Note: Descriptions are shown in the official language in which they were submitted.
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The invention relates to an axially-
ventilated electrical machine having a rotor with
salient poles, coolant-distributing conduits extending
in the axial direction being located in the pole-gaps.
A machine of this type is known from German
Auslegeschrift 1,085,606~ Electrical machines are
conventionally cooled in order to remove the heat losses
in such a way that during normal operation, heating of
the individual parts of the electrical machine does not
exceed the specified limiting temperatures.
It is commonly known that salient-pole
machines, which receive their coolant supply symme-
trically from opposite sides, exhibit higher tempera-
tures at the pole-windings in the center than in the
vicinity of the end-faces, shortly after the entry of
the coolant into the pole-gaps. This is caused by the
fact that, as viewed over the axial length of the
machine, the coolant passes over into the stator via
the air-gap between the rotor and the stator. As a
2~ result, the velocity in the pole-gaps continuously
decreases, as far as the center of the machine~ so that
a heat transmission coefficient adequately sufficing
for the removal of the losses is no longer achieved
~y the low coolant velocities.
~' '
In the case of the displacemen-t-bodies
disclosed in German Auslegeschrift 1~085,606, which
have been installed in the pole-gaps, the coolant is
admittely led to the surfaces to be cooled, in a
directed manner, particularly to the ~ield coils, and
the velocity of the coolant flowing radially into the
pole-gaps is at the same time increased, thereby
increasing the heat transmission coefficient of the
coolant. However, this expedient is obtained at the
expense of a higher static pressure-drop in the coolant
circuit of the machine, this higher pressure-drop
resulting in increased power being necessary for
circulating the coolant flow and, consequently, a
simultaneous increase in the power for driving the
fan is required. In unfavorable cases, this effect
can even lead to the requirement of adopting other
types of pressure-generators.
Accordingly, a feature of the present
invention is to provide a remedy in this area. The
invention solves the problem of producing an axially-
ventilated electrical machine possessing a rotor with
salient poles, coolant-distributing conduits extending
in the axial direction being located in the pole-gaps,
these bodies enabling the coolant to be channeled and
its velocity to be raised in an optimum manner, while
matching the cooling conditions applied in each case.
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The location and distribution of the coolant-
distributing conduits in the pole-gaps exhibit the
following advantages:
1. By reduci.ng the cross-section of the
longitudinal surfaces of the field coils) the radial
velocity of the coolant is increased to the extent
that a heat transmission coefficient which is adequate
for removing the heat is achieved,
2. By means of its shape, the installation
even adopts the function of the known pole-gap based-
- channel, that is to say~ it ensures that a relatively
large pxoportion of the coolant can flow into the
center o the machine, without first being heated;
3. The previously-known pole-gap base-
channel no longer needs to be made with the dimensions
previously speciied;
The same rate9 per second, o~ coolant
flow can be supplied without an increased static
pressure-drop in the machine, since the constriction
o~ the cross-section at the entry to the pole-gap is
very ~light9 due to the fact that the actual cross-
section is reduced only by the wall-thickness of the
coolant-distributing body; and
5. The installation can even lead to an
increased coolant flow, due to the fact that the
pressure-generation by the salient-pole rotor is
improved.
. . ,~
In accordance with the present invention 9
the longitudinal surfaces of the tubular coolant-
distributing conduits extend parallel to the flanks
of the pole-bodies and of the field coils9 which are
to be cooled, this arrangement resulting in simple
and readily visible coolant-paths. Furthermore, the
gap between the longitudinal surfaces of the tubular
coolant-distributing bodies and the flanks of the pole-
bodies and of the field coils which are to be cooled
is configured so that it tapers, or widens, in a
radially outward direction, and the possibility of
controlling the cooling effect in the longitudinal
direction of the machine results therefrom. Also
according to the present invention, the tubular coolant-
distributing conduit i5 attached to the rotor shaft of
the rotor by means of retaining bolts, and is spaced
from the rotor shaft by means of, for example, spacer~
sleeves. Additionally~ the effective cross-section
of the coolant flow-apertures in the coolant-distribu~-
ing conduit is varied in the axial flow direction9 ameasure which can be adopted, either on its own, or in
combination with the gap configuration discussed above,
and similarly brings about a uniform cooling effect in
the longitudinal direction of the machine.
In the case of machines which are ventilated
from opposite sides, at least two coolant-distributing
conduits are provided per pole-gap. These bodies
..~
~"~ .
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extend approximately symmetrically, Lrom the end~faces,
as far as the center o~ the rotor, where they are open,
partially closed, or completely closedg and possess
baffle devices.
As an alternative embodimentg a coolant-
distribu~ing body is partially or completely divided,
in the section at the mid-point of the rotor, by means
of a partition9 which is designed as a baffle device.
According to a further broad aspect of the
19 present lnvention there is provided an electrical machine
axially-ventilated from opposite ends thereo~. ~ rotor is
provided with a plurality of salient poles, field coils
and a rotor shaft. At least one coolant-distributing
conduit extends axially along the rotor and radially
between each of the poles. The conduit has lateral
surfaces spaced from the field coils so as to form a
gap therebetween wherein a portion of the conduit facing
the rotor shaft has a longitudinal aperture formed
therein for communication with the gap~ Means is
provided for supplying a gaseous coolant and for
communicating the coolant from the conduit to each of
the plurality of field coils.
Various other objects, features and attendant
advantages of the present invention will be more fully
appreciated as the same becomes better understood from
the following detailed description when considered in
connection with the accompanying drawings in which like
reference characters designate like or corresponding
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parts throughout the several views and wherein
FIGURE 1 shows a perspective, partially
sectional view of the rotor according to the present
invention;
FIGURE 2 shows a longitudinal sectional
view through a coolant-distributing conduit,
FIGURE 3 shows a partial cross-sectional
view through a rotor in accordance with the present
invention, according -to FIGURES 1 and 2, and taken
along line III-III of FIGURE 2;
FIGURE 4 shows a partial cross-sectional
view taken along line IV-IV of FIGURE 2 through a rotor
in accordance with the present invention corresponding
to FIGURES 1 and 2 but wherein the position of the
section differs from that of FIGURE 3, and the poles
are of a different configuration.
As shown in FIGURE 1, a central body 1 i~
positioned on a rotor-shaft 2 and is provided with
pole-cores 3 which carry pole-shoes 4 and field coils
5. An axial fan 6 is fitted on rotor-shaft 2, fan 6
being assembled from a blade-carrier 7 and a plurality
of fan-blades 8. Axial an 6 is located in an aperture
of an external fan casing. Shaft 2 is located in a
bearing, in a manner permitting rotation, and such
bearing is located inside bearing plate 10.
For reasons of clarity, only one half of
the rotor is represented in FIGURE 1, the other end of
the rotor also being provided with an axial fanO In
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this exa~ple, only two pole-cores 3 are drawn with
associated field coils 5. Pole-gap 11 is represented
in the interspace between the surfaces of pole-cores3
and of field coils 5, a coolant-distributing condui-t 12
being located in pole-gap 11. The lateral surfaces 13
of coolant-distributing conduit 12 extend parallel to
the lateral surfaces, which are to be cooled, of pole-
cores 3 and of field coils 5. In this manner, gaps 1
are formed between lateral surfaces 13 of coolant-
distributing conduit 12 and lateral surfaces of pole-
cores 3 and of field coils 5.
Coolant-distributing conduit 12 is open
towards axial fan 6 and towards central body 1. In
contrast, coolant-distributing conduit 12 is closed at
the other end thereof in the section at the mid-point
of the rotor, by means of a cover plate 15, which is
not represented in FIGURE 1, but which is represented
in ~IGURE 2.
For reasons of clarity, no attachment elements
of the coolant-distributing conduit 12 are shown in
FIGURE 1, but these are represented in more detail
in the drawings which follow. Reference number 16
marks the apertures which are made in that portion of
coolant-distributing conduit 12' which faces central
body 1 of the rotorO
,~
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FIGURE 2 shows a longitudinal sectional
representation of an illustrative embodiment of the
coolant-distributing conduit 12, but instead of
utilizing uninterrupted aperture 16 in the form o~ a
longitudinal gap, shown in FIGURE 1, a plurality of
interruptions in the apertures 17 are formed, in
FIGURE 2, in that portion 12l of coolant-distributlng
conduit 12 which faces the central body 1? these
interruptions being caused by the attachment-mechanism
of coolant-distributing conduit 12. The direction
in which the coolant flows is indicated by arrow 180
As can be seen from FIGURE 2, the effective cross-
section of apertures 17 is varied, in the direction
of coolant flow, as far as the center of the machine.
