U.S. patent application number 12/517830 was filed with the patent office on 2010-11-25 for stator coil heating apparatus and stator coil heating method.
This patent application is currently assigned to KABUSHIKI KAISHA OET. Invention is credited to Kenichiro Fukumaru, Ikuo Hayashi, Hideaki Kimura, Satoshi Koide, Keishi Matsumoto, Hideaki Miyake.
Application Number | 20100295412 12/517830 |
Document ID | / |
Family ID | 39608749 |
Filed Date | 2010-11-25 |
United States Patent
Application |
20100295412 |
Kind Code |
A1 |
Matsumoto; Keishi ; et
al. |
November 25, 2010 |
STATOR COIL HEATING APPARATUS AND STATOR COIL HEATING METHOD
Abstract
A stator coil heating apparatus and a stator coil heating method
that are capable of effectively preventing a core from thermal
deformation particularly caused due to a magnetic flux generated by
a coil head, without the problem of heating temperature variation,
and also shortening a time for the process of heating a stator
coil, are provided. A stator coil heating apparatus A to heat a
stator coil L wound around a circular core F, comprises: induction
heating coil heads 1 and 11 that heat the circular coil L by
generating an inductive effect acting from outside in the thickness
direction of the core F, against circular winding coil bases La and
Lb that are sticking out of end faces Fa and Fb of the core F in
the thickness direction thereof; and shields 2 and 12 that block a
magnetic flux generated by the coil heads 1 and 11, out of the end
faces Fa and Fb of the core F in the thickness direction
thereof.
Inventors: |
Matsumoto; Keishi;
(Osaka-fu, JP) ; Fukumaru; Kenichiro; (Aichi-ken,
JP) ; Hayashi; Ikuo; (Aichi-ken, JP) ; Miyake;
Hideaki; (Aichi-ken, JP) ; Kimura; Hideaki;
(Aichi-ken, JP) ; Koide; Satoshi; (Aichi-ken,
JP) |
Correspondence
Address: |
BUCHANAN, INGERSOLL & ROONEY PC
POST OFFICE BOX 1404
ALEXANDRIA
VA
22313-1404
US
|
Assignee: |
KABUSHIKI KAISHA OET
Osaka-shi
JP
TOYOTA JIDOSHA KABUSHIKI KAISHA
Toyota-shi
JP
|
Family ID: |
39608749 |
Appl. No.: |
12/517830 |
Filed: |
January 11, 2008 |
PCT Filed: |
January 11, 2008 |
PCT NO: |
PCT/JP2008/050301 |
371 Date: |
June 5, 2009 |
Current U.S.
Class: |
310/273 |
Current CPC
Class: |
H02K 15/12 20130101;
H05B 6/36 20130101 |
Class at
Publication: |
310/273 |
International
Class: |
H02K 57/00 20060101
H02K057/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 12, 2007 |
JP |
2007-005205 |
Claims
1. A stator coil heating apparatus to heat a stator coil wound
around a circular core, comprising: an induction heating coil head
that heats the circular coil by generating an inductive effect
acting from outside in the thickness direction of the core, against
a circular winding coil base that is sticking out of an end face of
the core in the thickness direction thereof; and a shield that
blocks a magnetic flux generated by the coil head, out of an end
face of the core in the thickness direction thereof.
2. The stator coil heating apparatus recited in claim 1, wherein:
the shield is provided to the induction heating coil head, in a
unified manner.
3. The stator coil heating apparatus recited in claim 1, wherein:
the coil head is looped in one plain or cylindrically, at
approximately the same diameter as that of the circular winding
coil base, and is positioned coaxially with the core, outside of
the core in the thickness direction thereof, against each of the
sides of the winding coil base in the thickness direction of the
core; and the shield is a circular one that blocks a magnetic flux
generated by the coil head, out of the outer circumference area of
an end face of the core in the thickness direction thereof.
4. The stator coil heating apparatus recited in claim 1, wherein:
the coil head is looped in one plain or cylindrically, and the coil
head is positioned in an arbitrary location in the circumferential
direction, from outside in the thickness direction of the core,
against the winding coil base on each of the end faces of the core
in the thickness direction thereof; the shield is an arch-shaped
one that blocks a magnetic flux generated by the coil head, out of
the outer circumference area of an end face of the core in the
thickness direction thereof; and the stator rotates about its axis
when the stator coil is inductively heated.
5. A stator coil heating method to inductively heat a stator coil
wound around a circular core, by an inductive heating coil head,
comprising: heating the circular coil, by generating an inductive
effect that acts from outside in the thickness direction of the
core, against a circular winding coil base that is sticking out of
an end face of the core in the thickness direction thereof, while
blocking by a shield, a magnetic flux that is generated by the coil
head and acts on an end face of the core in the thickness direction
thereof.
6. A stator coil heating apparatus comprising: a high-frequency
induction heating portion that heats a stator coil and a circular
core having the stator coil wound around the inner circumference of
the circular core itself, by a high-frequency induction heating
coil head provided in the central opening of the core, and wherein:
the high-frequency induction heating portion is positioned
coaxially with the core, outside of the core, against each of the
end faces of the core in the thickness direction thereof, and
further comprising: a shield that blocks a magnetic flux generated
by the coil head, out of the outer circumference area of the core
in the thickness direction thereof.
7. The stator coil heating apparatus recited in claim 6, wherein:
the shield is cylindrical or doughnut-shaped.
8. The stator coil heating apparatus recited in claim 6, wherein:
the shield is positioned in the vicinity of the outer end of the
stator coil in the radial direction of the core.
9. The stator coil heating apparatus recited in claim 6, wherein:
the high-frequency induction heating coil head has a looped portion
that is positioned in the vicinity of the stator coil, against one
or both of the end faces of the core in the thickness direction
thereof.
10. The stator coil heating apparatus recited in claim 6, wherein:
the high-frequency induction heating coil head is positioned in the
middle region of the core in the thickness direction thereof,
circumferentially around the core.
11. A stator coil heating method to heat with high-frequency
induction heat, a stator coil wound around the inner circumference
of a circular core, by inserting a high-frequency induction heating
coil head into the central opening of the circular core,
comprising: positioning a shield that blocks a magnetic flux
generated by the high-frequency induction heating coil head, out of
the outer circumference area of the core, coaxially with the core,
outside against each of the end faces of the core in the thickness
direction thereof, and then heating the stator coil and the core by
applying an alternating-current voltage to the coil head.
12. The stator coil heating method recited in claim 11, wherein:
the shield is cylindrical or doughnut-shaped.
13. The stator coil heating method recited in claim 11, wherein:
the shield is positioned in the vicinity of the outer end of the
stator coil in the radial direction of the core.
14. The stator coil heating method recited in claim 11, wherein:
the high-frequency induction heating coil head has a looped portion
that is positioned in the vicinity of the stator coil, against one
or both of the end faces of the core in the thickness direction
thereof.
