Note: Descriptions are shown in the official language in which they were submitted.
CA 02285763 1999-10-12
Fixing Member for Insulating Coil, Dynamoelectric Machine
therewith and Method for Fixing Insulating Coil therewith
The present invention relates to a fixing member of an
insulating coil in a dynamoelectric machine, a dynamoelectric
machine provided with the fixing member and a fixing method
of the insulating coil therewith.
Dynamoelectric machines such as electric motors, power
generators or the like are manufactured through installation
of insulating coils comprising insulating materials and
conductors into slots of an iron core. During operation,
various kinds of forces such as electromagnetic force in a
radial direction, thermal expansion/shrinkage force in a
longitudinal direction, or the like work on the insulating
coils. Therefore, usually, in order to endure these various
kinds of forces to maintain function as the insulating coil,
in motors or small power generators, after installation of
insulating (mica taping) coils in slots of an iron core,
impregnating/curing treatment of resin is carried out.
However, in a power generator of a larger size, it is
difficult to impregnate resin after installation of the coils.
Thus, the insulating (mica taping) coils are impregnated with
resin and cured in advance, followed by installation of the
treated insulating coils into the slots of an iron core.
Fig. 1 is a perspective view partly in section showing
one example of a stator of an existing dynamoelectric machine
of this kind. An insulating coil 28 comprising insulating
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materials 26 and conductors 27 that is impregnated with resin
and cured in advance is installed in a slot 3 of an iron core
2 that is obtained by laminating a number of silicon steel 1.
The insulating coil 28 is fixed by spacers 29 formed of FRP
and positioned on the top and bottom surfaces of Fig. 1 and
wedges 30 giving a compressing force to these spacers 29 in
an up and down direction of Fig. 1. The dimension of the
insulating coils 28 deviates and the dimension of the slots 3
of the iron core 2 also deviates. Therefore, in general the
slots 3 are formed with allowance. Thus, there occur gaps
between side surfaces of the insulating coil 28 and internal
surfaces of the slot 3. As a result of this, in an existing
example shown in Fig. l, in the gaps 22 remaining on the side
surface of the insulating coil 28, by inserting FRP sheets 20
conforming the size thereof, the insulating coil 28 is fixed.
Further, as shown in Fig. 2, in place of the
aforementioned FRP, a ripple spring 21 made of FRP is
inserted in the gaps 22. In this case, due to recovery force
and friction force of the ripple spring 21, the insulating
coil 28 is fixed.
Still further, in another example, as shown in Fig. 3,
on a side surface of the insulating coil 28 a fixing member
33 comprising a layer of elastic material 31 in which an
inorganic filler is filled, and a layer of elastic material
32 in which an inorganic filler is not filled is formed in
advance. Together with this fixing member 33, the insulating
coil 28 is installed into slot 3. Due to the repulsion force
of the fixing member 33 comprising two layers of elastic
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material 31 and 32, and friction force with the iron core 2,
the insulating coil 28 is fixed (Canadian Patent No. 932013).
Further, in still another example proposed in Japanese Patent
Application No. 8-243780, through formation of the inorganic
material in milled fibers, heat transmission from the
insulating coil 28 to the iron core 2 is improved.
Still another example is shown in Fig. 4, wherein a
sheet 34 of elastic material has one surface provided with
ridges as facing the internal surface of slot 3, thereby
apparent modulus of elasticity is reduced to facilitate to
easily install (USP4008409).
The gaps 22 occurring between the insulating coil 28
and slot 3 has high thermal resistance to cause difficulty in
transmitting Joule heat generated in conductor 27 during
operation to the iron core 2, thereby resulting in
temperature rise of the insulating coil 28. As a result of
this, electrical and mechanical characteristics of organic
material constituting insulating material 26 are accelerated
in degradation. Consequently, reducing the thermal
resistance of the gaps 22 by the use of the aforementioned
various kinds of fixing members improves the performance of a
dynamoelectric machine.
However, in the means shown in Fig. 1, stiffness of the
FRP sheet 20 is high. Therefore, the FRP sheet 20 can not
follow irregularities formed on the internal surface of the
slot 3 of an iron core 2 constituted of laminated thin
silicon steel 1. Therefore, even if the FRP Sheet 20 is
installed, minute gaps remain there to hinder thermal
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conduction to the iron core 2. Further, the FRP sheet 20 is
impossible to prepare in continuously different thicknesses.