As a further measure for stabilizing the
pressure and velocity o:E the coolant in the portion
at the mid-point of the rotor, baffle devices 19 are
arranged in coolant-distributing conduit 12, these
devices running obliquely and simultaneously serving
to mechanically stiffen body 12.
In order to secure the coolant-distributing
conduits 12,a plurality of holes 20 are drilled in
conduits 12, sleeves 21 being inserted into these holes
and made secure. Sleeves 21 enable retaining bolts 22
to pass therethrough, these bolts being screwed into
holes 23~ drilled in the central body 1 of the rotor~
~ ~ $
Only one retaining bolt 22 is drawn in the
example representedO Coolant-distributing conduits~l2
are secured to the retaining bolts 22, in each case;
by means of a nut 24.
Spacer-sleeves 25 are located between
coolant conduit 12 and central body 1 of the rotor,
so that the space between that portion 12~ of the
coolant-distributing conduit 12 which faces the
central body 1, and central body 1 itself can be
spaced according to choice. Spacer-sleeves 25 are
made from a metallic material, for example from
austenitic steel.
Only one coolant-distributing conduit 12
is shown in FIGURE 2, this body extending, from one
end-face of the rotor, to the center of the rotor. A
second coolant-distributing conduit 12~ represented in
FIGURE 2 only by way of indication, is located in the
right-hand half of the rotor, symmetrical to first
conduit 12.
In FIGURE 3 the spacial arrangement of
coolant-distributing conduit 12 in pole-gap 11 is
shown. Coolant-distributing conduit 12 is, in lower
portion 12~, spaced away from the central body 1 of
the rotor by means of spacer-sleeves 25~ and lateral
surfaces 13 are spaced away from lateral surfaces of
field coils 5 by means of winding-supports 26.
Winding-supports 26 are preferably made of plasticO
,..~
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FIGURE 3 shows how the configuration of coolant-
distributing conduit 12 can be matched to the confi-
gurations of pole-cores 3, of pole-shoes 4, and of
field coil 5.
In this example, coolant-distributing conduits
12 are made of austenitic steel, of aluminium-alloy,
or of glass fiber reinforced plastic. Baffle device
19 is made of the same material.
In order to show the possibility of matching
coolant-distributing conduit 12 to different design-
embodiments of pole-cores 3, pole-shoes 4 and field
coils 5, a partial cross-section view through a rotor
has been represented in FIGURE 4, pole-shoes 4 of this
rotor being considerably shorter than in FIGURE 3,
while field coils 5 project above pole-shoes 4.
In this case, coolant-distributing conduit 12
is designed with a shape which differs from the shape
represented in FIGURE 3, in order to ensure optimal
guidance of the coolant for this type of machineO A
sectional view through an aperture 17 is visible in
FIGURE 4, the coolant issuing from coolant-distributing
conduit 12 via aperture 17, and the direction in which
the coolant flows along the lateral surfaces of field
coils 5 is represented, in the direction of the arrows,
by reference number 18.
. ~
The mode of operation of -the example of
coolant-distributing conduit 12, represented here 7 iS
as follows. The flow of coolant, generated by axial
fans 6, located to the right and to the left, outside
the rotor body, is conveyed in the axial direction
corresponding to arrows 18 represented in FIGURE 1,
from the end-faces of the rotor, into coolant-
distributing conduits 12. The coolant flows through
coolant-distributing conduits 12, on both sides thereof,
in a longitudinal direction parallel to the axis of the
machine and is deflected towards the central body 1 of
the rotor, passes -through apertures 16 located in
that portion 12' of the coolant-distributing conduit
12 which faces the central body and is led into gaps
1~, which spaces lateral surfaces 13 of coolant-
distributing ~onduit 12 and lateral surfaces of pole-
cores 3 and of field coils 5~ In this process, the
axial flow direction of the coolant inside coolant-
distributing conduits 1~ is turned into a radial flow
corresponding to arrows 18 represented in the Figures.
This radial coolant flow is continuously led along
lateral surfaces of field coils 5 and of pole-cores
3, in all zones of the rotor, and enables stray heat
to be led away from tield coils 5 and from pole-cores
3 in an optimal manner and in all parts of the rotor,
when the coolant flow-rate and velocity is appropriately
matched to the particular type of machine in question.
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Obviously, numerous modifications and
variations of the present invention are possible in
light of the above teachings. It is therefore to be
understood that within the scope of the appended claims 9
the invention may be practiced otherwise than as
specifically described herein.
