Improvements in or relating to Dynamo Electric Machinery.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Improvements in or relating to Dynamo Electric Machinery.
We, P. R. JACKSON & COMPANY, LIMITED, and JOSEPH SLATER LEWIS, both of
Salford Rolling Mills, Manchester, in the County of Lancaster, Engineers, do
hereby declare the nature of this invention to be as follows:-
Our invention relates to dynamo electric machinery, and comprises an improved
construction of commutator for use in direct current dynamos and motors, and
also an improved construction of field magnets for dynamos and motors having
four or a greater number of poles.
In constructing our improved commutator the blades or segments preferably
with the radial strips attached are arranged in position with insulation between.
They are then forced together by any suitable means so as to form a rigid
cylinder. Insulation is then placed round the ends of the bars over a rebate
formed on the external periphery, and a steel or iron ring of the proper size is
shrunk on at each end of the cylinder. It may be desirable in some cases to
roll or press down the rings when in position and whilst hot in order that they
shall grip the ends of the bars more securely. Instead of heating the rings and
allowing them to cool after being placed in position we may employ for securing
the same a method similar to that now well known for setting wheel tyres in
the cold state by means of hydraulic rams arranged outside the tyre. After
the rings have cooled or have been sufficiently compressed, the primary restrain-
ing and compressing means are removed, the segments being kept securely in
place by the rings at each end. In order to secure the commutator in position
on the dynamo spindle we may proceed as follows:-
A shoulder is turned upon said spindle, and a collar is then fitted on, abutting
against said shoulder. This collar has an overhanging lip, forming an annular
groove, adapted to receive the ring at the end of the commutator which is now
slipped into position, and a second collar, similar to that above mentioned, is
placed at the other end thereof. A nut screwed on the end of the dynamo
spindle abuts against the second collar so that the commutator is tightly clasped.
between them, the pressure acting through the rings at the ends of the bars.
In a modification we employ rings having one or more transverse saw cuts so
that they may be sprung on to or placed in position on the ends of the com-
mutator bars. The outer periphery of each ring may be made tapered and a
corresponding taper formed inside the annular groove of each collar so that
when the two collars are forced together the rings are radially compressed on the
ends of the bars or segments. This tapering of the rings and collars may also
be employed when the rings are shrunk or compressed as herein before described.
The segments may be connected with the armature coils in any suitable
manner. We prefer, however, to use for this purpose radial strips which are
secured to the segments before the latter are assembled in the manner following,
that is to say: At or near the end of the segment a groove is milled out
approximately half through the segment, and of a width corresponding to that
of the radial strip. The radial strip to be secured to the segment is also milled
or drawn or exuded or cast to the required section, with a transverse groove near

page_text: its end to fit the groove in the segment, and the two are sweated or brazed
together at the half joint. It will be observed that by reason of the groove in
the strip being made at a little distance from the end of the same
a hook
is formed which engages with the commutator segment which prevents the strip
from being withdrawn radially without actual breakage, after the commutator
has been made up.
Our improved method of constructing field magnets is applicable only to four
pole or multipolar machines in which the magnet cores and pole
pieces project from the inner periphery of a ring. According to
our invention we cast the magnet cores and pole pieces in one
casting preferably in steel, the cores being connected by segments of an annulus
at their outer ends, and the pole pieces being connected together at their tips, so
that a good casting is very readily obtained. The casting is now machined at
the parts required, has the "headers" cut off and the central hole turned out
truly to suit the armature; and it will be observed that the machining, being
accomplished in the lathe or other special machine tool can be done very cheaply.
After this is finished the magnet cores still connected as in the casting are placed
within the ring to which they are to be secured, and the holes drilled and bolts
fitted for securing them in place in said ring. We further provide two gun
metal rings, preferably in halves, of suitable diameter to fit a groove provided
in the outer ring of the field magnet and also the edges or flanks of the pole
pieces. These rings are also drilled, and the bolts fitted for securing them to
the pole pieces and to the outer ring. The several parts are then marked so
that they can be readily put together again. The casting is then divided at
the proper places between the pole pieces, the spans of the polar faces cut down
to their proper limits, and the outer segments of the annulus connecting the
cores cut away. The cores and poles are then secured to the gun metal rings,
and the magnet coils slipped into position, and the electrical connections between
the field magnet coils are made, after which the whole can be lifted into position
in the outer ring of the field magnet. By this construction we not only secure
an accurate fit between the several parts composing the field magnet, but this
is done with a minimum of cost for "fitting" because a greater part of the
machining is done in the lathe, and furthermore very little time need be spent
on finishing the coils, and making the connections neatly, since all this portion
of the work is hidden or partially so if desired by the gun metal rings. These
rings not only serve to cover up or partially cover up the coils and connections
but also are very useful in steadying and checking noise and vibrations due to
magnetism and in assisting to support the cores and poles at their proper dis-
tances from each other. For convenience in dismembering the field magnets the
outer ring is preferably made in halves secured together by bolts.
