MEN IN DYNAMO-ELECTRIC MACHINES
Year: 1883

page_text: PROVISIONAL SPECIFICATION left by the said William Morris Mordey at
the Office of the Commissioners of Patents on the 15th September 1883.
WILLIAM MORRIS MORDEY of Putney in the County of Surrey
MENTS IN DYNAMO-ELECTRIC MACHINES
"2
"IMPROVE-
My invention relates to improvements in the construction of dynamo-electric
machines and has reference principally to a novel construction of armature more
particularly applicable to machines having armatures in the form of a flat ring or
ring-disc but also applicable to other types of dynamo-electric machines.
Flat ring or ring-disc armatures as hitherto constructed have been usually built
up of a number of iron plates or discs placed side by side, and connected by brass
or other metallic nonmagnetic bolts or rivets and washers. The use of such non-
magnetic connections has been customary on the supposition that the rapid change
in the magnetic condition of the iron of the armature was the principal cause of
licating of the same. The heating however is mainly due to Foucault currents, the
developement of such currents and the consequent useless absorption of power
being largely favored by the presence of the above-mentioned bolts or rivets and
washers, which with the iron plates form closed electric circuits.
One of the objects of my invention is to diminish heating of the armature by
separating the plates electrically as well as magnetically. For this purpose I
construct one form of my improved ring-disc armature for a dynamo machine as
follows:-
A number of thin iron rings, discs or plates are placed side by side, and connected
by means of brass or other non-magnetic bolts or rivets passing through tubes or
bushes, of suitable insulating non-inagnetic material such as wood. Washers of an
insulating substance, mica being a suitable material, surround the bushes and bolts
and are interposed between the rings, discs or plates for the purpose of slightly
separating them from each other, thus leaving air-spaces between the plates. To

page_text: facilitate air circulation through these spaces I sometimes drill holes thro' the
rings, discs, or plates at intervals leaving these holes open to the external air.
Where the size of the armature is such that sufficient strength can be obtained
without the above mentioned metallic bolts or rivets screwed bolts of lignum vite
or other dense unyielding nonconducting material may be substituted for them.
The armature core is wound with numerous coils of wire in such a manner that
the convolutions of each coil are nearly or quite parallel to each other and the
centre convolution of each coil is radial, the coils being close together at the inner
periphery of the ring but slightly separated towards the outer periphery. For tho
purpose of supporting the coils and for convenience of winding I fix pegs of wood
or other suitable insulating material through the ring disc near its outer circum-
ference, so that they project from the sides of the ring-disc, and are flush with the
outer surface of the coils. When the winding is complete it is sometimes
convenient to withdraw the pegs and take advantage of the holes to obtain
increased air circulation.
By the above described construction the iron of the core is laminated and the
rings, discs cr plates are electrically insulated in planes at right angles to the axis
of the ring.
In cases, however, in which the field magnet pole pieces act directly
on the sides of the armature as well as on its periphery it is necessary in order to
most effectually check the generation of Foucault currents that the lamination of
-the iron should be principally parallel to the axis of the armature; that is to say
the division of the iron should be chiefly at right angles to and perpendicular to
the wire passing over the sides of the core. Under such conditions I sometimes
construct the core of the armature of a number of thin rings, hoops or cylinders of
soft iron whose width is equal to the length or thickness of the core (except near
the periphery where the rings, hoops or cylinders are made a little narrower) and
constructed of graduated diameters. These are built up into an armature core by
arranging them concentrically one within the other with a small space separating
each ring, hoop or cylinder from the adjacent ones. The separation is effected by
suitable insulating material such as mica. This insulating material may be applied
in the form of rings or it may be (and I prefer that it should be) applied in the form
of slips placed at intervals thus leaving air spaces between the rings to facilitate
cooling. A convenient method is to use the insulating material in the shape of
washers surrounding the bolts by which the rings, hoops or cylinders are retained
in their relative positions and by which the armature core is mounted on the hub.
The method of mounting is as follows:-A hub of brass, gunmetal or other
suitable metal or alloy is fixed into the core by bolts passing through holes drilled
radially through the group of rings, hoops or cylinders and screwed into the arms
of the hub, the outer ends of the bolts being inade flush or nearly so with the
periphery of the core.
To prevent the bolts from electrically connecting the various hoops, rings or
cylinders the holes through which they pass are fitted with bushes or tubes of a
dense unyielding, nonconducting material, lignum vitæ being a suitable substance.
I also fit the core with projecting pegs for the purpose of separating and supporting
the coils near the periphery and for convenience of winding as in the armature
previously described.
Sometimes I make the armature of two or more sets of rings or hoops built up
as above and placed side by side with a slight air space or sheet of suitable
insulating material, such as asbestos paper between then.
Although the above described armatures may be used with two magnetic field-
magnet poles, I prefer to employ some multiple of two depending on the size of
the armature and these field-magnet poles which are alternately N and S I groove
or hollow out to a U shaped cavity for the purpose of enabling them to act directly
on the sides as well as the periphery of the ring-disc, thus almost the whole of the
wire on the armature is exposed directly to strong magnetic influence and is utilised
to the fullest extent.

