AN IMPROVED DYNAMO ELECTRIC MACHINE
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by Archibald Campbell Elliott at the
Office of the Commissioners of Patents on the 17th October 1882.
ARCHIBALD
CAMPBELL ELLIOTT of N° 71 Queen Street, Cheapside in the
County of Middlesex Civil Engineer "AN IMPROVED DYNAMO ELECTRIC
MACHINE"
My invention is an improved dynamo electric machine which may be used either
to transform mechanical energy into electric currents or to convert electric energy
into mechanical work.
This dynamo electric machine is constructed so that no magnetic changes or
reversals occur in any part of the machine after it has assumed a constant speed of
rotation; its form is such as to admit of the electrical resistance being reduced to
I am
a very small amount; and every portion of tlie magnetic field is effective.
also enabled to dispense with the use of commutators and brushes. These conditions
secure great efficiency.
The rotating part of my improved dynamo is almost wholly of iron. It is built
up of soft iron bars or segments laid round the shaft with their edges parallel to
the axis of rotation; they are insulated from each other by layers of insulating
material and held together with collars and bolts. These bars or segments are
generally shaped so that at their two ends they project in planes perpendicular to
the axis; the rotating part has then externally the shape of a cylinder with flanges
at each end. Through the axis of the cylinder passes the shaft which is mounted
horizontally or vertically in suitable bearings.
Round the middle of the cylinder or part of small diameter is wound a stationary
coil of insulated conductor which when a current traverses it magnetizes the rotating
part, which for brevity may be called a cylinder, causing the ends of all the bars
forming one of the flanges of the cylinder to assume a north and the ends of all the
bars forming the other flange a south polarity.
The flanges or projecting ends of the cylinder are completely enveloped in a
system of insulated conductor the parts of which are so connected and arranged
that the currents are all flowing in planes passing through the axis of rotation and
all in directions either from a plane passing through the middle of the cylinder
perpendicular to the axis, over the flanges towards the centres of the ends from which

page_text: the shaft issues; or all in the reverse direction. according to the direction in which
the current is supposed to flow.
The enveloping system of insulated conductor may be of insulated copper wire
or strip copper partly with air insulation and for some purposes I may employ
sheet copper properly stamped or shaped. In general it is necessary to couple sets
of these conductors together and these coupling conductors are arranged so that
the currents flowing through them tend to increase the efficiency of the machine or
when that is not possible carried round at distances from the active conductors
great enough to make the evil effect unappreciable; or I may neutralize such currents
by passing them through soft iron tubes.
The enveloping system of conductors aro connected either in series or in parallel
circuit with the fixed exciting coil for the rotating cylinder and the two free ends
connected to the terminals of the machine.
I may modify the design by permitting the coil exciting the rotating cylinder to
revolve with it; but in that case rubbing contacts would have to be employed
Another modification of the invention is the imagneto-electric analogue in which
the coil set apart to magnetize the rotating cylinder would be dispensed with and
the cylinder constructed' of permanently magnetized bars,