15. The stator coil heating method recited in claim 11, wherein:
positioning the high-frequency induction heating coil head, in the
middle region of the core in the thickness direction thereof,
circumferentially around the core, and then heating the stator coil
with high-frequency induction heat.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a stator coil heating
apparatus and a stator coil heating method that are used in the
manufacturing process of a stator such as an automotive electrical
generator.
BACKGROUND OF THE ART
[0002] As generally practiced, in the manufacturing process of a
stator that is an automotive electrical generator, a three-phase
stator coil is wound around a circular core, and after that, the
entire stator coil including a circular winding coil base that is
sticking out of an end face of the core in the axial direction
thereof, is impregnated with varnish. In this state of things, the
stator coil is heated, and thereby the impregnating varnish is
harden-dried.
[0003] After impregnating the stator coil with varnish, it is
conventionally practiced that the entire stator is inserted into a
heating furnace while being rotated, and thereby the impregnating
varnish is harden-dried with heated air.
[0004] However, in the method of harden-drying varnish by using a
heating furnace, a temperature of the stator is increased in a slow
manner after the stator is inserted into a heating furnace.
Therefore, in order to satisfy enough thermal and temporal
conditions to harden varnish material, a longer heating time is
required and more electrical energy is consumed, which causes high
costs. Furthermore, in order to keep a constant temperature in a
heating furnace, a temperature in a heating furnace is required to
be increased before inserting a workpiece therein and is required
to be kept all the while until entirely discharging a workpiece
therefrom, which makes costs still higher.
[0005] Meanwhile, in the process of preheating the stator coil
before impregnating the stator coil with varnish it is
conventionally suggested for the purpose of improving operating
efficiency and also saving electrical energy by reduction of a
heating time, that a high-frequency induction heating coil head is
positioned in the central opening of the circular core, then the
stator coil and the core are heated rapidly by the high-frequency
induction heating method.
[0006] A heating means using this above-mentioned high-frequency
induction heating coil head is probatively introduced to the
process of harden-drying varnish impregnating the stator coil.
Concretely, a high-frequency induction heating coil head is set
from outside in the thickness direction of the core of the stator,
against the winding coil base that is sticking out of each of the
end faces of the core in the thickness direction (the axial
direction) thereof, and then the stator coil is heated with
high-frequency induction heat applied by the high-frequency
induction heating coil head.
[0007] Furthermore, it is conventionally suggested that the stator
coil is energized to cause self-heating, and thus the stator coil
is heated (as referred to Patent Document 1: Japanese Unexamined
Laid-open Patent Publication No. S60-82050, for example). However,
in the case of heating the stator coil by employing the induction
heating method, a part of a magnetic flux generated by an induction
heating coil head acts on the end faces of the core in the
thickness direction thereof. Since a core is usually constructed of
layered silicon steel plates and the thermal conductivity in the
thickness direction of such a core is low, only the end faces of
the core in the thickness direction thereof are particularly
heated, and the end faces of the core in the thickness direction
thereof could be thermally deformed. And accordingly, the stator
coil could not be heated favorably, which leaves a problem.
[0008] As for the method of energizing the stator coil to cause
self-heating, there is a tendency that a self-heating temperature
is varied depending on a type of the stator coil. Therefore, this
method is not an easy choice and leaves a problem.
[0009] On the other hand, in the manufacturing process of a stator
such as an automotive electrical generator, a stator coil wound
around the inner circumference of a circular core is sometimes
impregnated with varnish or plastic-molded. In these cases, it is
necessary to heat the stator coil and the core before varnish
impregnation or plastic-mold processing.
[0010] Conventionally, the entire stator coil is heated in a
hot-air heating furnace before varnish impregnation or plastic-mold
processing.
[0011] However, in the conventional method above, since the stator
coil is heated from its surface in a slow manner, a longer heating
time is required. Accordingly, more electrical energy is
consumed.
[0012] And even trying to heat the stator coil and the core
uniformly and evenly, a long heating time is required and keeping
the stator coil at a predetermined temperature is not easy. As
results, varnish applied to the stator coil could not be
impregnated well and the molding could lose its quality because a
crack or etc. could be caused, which leaves a problem.
[0013] To cope therewith, it is suggested for the purpose of
improving temperature variation in the stator, saving electrical
energy by reduction of a heating time, and etc., that a
high-frequency induction heating coil head is positioned in the
central opening of the circular core, and thereby the stator coil
and the core are heated rapidly by the high-frequency induction
heating method.
[0014] And also, as described in Patent Document 1 above, it is
also suggested that the stator coil is heated more uniformly by
energization to cause self-heating in addition to the
high-frequency induction heating method.
[0015] However, in the method of positioning a high-frequency
induction heating coil head in the central opening of the circular
core and heating the stator coil and the core by the high-frequency
induction heating method, a large part of a magnetic flux generated
by the high-frequency induction heating coil head acts on the outer
circumference areas of the end faces of the core in the thickness
direction thereof. Since a core is usually constructed of layered
silicon steel plates and the thermal conductivity in the thickness
direction of such a core is low, only these parts are particularly
heated and thereby thermal deformation could be caused and its
insulating resin could be damaged, and thus the stator coil could
not be heated favorably, which leaves a problem.
[0016] And in the method of heating the stator coil and the core by
energization to cause self-heating in addition to the
high-frequency induction heating method, a self-heating temperature
is varied depending on a type of the stator coil, and the entire
stator coil could be vibrated by an electromagnetic force generated
when the stator coil is energized, which leaves a problem.
Furthermore, it is troublesome to determine a position of an
energization terminal and automation is not easy, and sparks could
be occurred between connection terminals due to poorly fitting
contacts when the stator coil and a power source for energization
are connected, which leaves a problem.
PROBLEMS TO BE RESOLVED BY THE INVENTION
[0017] The present invention is developed to cope with the current
circumstances described above, and it is an objective of the
present invention to provide a stator coil heating apparatus and a
stator coil heating method that are capable of effectively
preventing a core from thermal deformation particularly caused due
to a magnetic flux generated by a coil head, without the problem of
heating temperature variation, and also shortening a time for the
process of heating a stator coil.
[0018] It is another objective of the present invention to provide
a stator coil heating apparatus and a stator coil heating method
that are capable of uniformly heating a stator coil and a core and
also preventing temperature elevation caused by particularly
heating the core, by the high-frequency induction heating method
without the need for energizing the stator coil.
