Improvements in Alternating-current Dynamo-electric Machines.
Year: 1896

page_text: Date of Application, 14th July, 1896-Accepted, 26th Sept., 1896
COMPLETE SPECIFICATION.
Improvements in Alternating-current Dynamo-electric Machines.
1, HOWARD BLAIN LITTLE, of 36 Shaftesbury Avenue London in the County
of Middlesex, Electrician, do hereby declare the nature of this invention, and in
what manner the same is to he performed, to be particularly described and
ascertained in and by the following statement:--
My invention relates to alternators by means of which certain advantages are
obtained.
The object of my invention is to render the armature coils readily accessible and
capable of being easily and rapidly removed for alteration and substitution when
required.
In order that my said invention may be readily understood I shall now proceed
to describe it with reference to the accompanying drawings which illustrate, by
way of types or examples, two forms of my said invention. In the said drawings
similar letters of reference indicate similar or equivalent parts.
Figure 1, is a general view, partly in elevation and partly in section, of a well
known type of alternator and having the improvements constituting my invention.
Figure 2, is a perspective view of one of the detachable core parts.
Figure 3, is a plan view of one of the said core parts, with the coil shown in
position.
Figure 4, is a cross section through the armature and field magnet showing the
shell of the armature and the shaft of the machine.
Figures 5 and 6 illustrate a form of machine in which the armature rotates within
the field instead of the field rotating within the armature.
Figure 5, is a cross section showing the armature core and sustaining cheeks.
Figure 6, is an elevation of the same shown partly in section.
Alternators of the type shown are so well known that it is unnecessary for me to
refer to them further than by mere indication, except in so far as it is necessary to
show in what respects my invention differs from other known constructions.
In alternators of the type shown it has been the custom to form the armature
core plates with grooves or trough shaped recesses or with tunnels, in which the
wire of the coil is laid or threaded. In these cases an injured coil cannot be av
once removed and replaced by a new one.
It has also been customary to make the detachable core sections of the shape of
truncated cones when seen in section, contiguous core sections being placed either
in actual contact with one another or so close together as to reduce the resistance
of the magnetic circuit to the lowest possible limit, the said magnetic circuit, in so
far as the armature (whether fixed or rotating) is concerned, being through the
iron plates of the detachable core sections.
In my invention I adopt such an arrangement and construction of parts that my
armature coils, previously formed on a frame or former, as is well understood, can
be slipped over or removed from the detachable core-parts with the greatest ease.
Referring now to the figures, A is the shaft of the dynamo upon which is
mounted the inducing system B, magnetised by the single coil C. N and S are
respectively the north and south poles.
The induced system consists of a non-detachable core-part D of annular form
built up of thin soft iron plates and forming a part of the induced magnetic circuit,
a number of detachable core-parts E placed radially, and also built up of thin soft
iron plates and forming a part of the induced magnetic circuit, and a number of
armature-coils F adapted to be readily slipped over the detachable core-parts E.

page_text: The detachable core-parts and the non-detachable core-part are brought into
close contact at the line G (see Figure 4). The non-detachable core part is
enclosed in the shell H consisting of the two parts I and J fastened together by
the bolts K and the bolts. L.. The latter also serve to secure the plates of the
non-detachable core-part together. M and P are the two cheeks which when
attached together by the bolts Q retain the plates of the detachable core-parts in
position. The plates of the detachable core-parts and of the non-detachable core-
part are maintained in close contact by means of the bolts R, R passing through
orifices o (see Figure 2) in the flanges i, m and j, p.
Reference to Figures 2 and 3 will show how the coil F fits over the detachable
core-part E. The coil is passed from above downwards till it rests upon the
flanges e of the detachable core plates so as to occupy the position shown in
Figure 3. The detachable core section with its coil is then lifted into the position
shown in Figure 4 and fastened by means of the bolts R.
When it is desired to replace the coil F by a new one all that has to be done is
to remove the bolts R, R, pull out the detachable core section, lift off the old coil,
press the new one down into its place, slide the core section with its new coil
back into the position shown in Figure 4 and then fasten it up by means of the
bolts R.
It is equally easy to remove and replace the coils from the removable cure
sections in the case of a machine with an internal armature as will be understood
from a consideration of the form shown in Figures 5 and 6. In these figures D' is
the non-detachable core-part, E¹ the detachable core-part, F' the armature coil,
G' the meeting line of the plates of the detachable core-parts and those of the
non-détachable core-part, I and J the cheeks of the shell embracing the plates of
the non-detachable core-part D', L' the bolts holding these plates and cheeks
together, M and P₁ the cheeks which hold the plates of the detachable core-
parts E together by means of the bolts Q and R', R' the bolts passing through
the flanges i, m! and j, pl so as to keep the plates of E' and D' in close contact.
To replace a coil on this form of machine, all that requires to be done is to
remove the bolts R', pull out the detachable core part E, turn it upside down, lift
off the old coil, press down the new coil into the position formerly occupied by the
old coil, turn the detachable core-part right side up again, slide it back into position,
and fasten there by the bolts R¹.
It will be seen that in my invention I do not employ grooves or tunnels, and
that the plates of the non-detachable core-part form a part of the magnetic circuit
of the armature as well as the plates of the detachable core-parts.
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-
1. In the armature of an alternator the employment of detachable core-parts
substantially as set forth.
2. In the armature of an alternator the combination of a non-detachable core-part
and a number of détachable core-parts substantially as set forth.
3. The arrangement and combination of parts substantially as set forth with
reference to Figures 1 to 4 inclusive.
4. The arrangement and combination of parts substantially as set forth with
réference to Figures 5 and 6.
. Dated this 16th day of June 1896.
HOWARD B. LITTLE,
Per J. G. Lorrain, M.I.E.E., M.I. Mech. E.,
Norfolk House, Norfolk Street, Stränd, London, W.C.,
Chartered Patent Agent.