page_text: When the field magnets are a multiple of two the armature is connected and the
commutator constructed in the manuer described in my patent No 400 of 1883
according to which I am enabled to use two brushes only, however many poles
I employ. If the commutator be outside the bearing I reduce the number of leads
necessary to be brought through the shaft or sleeve bearing of the commutator to
one half in the case of the use of four poles; one third for six poles; one quarter
for eight poles and so on. Thus I am able to keep the bearing within moderate
dimensions.
I would have it understood that the term "dynamo-electric machines" includes
both electric generators and motors, and that in exciting the field magnets I do not
limit myself to any particular method.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Morris Mordey in the Patent Office on the 15th March
1884.
WILLIAM MORRIS MORDEY, of Putney, in the County of Surrey IMPROVE-
MENTS IN DYNAMO ELECTRIC MACHINES
In an improved dynamo electric machine according to my invention I build up
the core of the armature, which according to my invention is of the ring disc type
of a number of plates separated from one another by non-conducting material, I
not only separate the parts forming the core of the armature magnetically but also
electrically and to this end I insulte all the bolts or rivets by which the said parts
are connected together or I form them of non-conducting material, and thus I
obviate to a great extent the generation of Foucault or eddy currents
Fig 1. is an elevation of the partly wound core of the armature showing 4 poles.
Fig 2 is a section of the same.
Fig 3 is an elevation partly in section of the ring or hoop armature with hub.
Fig 4 is a section, shewing detail view of armature core, and the attachment to
the hub.
Fig 5 is a section shewing a ring having two sets of hoops.
A number of thin iron di-cs or plates a. a Figs 1 and 2 are placed side by side
and connected by means of brass or other non-magnetic bolts or rivets b. b passing
through tubes or bushes c. c of wood or other suitable insulating non-magnetic
material. The bushes and bolts pass through washers d. d of an insulating
substance (mica being a suitable material) for the purpose of slightly separating
the plates from each other thus leaving air spaces between the plates. To
facilitate air circulation through these spaces I sometimes drill holes e. e through
the ring disc at intervals leaving these holes open to the external air. The use of
metallic bolts or rivets b. b. which are used only for strength may be dispensed with
where the size of the armature is such that sufficient strength can be obtained
without them, and screwed bolts of lignum-vite or other dense unyielding

