U.S. patent application number 10/271865 was filed with the patent office on 2003-02-27 for rotating electrical machine with slotless stator.
This patent application is currently assigned to Honda Giken Kogyo Kabushiki Kaisha. Invention is credited to Fukuda, Takeo, Ozawa, Masaru.
Application Number | 20030038555 10/271865 |
Document ID | / |
Family ID | 17061766 |
Filed Date | 2003-02-27 |
United States Patent
Application |
20030038555 |
Kind Code |
A1 |
Ozawa, Masaru ; et
al. |
February 27, 2003 |
Rotating electrical machine with slotless stator
Abstract
A slotless stator assembling two divided cores which jointly
define a stator core into a cylindrical shape so as to contain
therebetween a cylindrically shaped stator winding, wherein the
stator winding has an outer diameter larger than an inner diameter
of the stator core in the uncompressed condition of the winding.
The stator winding is assembled inside the stator core in a
radially inward compressed condition. Since the stator winding
functions as a spring pressing the inside of the stator core so as
to expand in the normal direction (the radial outward direction),
the winding is mechanically secured by the resilient spring force
to the inner periphery of the stator core. Hence there is no longer
the need for a special fixation mechanism or adhesive when
assembling the stator core winding and stator core together.
Inventors: |
Ozawa, Masaru; (Wako-shi,
JP) ; Fukuda, Takeo; (Wako-shi, JP) |
Correspondence
Address: |
CARRIER BLACKMAN AND ASSOCIATES
24101 NOVI ROAD
SUITE 100
NOVI
MI
48375
|
Assignee: |
Honda Giken Kogyo Kabushiki
Kaisha
1-1, Minamiaoyama 2-chome, Minato-ku
Tokyo
JP
|
Family ID: |
17061766 |
Appl. No.: |
10/271865 |
Filed: |
October 16, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10271865 |
Oct 16, 2002 |
|
|
|
09648057 |
Aug 25, 2000 |
|
|
|
Current U.S.
Class: |
310/154.02 ;
310/179 |
Current CPC
Class: |
H02K 1/12 20130101; H02K
15/061 20130101; H02K 15/02 20130101; Y10T 29/49009 20150115; H02K
3/47 20130101 |
Class at
Publication: |
310/154.02 ;
310/179 |
International
Class: |
H02K 021/26; H02K
021/38 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 26, 1999 |
JP |
11-240589 |
Claims
1. A rotating electrical machine comprising a slotless stator, the
slotless stator including a cylindrical stator core having no slots
and a cylindrically shaped stator winding having a larger outer
diameter than an inner diameter of said stator core, disposed
within said stator core in a resiliently compressed condition, and
said stator winding being secured to an inner periphery of said
stator core by a resultant resilient force of said stator
winding.
2. A slotless stator comprising a cylindrical stator core having no
slots and a cylindrically shaped stator winding having a larger
outer diameter than an inner diameter of said stator core, disposed
within said stator core in a resiliently compressed condition.
3. A slotless stator according to claim 6, further comprising a
resilient material inserted between said stator core and said
stator winding.
4. A slotless stator according to claim 7, wherein a silicone sheet
is used as said resilient material.
5. A slotless stator according to claim 6, further comprising
resin, said resin being impregnated in said stator winding, in a
condition with said stator winding secured to an inner periphery of
said stator core.
6. A rotating electrical machine according to claim 1, wherein said
cylindrical stator core includes a plurality of divided cores which
jointly define the cylindrical stator core when assembled
together.
7. A rotating electrical machine according to claim 1, further
comprising a resilient insulating material inserted between said
stator core and said stator winding.
8. A rotating electrical machine according to claim 7, wherein a
silicone sheet is used as said resilient, insulating material.
9. A rotating electrical machine according to claim 7, further
comprising resin, said resin being impregnated in said stator
winding, in a condition with said stator winding secured to an
inner periphery of said stator core.
10. A slotless stator according to claim 2, wherein said
cylindrical stator core includes a plurality of divided cores which
jointly define the cylindrical stator core when assembled
together.
11. A slotless stator according to claim 3, further comprising
resin, said resin being impregnated in said stator winding, in a
condition with said stator winding secured to an inner periphery of
said stator core.
12. A rotating electrical machine comprising a slotless stator, the
slotless stator including a plurality of approximately rhombic
shape coil segments forming a hollow cylindrical shape winding, a
resilient insulating sheet wrapped around the outer periphery of
said cylindrical shape stator winding, two divided cores of a
cylindrical core mounted each on one end of the cylindrical stator
winding such that the stator winding pressed the inside of the
assembled core in the normal direction and in a resiliently
compressed condition, and varnish impregnated into the stator
winding.
