Improvements in Commutators for Dynamo Electric Machines and Motors.
Year: 1892

page_text: Date of Application, 14th Apr., 1892
Complete Specification Left, 8th Sept., 1892-Accepted, 17th Dec., 1892
PROVISIONAL SPECIFICATION.
Improvements in Commutators for Dynamo Electric Machines
and Motors.
We, BUCHANAN STEWART PATERSON, of Victoria Works, Gateshead-on-
Tyne, in the County of Durham, Electrical Engineer, and JOHN BROKENSHIRE
FURNEAUX, of Victoria Works, Gateshead-on-Tyne, aforesaid, Mechanical
Engineer, do hereby declare the nature of this invention to be as follows:-
This invention has reference to the construction of commutators for dynamo
electric machines. The strips of mica now commonly employed to insulate
longitudinally the metal strips of commutators are usually held together by lipped
flanges and rings, between which and the various strips there are interposed layers
of comparatively soft material such as asbestos, box-wood, vulcanized fibre, or
compressed paper; consequently any sections of the commutator receiving an
accidental blow have been liable to become sunk below the circumference of the
commutator. This has been found to occur for instance when putting armatures
into machines where no proper lifting means have existed; if under these
circumstances the armature has happened to be slung by the commutator, the
great weight of the core has sometimes been sufficient to force the segments out
of truth.
Furthermore the materials ordinarily employed as above set forth are all liable
to change form and to contract by heating, consequently although by proper baking
in an oven the insulation resistance could be made very high, it would drop enormously
as the result of exposure to moisture.
Now in order to obviate the evils above indicated, according to this invention
annular grooves are formed in the flange and ring on the commutator core or body
between which the metal strips and insulating strips of the commutator are
arranged; in the ends of the annulus of strips corresponding grooves are formed,
and in these grooves are inserted keys made of mica; they may be composed of
rectangular pieces of mica placed radially in the key ways or a key may be made
of strips of mica placed circumferentially. Between the ends of the commutator
strips (metal and mica) and the flange and ring are interposed washers that are also
made of mica.
Commutators constructed with mica keys as described will be found exceedingly.
strong and even able to resist blows without the solidity of the mica being seriously
affected; furthermore the construction described presents manufacturing facilities
and affords high insulation resistance even when the commutator is damp.
W. LLOYD WISE,
Per F. J. Brougham,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicants.

page_text: .
.
:
COMPLETE SPECIFICATION.
Improvements in Commutators for Dynamo Electric Machines
and Motors.
We, BUCHANAN STEWART PATERSON, of Victoria Works, Gateshead-on-
Tyne, in the County of Durham, Electrical Engineer, and JOHN BROKENSHIRE
FURNEAUX of Victoria Works, Gateshead-on-Tyne, aforesaid, Mechanical Engineer,
do 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 following
statement:—
This invention has reference to the construction of commutators for dynamo
electric machines. The strips of mica now commonly employed to insulate longi-
tudinally the metal strips of commutators are usually keyed together by lipped
flanges and rings, between which and the various strips there are interposed layers
of comparatively soft material such as asbestos, box-wood, vulcanized fibre, or
compressed paper; consequently any sections of the commutator receiving an
accidental blow have been liable to become sunk below the circumference of
the commutator. This has been found to occur for instance when putting
armatures into machines where no proper lifting means have existed; if under
these circumstances the armature has happened to be slung by the commutator,
the great weight of the core has sometimes been sufficient to force the segments
out of truth.
Furthermore the materials ordinarily employed as above set forth are all liable
to change form and to contract by heating; and, although by proper baking in an
oven the insulation resistance could be made very high, it would drop enormously
as the result of exposure to moisture.
Now in order to obviate the evils above indicated according to this invention
annular grooves are formed in the flange and ring on the commutator core or body
between which the metal strips and insulating strips of the commutator are arranged;
in the ends of the annulus of strips corresponding grooves are formed, and in these
grooves are inserted keys made of mica.
In the accompanying drawings,
:
Fig. 1 is a view half in end elevation and half in cross section of a commutator
according to my invention.
Fig. 2 is a central longitudinal section of same.
.:
Fig. 3 is a view corresponding to Fig. 1, but illustrating a modification in which
the mica key is composed of strips arranged circumferentially.
a is the commutator core or body; the flange thereof formed with an annular
groove in its inner face as shewn ; c is the ring formed with a like annular groove;
dd are the metal strips; and ee the insulating mica strips arranged on the
commutator body; the ends of the compound annulus composed of these strips
being formed, as shewn, each with an annular groove so as to form with the grooves
in the flange and ring, key ways to receive the mica keys ff. In Figs. 1 and 2 they
are shown composed of rectangular pieces of mica placed radially in the key ways;
but a key may be made of strips of mica placed circumferentially as in Fig. 3.
Between the ends of the commutator strips (metal and mica) and the flange and
ring are interposed washers g that are also made of mica.
Commutators constructed with mica keys as described will be found exceedingly
strong and even able to resist blows without the solidity of the mica being
seriously affected; furthermore the construction described presents manufacturing
facilities and affords high insulation resistance even when the commutator is
damp.

page_text: Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
1. A commutator for a dynamo electric machine or motor in which the commutator
strips are held in place on the commutator core or body by means of keys composed
of mica substantially as and for the purpose described.
2. The improved commutator for a dynamo electric machine or motor, con-
structed and arranged substantially as hereinbefore described with reference to
and shewn in Figs. 1 and 2, or modified according to Fig. 3, of the drawings
annexed.
Dated this cl 1
B. S. PATERSON.
JOHN B. FURNEAUX.
W. Lloyd Wise,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicants.