Title of Invention

ROTOARY ELECTRICAL MACHINE

Abstract The present invention relates to a rotary electrical machine (70) comprising a rotor rotational about an axis of a rotating shaft (72) in a first rotational direction; and a stator (88) disposed so as to oppose to the rotor (71), wherein one of the rotor (71) and the stator (88) is divided into at least two portions (83, 87) in the axial direction, a first portion (83) of the at least two portions (83, 87) being movable at least in a rotational direction or a reverse rotational direction of the first rotational direction relative to a second of the at least two portions (83, 87) in such a manner that a gap between the first portion (83) and the second portion (87) forms a magnetic resistance that is variable, the first portion (83) being a first stator core (80) having a first set of teeth (81), each tooth of the first set of teeth (81) having an end surface (81a) opposite the rotor (71) and a second end surface (81b) facing away from the end surface (81a), each tooth (81) of the first set of teeth having a winding (82) wound around a circumferential side surface (81c) thereof, and the second portion (87) being a second stator core (87) having a second set of teeth (84), the second set of teeth (84) having end portions (84a) facing the second end surfaces (81a) of the first set of teeth (81).
Full Text ROTARY ELECTRICAL MACHINE
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a small rotary electrical
machine in which a current flowing through a coil is not used
for a f ieldmagnet weakening control so that an extensive operation
range covering a high torque low speed rotation thrQug2i.iL_.low
torque high speed rotation is provided, and a control thereof
is easily done with high efficiency.
2. Description of the Related Art
Conventionally, radial gap type electric motors that are
used as a radial gap type rotary electrical machine, as a drive
source for electromotive two-wheeled vehicles or the like, and
other general electric motors, have a structure in which a yoke
of a rotor (rotor side yoke) having a rotating shaft supported
by its bearings and a yoke of a stator (stator side yoke) oppose
to each other, and their opposing surfaces extend parallel to
an axis of the rotating shaft.
The opposing surface of the rotor side yoke has a plurality
of field magnets circumferentially disposed on a cylindrical
inner wall, while the opposing surface of the stator side yoke
has a plurality of teeth radially disposed to oppose to the
cylindrical opposing surface of the rotor side yoke. A coil
is wound around each one of the plurality of teeth.
That is, in the radial gap type electric motor, the opposing
surfaces of the field magnets and the teeth extend parallel
to the axis of the rotating shaft, and a gap between the opposing
surfaces are formed to be cylindrical along the rotating shaft.
That is, as called the radial gap type, the gap is formed to
extend radially from the rotating shaft.
Also, to the contrary, although being a kind of the radial
gap type electric motor, there is another electric motor that
has a configuration in which the stator side yoke is cylindrically
formed, and the rotor side yoke is columnar to be positioned
within the cylinder. As one of this type of electric motors,
an electric motor is proposed so that a cylindrical member in
which a permeable section and an impermeable section are
alternately positioned is laid between opposing surfaces of
ends of respective projections of a stator core of the stator
core side yoke and opposing surfaces of respective permanent
magnets of the rotor side yoke to prevent cogging from occurring
and also to bring in a low torque operation in a high speed
rotation. (For example, see JP-A-2000-261988, laid-open
application publication ([Abstract], [0025] and Figs. 1 and
2) .)
Also, similarly, as one of the type of electric motors
in which the stator side yoke is cylindrically formed and the
rotor side yoke is columnar to be positioned within the cylinder,
in order to reduce the stator flux linkage in the high speed
rotation, another electric motor is proposed such that the stator
core of the stator side yoke is constructed with a cylindrical
core and a bar-like core reciprocating within the cylindrically
shaped core, and the bar-like shaped core moves in a radial
direction of the stator side coil relative to a coil that is
circumferentially wound around the cylindrically shaped core.
(For example, see JP-A-2004-166369, laid-open application
publication ([Abstract], [0020]-[0023] and Figs. 1 and 3).)
On the other hand, recently, in addition to the radial
gap type rotary electrical machines, axial gap type rotary
electrical machines attract a great deal of attention.
For example, an axial gap type electric motor, as one of
the axial gap type rotary electrical machines, has a disk-like
rotor side yoke including a rotational shaft supported by its
bearings and a disk-like stator side yoke which center is
consistent with an axis of a rotational shaft of the rotor side
yoke disposed to oppose to each other.