13. A slotless stator according to claim 12, wherein an outer
diameter of said stator winding in an uncompressed condition is
larger than an inner diameter of said cylindrical core.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a slotless stator where a
stator winding is secured to the inner periphery of a stator core
having no slots, and to an improved rotating electrical machine
incorporating the slotless stator, in which the conventional need
for a special fixation mechanism or adhesive between the winding
and the core is eliminated.
[0003] This application is based on Japanese Patent Application No.
11-240589.
[0004] 2. Description of the Related Art
[0005] Heretofore as a rotating electrical machine incorporating a
slotless stator where a cylindrically shaped stator winding is
fitted to the inner periphery of a cylindrically shaped stator core
having no slots, there is known the rotating electrical machine
disclosed in Japanese Patent No. 2554859.
[0006] Moreover, in the same publication there is disclosed a
method where a rod shape temporary support member on the outer
periphery of which a stator winding has been preformed, is inserted
from one end opening of a cylindrically shaped stator core. The
temporary support member is then withdrawn leaving the stator
winding inside the stator core, and the stator winding is affixed
to the inner periphery of the stator core by impregnating the
winding with resin and then hardening the resin.
[0007] However, with this method, since this involves inserting the
stator winding from the end opening of the stator core with the
stator winding secured to the temporary support body, the outer
diameter of the stator winding must be formed smaller than the
inner diameter of the stator core.
[0008] Consequently, by simply withdrawing the temporary support
member and arranging the stator winding inside the stator core, the
stator winding is not secured to the inner periphery of the stator
core.
[0009] Therefore, resin must be impregnated into the stator winding
and hardened, to secure the stator winding to the inner periphery
of the stator core with adhesive force. Hence the assembly process
becomes complicated.
SUMMARY OF THE INVENTION
[0010] The present invention takes into consideration the above
situation, with the object of obviating the need for a special
fixation mechanism or adhesive, to thereby simplify the assembly of
a slotless stator and reduce the cost of the stator.
[0011] In order to achieve the above object, the present invention
adopts the following means.
[0012] That is to say, a slotless stator according to the present
invention is characterized in comprising a slotless stator, the
slotless stator including a cylindrical stator core having no slots
and a cylindrically shaped stator winding, the winding having a
larger outer diameter than an inner diameter of said stator core
when in an uncompressed condition, the winding being disposed
within said stator core in a resiliently compressed condition, and
said stator winding being secured to an inner periphery of said
stator core by a resultant resilient force of said stator
winding
[0013] With this construction, the stator winding is fitted inside
the stator core in a condition of being compressed radially
inwards.
[0014] At this time, since the stator winding functions as a spring
pressing the inside of the stator core so as to expand in the
normal direction (the radial outward direction), the winding is
pressed by the resilient spring force at that time against the
inner periphery of the stator core.
[0015] Therefore, by this resilient force the stator winding is
mechanically secured to the inner periphery of the stator core, and
hence a special fixation mechanism or adhesive is not required.
[0016] Furthermore, when a current flows in the stator winding,
heat is generated so that an outward expanding force acts on the
stator winding. Hence at the time of operating, the winding is
secured even more stably within the core.
[0017] With the slotless stator according to the present invention,
in the case where a resilient material is provided between the
divided core and the stator winding, the resilient force acting in
the normal direction can be further strengthened, and hence the
stator winding can be more stably secured within the core.
[0018] In particular, in the case where a silicone sheet which
contains a filler with good thermal conductivity such as boron
nitride, such as used for transistor heat dissipation purposes is
used as the resilient material, the heat dissipation is improved
and cooling efficiency is also improved.
[0019] With the slotless stator according to the present invention
as described above, there is no need for an adhesive for securing
the stator winding to the inner periphery of the stator core.
However, there is the case where the stator winding is immersed in
a resin such as varnish in order to electrically insulate between
the windings.
[0020] In this case, preferably the resin is impregnated, in a
condition with the stator winding secured to the inner periphery of
the stator core.
[0021] With this construction, the situation where the resin which
is thickly attached to the outer peripheral side of the stator
winding hardens so that elastic restoration of the stator winding
is restricted, can be effectively avoided.
[0022] That is to say, if the stator winding is fitted to inside
the stator core after being impregnated with resin, the resin
hardens before fitting, giving the undesirable situation in that
fixation utilising the resilient force of the stator winding
becomes difficult. With the above construction, this undesirable
situation does not arise.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is a longitudinal cross-section showing an embodiment
of a rotating electrical machine according to the present
invention.
