, the iron part
of the armature being preferably formed of separate insulated iron discs in
both cases.
.
The wire must be wound upon the armature core so as to ensure all the coils
being of uniform resistance.
In dynamo machines I may employ the ordinary form of field magnets and pole
extensions, but in the case of motors the field poles are of special construction, the
object being to allow a freer passage to the poles formed in the armature after
they have ceased to be attracted by the field poles, and to prevent opposite
polarity being induced in that part of the armature core which has so ceased to
be attracted. For this purpose I construct my field of two cores connected by
extensions, in the middle of which consequent poles are formed, which act upon
the armature. That half of the field pole extensions facing the approaching
armature poles is much nearer to the body of the armature than the other half,
the latter half falling abruptly away, leaving a considerable space between itself
and the armature.
The field poles and extensions are formed in two parts, and for simplicity
I sometimes make the pole extensions serve as supports of the armature spindle,
each extension being suitably formed to carry one end of such spindle, thus doing
away with the necessity of using special brackets for that purpose.

page_text: COMPLETE SPECIFICATION.
Improvements in Electro-motors and Dynamo Machines.
I, MORITZ IMMISCH, of 119 Torriano Avenue, Camden Town, London, in the
County of Middlesex, Electrician, 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 improvements in electro-motors and dynamo machines
where two field magnet poles and two brushes are employed, with three armature
coils wound on an iron core, such coils being either single coils proper, or they may
be subdivided into a greater number which shall always be the product of three
and any even number, for instance, there may be 6, 12, 24 and so on.
The commutator segments are divided into two series. The number of segments
is always double the number of coils employed, so that when 6 sub-coils are used
the number of segments is 12, six segments in each series. The segments of the
two series have an angular displacement with regard to each other such that the
line of division between two adjacent segments in one series shall be opposite
the middle of a segment belonging to the other series. The third part of the total
number of segments belong to one coil proper, no matter into how many sub-coils
this one coil may be divided. If for instance each coil proper is divided into two
sub-coils, by testing the commutator by means of a galvanometer it will be seen
that 4 segments are connected together by means of the sub-coils, while these four
have no connection with the eight remaining segments.
The brushes rest simultaneously on segments belonging to two different coils,
and it therefore follows that the third remaining coil is always cut out while the
other two are active.
In the case where only 3 coils (undivided) are used, each coil is twice in a
revolution cut out for the sixth part of a circle, and there are therefore six impulses
during such revolution.
When the 3 coils proper are subdivided into 6 sub-coils, each coil proper is four
times in a revolution cut out for the twelfth part of a circle and there are therefore
twelve impulses during such revolution.
It may be generally stated that the number of impulses during a revolution
corresponds to the number of commutator segments.
Considering that (when the system is employed as a dynamo machine) the
generation of electricity takes place equally on both sides of the poles formed in
the armature, and that there are only two coils active-one on each side of such
poles I may, instead of having a single brush overbridging both series of com-
mutator segments, and thereby putting both coils in parallel, divide each single
brush into two, leaving two halves to form the terminals proper, and connecting
the other two halves together. I may thus connect the two coils in series with
each other. I sometimes avail myself of this facility to get a higher tension at the
terminals in the case of a dynamo, or to increase the internal resistance of a
motor in order to decrease its speed when the electromotive force and the load
are constant.