On an opposing surface of the rotor side yoke, a plurality
of field magnets are circularly (or annulaly) disposed along
a disk-like circumferential portion thereof, while, on an
opposing surface of the stator side yoke, a plurality of teeth
is disposed along a disk-like circumferential portion thereof.
Also, the gap is made between opposing surfaces of the field
magnets and of the teeth and the opposing surfaces define a
surface that crosses the rotational shaft at right angles (i.e.,
perpendicularly crosses the rotational shaft). That is, as
called the axial gap type, the gap is formed to extend in a
direction along the rotational shaft, i.e., axially.
In the axial gap type electric motor as thus described,
as one of methods to vary an output characteristic thereof,
a method is known in which either a rotor (the rotor side yoke
having field magnets) or a stator disposed to oppose to the
rotor (a coiled core positioned on the stator side yoke) is
movable in a direction of the rotational shaft to control a
distance between the rotor and the stator; therey., an amount
of magnetic flux flowing between the field magnets and the coiled
core is controlled to increase or decrease.
SUMMARY OF THE INVENTION
However, any one of the structures of the conventional
art described above is a structure in which a configuration
of the whole device can be large to increase mechanical loss.
In other words, the radial gap type motor is required to be
slimmer as possible, while the axial gap type motor is required
to be thinner as possible; however, both of the requirements
cannot be satisfied. Also, no remarkable improvements are given
to a point that electric power is wasted without contributing
to increasing torque.
In view of the circumstances, a subject of the present
invention is to provide a rotary electrical machine in which
a stator disposed to oppose to a rotor is divided into at least
two portions, one is fixed, and another one is movable in a
rotatiqnal direction of the rotor relative to the fixed one
portion to greatly change flow of flux flow, i.e., a base portion
of the stator is rotational (movable) to control the field.
Hereunder, a structure of a rotary electrical machine
according to the present invention is described.
First, the rotary electrical machine of a first invention
includes: a rotor rotational about an axis of a rotating shaft;
and a stator disposed to oppose to the rotor, wherein one of
the rotor and the stator is divided into at least two portions
along a direction in which direction the rotor and the stator
oppose to each other, and one portion of the divided two portions
is movable in a rotational direction or a reverse rotational
direction of the rotor relative to another one portion in such
a manner that a gap to form a magnetic reluctance between the
first portion and the second portion is variable.
This rotary electrical machine is constructed, for example,
such that the movement of the one portion relative to the another
one portion is a reciprocal movement within a predetermined
angle.
Also, the rotary electrical machine can be constructed,
for example, in such a manner that the one portion and the another
one portion are stators, the another one portion is a first
stator core having a plurality of first teeth respective one
end surfaces of which oppose to the rotor and a winding is wound
around a circumferential side surface of each one of the first
teeth, and the one portion is a second statqr core having a
plurality of second teeth respective one end portions of which
are positioned to oppose to respective opposite end surfaces
that oppositely exist relative to the one end ,'surfaces of the
first teeth that oppose to the rotor.
In this connection, the rotary electrical machine is
constructed, for example, in such a manner that a rotational
angle of the one portion relative to the another one portion
is less than an angle of nip that is defined by two neighboring
teeth of the second teeth.
Also, the rotary electrical machine can be constructed,
for example, in such a manner that the one portion and the another
one portion are rotors, the another one portion is a first rotor
section having a plurality of first magnetic members respective
one end surfaces of which oppose to the stator, and the one
portion is a second rotor section having a plurality of second
magnetic members respective end portions of which are positioned
to oppose to respective other end surfaces of the first magnetic
members that oppositely exist relative to the one end surfaces
that oppose to the stator.
In this connection, the rotary electrical machine is
constructed, for example, in such a manner that a rotational
angle of the one portion relative to the another one portion
is less than an angle of nip that is defined by two neighboring
magnetic members of the second magnetic members.
