Improvements in Dynamo Electric Machines.
Year: 1888

page_text: COMPLETE SPECIFICATION.
Improvements in Dynamo Electric Machines.
I CARL COERPER, of Cologne, in the Empire of Germany, Engineer, do hereby
declare the nature of this invention and in what manner the same is to bo
performed, to be particularly described and ascertained in and by the following
statement:-
In the transmission of power by means of electricity the driving of the motor
constitutes a special difficulty; especially in cases where the great number of
revolutions of the dynamo is to be transmitted to slowly turning shafts, and where
varying velocities, such as in tramway-working and the like, are to be obtained.
The present invention relates to a new construction of dynamo for such purposes.
In carrying the said invention into practice I mount upon the shaft or axle to be
driven the two elements of the dynamo that is to say the armature and the field magnet
in such a manner that the field magnet is rigidly connected with the shaft, whilst the
armature can turn freely upon the said shaft. The said armature can however be
retarded in its motion or brought to rest by a brake device. If a current is passed to
the dynamo, the armature and the field magnet element will tend to turn in opposite
directions; and if, as in this case the field magnet is fixed to the shaft, the armature
will turn alone. In proportion, however, as the rotation of the same is retarded by the
application of a brake, the field magnet which is fixed to the shaft will tend to set the
shaft in motion. This motion will be accelerated the stronger the brake is applied to
the armature until with the stoppage, caused by the application of the brake, of the
said armature the axle receives from the field magnet fixed upon it its maximum
velocity corresponding to the current introducet.
By means of this construction it is possible, for example in tramway working, to
give the dynamo, at the place where the car stands, the proper number of revolutions

page_text: then to start slowly by gradually applying the brake to the movable machine element,
and after that to drive at different velocities by varying the braking power, without
rendering necessary a material change in the amount of the current."
The armature and field magnet can also be mounted in such a manner that both are
free to move upon the shaft or axle to be driven, and their revolving power is controlled
by brake devices either from the axle or independently of this axle. In lieu of brakes
couplings or stopping devices of any kind can be employed..
In this case a brake apparatus is firmly connected with the axis, in such a manner
that by applying this brake one machine element will be firmly held by means of
the axis, so that its tractive power serves for driving the axis. This arrangement
corresponds to the principle of friction couplings, in which the carrier device is
likewise fixed upon the shaft, whereas the pulley to be carried away must first be set
in motion by applying the coupling. The other machine element is then actuated by
a brake apparatus secured to the carriage or truck frame and independent of the
driving axis.
In case the armature and field magnet are to be mounted directly upon the axle of
a vehicle, it is advisable, in order to obviate the direct thrust, to employ elastic
intermediate parts. In order to let the armature and field magnet run in opposite
directions, a changed admission of the current to the arinature is sufficient.
By the arrangement in which both armature and field magnets turn in the working,
namely in opposite directions, the number of revolutions of the dynamo is, under
otherwise equal conditions, reduced to one half.
It is therefore rendered possible by this construction to drive direct with slower
moving shafts or axles such as occur in tramway working by comparatively small
dynamos with a high useful effect.
Not less important is the arrangement in which dynamos are driven by a shaft with
different velocities, as is for example the case in electric railway train lighting, if the
dynamo is connected with an axle of a vehicle. If then this construction is chosen,
the electric potential can be kept at an equal height between wide limits with different
velocities of the motion of the vehicle by regulating the armature and field magnet
element in its rotary velocity by the application of the brake, or, if both are arranged
movably upon the axle, the two can be controlled in their rotary velocity by applying
the brake.
For the aforesaid arrangements most of the existing dynamos can be used with
some constructive changes; that construction however is most suitable in which both
the armature and the field magnet have the ring form. If in the latter case both
these are formed symmetrical, upon the armature as well as the field magnet can be
obtained a very considerable difference in the effect and rotary velocity by displacing
the brushes.
In the accompanying drawing the principle of construction is indicated for one form
of the improved dynamo.
Upon the axle a are the two parts the field magnet b being fixed and the armature c
movable; the latter can turn upon the axle at will by means of the bearing d. At
one point upon the nave e, of the armature is arranged a fixed brake device f. By
applying this brake device the motion of the armature c is controlled, as above
described. If the field magnet is made movable also, the brushes would have to
rotate.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
--
First. The construction of the armature and field magnet of a dynamo electric
machine with a shaft or axle to be driven, in such a manner that either the armature
or the field magnet is rigidly connected with the shaft or axle, whilst the other can
turn thereon but is controlled in its movement by a brake, coupling or other stopping
device, or in such a manner that both the armature and the field magnet are arranged
movably upon the shaft to be driven but are controlled in their motion by brakes on

page_text: couplings or stopping devices either from the shaft or independently of the said
shaft.
Second. The arrangement in which the armature and field magnet turn in opposite
directions during the working, and thereby require to be run, with given machines
and with equal circumferential velocity with only half the number of revolutions.
Third. In a dynamo-electric machine driven by a rotary shaft or axle the reverse
of the construction described in the first and second claim, for the purpose 1st of
keeping the electric potential constant with a changing velocity of the axle or shaft,
and 2nd of reducing the number of revolutions of the dynamo-electric machine.
Fourth. In the combination above described the employment of the armature and
field magnet in a symmetric form in order to obtain by the displacement of the brushes
a great difference in the effect and in the rotary velocity or generation of current.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.