We prefer to machine the annular recesses on the internal surface of the said
outer ring to receive the ends of the cores in order to prevent the same shifting,
but this is not absolutely necessary.
Improvements in or relating to Dynamo Electric Machinery.
We, P. R. JACKSON & COMPANY, LIMITED, and JOSEPH SLATER LEWIS, both of
Salford Rolling Mills, Manchester, in the County of Lancaster, Engineers, do 5

page_text: 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 follow-
ing statement:—
Our invention relates to dynamo electric machines and motors, and comprises
an improved construction of commutator for use in direct current dynamos and
motors and also an improved construction of field magnet for dynamos and motors
having four or a greater number of poles..
Our invention is illustrated in the accompanying drawings which we will now
describe.
Figure 1 is a side elevation partly in longitudinal section illustrating our
improved construction of commutator.
Figures 2, 3 and 4 are similar views illustrating modifications.
Figure 5 is a portion of a section on the line a-, Figure 2, looking in the
direction of the arrow, shewing our preferred method of connecting the com-
mutator segments to the radial bars.
Figure 6 is an end elevation partly in section illustrating the field magnet of a
four pole machine constructed in accordance with our invention.
Figure 7 is a section on the line y-y Figure 6.
Figure 8 is an end elevation of a casting from which we construct the cores
and pole pieces of the magnet.
Referring now to Figures 1 and 2, the commutator blades or segments are
indicated at 1 and the radial strips connecting the blades or segments with the
ends of the armature conductors are shewn at 2. In constructing our improved
commutator the blades or segments with the radial strips attached are assembled
in position with insulation 3 interposed between adjacent segments. They are
then forced together by clamps or any other suitable means so as to form a rigid
cylinder. The ends of the blades are formed with a rebate over which insula-
tion 5 is placed and then a steel or iron ring 6 is heated and shrunk on to each
end of the cylinder. After said ring has cooled the clamps or primary restrain-
ing and compressing means are removed, the segments of the commutator being
secured in place by the rings aforementioned at each end. In order to secure
the commutator in position on the dynamo spindle we proceed as follows:-the
spindle 7 has a shoulder 8 formed thereon and a collar 9 is provided abutting
against said shoulder. The collar has an overhanging lip 11 forming an
annular groove which is adapted to receive the ring 6 on the end of the com-
mutator when the latter is slipped into position as shewn.
A second collar 12, similar to the collar 9, is now slipped over the ring at
the other end of the commutator, and a nut 13 engaging with a screw thread 14
is screwed tightly against the collar 12 forcing the same along the spindle so
that the commutator is tightly clasped between them, the pressure acting through..
the rings at the ends of the commutator segments. In a modification we employ
rings having one or more transverse saw cuts so that they may be sprung on to
or placed in position on the rebates at the ends of the commutator segments.
The outer periphery of each ring may be made taper, and a corresponding taper
formed inside the annular groove of each collar so that when the two collars are
forced together the rings are radially compressed on the ends of the bars or seg-
ments. This tapering of the rings and collars may also be employed when the
rings are shrunk or compressed as hereinbefore described. A thin metal ring 6"
is sometimes placed behind the taper rings in order that buckling of the insulat-
ing ring may not take place when the taper ring is being forced home. The
thin ring is placed next to the insulation and the taper ring slides upon it as
it is compressed.
In the modification shewn in Figure 2 the two collars are pulled together by
means of bolts 40 passing between the shaft and the inside of commutator as
shewn. By key-ways and keys expansion and contraction of the commutator is
provided for, and the commutator may be built up before it is placed on the

page_text: shaft. In some cases we build up the commutator on a sleeve formed by an
extension of one of the collars, as shewn for example in Figures 3 and 4.