Thus, if there is no proper FRP sheets 20, the FRP sheet 20
might not be used. Consequently, in this case, due to the
gaps 22 the thermal conduction is hindered over a wide area,
and the force fixing the insulating coil 28 would be
deteriorated.
When the means shown in Fig. 2 is adopted, it can
conform sufficiently to dimension changes of the gaps 22.
However, due to using a ripple spring, there remain gaps
between the insulating coil 28 and slot 3. This is not
desirable from the point of view of thermal conduction.
The means shown in Fig. 3, by the use of the elastic
material layer 31 in which an inorganic material is
compounded and the elastic material layer 32 in which an
inorganic material is not compounded, can conform to the
irregularities in the slot 3 and does not allow for the gaps
to remain. However, due to the existence of the elastic
material layer 32 consisting only of an organic material
which has low thermal conductivity compared with the
inorganic material or metals, the elastic material layer 32
hinders the thermal conduction. Further, when the insulating
coil 28 to which a fixing member 33 comprising elastic
material layers 31 and 32 is stuck is installed into the slot
3 of the iron core 2, when various kinds of vibrations
affecting the insulating coil 28 during operation, the fixing
member 33 can be cracked by edges of thin silicon steels 1 to
peel or drop off the surface of the insulating coil 28.
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Consequently, through operation of a long time, over a wide
area, the gaps are likely to occur. When milled fibers or
the like are filled, as identical with the above, the fixing
member 33 is likely to tear which results in occurrence of
the gaps.
In the case of the means shown in Fig. 4, an elastic
material layer 34 having a surface provided with ridges is
formed in corrugation is formed on the insulating coil 28 to
install. Consequently, the gaps occur between the insulating
coil 28 and the iron core 2 to hinder the thermal conduction.
The present invention is carried out considering the
aforementioned circumstances. An object of the present
invention is to provide a member for fixing an insulating
coil into a coil-receiving slot of a dynamoelectric machine,
a dynamoelectric machine provided with the fixing member and
a fixing method thereof. Here, the fixing member of the
insulating coil, while maintaining a fixing force of the
insulating coil, enhances thermal conductivity to prevent
temperature rise of the insulating coil from occurring and
performance thereof from degradation, thereby maintaining
high reliability over a long time.
A fixing member of the present invention to attain the
aforementioned object is used for fixing an insulating coil
prepared in advance in a slot of an iron core. Here, the
fixing member of the insulating coil of the present invention
is characterized in that the fixing member is a laminate
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sheet comprising at least one of reinforcement sheet and a
rubber-like elastic material layer laminated on at least one
surface of the each reinforcement sheet.
The fixing member of the insulating coil, comprising a
laminate sheet including at least one reinforcement sheet and
a rubber-like elastic material layer laminated on at least
one surface of reinforcement sheet, compared with a fixing
member that is composed only of a rubber-like elastic
material layer or an elastic material layer in which
inorganic material is filled, is high in tear strength.
Consequently, the peeling or dropping off of the fixing
member from the insulating coil due to tear through contact
with edges of thin silicon steels constituting the iron core
can be suppressed.
In addition, the fixing member composed of the
reinforcement sheet and the rubber-like elastic material
layer can conform to the irregularities of the internal
surface of the slot to hinder occurrence of the gaps,
resulting in firm holding of the insulating coil and
excellent thermal conduction. Furthermore, the fixing member
which is less in occurrence of peeling or dropping off from
the insulating coil, can suppress the temperature rise of the
insulating coil over a long period with stability.
Consequently, by the use of the fixing member of the present
invention, a dynamoelectric machine having high reliability
can be manufactured.
Here, in the fixing member of the insulating coil, the
reinforcement sheet is at least one selected from a plastic
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film, a woven fabric or nonwoven fabric formed of inorganic
material, organic material or both of these, and a calendered
nonwoven fabric formed of inorganic material, organic
material or both of these. Thereby, the fixing member can
reduce further the rate of incidence of tear and enables to
suppress the temperature rise of the insulating coil over a
long period with stability.
Further, the fixing member is a member for fixing an
insulating coil in the aforementioned dynamoelectric machine,
and the aforementioned layer of rubber-like elastic material
is filled by at least one of inorganic filler and powder of
metal each having a high thermal conductivity. Thereby, the
thermal conduction is further enhanced.