[0024] FIG. 2 is a diagram for explaining an embodiment of a
manufacturing method for a slotless stator winding according to the
present invention, being a perspective view showing a condition
where a band shaped body is formed from a plurality of coil
segments.
[0025] FIG. 3 is a perspective view showing a stator winding formed
by wrapping the band shaped body comprising the plurality of coil
segments, into a cylindrical shape.
[0026] FIG. 4 is a diagram showing a condition where the stator
winding is immersed in an alcohol solvent in which BN particles
have been mixed.
[0027] FIG. 5 is a perspective view showing a condition where the
stator winding is being fitted inside a stator core of divided
construction.
[0028] FIG. 6 is a transverse cross-sectional view showing a
condition where the stator winding is arranged inside divided cores
which are oppositely arranged at a predetermined spacing.
[0029] FIG. 7 is a transverse cross-section showing the divided
cores assembled into a cylindrical shape so as to contain the
stator winding.
[0030] FIG. 8 is a diagram showing a condition where the stator
core and stator winding are immersed in a varnish tank while being
held together.
[0031] FIG. 9 is a longitudinal cross-section showing the completed
slotless stator with the varnish hardened.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0032] Hereunder is a description of embodiments of the present
invention with reference to the drawings.
[0033] FIG. 1 shows a rotating electrical machine 3 incorporating a
slotless stator 1. This rotating electrical machine 3 is suitable
for use in a high speed rotating electric machine which is used for
example at several kW to several tens of kW, and at rotational
speeds above several ten thousand rpm.
[0034] With the rotating electrical machine 3, the outer shape is
formed from a casing 5, and a rotor 7 is rotatably arranged via
bearings (not shown) along a central axis of the casing 5.
[0035] An oil passage 6 constituting one part of an oil pressure
circuit 4 is formed in the casing 5.
[0036] Lubricating oil is supplied to the oil passage 6 from a
supply source 8, and by means of this lubricating oil, lubrication
of the bearings and cooling of the slotless stator 1 is
simultaneously performed.
[0037] At this time, the cooling of the slotless stator 1 is
performed in sequence from the inner periphery thereof to the outer
periphery thereof, as shown by the arrow in FIG. 1.
[0038] A permanent magnet serving as a magnetic field generating
device is incorporated into the rotor 7.
[0039] The permanent magnet is constructed so that p (where p is an
even number of two or more) magnetic poles for generating a
magnetic flux in the radial direction, are formed on the outer
surface of the rotor 7.
[0040] For the permanent magnet, a rare earth magnet such as a
Sm--Co, Nd--Fe--B sintered magnet is suitable.
[0041] The slotless stator 1 is arranged around the rotor 7,
forming a small gap 11 via an inner tube (omitted from the
figure).
[0042] This inner tube is for containing the lubricating oil which
flows on the inner peripheral side of the slotless stator 1 (shown
by the arrow in FIG. 1), and is made for example from a zirconia
ceramic having non magnetic and non conducting properties. The
inner tube may be replaced with another ceramic material such as
alumina.
[0043] The slotless stator 1 is one which is not formed with slots
for securing a stator winding 15.
[0044] Moreover, the slotless stator 1 is constructed with the
stator winding 15 located on the rotor 7 side and a stator core 17
located on the casing 5 side. The stator winding 15 having an outer
diameter larger than the inner diameter of the stator core 17 in
its non-compressed or natural condition is arranged inside the
stator core 17 with a resiliently contracted diameter.
[0045] The stator core 17 is in the form of a hollow cylindrical
body with a cylindrical surface which is not formed with slots on
the inner peripheral surface thereof, and is secured to the casing
5 so that the oil passage 6 for passing lubricating oil (shown by
the arrow in FIG. 1) is formed between the outer periphery thereof
and the inner periphery of the casing 5.
[0046] Moreover, the stator core 17, as shown in FIG. 5 through
FIG. 7 is made up of two divided cores 13 evenly divided
circumferentially.
[0047] The division surfaces 13A of these divided cores 13 are
respectively formed with engaging protrusions and engaging recess
12a, 14a and 12b, 14b (see FIGS. 6-7). The engaging protrusion and
engaging recess 12a, 14a of one of the divided cores 13 engage with
the engaging recess and engaging protrusion 14a and 12b of the
other divided core 13.
[0048] In FIG. 5, the shape of the divided cores 13 is simplified,
and a more accurate shape is as shown in FIG. 6 and FIG. 7.