MEANS OF SOLVING THE PROBLEMS
[0019] The objectives described above will be achieved by the
following means. [0020] (1) A stator coil heating apparatus to heat
a stator coil wound around a circular core, comprising: [0021] an
induction heating coil head that heats the circular coil by
generating an inductive effect acting from outside in the thickness
direction of the core, against a circular winding coil base that is
sticking out of an end face of the core in the thickness direction
thereof; and [0022] a shield that blocks a magnetic flux generated
by the coil head, out of an end face of the core in the thickness
direction thereof. [0023] (2) The stator coil heating apparatus
recited in (1), wherein:
[0024] the shield is provided to the induction heating coil head,
in a unified manner. [0025] (3) The stator coil heating apparatus
recited in (1) or (2), wherein: [0026] the coil head is looped in
one plain or cylindrically, at approximately the same diameter as
that of the circular winding coil base, and is positioned coaxially
with the core, outside of the core in the thickness direction
thereof, against each of the sides of the winding coil base in the
thickness direction of the core; and [0027] the shield is a
circular one that blocks a magnetic flux generated by the coil
head, out of the outer circumference area of an end face of the
core in the thickness direction thereof. [0028] (4) The stator coil
heating apparatus recited in (1) or (2), wherein: [0029] the coil
head is looped in one plain or cylindrically, and the coil head is
positioned in an arbitrary location in the circumferential
direction, from outside in the thickness direction of the core,
against the winding coil base on each of the end faces of the core
in the thickness direction thereof; [0030] the shield is an
arch-shaped one that blocks a magnetic flux generated by the coil
head, out of the outer circumference area of an end face of the
core in the thickness direction thereof; and [0031] the stator
rotates about its axis when the stator coil is inductively heated.
[0032] (5) A stator coil heating method to inductively heat a
stator coil wound around a circular core, by an inductive heating
coil head, comprising: [0033] heating the circular coil, by
generating an inductive effect that acts from outside in the
thickness direction of the core, against a circular winding coil
base that is sticking out of an end face of the core in the
thickness direction thereof, while blocking by a shield, a magnetic
flux that is generated by the coil head and acts on an end face of
the core in the thickness direction thereof. [0034] (6) A stator
coil heating apparatus comprising: [0035] a high-frequency
induction heating portion that heats a stator coil and a circular
core having the stator coil wound around the inner circumference of
the circular core itself, by a high-frequency induction heating
coil head provided in the central opening of the core, and wherein:
[0036] the high-frequency induction heating portion is positioned
coaxially with the core, outside of the core, against each of the
end faces of the core in the thickness direction thereof, and
further comprising: [0037] a shield that blocks a magnetic flux
generated by the coil head, out of the outer circumference area of
the core in the thickness direction thereof. [0038] (7) The stator
coil heating apparatus recited in (6), wherein: [0039] the shield
is cylindrical or doughnut-shaped. [0040] (8) The stator coil
heating apparatus recited in (6) or (7), wherein: [0041] the shield
is positioned in the vicinity of the outer end of the stator coil
in the radial direction of the core. [0042] (9) The stator coil
heating apparatus recited in (6), (7) or (8), wherein: [0043] the
high-frequency induction heating coil head has a looped portion
that is positioned in the vicinity of the stator coil, against one
or both of the end faces of the core in the thickness direction
thereof. [0044] (10) The stator coil heating apparatus recited in
(6), (7), (8) or (9), wherein: [0045] the high-frequency induction
heating coil head is positioned in the middle region of the core in
the thickness direction thereof, circumferentially around the core.
[0046] (11) A stator coil heating method to heat with
high-frequency induction heat, a stator coil wound around the inner
circumference of a circular core, by inserting a high-frequency
induction heating coil head into the central opening of the
circular core, comprising: [0047] positioning a shield that blocks
a magnetic flux generated by the high-frequency induction heating
coil head, out of the outer circumference area of the core,
coaxially with the core, outside against each of the end faces of
the core in the thickness direction thereof, and then heating the
stator coil and the core by applying an alternating-current voltage
to the coil head. [0048] (12) The stator coil heating method
recited in (11), wherein: [0049] the shield is cylindrical or
doughnut-shaped. [0050] (13) The stator coil heating method recited
in (11) or (12), wherein: [0051] the shield is positioned in the
vicinity of the outer end of the stator coil in the radial
direction of the core. [0052] (14) The stator coil heating method
recited in (11), (12) or (13), wherein: [0053] the high-frequency
induction heating coil head has a looped portion that is positioned
in the vicinity of the stator coil, against one or both of the end
faces of the core in the thickness direction thereof. [0054] (15)
The stator coil heating method recited in (11), (12), (13) or (14),
wherein: [0055] positioning the high-frequency induction heating
coil head, in the middle region of the core in the thickness
direction thereof, circumferentially around the core, and then
heating the stator coil with high-frequency induction heat.
ADVANTAGEOUS EFFECTS OF THE INVENTION
[0056] According to the invention recited in the item (1), a stator
coil is heated by using an induction heating coil head, not by
using a hot-air heating furnace. Therefore, a heating time for the
process of heating and harden-drying after impregnating a coil with
varnish, for example, can be reduced. Furthermore, the
inconvenience occurring in the case of harden-drying by a hot-air
heating method using a heating furnace, which is the high cost
caused due to a longer heating time and more electrical energy
consumption, and also environmental inconveniences, are
eliminated.
[0057] Furthermore, the inconvenience occurring in the method of
energizing the stator coil, which is self-heating temperature
variation, is eliminated. And thus, a favorable heating process is
enabled.
[0058] Particularly, an end face of a core in the thickness
direction thereof is shielded by a shield from a magnetic flux
generated by the induction heating coil head. Therefore, the risk
that an end face of the core is particularly heated and thermally
deformed is eliminated. Furthermore, a large part of a magnetic
flux acts on the stator coil accordingly, and the stator coil is
efficiently heated and varnish or etc. can be harden-dried
rapidly.
[0059] According to the invention recited in the item (2), the
shield is provided to the induction heating coil head, in a unified
manner. Therefore, the shield can be set at the same time as
loading the induction heating coil head, which would contribute to
promptness of preparation for heating.
[0060] According to the invention recited in the item (3), the
induction heating coil head which diameter is approximately the
same as that of the circular winding coil base that is sticking out
of each of the end faces of the core in the thickness direction
thereof, is used. Therefore, the whole circumference of the winding
coil base can be heated at the same time by a magnetic flux
generated by the induction coil head, without moving the
stator.
[0061] Furthermore, the outer circumference area of an end face of
the core in the thickness direction thereof is shielded by the
circular shield. Therefore, each of the end faces can be
effectively prevented from being thermally deformed.
[0062] According to the invention recited in the item (4), the
induction heating coil head is positioned against the winding coil
base, in an arbitrary location in the circumferential direction
thereof, and then the stator coil is rotated about its axis and
inductively heated. And thus, an induction heating process can be
easily performed without using a coil head which diameter is the
same as that of the winding coil base.
[0063] According to the invention recited in the item (5), the
stator coil is heated by using the inductive heating coil head, not
by using a heating furnace. Therefore, the process of heating and
harden-drying after impregnating the coil with varnish, for
example, can be efficiently performed in a short time.