The radial strips 2 which connect the commutator segments with the arma-
ture conductors are preferably secured to the segments before the latter are
assembled, in the manner following, that is to say, at or near the end of each
segment a groove approximately at right angles with the segment is milled out
about half through the segment and of a width corresponding to that of the
end 15 of the radial strip 2. The radial strip to be secured to the segment is
also milled or drawn or exuded or cast to the desired section with a transverse
groove near its end as shewn in Figure 2 to fit the groove in the segment and
the strips and segments are secured together by sweating or brazing at the half
joint. It will be observed that by reason of the groove in the strips being made
at a little distance from the end of the same a hook is formed which engages
with the commutator segment and effectually prevents the strip from being with-
drawn radially without actual breakage of the commutator.
We will now refer to Figures 6 to 8 which illustrate our improved construction
of field magnet as applied to a four pole machine, it will be understood, however,
that the same method is applicable for constructing multipolar machines in which
the magnet cores and pole pieces project from the inner periphery of the ring.
The ring as shewn in Figure 6 is formed of halves 16, 17 secured together by
bolts 29, the lower half being provided with suitable projecting wings 301 by
which it may be secured to the foundations or to the rails supporting the
machine. The magnet cores, four in number in the present instance, are indi-
cated at 18 and the pole pieces at 19.
According to our invention we cast the four magnet cores 18 and the pole
pieces 19 in one casting preferably in steel an end elevation of which is shewn
in Figure 8 and in such manner that the pole-pieces are connected together at
their tips. The casting is machined at the parts required, the "headers" are
cut off, and the central hole 21 bored out truly to suit the armature. After this
is finished the pole pieces still connected as shewn in Figure S are placed between
the outer magnet yoke or rings 16 and 17 and holes are drilled and the bolts 25
are fitted for securing said cores in place. At the same time two gun-metal
annular plates 26 preferably in halves are fitted as shewn in Figure 4 at each
end so as to enclose the magnet cores and poles pieces, said plates may be pro-
vided with orifices or slots to permit of ventilation. The bolts 27 for securing
these in place are screwed into the pole pieces and into the outer ring as shewn.
It is obvious that the gun-metal plates 26 may take various forms and be fitted
and secured in several different ways, all of which fall within the scope of our
invention. The carcase is now taken to pieces the several parts being marked
before so doing so that they can be readily put together again and the casting is
divided at the proper points between the pole pieces 19, the spans of the polar
faces cut down to their proper limits and the polar tips shaped to the required
section. The cores and poles are now secured to the gun-metal rings or plates 26
by the bolts 27. The coils 28, which may be previously wound upon formers,
are slipped into position on the cores when electrical connection between the
field magnet coils are made, and the whole lifted into position between the
halves 16, 17 of the outer ring and secured there by the bolts 25, the two halves
being fastened by the bolts 29. By this construction we not only secure an
accurate fit between the several parts composing the field magnet, but this is
done with a minimum of cost for "fitting" because a greater part of the
machining is done in the lathe. Furthermore, very little time need be spent
on finishing the coils, and making the connections, since all this portion of the
work is hidden or partially so if desired by the gun-metal rings. These rings
not only serve to cover up or partially cover up the coils and connections, but
also are very useful in steadying and checking noise and vibrations due to mag-
netism and in assisting to support the cores and poles at their proper distances
from each other.
•

page_text: We prefer to machine the annular recesses on the internal surface of the said
outer ring to receive the ends of the cores in order to prevent the same twisting
in their seats, but this is not absolutely necessary.
Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that what
we claim is:―
1. A commutator in which the segments are held in position by means of rings
shrunk on or cut rings, held in annular grooves in collars secured to the shaft at
each end of the commutator, and with or without thin rings such as 6ª, located
between the first mentioned rings and insulation at the end of the segments.
2. Securing a commutator to its shaft by means of keys which allow the com-
mutator to move freely endwise on the shaft, but not to rotate relatively thereto,
substantially as and for the purpose specified.
3. The connection of the commutator segments to radial strips, substantially
in the manner described with reference to Figure 5 of the drawings.
4. In a multipolar dynamo electric machine, a field magnet comprising an
outer magnet ring, inwardly projecting radial cores with pole pieces secured to
the same, and annular plates of non-magnetic metal secured to the rings and
pole pieces, so as to partially or entirely cover in the magnet coils.
5. Commutators constructed substantially as described with reference to either
of Figures 1, 2, 3 and 4 of the accompanying drawings.
Dated the 11th day of October 1898
W. P. THOMPSON & Ca,
322, High Holborn, London, W.C., Patent Agents for the Applicants.