Next, the rotary electrical machine of a second invention
includes a rotor having a annular section that rotates about
an axis of a rotating shaft, a first stator core having a plurality
of first teeth each of which has a portion one end surface of
which is positioned to oppose to the annular section and a winding
is wound around a side circumferential surface of the portion
except for both end surfaces, and a second stator core having
a plurality of second teeth respective one end portions of which
are positioned to oppose to respective other end surfaces of
the first teeth of the first stator core that oppositely exist
relative to the one end surfaces that oppose to the rotor, and
is constructed such that the second stator core is movable in
a rotational direction or a reverse rotational direction of
the rotor.
The second stator core is constructed, for example, to
be movable in the rotational direction or the reverse rotational
direction of the rotor and also movable in an axial direction
of the rotor.
Also, each one of the first teeth is constructed, for example,
to have has a projection abutting on a side surface of each
one of the second teeth at one of the end surfaces that opposes
to the one end portion of each one of the second teeth.
This rotary electrical machine is constructed, for example,
in such a manner that a lower portion of each one of the first
teeth opposing to the annular section of the rotor is divided
into a portion which has a winding on a circumferential surface
thereof and another one portion which has no winding oh a
circumferential surface thereof, and the second teeth include
teeth corresponding to the portion of the first teeth that has
the winding on the circumferential surface thereof and other
teeth corresponding to the another one portion of the first
teeth that has no winding on the circumferential surface thereof.
Also, respective opposing surfaces of the rotor and the
first teeth can be formed to obliquely extend in such a manner
that an inner side of the opposing surface of the rotor that
is positioned closer to the axis of a rotating shaft is thick
and an outer side is thin.
The rotary electrical machine of a third invention includes
a cylindrical rotor rotational about an axis of a rotating shaft,
a first stator core having a plurality of first teeth one end
surfaces of which are positioned inside of the cylindrical
configuration of the cylindrical rotor to oppose to the rotor
and a winding is wound around a circumferential side surface
of each one of the first teeth except for both end surfaces,
and a second stator core having a plurality of second teeth
respective one end portions of which are positioned to oppose
to respective other end surfaces of the first teeth of the first
stator core that oppositely exist relative to the one end surfaces
that oppose to the rotor, and is constructed such that the second
stator core is movable in a rotational direction or a reverse
rotational direction of the rotor.
Further, the rotary electrical machine of a fourth invention
includes a columnar of cylindrical rotor rotational about an
axis of a rotating shaft, a first stator core having a plurality
of first teeth one end surfaces of which are positioned outside
in a radial direction of the rotor to oppose to the rotor and
a winding is wound around a circumferential side surface of
each one of the first teeth except for both end surfaces, and
a second stator core having a plurality of second teeth respective
one end portions of which are positioned to oppose to respective
other end surfaces of the first teeth of the first stator core
that oppositely exist relative to the one end surfaces that
oppose to the rotor, and respective other end portions are retained
by a retainer, and is constructed such that the second stator
core is movable in a rotational direction or a reverse rotational
direction of the rotor.
The rotary electrical machine of the second, third or fourth
invention is constructed, for example, in such a manner that,
when the second teeth are positioned to entirely face the first
teeth, a magnetic reluctance existing between one of the first
teeth and one of the second teeth that entirely faces the one
of the first teeth is smaller than a magnetic reluctance existing
between the one of the first teeth and another one of the first
teeth neighboring the one of the first teeth, and, when the
second teeth moves so that the one of the second teeth is placed
ajt a right middle position between the one of the first teeth
and the another one of the first teeth, a magnetic reluctance
passing through the one of the second teeth to exist between
the one of the first teeth and the another one of the first
teeth neighboring to the one of the first teeth is larger than
a magnetic reluctance existing between the one of the first
teeth and another one of the first teeth neighboring the one
of the first teeth.
In this connection, the rotary electrical machine is
constructed, for example, in such a manner that the magnetic
reluctances are adjustable by a distance between the one of
the first teeth and another one of the first teeth neighboring
the one of the first teeth, or a distance between the one of
the first teeth and the one of the second teeth.