[0064] According to the invention recited in the item (6), a shield
that blocks a magnetic flux generated by a high-frequency induction
heating coil head, out of the outer circumference area of a
circular core, is positioned coaxially with the core, outside on
each of the end faces of the core in the thickness direction
thereof. Therefore, a magnetic flux generated by the high-frequency
induction heating coil head is prevented from acting on the outer
circumference area of the core, and heat is applied mainly from the
inner circumference thereof, and meanwhile, a large part of the
high-frequency magnetic flux goes through a stator coil and the
stator coil is heated favorably. Thus, the stator coil and the core
can be heated uniformly, at the same time, the inconveniences:
thermal deformation and damage on insulating plastic, which may be
brought by particularly heating only the outer circumference area
of an end face of the core in the thickness direction thereof, can
be eliminated. Furthermore, since the stator coil is not energized,
the inconveniences: heating temperature variation in the stator
coil, which is caused by energization; vibration of the stator
coil; troubles in determining a position of a terminal in the case
of energization; and occurrence of sparks due to poorly fitting
contacts when connecting for energization, never arise.
[0065] According to the invention recited in the item (7), a
magnetic flux generated by the high-frequency induction heating
coil head can be effectively blocked out of the outer circumference
area of the core, by the cylindrical or doughnut-shaped shield.
[0066] According to the invention recited in the item (8), the
shield is positioned in the vicinity of the outer end of the stator
coil in the radial direction of the core. Therefore, a magnetic
flux generated by the coil head can be more surely blocked out of
the outer circumference area of the core, and the core can be more
evenly heated from its inner circumference due to thermal
conduction from one to another layer thereof.
[0067] According to the invention recited in the item (9), the
high-frequency induction heating coil head has a looped portion
that is positioned in the vicinity of the stator coil, against one
or both end faces of the core in the thickness direction thereof.
Therefore, a high-frequency magnetic flux generated by the coil
head, acting from each looped portion, goes through the stator coil
more effectively, in comparison to the case in which the looped
portion of the coil head is provided only in the middle region of
the core in the thickness direction thereof. And thus, heat can be
applied more efficiently.
[0068] According to the invention recited in the item (10), the
high-frequency induction heating coil head is positioned in the
middle region of the core in the thickness direction thereof,
circumferentially around the core. Therefore, the stator coil and
the core are inductively heated by this outside coil head,
additionally. Consequently, in comparison to the case of heating
only by an inside coil head, induction heating both from inside and
outside requires a less heating time to increase a temperature of
the core and the stator coil and less energy is required for
heating, which would contribute to reduction of electrical
energy.
[0069] According to the invention recited in the item (11), a
shield is provided then high-frequency induction heat is applied.
Therefore, a magnetic flux generated by a high-frequency induction
heating coil head is blocked out of the outer circumference area of
a core, and heat is applied mainly from the inner circumference
thereof, and meanwhile, a large part of a high-frequency magnetic
flux goes through a stator coil and the stator coil is heated
favorably. Thus, the stator coil and the core can be heated
uniformly, and the inconveniences: thermal deformation and damage
on insulating plastic, which may occur to the outer circumference
area of an end face of the core in the thickness direction thereof,
can be eliminated at the same time.
[0070] According to the invention recited in the item (12), a
magnetic flux generated by the high-frequency induction heating
coil head can be effectively blocked out of the outer circumference
area of the core, by the cylindrical or doughnut-shaped shield.
[0071] According to the invention recited in the item (13), the
shield is positioned in the vicinity of the outer end of the stator
coil in the radial direction of the core. Therefore, a magnetic
flux generated by the high-frequency induction heating coil head
can be more surely blocked out of the outer circumference area of
the core.
[0072] According to the invention recited in the item (14), the
high-frequency induction heating coil head has a looped portion
positioned in the vicinity of the stator coil, against one or both
of the end faces of the core in the thickness direction thereof.
Therefore, a high-frequency magnetic flux generated by the coil
head, acting from each looped portion, goes through the stator coil
more effectively, in comparison to the case in which the looped
portion of the coil head is positioned only in the middle region of
the core in the thickness direction thereof. And thus, heat can be
applied more efficiently.
[0073] According to the invention recited in the item (15), the
high-frequency induction heating coil head is positioned in the
middle region of the core in the thickness direction thereof,
circumferentially around the core, and then high-frequency
induction heat is applied. Therefore, the stator coil and the core
are inductively heated by this outside coil head, additionally. As
a result, in comparison to the case of heating only by an inside
coil head, a less heating time is required to increase a
temperature of the core and the stator coil and less energy is
required for heating.
BRIEF DESCRIPTION OF THE DRAWINGS
[0074] FIG. 1 This is an exploded perspective view showing a stator
coil heating apparatus according to one embodiment of the present
invention.
[0075] FIG. 2 This is a plain view showing the stator coil heating
apparatus set on a stator.
[0076] FIG. 3 This is a half cutaway view showing the stator coil
heating apparatus set on a stator.
[0077] FIG. 4 This is an enlarged view showing a principal part of
the stator coil heating apparatus with explanation of its
operation.
[0078] FIG. 5 This is a perspective view showing a stator coil
heating apparatus according to another embodiment of the present
invention, which is set on a stator.
[0079] FIG. 6 This is a cutaway view showing a stator rotary
driving mechanism of the stator coil heating apparatus according to
another embodiment of the present invention.
[0080] FIG. 7 This is an outline plain view showing a stator
manufacturing system that includes the heating apparatus according
to yet another embodiment of the present invention.
[0081] FIG. 8 This is an outline elevational view showing the same
stator manufacturing system.
[0082] FIG. 9 This is an elevational view showing a high-frequency
induction heating apparatus according to one embodiment of the
present invention, to heat a stator coil and a core.
[0083] FIG. 10 This is a cutaway view showing the same
high-frequency induction heating apparatus.
[0084] FIG. 11 This is a perspective view showing a coil head of
the same high-frequency induction heating apparatus.
[0085] FIG. 12 This is a perspective view showing a cylindrical
shield of the same high-frequency induction heating apparatus.
[0086] FIG. 13 (A) is a view to explain the state of conveying a
stator by a chuck mechanism, and (B) is a view showing a stator
conveyed to a heating area and set therein.
[0087] FIG. 14 (C) is a view showing a coil head that is a
high-frequency induction heating means, set on a stator, and (D) is
a view to explain the state of conveying a heated stator to a
varnish application area.
[0088] FIG. 15 (E) is a view to explain the state of applying
varnish to a stator coil after heating.
[0089] FIG. 16 This is an elevational cutaway view showing a
high-frequency induction heating apparatus according to another
embodiment of the present invention, to heat a stator coil and a
core.
[0090] FIG. 17 This is an elevational cutaway view showing a
high-frequency induction heating apparatus according to yet another
embodiment of the present invention, to heat a stator coil and a
core.
