Improved Appliances for Cooling Dynamos,
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Improved Appliances for Cooling Dynamos,
We, SIEMENS BROTHERS & Co. LIMITED, of 12, Queen Anne's Gate, West-
minster, S.W., Electrical Engineers, do hereby declare the nature of this inven-
tion (as communicated to us from abroad by Siemens and Halske Aktien-Gesell-
schaft, Markgrafen Strasse No. 94, Berlin, S.W., Germany, Electrical Engineers)
to be as follows:-
Methods for cooling dynamos by air currents are defective in that large
quantities of air have to be moved in order to effect a comparatively small amount
of cooling.
In order to cool a dynamo with the least possible expenditure of energy the
air, during its passage through the machine, must be utilised as much as possible,
for which purpose it must be brought into close contact with the surfaces to be
cooled and must pass over them at a high speed and with an eddying motion.
The surfaces moreover, must be so arranged that they part with a considerable
quantity of heat.
The present invention relates to improved appliances whereby the foregoing
conditions are fulfilled. The underlying principle of these appliances is that the
air passes in thin layers at high speed and with eddying motion in contact with
the largest possible surface of the magnets and armature, being moved by a
suitable device, such as by a fan constructed as a part of the dynamo, or by a
separate fan or a chimney shaft communicating with a casing on the dynamo.
For instance one end of the dynamo may form the casing of a suction fan
mounted on the shaft of the dynamo. Into this casing there open passages which
are formed around the bobbins of the field magnets, around the armature and
through the armature.
For forming these passages, filling pieces of sheet metal or other material
are inserted in the spaces between the bobbins of the field magnets, these filling
pieces being made to surround the periphery of the bobbins and also the exposed
parts of the armatures periphery between the pole pieces of the magnets, so as to
leave only narrow spaces between the filling pieces and these parts, which spaces
communicate at the one end with the outer air and at the other end with the
said suction fan.
Furthermore, passages are formed longitudinally through the armature, and
through the commutator which also communicate with the fan at one end and
with the outer air at the other.
For increasing the surface within such spaces corrugated sheets of meta! may
be interposed between the filling pieces and the magnets. The passages through

page_text: the armature may be circular in cross section and may contain helically twisted
pieces of metal which impart to the air an eddying motion.
At the end of the dynamo opposite the fan may be formed a chamber into which
outside air or artificially cooled air is conducted by means of pipes; the narrow
passages round the magnet bobbins of the machine round the armature and
through the armature open out of this chamber.
By the above described arrangement the air may be drawn through the dynamo
in three separate courses, namely directly around the magnets, directly around
the armature, and through the commutator and armature. Furthermore, by
suitably enclosing the ends of the dynamo the air may be drawn from outside
the building, or the casing may be made to communicate with a supply of
artificially cooled air, so as to effect a greater degree of cooling; the air on leaving
the dynamo may also be conducted to the outside through pipes connected to the
casing.
It is obvious that the air may be driven through the dynamo passages instead of
being drawn through them.
ABEL & IMRAY,
Agents for the Applicants.
We, SIEMENS BROTHERS & Co. LIMITED, of 12, Queen Anne's Gate, West-
minster, S.W., Electrical Engineers, do hereby declare the nature of this inven-
tion (as communicated to us from abroad by Siemens and Halske Aktien-Gesell-
schaft, of Markgrafenstrasse No. 94, Berlin, S.W., Germany, Electrical Engineers)
and in what manner the same is to be performed to be particularly described and
ascertained in and by the following statement:-
Methods for cooling dynamos by air currents are defective in that large
quantities of air have to be moved in order to effect a comparatively small amount
of cooling.
In order to cool a dynamo with the least possible expenditure of energy the
air, during its passage through the machine, must be utilised as much as possible
for which purpose it must be brought into close contact with the surfaces to be
cooled and must pass over them at a high speed and with an eddying motion.
The surfaces moreover must be so arranged that they part with a considerable
quantity of heat.
The present invention relates to improved appliances whereby the foregoing
conditions are fulfilled. The underlying principle of these appliances is that the
air passes in thin layers at high speed and with eddying motion in contact with
the largest possible surface of the magnets and armature being moved by a
suitable device, such as by a fan constructed as a part of the dynamo, or by a
separate fan or a chimney shaft communicating with a casing on the dynamo.
Fig. 1 of the accompanying drawings is an end view partly in section and
Figs. 2 and 3 are sections taken on the lines a-b and cd respectively illus-
trating the application of this principle to a four pole dynamo.
One end of the machine forms the casing of a suction fan, the blades S S of
which are mounted radially on the nave N. This fan sucks air through the
machine the air being compelled to travel along certain passages (as indicated by
the arrows) by the baffle plates 11 and D2, the first of which is annular and is