Also, the rotary electrical machine of the second, third
or fourth invention is constructed, for example, to include
a movement drive force transmitting mechanism for moving the
second stator core in the rotational direction or the reverse
rotational direction of the rotor. The rotary electrical machine
of the second, third or fourth invention is constructed, for
example, such that the movement of the second stator core relative
to the first stator core is a reciprocal movement within a
predetermined angle in the rotational direction or the reverse
rotational direction of the rotor. The rotary electrical machine
of the second, third or fourth invention is constructed, for
example, such that the movement of the sepond stator core relative
to the first stator core is an intermittently rotational movement
in the rotational direction of the rotor,. The rotary electrical
machine of the second, third or fourth invention is constructed,
for example, such that the plurality of the first teeth and
the winding are unitarily molded together. The rotary electrical
machine of the second, third or fourth invention is constructed,
for example, such that the plurality of the second teeth and
the winding are unitarily molded together.
According to the present invention, a robust and small
rotary electrical machine can be provided which has a mechanism
capable of varying output characteristic, without enlargement
of the whole configuration, without increase of mechanical loss,
without any transmission, or without consumption of electric
power that does not contribute to increasing torque.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a side elevational view of an electromotive
two-wheeled vehicle as an example of a device on which an axial
gap type rotary electrical machine as a rotary electrical machine
according to a first embodiment of the present invention is
mounted.
Fig. 2 is a cross-sectional view, showing a structure of
the axial gap type electric motor (electric motor) together
with a structure around the rear end of a rear arm.
Fig. 3 shows a structure of a stator of the electric motor -
and the circumference thereof, as viewed from the side of the
rear wheel.
Fig. 4 is a perspective view, simply and comparatively
showing a schematic structure of the major part of the stator
with a rotor disposed to oppose to the stator and its rotational
shaft shown in an exploded configuration.
Figs. 5(a) through (f) are illustrations for describing
the drive principle of the axial gap type electric motor.
Fig. 6 shows that one tooth opposes to both of a N pole
magnet and a S pole magnet in an actual arrangement such that
the N pole magnet and the S pole magnet are positioned close
to each other.
Fig. 7 is an illustration for describing reasons for the
limit of the rotational speed of a normal axial gap type electric
motor.
Fig. 8 schematically shows a field magnet weakening control
method used for increasing the rotational speed of the normal
axial gap type electric motor.
Fig. 9 is a cross sectional view, showing the axial gap
type electric motor in the first embodiment together with the
structure around the rear end of the rear arm.
Fig. 10 is a perspective exploded view of the axial gap
type electric motor of the first embodiment.
Fig. 11 is a perspective view, showing a condition under
which the axial gap type electric motor of the first embodiment
is completely assembled/ together with a rotation control system.
Figs. 12 (a), (b) and (c) are illustrations for describing
a pivot angle and an operation of a reciprocal movement made
by a second stator section of the axial gap type electric motor
in the first embodiment along the rotational direction of the
rotor relative to a first stator section.
Figs. 13 (a) and (b) are illustrations for describing the
principle of the rotation control of the axial gap type electric
motor of the first embodiment made in a range from a high torque
low speed rotation to a low torque high speed rotation.
Figs. 14 (a) through (e) are illustrations for describing
a gap that causes a magnetic reluctance.
Figs. 15 (a) and (b) shows a structure of the major part
of an alternative (first one) of the axial gap type electric
motor of the first embodiment.
Figs. 16 (a) through (d) show a structure of the major
part of another alternative (second one) of the axial gap type
electric motor of the first embodiment.
Figs. 17 (a) through (d) show a structure of the major
part of an axial gap type electric motor in a second embodiment.
Figs. 18 (a) and (b) show an alternative, in which the
opposing surfaces of the rotor and the stator, and the opposing
surfaces of the stator sections, which are two portions of the
divided stator, form surfaces other than horizontal surfaces.
Fig. 19 is a cross sectional view, showing a structure
of a radial gap type electricmotor according to a third embodiment.
Fig. 20 is a cross sectional view, showing a structure
of a radial gap type electric motor according to a fourth
embodiment.
Fig. 21 is a perspective view, showing a structure of a
radial gap type electric motor according to a fifth embodiment.
Fig. 22 shows a relationship of displacement of a rotational
phase between the first rotor section and the second rotor section
when the rotor makes a high speed low torque rotation in the
structure of the axial gap type electric motor according to
the fifth embodiment.
Fig. 23 shows a structure of the major part of the axial
gap type electric motor according to a sixth embodiment.