EXPLANATION OF THE CODES
[0091] 1, 11 High-frequency Induction Heating Coil Head [0092] 2,
12 Shield [0093] A, B High-frequency Induction Heating Apparatus
[0094] F Core of a Stator [0095] Fa, Fb End Face of a Core in the
Thickness Direction Thereof [0096] L Stator Coil of a Stator [0097]
La, Lb Winding Coil Base of a Stator Coil [0098] M Stator [0099]
High-frequency Induction Heating Apparatus [0100] Varnish
Application Means [0101] 330 Coil Head of a High-frequency
Induction Heating Apparatus [0102] 330a, 330b Looped Portion of a
Coil Head [0103] 360 Cylindrical Shield [0104] F1 Core of a Stator
[0105] F1a Outer Circumference Area of a Core [0106] L1 Stator Coil
[0107] M1 Stator [0108] M1a Central Opening of a Stator
PREFERRED EMBODIMENTS TO IMPLEMENT THE INVENTION
[0109] FIG. 1 is an exploded perspective view showing a stator coil
heating apparatus according to an embodiment of the present
invention, FIG. 2 is a plain view showing the same stator coil
heating apparatus set on a stator, and FIG. 3 is a half cutaway
view showing the same stator coil heating apparatus set on a
stator.
[0110] This embodiment will be explained with the example of
heating a stator coil of a stator that is an automotive electrical
generator. However, it is not limited thereto.
[0111] As shown in FIG. 1 through FIG. 3, a stator M comprises a
circular core F constructed of a plurality of thin silicon steel
plates layered in the thickness direction and a three-phase stator
coil L wound around the core F. And circular winding coil bases La
and Lb are sticking out of the end faces Fa and Fb of the core F in
the thickness direction (the axial direction: the vertical
direction in Figure) thereof, respectively. The entire stator coil
L including these winding coil bases La and Lb is varnish-applied
and impregnated (not shown in Figure) in the pre-process or in the
post-process.
[0112] T represents a three-phase external terminal drawn from the
stator coil L.
[0113] In order to heat the stator coil L impregnated with varnish,
stator coil heating apparatuses A and B are positioned against both
of the end faces in the thickness direction thereof, respectively
(only the heating apparatus A on one end face is shown in FIG.
1).
[0114] Hereinafter, the heating apparatus A on one end face (the
upper end face) thereof, will be explained on behalf, since the
heating apparatuses A and B have the same structure.
[0115] The heating apparatus A is structured as a high-frequency
induction heating apparatus, and comprises a high-frequency
induction heating coil head 1 driven by an output from a
high-frequency oscillator not shown in Figure, and a shield 2.
[0116] The high-frequency induction heating apparatus A allows an
operator to specify heating conditions such as a heating
temperature, a heating time and etc., appropriate for a type of the
stator M, via an operation panel not shown in Figure. And the
specified heating conditions are recorded in a memory (not shown in
Figure), as a heating chart.
[0117] And he/she calls a preferable heating chart by selecting and
specifying a heating chart appropriate for a type of the stator M
that is a heating target, and then the heating conditions of the
stator coil L are implemented according to the heating chart, by
computer control.
[0118] The high-frequency induction heating coil head 1 is looped
some times (twice, for example) in one plain or cylindrically (in a
circular cylinder, in this embodiment), at approximately the same
diameter as that of the circular winding coil base La, and is
positioned coaxially from outside in the thickness direction of the
core F, against the winding coil base La.
[0119] On the outer circumferential surface of a circumferential
loop is of this high-frequency induction heating coil head 1, a
plurality of, for example, four L-shaped shield supporting brackets
4 . . . are provided at equal spaces in the circumferential
direction, and a vertical part 4a of each of the shield supporting
brackets 4 . . . is fixed by brazing (as referred to FIG. 4).
[0120] As for loading this high-frequency induction heating coil
head 1, this may be conveyed manually by an operator, or may be
conveyed automatically by a coil holding means prepared for
exclusive use. These can be arbitrarily selected.
[0121] As for the time of turning the high-frequency induction
heating coil head 1, it is not limited to a two-turn loop as
exemplified here. The time of turning can be arbitrarily increased
or reduced depending on a preferable coil heating temperature,
processing speed, and etc.
[0122] The shield 2 blocks a high-frequency magnetic flux generated
by the high-frequency induction heating coil head 1, out of the
outer circumference area of the end face Fa (the upper end face) of
the core F in the thickness direction thereof. It is made from a Cu
plate for example, and is shaped into a brim at a diameter that is
larger than that of the winding coil base La of the stator coil L
in order not to be interfered by the winding coil base La. And it
is positioned coaxially, from outside in the thickness direction of
the core F, against the outer circumference area of the end face Fa
thereof.
[0123] The shield 2 is connected and attached to the outer
circumferential surface of the circumferential loop is of the
heating coil head 1, by the four L-shaped shield supporting
brackets 4 . . . , in the state of being electrically insulated
from the coil head 1. Concretely, as shown in FIG. 4, the shield 2
is placed on a horizontal part 4b of each of the four L-shaped
shield supporting brackets 4 . . . and fixed with plastic (vinyl)
screws 6.
[0124] Meanwhile, a means to connect the shield 2 to the
circumferential surface of the circumferential loop is of the
high-frequency induction heating coil 1 is not limited to the
structure exemplified here, and the shield 2 is not necessarily
connected to the high-frequency induction heating coil 1. Any
arbitrary means can be employed as long as its structure allows the
shield 2 to e attached to the circumferential loop 1a of the
high-frequency induction heating coil 1, in a unified manner.
[0125] Hereinafter, operations of the stator coil heating apparatus
A having the above-mentioned structure, will be explained.
[0126] When the stator M having the stator coil L that is
impregnated with varnish is conveyed and placed at a predetermined
heating position, the high-frequency induction heating coil head 1
is set to a predetermined position, and meanwhile the shield 2
attached to the high-frequency induction heating coil head 1 in a
unified manner is positioned against the outer circumference area
of the end face Fa of the core F.
[0127] The shield 2 that is independent from the high-frequency
induction heating coil head 1, may be held in a specified position
by a holding means for exclusive use. Although, if the shield 2 is
attached to the high-frequency induction heating coil head 1 in a
unified manner as exemplified here, the shield 2 can be set at the
same time as loading the high-frequency induction heating coil head
1, which would contribute to promptness of preparation for
heating.
[0128] When the high-frequency oscillator of the high-frequency
induction heating apparatus A is driven in this state of things, a
high-frequency output is given to the high-frequency induction
heating coil head 1. Then, high-frequency induction heat is applied
to the stator coil L of the stator M due to a high-frequency
magnetic flux generated by the coil head 1, and thus the stator
coil L is heated, and thereby the varnish impregnating the stator
coil L is harden-dried.
[0129] When the stator coil L is heated at a predetermined
temperature with high-frequency induction heat applied by the
high-frequency induction heating coil head 1, the high-frequency
induction heating operation by the coil head 1 is resumed.
[0130] As described above, high-frequency induction heat is applied
to the varnish-applied and impregnated stator coil L by using the
high-frequency induction heating coil head 1, and thus the stator
coil L is heated directly. Therefore, a long heating time is not
required contrary to the case of heating by using a heating
furnace, which would contribute to reduction of electrical
energy.
[0131] Furthermore, the inconvenience occurring in the case of
energizing the stator coil L to cause self-heating, which is
self-heating temperature variation, is eliminated. And thus, the
stator coil L is heated favorably.