Furthermore, the fixing member is a member for fixing
the aforementioned insulating coil, and on a surface of the
rubber-like elastic material layer constituting the outermost
layer slits or dimples are provided.
Thereby, apparent elastic coefficient of the fixing
member of the insulating coil is reduced to facilitate
installation of the insulating coil into the slot. Further,
the fixing member having the slits covers the insulating coil
so that the direction of slits matches a direction having an
angle with respect to installation direction into the slot,
followed by installation. By implementing like this, upon
installing, the slits do not catch the edges of the iron core
to suppress peeling-off and dropping-off of the rubber-like
elastic material layer. As a result of this, occurrence of
uninstalled portion can be reduced to suppress firmly the
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temperature rise of the insulating coil. Further, the fixing
member having the layer of reinforcement sheet, compared with
one that consists only of rubber-like elastic material, is
less in a rate of incidence of tearing-off upon insertion.
Incidentally, the fixing member is a member for fixing
an insulating coil of the aforementioned dynamoelectric
machine, and the volume resistivity thereof in lamination
direction is in the range of from 10° to 105 ~~cm. Therefore,
by disposing a semi-conductive layer of volume resistivity of
the same range on the outermost layer of the insulating coil,
the surface of the insulating coil and the iron core is held
at the same potential to suppress partial discharge between
the both. Thus, denaturing, damaging, drop-off, and peeling-
off due to partial discharge degradation of the fixing member
can be prevented from occurring. As a result of this, heat
generated in the insulating coil can be transmitted further
more efficiently to the iron core.
On the other hand, the dynamoelectric machine of the
present invention is characterized in that any one of the
aforementioned fixing members of the insulating coil fixes an
insulating coil prepared in advance. As the fixing member of
insulating coil, one comprising of a laminate sheet of one or
more layers of reinforcement sheet and rubber-like elastic
material layer is used. Accordingly, compared with a fixing
member composed only of a rubber-like elastic material layer
or an elastic material layer in which inorganic filler is
filled, tear strength is high. Thereby, occurrence of
peeling and dropping of the fixing member off the insulating
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coil due to tear caused by contact with edges of thin silicon
steels constituting the iron core can be reduced. Further,
the fixing member composed of layers of reinforcement sheet
and rubber-like elastic material, can conform to the
irregularities of internal surface of a slot, resulting in a
difficulty in causing gaps. Thereby, the fixing member can
be held firmly and is excellent in thermal conduction.
Furthermore, since peeling or dropping of the fixing member
off the insulating coil occurs less, over a long period, the
temperature rise of the insulating coil can be suppressed
with stability, thereby a dynamoelectric machine of high
reliability can be provided.
Now, in a dynamoelectric machine of the present
invention, at the outermost layer of an insulating coil, a
semi-conductive layer of volume resistivity of from 10° to
105 ~-cm is disposed. Thereby, when a laminate sheet having
volume resistivity in lamination direction in the same range
as the outermost layer is used as a fixing member, the
surface of the insulating coil and the iron core can be held
at the same potential, thereby preventing partial discharge
between the both from occurring. Consequently, as mentioned
above, heat generated in the insulating coil can be more
efficiently conducted to the iron core.
Further, in the aforementioned dynamoelectric machine,
between the fixing member and an internal surface of the slot,
a layer of grease, oil compound, or inorganic lubricant of
high thermal conduction is formed. Thereby, contact with the
irregularities of an internal surface of the slot and the
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CA 02285763 1999-10-12'
insulating coil can be enhanced to contribute in improvement
of thermal conductivity. In addition, since friction
occurring between the internal surface of the slot and the
surface of the laminate sheet as a fixing member can be
reduced, occurrence of tearing at the surface of the laminate
sheet can be further reduced.
On the other hand, a fixing method of the
aforementioned insulating coil is characterized in that, when
an insulating coil prepared beforehand is installed into a
slot of an iron core of a dynamoelectric machine to fix, by
the fixing member of the insulating coil, at least one side
surface of the insulating coil is covered, followed by
installation. Thereby, the tearing-off of the rubber-like
elastic material layer due to friction generated between the
fixing member of the insulating coil and the internal surface
of the slot can be suppressed. As a result, a dynamoelectric
machine having high reliability can be manufactured.