[0049] The stator winding 15 is of a hollow cylindrical shape
having an outer diameter larger than the inner diameter of the
stator core 17 in the natural or non-compressed condition, and is
secured to the stator core 17 via an insulation layer 19 so that
the inner peripheral face of the stator core 17 faces the outer
peripheral face of the stator winding 15.
[0050] Next is a description using FIG. 2 through FIG. 9, of an
embodiment of a manufacturing method for the slotless stator
according to the present invention.
[0051] At first, a hollow cylindrically shaped stator winding 15 is
formed by combining together a plurality of approximately rhombic
shape coil segments 23a, 23b, and 23c.
[0052] The coil segments 23a, 23b and 23c are formed by forming
turns by winding a wire sheaf 25 of a plurality of fine wires
composed of conductors bundled together, through one turn in an
approximately rhombic shape, and then winding and arranging a
plurality of the turns so that the turns are sequentially shifted
continuously so as to be adjacent to each other in the direction of
one diagonal Al of the rhombic shape (refer to FIG. 2).
[0053] Then after sequentially shifting and overlapping the coil
segments 23a, 23b and 23c in the direction of the diagonal line Al
to form a band shaped body 27, the band shaped body 27 is rolled
into a hollow cylindrically shaped to thereby give the hollow
cylindrically shaped stator winding 15 (refer to FIG. 3).
[0054] After this, the stator winding 15 is immersed in an alcohol
solvent 16 into which BN particles 18 have been mixed so that the
BN particles 18 are filled from the surface of the stator winding
15 to the interior thereof (refer to FIG. 4). Here rather than
immersing, a technique involving dripping may be used.
[0055] After this, the stator winding 15 is withdrawn from the
alcohol solvent 16 and air dried to evaporate the volatile
alcohol.
[0056] Next, the silicone sheet 19a (omitted from FIG. 5)
constituting one portion of the insulating layer 19 is wrapped
around the outer periphery of the stator winding 15, and the stator
winding 15 is then assembled inside the stator core 17.
[0057] Hereunder is a detailed description using FIG. 6 and FIG. 7,
of the steps of assembling the stator winding 15 inside the stator
core 17.
[0058] At first, the two divided cores 13 are oppositely arranged
so that the inner peripheral faces thereof face each other with a
constant gap therebetween in the vertical direction.
[0059] This gap is set sufficiently larger than the outer diameter
of the stator winding 15.
[0060] Then the stator winding 15 is mounted on the inner
peripheral face of the lower divided core 13, using a rod shape jig
M. This divided core 13, and the upper divided core 13 are then
brought together to engage the engaging protrusions 12a and 12b
with the engaging recesses 14a and 14b.
[0061] By so doing, the stator winding 15 is assembled inside the
stator core 17 in a radially inward compressed condition.
[0062] At this time, since the stator winding 15 effectively
functions as a spring pressing the inside of the stator core 17 so
as to expand in the normal direction (the radial outward
direction), the winding is pressed by the resilient force at that
time against the inner periphery of the stator core 17.
[0063] By this resilient force, the stator winding 15 is
mechanically secured to the inner periphery of the stator core 17,
and hence a special fixation mechanism or adhesive is not
required.
[0064] Moreover, since the stator winding 15 is assembled inside
the stator core 17 with the silicone sheet 19a wrapped around the
outer periphery thereof, the resilient force acting in the normal
direction is further strengthened by the resiliency of the silicone
sheet 19a which is compressed between the winding and the core, so
that the stator winding 15 is more stably secured.
[0065] After this, the stator core 17 and the stator winding 15 are
held together as one and immersed in a varnish impregnation tank 31
(refer to FIG. 8).
[0066] At this time, since the outer peripheral face of the stator
winding 15 and the inner peripheral face of the stator core 17 are
in close contact with the silicone rubber sheet 19a, there is
practically no impregnation between these forces with the
varnish.
[0067] Then, after impregnating the varnish into the stator winding
15, the stator core 17 and the stator winding 15 are withdrawn from
the varnish impregnating tank 31 as one. Then by heat hardening the
varnish, the manufacture of the slotless stator is completed (refer
to FIG. 9).
[0068] As described above, with the manufacturing method for a
slotless stator according to the present invention, by assembling
the two divided cores 13 into a cylindrical shape so as to contain
the stator winding 15 which normally has an outer diameter larger
than the inner diameter of the stator core 17 in the natural or
non-compressed condition, the stator winding 15 functions as a
spring and produces a resilient force pressing the inside of the
stator core 17 so as to expand in the normal direction (the radial
outward direction). Therefore, the stator winding 15 is
mechanically secured by this resilient force to the inner periphery
of the stator core 17.