[0132] On the other hand, if the winding coil base La of the stator
coil L is heated by the high-frequency induction heating coil head
1 not having the shield 2 set thereto, a part of a high-frequency
magnetic flux generated by the coil head 1 acts particularly on the
outer circumference area of the end face Fa of the core F in the
thickness direction thereof and the end face Fa is particularly
heated, and could be thermally deformed.
[0133] To cope with this, in this embodiment of the present
invention, the shield 2 is provided in each position against the
outer circumference area of the end face Fa of the core F in the
thickness direction thereof. Therefore, a high-frequency magnetic
flux generated by the coil head 1, trying to act on the outer
circumference area of the end face Fa of the core F, is blocked
out. Accordingly, the outer circumference area of the area face Fa
of the core F is prevented from being heated particularly, and this
part is effectively prevented from being thermally deformed.
[0134] Furthermore, since the outer circumference area of the end
face Fa of the core F is shielded from a high-frequency magnetic
flux, a large part of the high-frequency magnetic flux generated by
the high-frequency induction heating coil head 1 acts on the stator
coil L. Thus, the stator coil is heated efficiently, which would
contribute to reduction of a heating time.
[0135] FIG. 5 shows another embodiment of the present
invention.
[0136] As shown in FIG. 5, the high-frequency induction heating
apparatus A comprises a small high-frequency induction heating coil
head 11. This high-frequency induction heating coil head 11 is
positioned in an arbitrary location in the circumferential
direction of the stator coil L, from outside in the thickness
direction of the core F. Similarly, a high-frequency induction
heating apparatus B having the same structure is provided on the
other end face (the lower end face in FIG. 5) of the core F in the
thickness direction thereof, and the high-frequency induction
heating coil head 11 is positioned from outside in the thickness
direction of the core F, although it is not shown in FIG. 5.
[0137] These high-frequency induction heating coil heads 11 are
shaped in an arbitrary loop, and looped some times (twice, for
example) in one plain or cylindrically (in a circular cylinder, for
example).
[0138] Furthermore, an arch-shaped shield 13 is connected to the
outer circumferential surface of the high-frequency coil heads 11,
by the bracket 14.
[0139] The shield 12 is made from a Cu plate for example, and is
shaped into an arc. And it shields the outer circumference area of
the end face Fa of the core F in the thickness direction thereof,
from a high-frequency magnetic flux generated by the high-frequency
induction heating coil head 11.
[0140] Furthermore, this high-frequency induction heating apparatus
A comprises a stator rotary driving mechanism 20 that is capable of
chucking the stator M and letting it rotate about its axis.
[0141] This stator rotary driving mechanism 20 comprises a driving
axis 21 that is driven by a rotary driving apparatus such as a
motor not shown in Figure, in the state of being in a central
opening Fx of the core F of the stator M, and a plurality of stator
chuck members 23 that is provided at equal spaces around the
driving axis 21 and in the end region of this driving axis 21, and
have pushing portions 22 at the end.
[0142] This stator rotary driving mechanism 20 rotates the driving
axis 21. With rotation, the stator chuck members 23 extends out in
the radial direction and pushes the pushing portions 22 against the
inner wall of the central opening Fx of the circular core F, and
thus it rotates the stator M about its axis.
[0143] In this embodiment, in the case of applying high-frequency
induction heat by the high-frequency induction heating coil head
11, the coil head 11 is positioned in an arbitrary location in the
circumferential direction, against the winding coil base La of the
stator coil L, then the stator M is rotated about its axis. And
thereby the whole circumference of the winding coil base La of the
stator coil L is heated.
[0144] In this case, since the stator M is rotated, the coil head
11 that is smaller than the circular coil head 1 mentioned in the
prior embodiment can be used, and accordingly the shield 12 that is
small and arc-shaped can be applicable.
[0145] In this embodiment explained above, the high-frequency
induction heating method is employed. Alternatively, the
low-frequency induction heating method using commercial power
frequency and etc. for example, may be employed. Furthermore, in
the example using the large-diameter heating coil head of FIG. 1
through FIG. 4, the coil L is heated without rotating the stator M.
Alternatively, the coil L may be heated with rotating the stator
M.
[0146] Furthermore, heat is applied when the axial direction (the
thickness direction) of the stator M is vertically positioned. Or
alternatively, heat may be applied when the axial direction of the
stator M is horizontally positioned, and thus the position of the
stator M can be arbitrarily specified. In this case, an induction
heating coil head can be positioned not under the stator, and thus,
even if low-viscosity varnish material or etc. before being
hardened happens to drop off the coil end or a slot, it would not
stick to the induction heating coil head, which would contribute to
ease of maintenance.
[0147] Furthermore, the shield 2 and 12 are positioned so as to
shield only the outer circumference areas of the end faces of the
circular core F in the thickness direction thereof. As necessary,
these may also shield the inner circumference area thereof.
However, since the outer circumference areas of the end faces of
the circular core F in the thickness direction thereof are exposed
more broadly and coils are wound around the inner circumferences,
it is generally preferred to let a magnetic flux act also on the
wound coils and apply inductive heat thereto. Therefore, like in
this embodiment, it is better to shield only the outer
circumference areas of the end faces of the circular core F in the
thickness direction thereof.
[0148] FIG. 7 and FIG. 8 are an outline plain view and an outline
elevational view, respectively, showing a stator manufacturing
system including a stator coil and core heating apparatus according
to one embodiment of the present invention.
[0149] As shown in FIG. 7 and FIG. 8, a stator coil and core
heating apparatus is used to heat a coil (stator coil) L1 of a
stator M1 shown in FIG. 9 and FIG. 10, and a core F1, in the
process of pre-heating before applying varnish W (FIG. 15) to the
coil L1, and in the process of harden-heating after varnish
application.
[0150] As shown in FIG. 9 and FIG. 10, the stator M1 has the stator
coil L1 that is wound around an inner-circumferential protrusion
Fib of the circular core F1 constructed of many steel plates
layered in the thickness direction thereof, and a three-phase
external terminal T1 is provided to the stator coil L1.
[0151] Mostly, this stator manufacturing system comprises a main
workbench 10, a conveyance mechanism 20 to convey the stator M, a
high-frequency induction heating apparatus 30 that applies
high-frequency induction heat to the stator coil L1 of the stator
M1 and the core F1 in a predetermined position, and a varnish
application means 40 that applies varnish to the stator M1.
[0152] The main workbench 10 is a plate shaped in a rectangular
that is long in the horizontal direction for example, and the top
surface thereof has a receiving area S1, a heating area S2, a
varnish application area S3 and a discharge area S4, specified from
the right at predetermined intervals.
[0153] The conveyance mechanism 20 grasps the stator M1 from an
upper area of the main workbench 10 and conveys it from the
receiving area S1, through the areas S2 and S3, to the discharge
area S4.
[0154] This conveyance mechanism 20 comprises a rail 210 that is
supported by a pillar 20a and another pillar 20a for example and
provided along the horizontal direction in an upper area of the
main workbench 10, a trolley 230 supported by this rail 210 so as
to be movable in the horizontal direction, and a chuck apparatus
240 strung out from the trolley 230 by a wire 230a so as to be
movable up and down, and the stator M1 is grasped by a chuck 240a
of the chuck apparatus 240.