Further, a fixing method of an insulating coil of the
present invention relates to a fixing method of the
aforementioned insulating coil, and a surface thereof facing
the internal surface of a slot is covered to be a rubber-like
elastic material layer. By implementing like this, the
rubber-like elastic material layer follows the irregularities
of the internal surface of the slot to improve contact.
Thereby, thermal conduction can be further improved.
In addition, a fixing method of an insulating coil of
the present invention, in the fixing method of the
aforementioned insulating coil, when a fixing member having
CA 02285763 2004-06-14
slits provided on a surface of a rubber-like elastic material
layer constituting the outermost layer is used, covers so
that the slits have an angle with respect to installation
direction of the insulating coil.
Thereby, upon installation of the insulating coil, the
slits do not catch edges of an iron core and thus can
suppress peeling-off and dropping-off of the rubber-like
elastic material layer. Consequently, since occurrence of
uninstalled portion can be reduced, temperature rise of the
insulating coil can be firmly suppressed.
According to an aspect of the present invention there
is provided a member for fixing an insulating coil in a
slot of an iron core of a dynamoelectric machine from a
side surface of the insulating coil, the insulating coil
being prepared in advance, the member comprising a laminate
sheet having at least one layer of reinforcement sheet, and
a rubber-like elastic material layer laminated on at least
one surface of the layer of reinforcement sheet, the
rubber-like elastic material layer having an outermost
layer, the outermost layer having slots or dimples on the
surface thereof and the outermost layer facing an internal
surface of the slot.
According to another aspect of the present invention
there is provided a method of fixing an insulating coil,
comprising the step of installing an insulating coil
prepared in advance into a slot of an iron core of a
dynamoelectric machine to fix, wherein a side surface of
the insulating coil facing an internal surface of the slot
of the iron core is covered by a fixing member as described
herein, wherein a surface of the fixing member facing the
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inner surface of the slot is covered with a rubber-like
elastic material having slits on the surface thereof and
wherein the slits are at an angle with respect to an
installation direction of the insulating coil.
Fig. 1 is a partially sectional view of a
dyriamoelectric machine for explaining a fixing member and a
fixing method of a conventional insulating coil.
Fig. 2 is a partially sectional view of a
dynamoelectric machine for explaining a fixing member and a
fixing method of a conventional insulating coil.
Fig. 3 is a partially sectional view of a
dynamoelectric machine for explaining a fixing member and a
fixing method of a conventional insulating coil.
Fig. 4 is a partially sectional view of a
dynamoelectric machine for explaining a fixing member and a
fixing method of a conventional insulating coil.
Fig. 5 is a perspective view showing one embodiment of
a fixing member of an insulating coil according to the
present invention.
Fig. 6 is a perspective view showing another embodiment
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of a fixing member of an insulating coil according to the
present invention.
Fig. 7 is a partially sectional view showing a test
model of a dynamoelectric machine using a fixing member
according to the present invention.
Fig. 8 is a partially sectional view showing a test
model of a dynamoelectric machine in a conventional fixing
member.
Fig. 9 is a partially sectional view showing a test
model of a dynamoelectric machine in another conventional
fixing member.
Fig. 10 is a partially sectional view showing a test
model of a dynamoelectric machine in still another
conventional fixing member.
Fig. 11 is a partially sectional view showing a test
model of a dynamoelectric machine using a fixing member
according to another embodiment of the present invention.
With reference to the drawings, the present invention
will be explained in more detail. Fig. 5 is a perspective
view showing schematically one embodiment of a fixing member
of an insulating coil of the present invention. In this
figure, the fixing member is a laminate sheet 5.
The laminate sheet 5 has an aramid paper 18 that is a
calendered nonwoven fabric. The aramid paper 18 constitutes
a reinforcement sheet layer in the present embodiment. On
both surfaces of the aramid paper 18 that is a reinforcement
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sheet layer, silicone rubber 19 having high thermal
conductivity which constitutes a rubber-like elastic material
layer is laminated. Thus, in the present embodiment, the
aramid paper 18 is sandwiched by silicone rubber layers 19
having high thermal conductivity. However, without
restricting to this, one in which silicone rubber 19 having
high thermal conductivity is laminated only on one surface
can be used. Further, a plurality of reinforcement sheets
each having at least one surface on which a rubber-like
elastic material layer is laminated can be used. Further, as
shown in Fig. 6, an aramid paper 18' that is not calendered
can be used.