page_text: The facility with which the two active coils can be put either in parallel or in
series, shows that they can be regarded as two independent sources of power, like
two cells in a battery or two separate dynamo machines. As a practical illustra-
tion that this is the case, I find that what is known as Edison's three-wire system
can be employed with one of my machines when the coils are coupled up in series,
by connecting the third wire of such system to either of the half brushes not
forming terminals of the machine.
The system is equally applicable to armatures of the ring or of the drum type.
In the case of motors I sometimes use an armature with radial pole extensions,
the recesses between which extensions serve to receive the insulated wire; in the
case of dynamo machines the wire may be wound upon a plain iron core without
pole extensions, in the manner of the ordinary "drum" armature, the iron part
of the armature being preferably formed of separate insulated iron discs in both
cases.
In order that my invention may be fully understood I will proceed to explain
the same by the aid of the accompanying drawings.
For the sake of clearness the two series of commutator segments are drawn in
Figs. 1 to 4, one within the other, whereas in reality they are placed side by side
as shown in Figs. 5 and 6.
The coils are hereinafter referred to by the letter borne by the commutator
segments to which their ends are connected.
The three coils proper are in all the drawings named a, b and c, and in order to
better follow the connections they are distinguished by differently formed lines.
The a coil is shown in full lines; the b coil in broken lines consisting of a dash
and one dot, and the c coil by broken lines consisting of a dash and two dots.
Fig. 1 represents the simplest form of my invention as applied to a drum
armature, and the connections will be at once apparent on referring to such
Figure.
Fig. 2 represents the simplest form of my invention as applied to a ring
armature. There are here apparently six coils, but, taking into account how
they are connected, there are only three, the six free ends of such coils being
attached to the six commutator segments as the drawing clearly shows.
Fig. 3 is a ring armature in which the three coils proper are divided into six
sub-coils, the twelve free ends of which are attached to the twelve commutator
segments as shown.
Imagining brushes pressing on opposite points of the commutator, it is easy to
follow the direction the current takes. Supposing in the case of a motor that the
current enters at segment a (Fig. 3) it is evident that it cannot be taken off by
the opposite brush resting on segment a², until it has traversed all the a sub-coils.
As the brushes also rest on the segments b and 62, the current will therefore at the
same time pass through all the sub-coils forming the 6 coil proper, before it is
taken off, while the c coil will be cut out.
Fig. 4 shows the same number of sub-coils as in Fig. 3, as applied to a drum
armature. To enable the principle of sub-division to be carried out in drum
armatures it is necessary to wind each sub-coil in two halves, one half upon the
other, and to connect them up as shown in Fig. 4.
In order to lessen the effect of self-induction in the coils, I sometimes employ a
mixed winding in the manner shown in Figs. 7, 8, 9 and 10. Fig. 7 shows this
mode of winding with 3 simple coils, and Fig. 8 with 6 sub-coils, both as applied
to drum armatures, and it will readily be seen that the space which is taken up by
say the a coil in Figs. 1 and 4, is here taken up partly by the a coil and partly
by the c coil. Fig. 9 shows the mode of application of this mixed winding to
ring armatures. Fig. 10 also shows the method of mixed winding as applied to
drum armatures, the numbers 1 to 12 marked on the coils indicating the consecutive
order in which the halves of the sub-coils are wound.
In Figs. 3, 4, 7, 8, 9 and 10 I have drawn arrows on the lines of coils a and b,
which are supposed to be the active coils, in order to show the direction of the

page_text: current. It is clear that this direction is always the same no matter what segments
happen to be in contact with the brushes.
When twelve sub-coils and twenty-four commutator segments are used the
order of succession of the coils is precisely the same as shown in Figs. 3 and 4
respectively, the only difference being that more sub-coils are connected together
in series.
In dynamo machines may employ the ordinary form of field magnets and pole
extensions, and such machines can of course also be used as motors, but for the
latter I sometimes employ field poles of special construction, the object being to
allow a freer passage to the poles formed in the armature after they have ceased
to be attracted by the field poles, and to prevent opposite polarity being induced in
that part of the armature core which has so ceased to be attracted. For this
purpose I construct my field of two cores connected by extensions as shown in
Fig. 4, in the middle of which consequent poles are formed, which act upon the
armature. That half of the field pole extensions facing the approaching armature
poles is much nearer to the body of the armature than the other half, the latter
half falling abruptly away, leaving a considerable space between it and the
armature.
The above described form of field poles is applicable only to motors which are
required to run in one direction. In reversible motors I modify the pole extensions
and make them symmetrical on both both sides of the vertical line through the
centre.
The field poles and extensions are formed in two parts, and for simplicity
I sometimes make the pole extensions serve as supports of the armature spindle,
each extension being suitably formed to carry one end of such spindle, thus doing
away with the necessity of using special brackets for that purpose.
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. In the armature of an electro-motor or dynamo machine in which opposite
poles are formed, the use of three separate coils in connection with two contact
brushes proper (such brushes being either left whole or each subdivided into two
halves) for the purpose of periodically cutting out each of the coils in succession,
while the other two coils are active, substantially as and for the purpose specified.
2. In the armature of electro-motors or dynamo machines in which opposite
poles are formed, the use of three coils subdivided into six, twelve, twenty-four, or
more sub-coils, being a multiple of three and any even number, substantially as and
for the purpose specified.
3. The method of "mixed" winding the coils of the armature of electro-motors
or dynamo machines in which opposite poles are formed, and three coils (either
subdivided or not) are employed, substantially as and for the purpose described
with reference to Figs. 7, 8, 9 and 10 of the accompanying drawings.