page_text: attached at its circumference to the housing of the machine while its central
opening is of a diameter corresponding with that of the armature. The second
plate 1 is circular and of smaller radius than the housing of the machine.
In this example, then, the cooling air passes through the machine in three
different ways: between the magnets around the armature and through the
armature,
The space between the magnets is nearly filled by prismatic shaped filling
pieces CC which are attached to the housing and to the baffle plate D' but
leave narrow air passages K K between themselves and the magnets and form,
together with the pole pieces of the magnets, an annular passage around the
armature.
The air passages K, K open into the chambers R, R which are in connection
with the casing of the fan through the central opening of the baffle plate D¹
(Fig. 3).
For increasing the surface within the passages K corrugated sheets of metal W
may be interposed between the filling pieces and the magnets.
The annular passage around the armature and the passages through the
armature open directly into the casing of the fan. The course of the air drawn
through the last-named passages is through holes in the commutator and
through the connecting frame B, B of the rod windings. In the holes L L in
the armature helically twisted metal strips T T may be inserted so as to give the
air a powerfully eddying motion.
At the end of the dynamo opposite the fan may be formed a chamber into which
outside air or artificially cooled air is conducted by means of pipes; the narrow
passages round the magnet bobbins of the machine, round the armature and
through the armature open out of this chamber. By the above described arrange-
ment the air may be drawn through the dynamo in three separate courses, namely,
directly around the magnets, directly around the armature and through the
commutator and armature. Furthermore, by suitably enclosing the ends of
the dynamo the air may be drawn from outside the building or the casing may
be made to communicate with a supply of artificially cooled air, so as to effect a
greater degree of cooling; the air on leaving the dynamo may also be conducted
to the outside through pipes connected to the casing.
It is obvious that the air may be driven through the dynamo passages instead
of being drawn through them.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, we declare that what
we claim is:
-
1. Means for cooling dynamos consisting in surrounding the field magnet
arms and also the armature with insertion pieces in such manner as to produce
narrow channels through which the cooling air is made to pass rapidly in thin
layers in contact with the outer surfaces of the magnet's arms and the armature,
and also through the latter, such channels being made to communicate with a
common chamber at one end of the machine from which the air is led away
through a branch pipe to a fan or other device for producing air currents sub-
stantially as described.
2. In the arrangement for cooling dynamos referred to in the first claim, pro-
ducing the requisite air currents through the narrow channels by means of a
fan fixed on the armature within-the chamber at the end of the dynamo,
substantially as described.
3. In the arrangement for cooling dynamos referred to in the first and second
claims, enclosing both ends of the dynamo casing and providing branch pipes
both on the inlet side and the outlet of the air passages, such pipes being
arranged to lead the fresh air supply to the dynamo from the outside and also to
convey the discharged air to the outside, substantially as described.
4. In the arrangement for cooling dynamos referred to in the first claim the

page_text: use of corrugated sheet metal enclosures surrounding the magnet arms for
forming the narrow air passages, substantially as and for the purposes described.
5. In the arrangement of cooling dynamos referred to in the first claim, the
use of helically twisted strips of metal introduced into axial passages of the
armature core, for the purpose of producing strong eddies in the currents passing
through, substantially as described.
1000