[0069] Consequently, the manufacturing method of the invention is
simplified in comparison to conventional methods because high
accuracy axial alignment not being required, as with the case where
the stator winding 15 is inserted from one open end of a stator
core formed integrally in a cylindrical shape, and because adhesive
or a special fixation mechanism for securing the stator winding 15
inside the stator core 17 is not required. Hence the assembly of
the slotless stator 1 can be performed very easily.
[0070] Moreover, since the stator core 17 and the stator winding 15
are immersed in a varnish impregnation tank 31 with the stator
winding 15 secured to the inner periphery of the stator core 17,
the varnish is hardly impregnated into the outer peripheral side of
the stator winding 15.
[0071] Consequently, the situation where varnish which is thickly
attached to the outer peripheral side of the stator winding 15
hardens so that the elastic restoration of the stator winding 15 is
restricted, can be effectively avoided. Hence the stator winding 15
can be stably secured to the inner periphery of the stator core
17.
[0072] Furthermore, when a current flows in the stator winding 15,
heat is generated so that an additional outward expanding force
acts. Hence at the time of operating, the stator winding 15 is
secured even more stably to the stator core.
[0073] Moreover, with the present embodiment, since the silicone
sheet 19a is disposed between the divided core 13 and the stator
winding 15, the resilient force acting in the normal direction is
further strengthened by the resiliency of the silicone sheet which
is compressed between the winding and the core, so that the stator
winding 15 is even more stably secured.
[0074] In particular, in the case where a silicone sheet which
contains a filler with good thermal conductivity such as boron
nitride, such as used for transistor heat dissipation purposes is
used as the resilient material, since the thermal conductivity is
higher than that of varnish, the heat dissipation for the stator
winding 15 is improved and cooling efficiency is also improved.
[0075] In particular, with the present embodiment, since
lubricating oil is circulated on the inner peripheral side of the
stator winding 15, a further improvement in the cooling efficiency
is achieved.
[0076] Here with the above embodiment, the cylindrically shaped
stator winding 15 is formed by combining together the approximately
rhombic shaped plurality of coil segments 23a, 23b, and 23c.
However, this may of course be formed by some other method.
[0077] Moreover, the stator core 17 is constructed from two divided
cores 13. However, the number of divisions may be three or
more.
[0078] As will be clear from the above description, with the
present invention, by having a divided construction for the stator
core, and assembling a stator winding having an outer diameter
greater than the inner diameter of the stator core thereinside, the
winding functions as a spring for producing a resilient force in
the normal direction on the stator winding. By this resilient
force, the stator winding is mechanically secured to the inner
periphery of the stator core. Therefore a special fixation
mechanism or adhesive is not required, thus simplifying assembly of
the slotless stator.
[0079] Furthermore, in the case where a resilient material is
disposed between the divided core and the stator winding, the
resilient force in the normal direction is further strengthened by
the resiliency of the material which is compressed between the
winding and the core. Hence the securing force for the stator
winding can be further increased.
[0080] In particular, in the case where a silicone sheet which
contains a filler with good thermal conductivity such as boron
nitride, such as used for transistor heat dissipation purposes is
used as the resilient material, the heat dissipation is improved.
Hence not only is the securing strength improved but also an
improvement in cooling efficiency can be achieved.
[0081] Moreover, in the case where a resin is impregnated into the
stator winding, by impregnating the resin in a condition with the
stator winding secured to the inner periphery of the stator core,
the resin is no longer thickly attached to the outer peripheral
side of the stator winding. Therefore any restriction on elastic
restoration of the stator winding due to the resin attached to the
outer periphery hardening can be effectively avoided. Hence the
stator winding can be stably secured inside the stator core.
[0082] Moreover, with the stator winding according to the present
invention, by arranging the cylindrically shaped stator winding
having a larger outer diameter than the inner diameter of the
stator core in a resiliently compressed condition inside the
cylindrical stator core having no slots, then in the above manner,
the stator winding functions effectively as a spring inside the
stator core, so that the winding is mechanically secured to the
inner periphery of the stator core by the resilient spring force.
Hence a special fixation mechanism or adhesive is not required,
thus simplifying assembly of the slotless stator.
[0083] Although there have been described what are presently
considered to be the preferred embodiments of the invention, it
will be understood by any persons skilled in the art that
variations and modifications may be made thereto without departing
from the gist, spirit or essence of the invention. The scope of the
invention is indicated by the appended claims.
* * * * *