page_text: non-conducting material may be substituted. The armature core is wound with
numerous coils of wire in such a manner that the convolutions of each coil ff (Fig 1)
are nearly or quite parallel to each other but the centre convolution of each of the
coils is radial the coils being close together at the inner periphery of the ring, but
slightly separated towards the outer periphery. For the purpose of supporting the
coils and for convenience of winding I fix pegs g. g of wood or other suitable
insulating material through the ring disc near its outer circumference, so that they
project from the side of the ring disc, and are flush with the outer surface of the
coils. Sometimes after the winding is completed I withdraw these pegs thus
availing myself of the holes to obtain increased air circulation
It will be seen on reference to Figs 1 and 2 that the iron is laminated and the
plates are electrically insulated in planes at right angles to the axis of the ring.
As however the field magnet pole pieces P. P. as shewn in the drawings are
constructed to act directly on the sides of the armature as well as on its periphery
it will be observed that to most effectually check the generation of Foucault or
eddy currents in the core of the armature when the machine is of the construction
here illustrated the lamination of the iron should be principally parallel to the axis
of the armature; that is to say, the division of the iron should be chiefly
perpendicular to the wire passing over the side of the ring disc. For these reasons
I sometimes construct the armature as shewn in Figs 3, 4 and 5. A number of
thin rings or hoops of soft iron h. h whose width is the thickness of the ring disc
(except near the periphery, where the rings are made a little narrower) are
constructed of graduated diameters. These are built up into a ring disc by
arranging them concentrically one within the other with a small space separating
each ring or hoop from the adjacent ones. The separation is effected by suitable
insulating material such as mica. This insulating material may be in the form of
rings or it may be (and I prefer that it should be) merely in the form of slips
placed at intervals thus leaving air spaces between the rings or hoops to facilitate
cooling. A method I find convenient is shewn in Figs 3, 4 and 5 where the
washers i. i surrounding the bolts k. k. are the separating pieces. The ring disc so
constructed is mounted in the following manner. A hub of brass gun-metal or
other suitable metal or alloy is fixed into the ring disc by bolts k. k passing through
holes drilled radially through the group of rings or hoops, and screwed into the
arms of the hub, the outer ends of the bolts being made flush or nearly so with the
periphery of the ring disc. To prevent the bolts from electrically connecting the
various hoops of the ring disc the holes through which they pass are fitted with
bushes or tubes 1. 1 of a dense unyielding non-conducting material, lignum vitæ
being a suitable substance. I also fit the ring disc with projecting pegs g. 9 for
the purpose of separating and supporting the coils near the periphery and for
convenience of winding as in the armature shewn in Figs 1 and 2. Sometimes I
make the armature of two or more sets of hoops built up as above and placed side
by side as shewn in Fig 5 with a slight air space or sheet of suitable insulating
material such as asbestos paper between them.
Although the above described armatures may be used with two magnetic field
magnet poles, I prefer to employ some multiple of two depending upon the size of
the armature. Fig 1 shews the arrangement of four field magnet poles about such
a ring disc armature these poles being alternately of N. and S. polarity and
grooved or hollowed out to a U shaped cavity for the purpose of enabling them to
act directly on the sides as well as the periphery of the ring disc-Thus almost the
whole of the ring is exposed to strong magnetic influence and is utilized to the
fullest extent.
When the field magnets are a multiple of two the armature is connected and the
commutator constructed in the manner described in my patent N° 400 of 1883
according to which I am enabled to use two brushes only however many poles I
employ. If the commutator be outside the bearing I reduce the number of leads
necessary to be brought through the shaft or sleeve bearing of the commutator to
one half in the case of the use of four poles; one third for six poles; one quarter

page_text: for eight poles and so on.
dimensions.
Thus I am able to keep the bearing within moderate
I would have it understood that the term "dynamo electric machines" includes
both electro generators and motors and that in exciting the field magnets I do not
limit myself to any particular method.
Having described the nature of my said invention and the manner of carrying
it into practical effect I desire it to be understood I do not claim generally the
building up of a ring armature of thin iron rings with separating slips or washers,
of non-conducting material, but what I do claim as of my invention is :-
1. The improved compound ring disc armature wherein the compound annulus
or ring disc is larger in cross section in a direction at right angles to the axis of
the armature than it is in a direction parallel with the said axis the coils being
separated and supported by means of pegs of non-conducting inaterial as shown in
and described with reference to Figs 1 and 2 of the drawings.
2, In a compound ring disc armature, the use of pegs of non-conducting material
such as wood for separating and supporting the coils substantially as described.
3, In a compound ring disc armature forming the compound disc with a number
of hoops arranged concentrically one within another and insulated from each
substantially as described with reference to and illustrated in Figs 3, 4 and 5 of
the drawings.
In Witness whereof I the said William Morris Mordey have hereunto set my
hand and seal this fourteenth day of March in the year of Our Lord one thousand
eight hundred and eighty-four.
W. M. MORDEY. (L….S.)