Although in the present embodiment, an aramid paper 18
is used as a reinforcement sheet layer, of course it is not
restricted to this. The reinforcement sheet layer needs to
be capable of preventing peeling-off or dropping-off from
occurring that accompanies tear of rubber-like elastic
material during installation of an insulating coil or
operation, and to be flexible so as to be installed easily
into the gap of an insulating coil and a slot. For instance,
a woven fabric or nonwoven fabric formed of inorganic
material, organic material or both of these, calendered
nonwoven fabric formed of inorganic material, organic
material or both of these, or plastic film can be adopted.
Other than the aramid paper, for instance, a glass fabric or
polyester fabric can be useful.
The rubber-like elastic material is not restricted to
silicone rubber 19 having high thermal conductivity such as
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shown in Figs. 5 and 6. In addition, it is preferable to be
one that contains any one or both of inorganic filler having
high thermal conductivity such as boron nitride, aluminum
nitride or aluminum oxide and metallic powder.
The thickness of a laminate sheet 5 is not particularly
restricted and various thicknesses can be selected
appropriately depending on the dimension of the slot to be
employed and the dimension of the insulating coil. The
volume resistivity in lamination direction is, however,
preferable to be in the range of from 10° to 105 ~~cm. When
a semi-conductive layer (not shown in the figure) whose
volume resistivity is in the same range is provided on the
outermost layer of the insulating coil, the surfaces of the
insulating coil and iron core can be held at the same
potential. Thereby, partial discharge therebetween can be
suppressed.
Further, when the outermost layer of a laminate sheet 5
comprising a reinforcement sheet and a rubber-like elastic
material layer, that is, the layer that contacts with
internal surface of a slot, is composed of a rubber-like
elastic material layer, as shown in Fig. 6, it is preferable
to have slits 25 thereon. The .slits 25 reduce apparent
elasticity to facilitate to install the insulating coil into
the slot. Incidentally, when the slits 25 are provided, it
is preferable to cover the insulating coil with the laminate
sheet 5 as a fixing member, so that formation direction of
the slits 25 matches a direction having an angle with respect
to installation direction of the insulating coil into the
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slot. Thereby, upon installation, the slits 25 do not catch
edges of an iron core, dropping-off or peeling-off of the
rubber-like elastic material can be suppressed, and a portion
that is not installed can be suppressed in occurrence. The
slits 25 are preferable to be provided with a depth about to
reach the aramid paper 18' in the thickness direction of
silicone rubber 19 having high thermal conductivity, a layer
of rubber-like elastic material. When silicone rubber 19
having high thermal conductivity is formed on both surfaces
of the aramid paper 18', a layer of reinforcement sheet, as
in the present embodiment, it is preferable to form slits 25
on both surfaces thereof.
When the slits 25 are provided like this, upon
providing the slits 25 so as to match a direction that form a
prescribed angle with respect to an installation direction of
the insulating coil into the slot, during covering the
insulating coil with the laminate sheet 5, it is only
necessary to pay attention to this directionality.
In addition, when a rubber-like elastic material layer
is provided on the outermost layer, instead of forming slits
as described above, a plurality of dimples can be provided
on the surface thereof. Even thereby, apparent elasticity of
the rubber-like elastic material layer can be reduced to
facilitate to install the insulating coil into the slot.
Further, compared with the case where the slits 25 such as
shown in Fig. 6 are provided, catch by edges of the iron core
can be reduced in occurrence upon installation.
The laminate sheet 5 that is a fixing member of the
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aforementioned insulating coil is disposed so as to cover at
least both side surfaces of the insulating coil prepared in
advance. The insulating coil thus covered by the fixing
member is installed into the slot of an iron core of a
dynamoelectric machine and fixed.
The laminate sheet 5 must be disposed so as to cover at
least one side surface of the insulating coil. However, both
side surfaces and the bottom surface of the insulating coil
also can be covered. However, even in this embodiment, after
disposition of the insulating coil and fixing member, as
explained in the section of background of the invention,
wedges are installed. In the present embodiment, both or any
one of top and bottom surfaces of an insulating coil are also
covered by laminate sheet 5 having a rubber-like elastic
material layer. Therefore, compared with the case where only
both side surfaces of an insulating coil are covered, creep
deformation of the laminate sheet 5 in up and down direction
of the insulating coil due to compression force of the wedge
can be suppressed. Thereby, the insulating coil can be fixed
more firmly.