[0155] As a matter of course, the conveyance mechanism 20 of the
stator M1 is not limited to what uses the rail 210 and the trolley
230 above, and various conveyance mechanisms may be employed.
Alternatively, a self-propelled robot may be employed.
[0156] The high-frequency induction heating apparatus 30 heats the
stator coil L1, particularly, of the stator M1 and keeps it at a
predetermined temperature, in advance of applying varnish to the
stator coil L1 of the stator M1. And it comprises for example, a
high-frequency oscillator 310, a receiving table 320 that receives
the stator M1 conveyed to the heating area S2, a heating coil head
330 that is drawn from the high-frequency oscillator 310 via a
cable 340, a coil head setting mechanism 350 that inserts and
positions this coil head 330 in the stator M1, and a cylindrical
shield 360.
[0157] This high-frequency induction heating apparatus 30 is
capable of letting heating conditions such as a heating
temperature, a heating time and etc. appropriate for a type of the
stator M1, specified via an operation panel (not shown in Figure).
The specified various heating conditions are recorded as a heating
chart into a memory (not shown in Figure). Then, the appropriate
heating chart for a type of the stator M1 that is a heating target
is selected/specified via an operation panel or etc., thereby it is
called out of the heating chart, and then the heating conditions to
heat the stator M1 are executed according to the heating chart
under computer control.
[0158] A plurality of supporting pins not shown in Figure stand on
the top surface of the receiving table 320, and when the stator M1
is placed on the receiving table 320, the supporting pins are
inserted into a plurality of fitting holes (not shown in Figure)
cut in the stator M1, and thus the stator M1 is positioned.
[0159] As a matter of course, this receiving table 320 is not
necessarily provided. Alternatively, the stator M1 may be received
directly on the workbench 10.
[0160] As shown in FIG. 5, the heating coil head 330 has a
two-stage structure constructed of a upper looped portion 330a and
a lower looped portion 330b in the thickness direction (the
vertical direction) of the core F1. And the upper looped portion
330a is for example a two-turn loop that is provided on one end
face (the upper end face) of the core F1 in the thickness direction
thereof, approximately at the upper end region of the stator coil
L1, meanwhile the lower looped portion 330b is for example a
two-turn loop that is provided on the other end face (the lower end
face) of the core F1 in the thickness direction thereof,
approximately at the lower end region of the stator coil L1.
[0161] As described above, providing the upper looped portion 330a
on one end face of the core F1 in the thickness direction thereof
in the vicinity of the upper end region of the stator coil L1, and
the lower looped portion 330b on the other end face of the core F1
in the thickness direction thereof in the vicinity of the lower end
region of the stator coil L1, is intended to let a high-frequency
magnetic flux generated by the looped portions 330a and 330b act on
and go trough the stator coil L1 of the stator M1, effectively from
a near position.
[0162] The heating coil head 330 is not necessarily a two-stage one
having the upper looped portion 330a and the lower looped portion
330b, and only needs to have at least one of the loops, 330a
(330b). Furthermore, the number of turns of the looped portions
330a and 330b may be set to three, one or other plural number,
depending on a preferable coil heating speed.
[0163] The coil head setting mechanism 350 has a coil head holding
member 351 that holds the coil head 330 from the bottom, and a
cylinder 352 that moves this coil head holding member 351 up and
down. And its structure extends a piston rod 352a and lets it
insert the coil head 330 into a central opening Mia of the stator
M, when the stator M is placed on the receiving table 32.
[0164] The coil head setting mechanism 350 is not limited to the
structure above, and an arbitrary structure that inserts the coil
head 330 into the stator M1 from the top, for example, may be
employed.
[0165] The cylindrical shield 360 is shaped in a circular cylinder
in this embodiment. And in order to let an induction magnetic flux
generated by the coil head 330 intensively go through the stator
coil L1, it blocks out the magnetic flux trying to act on the outer
circumference area F1a of the core F1 and directs it to the stator
coil L1, and is positioned coaxially with the core F1, in the
vicinity of the outer end of the stator coil L1 in the radial
direction of the core F1 and outside on the upper and lower end
faces of the stator coil L1 in the thickness direction of the core
F1. From the point of view of letting a magnetic flux act on the
stator coil L1 more effectively, the interval between the stator
coil L1 and each of the cylindrical shields 360 is preferably
specified within about 5 mm.
[0166] A constituent material of this shield 360 can be any
metallic material, and it is preferably a less magnetoresistive
metallic material, for example a Cu plate, etc. It is not limited
to a plain plate, and punched metallic material, meshed material or
etc. may be used.
[0167] This cylindrical shield 360 may be cooled by a cooling
apparatus not shown in Figure, in order to avoid being heated due
to an electrical current passing circumferentially. Furthermore, in
this example, as shown in FIG. 12, a slit 360a is made in a
location in the circumferential direction of the cylindrical shield
360, and it blocks out an eddy current in the circumferential
direction and thereby prevents the cylindrical shield 360 itself
from being heated. Meanwhile, the slit 360a may be left out if a
cooling apparatus is provided.
[0168] The varnish application means 50 applies varnish W (FIG. 15)
to the stator coil L1 of the stator M that is conveyed to the
varnish application area S3 after being heated with high-frequency
induction heat, and it comprises for example, a receiving table 410
that receives the stator M1, a varnish provider 420 that is
positioned behind the workbench 10, and a varnish application gun
440 that is connected by a varnish providing pipe 430 from the
varnish provider 420 and applies the varnish W from an upper area
of the stator M1.
[0169] As a matter of course, the receiving table 410 is not
necessarily provided. Alternatively, the heated stator M1 may be
received directly on the workbench 10.
[0170] Hereinafter, the method of manufacturing the stator M1 by
the manufacturing system of the structure described above will be
explained.
[0171] Initially, the stator M is conveyed to the receiving area S1
on the workbench 10 after a previous process. Then, as shown in
FIG. 13 (A), the stator M1 is grasped by the chuck 240a of the
chuck apparatus 240. And the stator M1 grasped by the chuck 240a is
conveyed to the heating area S2 by trolley 230's leftward moving
operation.
[0172] When the stator M1 arrives in the heating area S2, the
stator M1 grasped by the chuck 240a is received on the receiving
table 320 and positioned thereon, as shown in FIG. 13 (B).
[0173] In this state of things, the cylinder 351 of the coil head
setting mechanism 350 is driven. Then, as shown in FIG. 4 (C), the
piston rod 352a is extended, and thereby the coil head 330 is moved
upward together with the coil head holding member 351, and inserted
and set into the central opening M1a of the stator M1.