A means for covering an insulating coil with a laminate
sheet 5 is not particularly restricted. Adhesive or the like
(not shown in the figure) can be adhered or wound to cover.
However, when covered without using such an adhesive, without
being influenced by thermal conductivity, mechanical property
or thermal endurance that the adhesive has, a dynamoelectric
machine of high reliability can be manufactured.
As described above, the laminate sheet 5 is formed
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through lamination of a rubber-like elastic material layer to
a reinforcement sheet layer. When covering the insulating
coil with this, it is preferable to cover the insulating coil
so that a rubber-like elastic material layer, that is, a
silicone rubber layer 19 having high thermal conductivity in
this embodiment, is positioned on the side facing the
internal surface of the slot. Since an iron core forming a
slot is a stack of a plurality of silicon steels, there are
formed a plurality of irregularities on the internal surface
of the slot. Consequently, a rubber-like elastic material
layer, when being in contact with this irregular surface, due
to elastic force thereof makes an intimate contact with the
irregular surface thereof to result in difficulty of
occurrence of the gaps.
When an insulating coil covered by a laminate sheet 5
is disposed inside a slot, between the laminate sheet 5 and
the internal surface of the slot, it is preferable to dispose
any one of layers of grease, oil compound, and inorganic
lubricant having high thermal conductivity. Thereby, contact
with the surface of the insulating coil or internal surface
of the slot can be heightened to result in a further
improvement of thermal conduction. As a means of disposing
any one of the layers of grease, oil compound, and inorganic
lubricant of high thermal conductivity, typically, a means of
coating these on the surface of the laminate sheet 5 in
advance can be adopted. In addition, when taking a
constitution of coating these on the internal surface of the
slot in advance, during transportation or storage of the
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insulating coil itself covered by the laminate sheet 5, the
grease or the like can be prevented from peeling.
Next, thermal conduction and tear strength when fixing
members of the present embodiments are applied in test models
shown in Figs. 7 to 11 will be explained with embodiments.
Embodiment 1
Fig. 7 is a partially sectional view showing a testing
model of the same shape with a dynamoelectric machine that
employs a fixing member according to one embodiment of the
present invention. The present model is constituted of an
iron core 2 composed of a stack of silicon steels 1, a slot 3
formed in the iron core 2, an aluminum block 4 of the same
external shape with that of an insulating coil, and a
laminate sheet 5 that is a fixing member wound around the
aluminum block 4. Incidentally, the size of the slot of the
present model is 22 cm in height direction, 3 cm in breadth
direction, and 20 cm in depth direction. On the iron core 2
and aluminum block 4, in order to check thermal conduction,
as shown in Fig. 7, with the aluminum block 4 as the center,
on right side thereof thermocouples 6, 7, 8, 9, and 10 are
disposed, and on left side thereof thermocouples 11, 12, 13,
14, and 15 are disposed. Further, on top side and bottom
side of the aluminum block 4 in slot 3, urethane foams 16 and
17 are disposed as a thermal insulator, respectively.
Incidentally, though not shown in the figure, on both end
sides in depth direction of the aluminum block 4 too,
urethane foams are disposed for heat radiation from other
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than the side surfaces of the aluminum block 4, that is,
measurement surfaces, to be as small as possible.
Further, in the present embodiment, upon checking the
thermal conduction when the fixing member of the present
invention is adopted, to eliminate influence of the
insulating layer in the insulating coil, without disposing
one that corresponds to the insulating layer of the
insulating coil, only the aluminum block 4 is used.
The laminate sheet 5 that is a fixing member used in
the present embodiment is one in which calendered aramid
paper 18 is sandwiched by silicone rubber 19 having high
thermal conductivity (shown in Fig. 5).
To the aluminum block 4 of the test model of such
constitution, heat amount of 300 W is supplied by the use of
a sheathed heater, and with respective thermocouples shown in
Fig. 7, temperatures of the respective portions are measured.
With these temperatures, total thermal conductance of
the both side surfaces of the aluminum block 4 is calculated.
The result is shown in table 1.
Comparative Example 1
Fig. 8 is a partially sectional view of a test model of
a dynamoelectric machine used for confirming thermal
conduction when a fixing member according to a conventional
technology is used. In the present model, in place of the
laminate sheet 5 of Fig. 7, a FRP sheet 20 is applied only on
one surface of aluminum block 4. Other constitutions and
conditions are identical with those of the case of embodiment
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1 shown in Fig. 7. Incidentally, the FRP sheet 20 is formed
of laminated glass fabric and epoxy resin.
To the aluminum block 4 of the test model shown in Fig.
8, with a sheathed heater, the amount of heat of 300 W is
supplied, and with the respective thermocouples shown in Fig.
8, temperatures of the respective portions are measured.
From these temperatures, total heat conductance of both side
surfaces of the aluminum block 4 is calculated. The result
is shown in Table 1.
Comparative Example 2
Fig. 9 is a partially sectional view of a test model of
a dynamoelectric machine used for confirming thermal
conduction when a fixing member according to another
conventional technology is used. In the present model, in
place of the FRP sheet 20 of Fig. 8, a FRP sheet of
corrugated section 21 is applied only on one surface of the
aluminum block 4. Other constitutions and conditions are
identical with those of the case of comparative example 1
shown in Fig. 8. Incidentally, the FRP sheet 21 having
corrugated section is, as identical with comparative example
1, is composed of laminated glass fabric and epoxy resin.
To the aluminum block 4 of the test model shown in Fig.
9, with a sheathed heater, amount of heat of 300 W is
supplied, and with the respective thermocouples shown in Fig.
9, temperatures of the respective portions are measured.
From these temperatures, total thermal conductance of both
side surfaces of the aluminum block 4 is calculated. The
CA 02285763 1999-10-12
result is shown in Table 1.
Comparative Example 3
Fig. 10 is a partially sectional view of a test model
of a dynamoelectric machine employed for confirming thermal
conduction when a fixing member according to still another
conventional technology is used. In the present model, a
fixing member is not disposed between the side surface of the
aluminum block 4 and internal surface of the slot 3, and the
gap 22 is left as it is. This is a model of the case where
during manufacture, upon considering thickness of the FRP
sheet and dimension of the gaps 22 the FRP sheet can not be
installed partially. Incidentally, the gaps 22 is formed by
partially installing FRP sheet between the internal surface
of the slot 3 and the side surface of the aluminum block 4
(not shown in the figure).
To the aluminum block 4 of the test model shown in Fig.
10, with a sheathed heater, 300 W of heat amount is supplied,
and with the respective thermocouples shown in Fig. 10,
temperatures of the respective portions are measured. From
these temperatures, total thermal conductance of both side
surfaces of the aluminum block 4 is calculated. The result
is shown in Table 1.
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Table 1
Total Thermal Conductance of Embodiment 1 and Comparative
Examples 1, 2, and 3
Embodiment Comparative Comparative Comparative
1 Example 1 Example 2 Example 3
Total 223 142 194 100
thermal
conductanc
a
NOTE: All figures are calculated assigned the value of
comparative example 3 as 100. The larger the value is, the
better the thermal conductance is.
As obvious from Table 1, embodiment 1, compared with
comparative examples 1, 2, and 3, is high in the total
thermal conductance. Accordingly, embodiment 1 can
efficiently transmit Joule heat generated in the insulating
coil to the iron core to result in suppression of temperature
rise.
Embodiment 2
Fig. 11 is a partially sectional view showing a test
model of a dynamoelectric machine using a fixing member
according to another embodiment of the present invention.
This model is constituted of an iron core 2 composed of
stacked silicon steels l, a slot 3 formed in the iron core 2,
an aluminum block 4 imitated an insulating coil, and a
laminate sheet 5 wound on the aluminum block 4. Incidentally,
employed laminate sheet 5, as identical with embodiment 1, is
one obtained by sandwiching the calendered aramid paper 18 by
silicone rubber having high thermal conductivity 19 that is
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shown in Fig. 5.
In addition, in this embodiment, preceding installation
of the aluminum block 4 provided with the laminate sheet 5
into the slot 3, on both internal side surfaces of the slot 3
silicone grease 23 having high thermal conductivity (thermal
conductivity = 0.8 W/m° K) is coated. Consequently, when the
aluminum block 4 is installed into the slot 3, the silicone
grease 23 intervenes between the laminate sheet 5 and slot 3.