[0174] In this state of things, initially, the high-frequency
oscillator 310 of the high-frequency induction heating apparatus 30
is driven. Then, a high-frequency output is given to the coil head
330, and a high-frequency induction effect acts on the stator coil
L1 of the stator M1 due to a high-frequency magnetic flux generated
by the coil head 330, and thereby the stator coil L1 is heated
directly. In addition, the protrusion F1b of the inner
circumference of the core F1 is heated due to a high-frequency
induction effect, and thereby the stator coil L1 is heated through
the core F1.
[0175] As for heating conditions, an appropriate heating chart for
the stator M1 can be selected among various heating charts
preliminarily recorded in a memory of the high-frequency induction
heating apparatus 30, by using an operation panel or etc.
[0176] When the stator coil L1 of the stator M1 is heated at a
predetermined temperature with high-frequency induction heat
applied by the coil head 330, the high-frequency induction heat
applied by the coil head 330 is stopped.
[0177] Subsequently, the piston rod 351 of the cylinder 352 is
shortened, and thereby the coil head 330 is discharged from the
central opening M1a of the stator M1.
[0178] After that, as shown in FIG. 14 (D), the stator M1 is
grasped by the chuck 240a of the chuck apparatus 240, conveyed to
the varnish application area S3, then placed on the receiving table
410 and positioned thereon.
[0179] When the varnish provider 420 is driven in this state of
things, the varnish W is applied to the stator coil L1 of the
stator M1 from the varnish application gun 40 that is positioned in
an upper area of the stator M1, as shown in FIG. 15. Then, the
stator coil L1 is impregnated with the varnish W.
[0180] As described above, in the process of varnish application,
the stator M1 is inductively heated by the high-frequency induction
heating coil head 330, and thereby the stator coil L1 is heated
directly, and also heated through the core F1. Therefore, contrary
to the case of using a heating furnace, it is not necessary to
bother to insert the stator M1 in a heating furnace and discharge
it therefrom. That would improve operating efficiency. As a matter
of course, after the stator M1 is heated with high-frequency
induction heat, the stator M1 may be inserted into a heating
furnace in order to be heated uniformly and prevent from being
cooled, and then varnish may be applied thereto.
[0181] By the way, when the stator M1 is inductively heated by the
high-frequency induction heating coil head 330 without providing
the cylindrical shield 360 and the other cylindrical shield 360,
there is a risk that a large part of a high-frequency magnetic flux
generated by the coil head 330 acts on the circumference,
specifically the outer circumference area F1a of the core F1 in the
thickness direction thereof, and thereby only this area is
particularly heated.
[0182] To cope with this, in this embodiment, the cylindrical
shield 360 and the other cylindrical shield 360 are provided
outside on the upper and lower end faces of the stator coil L1 in
the thickness direction of the core F1. Therefore, a blocking
effect of the cylindrical shield 360 and the other cylindrical
shield 360 acts against a high-frequency magnetic flux trying to
act on the outer circumference area F1a of the core F1 from the
coil head 330 and prevents it from acting on the outer
circumference area F1a of the core F1, and thereby a large part of
the high-frequency magnetic flux is directed to the stator coil L1.
Thus, the outer circumference area F1a of the core F1 is not
particularly heated, and the stator coil L1 is heated efficiently
and rapidly.
[0183] Furthermore, the cylindrical shields 360 are positioned in
the vicinity of the outer end of the stator coil L1 in the radial
direction of the core F1, which could let the high-frequency
magnetic flux go through the stator coil L1 more effectively.
[0184] FIG. 16 shows yet another embodiment of the present
invention.
[0185] In the embodiment shown in FIG. 16, an outside core heating
coil head 500 of one-turn loop, for example, is provided
approximately in the middle region of the stator M1 in the
thickness direction thereof, circumferentially.
[0186] Providing this outside coil head 500, the core F1 is heated
from outside with high-frequency induction heat, and through the
core F1 which temperature is increased due to being heated in this
way, the stator coil L1 is also heated, and thus the entire stator
M1 is heated more efficiently. In comparison to the case of
applying heat only by the coil head 330, a less heating time is
required to heat the stator coil L1 and the core F1 at a
predetermined temperature and less energy is required for heating,
which would contribute to reduction of electrical energy.
[0187] For more efficient heat application, it is preferable that
heat is initially applied by the inside coil head 330, and after
that, heat is started to be applied by the outside heating head
500. The inside coil head 330 and the outside coil head 500 may be
connected to the same high-frequency power source and heating
timings and power may be adjusted thereby. Alternatively, those may
be driven by different power sources.
[0188] By the way, high-frequency induction heat is applied by
using the coil head 330 shown in FIG. 11 under the same conditions
excluding the shield 360: in the case of positioning the copper
cylindrical shields 360 (outside diameter: 203 mm, height: 70 mm,
thickness: 3 mm) shown in FIG. 12, coaxially with the core F1 of
the stator coil, outside on the upper and lower end faces of the
stator coil L1 in the thickness direction of the core F1 (the
interval between the stator coil L1 and each of the cylindrical
shields 360 is specified as 10 mm), with their circumferential
surfaces adjusted at the same level as the external sides of the
stator coil L1 in the radial direction of the core F1; and in the
case of not positioning the shield 360. Electrical energy used
therein is specified as 10 kw (180V, 56 A) and a frequency is
specified as 44.1 kHz.
[0189] As a result, in the case of not using the cylindrical shield
360, the speed of increasing a temperature of the outer
circumference area F1a of the core F1 in the thickness direction
thereof, was extremely higher than the speed of increasing a
temperature of the stator coil L1, and thereby heat application
could not be continued until a temperature of the stator coil L1
reaches a predetermined temperature. On the other hand, in the case
of using the cylindrical shield 360, the speed of increasing a
temperature of the stator coil L1 became higher, meanwhile the
speed of increasing a temperature of the outer circumference area
F1a of the core F1 in the thickness direction thereof became lower,
and thereby heat application could be continued until a temperature
of the stator coil L1 reaches a predetermined temperature.
[0190] Meanwhile, in the embodiment explained above, the stator M1
is positioned with the thickness direction of the core F1 (the
axial direction of the stator M1) adjusted to the vertical
direction, and then heated. However, a position of the stator M1 is
not limited to a specific one, and it may be positioned with the
thickness direction of the core F1 (the axial direction of the
stator M1) adjusted to the horizontal direction as shown in FIG.
17, and then heated.
[0191] Furthermore, the shield 360 is exemplified to be
cylindrical. Alternatively, the shield 360 of a doughnut-like
shape, which width exits in the radial direction, may be positioned
outside of the stator coil L1 as shown in FIG. 17, or the shield of
another shape may be positioned there. Briefly, any shape is
applicable as long as it is capable of blocking a magnetic flux
generated by the coil head 330, out of the outer circumference area
of the core F1.
[0192] This application claims priority under Japanese Patent
Application No. 2007-5205 filed on Jan. 12, 2007, the entire
disclosure of which is incorporated herein by reference in its
entirety.
[0193] The words and expressions employed herein are intended for
explanation, and neither for expounding in a limited way nor for
excluding any equivalent to the aspects, features and/or advantages
illustrated and described herein. And those should be understood to
include various modifications within the scope of the claimed
invention.
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