In order to check thermal conduction, to the iron core
2 and aluminum block 4, as identical with embodiment l, in
the perpendicular direction with respect to the side surface
of the aluminum block 4, a set of five thermocouples 24 is
disposed. Here, the sets of thermocouples 24 are disposed
three in depth direction of the aluminum block 4 and also
three of set 24 on the opposite side with respect to the
aluminum block 4, that is, in total six sets of thermocouples
are disposed. Thereby, variation of the total thermal
conductance in depth direction due to dimensional scattering
of the aluminum block 4 and slot 3 is measured. Here, other
constitution of the test model is identical with embodiment 1.
To the aluminum block 4 of the test model, with a
sheathed heater, heat amount of 300 W is supplied, and with
the respective thermocouples shown in Fig. 11, temperatures
of the respective portions are measured. From these
temperatures, the variation in depth direction of total
thermal conductance of both side surfaces of the aluminum
block 4 is calculated. The results are shown in Table 2.
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Comparative Example 4
To the test model identical with embodiment 2 except
for that silicone grease of high thermal conductivity is not
coated on the internal surface of the slot 3, with a sheathed
heater, heat amount of 300 W is supplied, and with the
respective thermocouples, temperatures of the respective
portions are measured. From these temperatures, the
variation in depth direction of total thermal conductance of
both side surfaces of the aluminum block 4 is calculated.
The results are shown in Table 2.
Table 2
Total Thermal conductance of Embodiment 2 and Comparative
Example 4
Temperature measurement
position
1 2 3
Embodiment 2 100 100 100
Comparative 90 95 61
example 4
As obvious from Table 2, at measurement positions 1 and
2, there is no remarkable difference in the total thermal
conductance. However, at the measurement position 3,
embodiment 2 has higher value. From this, it is understood
that due to the grease of high thermal conductivity, Joule
heat generated in the insulating coil is particularly
efficiently transmitted to the iron core to result in
suppression of temperature rise.
Embodiment 3
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With a laminate sheet 5 according to another embodiment
shown in Fig. 6, tear strength is evaluated of the case
having slits 25. The laminate sheet 5 has a structure in
which aramid paper 18' that is not calendered is sandwiched
by silicone rubber layers 19 having high thermal conductivity.
The silicone rubber layer 19 having high thermal conductivity
disposed on both surfaces has twenty slits 25 per 10 cm with
a depth that reaches to the surface of the aramid paper 18'.
The laminate sheet 5 of such structure is wound around
an aluminum block 4 imitating an insulating coil so that the
direction of slits 25 forms an angle of 45° with respect to
the installation direction. On installing the wound aluminum
block into the slot 3 identical with Fig. 7, the aluminum
block 4 can be installed into the slot 3 without inducing
tear of the laminate sheet 5.
Comparative Example 5
The laminate sheet of embodiment 3 is wound around an
aluminum block 4 so that the slits 25 are perpendicular with
respect to the installation direction of the aluminum block 4,
followed by installation into the slot 3. All the other
conditions are identical with embodiment 3.
As a result of this, on installing the aluminum block 4,
the laminate sheet 5 is torn at portions where the laminate
sheet 5 contacts with corners of a bottom surface of the
aluminum block 4. As a result of this, upon completion of
installation, approximately one fifth of the laminate sheet 5
is forced out to cause gaps between the aluminum block 4 and
CA 02285763 1999-10-12
internal surface of the slot 3.
From the above, when the laminate sheet 5 is provide
with the slits 25 on the surface thereof and wound around an
aluminum block 4 with an angle of 45° with respect to
installation direction, compared with the case where the
slits 25 are disposed perpendicular with respect to the
installation direction, the gaps are not likely to occur
between the aluminum block 4 and slot 3 due to tear.
Accordingly, it is confirmed that with such constitution,
Joule heat generated in an insulating coil can be transmitted
efficiently to result in suppression of temperature rise.
It will be apparent to those familiar with the
manufacture of dynamoelectric machines that various
modifications and improvements of the invention may be made
without departing from the foregoing teaching in the
invention, accordingly, it is our intention to encompass
within the appended claims the true spirit and scope of the
invention.
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