Fig. 24 shows a relationship of displacement of the
rotational phase between the first rotor section and the second
rotor section when the rotor makes a high speed low torque rotation
in the structure of the axial gap type electric motor according
to the sixth embodiment.
DETAILED DESCRIPTION OF THE PREFFERED EMBODIMENTS
Hereunder, an embodiment of the present invention is
described with reference to the accompanying drawings.
(Electromotive two-wheeled vehicle on which rotary electrical
machine ff the present invention is mounted)
Fig. 1 is a side elevational view of an electromotive
two-wheeled vehicle as an example of a device having an axial
gap type rotary electrical machine thereon, which is a rotary
electrical machine according to a first embodiment of the present
invention. As shown in Fig. 1, the electromotive two-wheeled
vehicle of this embodiment has a head pipe 2 disposed at a forward
top of its vehicle body. A steering shaft (not shown) for changing
a direction of the vehicle body is inserted into the head pipe
2 for pivotal movement.
A handlebar supporting portion 4 to which handlebars 3
are fixed is attached to a top end of this steering shaft, and
a grip 5 is attached to each end of the handlebars 3. Also,
in Fig. 1, the grip on the right hand side (the verso of Fig.
1), invisible because of being hidden, forms a throttle grip
that is rotational.
A front fork 6 having a right and left pair is coupled
with a bottom of the head pipe 2 to extend downward. The pair
of the front fork 6 has a front axle 8 interposed therebetween
under being suspended condition for damping and bearing a front
wheel for rotation.
The foregoing handlebar supporting portion 4 has indicators
9 disposed in front of the handlebars 3. A head lamp 11 is
fixed to a lower portion of the indicators 9. Flasher lamps
12 (one of the flasher lamps 12 positioned on the right hand
side, i.e., on the verso of (Fig. 1, is invisible because of
being hidden) are positioned on both sides of the head lamp
11.
A right and left pair of vehicle body frame 13 each generally
forming an L-shape in a side view extends rearward relative
to the vehicle body. Each vehicle body frame 13 is a round
pipe that obliquely extends downward rearward of the vehicle
body and then extends horizontally rearward to generally form
the L-shape in the side view.
A pair of right and left seat rails 14 are coupled with
respective rear side ends of the pair of the vehicle body frames
13 to further obliquely extend rearward upward from the respective
rear side ends of the vehicle body frames 13. A rear side end
14a of each seat rail 14 is curved rearward along a configuration
of a seat 15.
A battery 16 is detachably disposed between the pair of
the right and left seat rails 14. This battery 16 is constructed
to incorporate a plurality of second cells which are rechargeable.
A seat stay 17 having a reversed U shape is welded to a portion
of the pair of the right and left seat rails 14 positioned adjacent
to the foregoing curved portions to slant upward forward relative
to the vehicle body. The foregoing seat is placed at a portion
surrounded by the seat stay 17 and the pair of the right and
left seat rails 14 such that the seat 15 can move between opening
and closing positions with its forward end pivotal vertically.
Also, a rear fender 18 is attached to the rear ends of
the seat rails 14, and a tail lamp 19 is attached to a rear
surface of the rear fender 18. Further, flasher lamps 21 (one
of the flasher lamps 21 positioned on the right hand side, i.e.,
the verso of Fig. 1 is invisible because of being hidden) are
positioned on both sides of the tail lamp 19.
On the other hand, a rear arm bracket 22 (in Fig. 1, only
the bracket 22 on the recto is shown) is welded to a horizontal
portion of each one of the pair of the right and left vehicle
body frames 13 below the seat 15. A forward end of a rear arm
23 is supported by the pair of the right and left rear arm brackets
22 for vertical swing movement via a pivot shaft 24.
A rear wheel 25 as drive wheel is supported for rotation
at a center of a generally circularly formed rear end 23a of
the rear arm 23 for rotation. The rear arm 23 and the rear
wheel 25 are suspended by a rear shock absorber for damping.
A pair of right and left footsteps 27A (in Fig. 1, only
the bracket 22 on the recto is shown) are disposed below the
respective horizontal portions of the pair of the right and
left vehicle body frames 13. Also, a side stand 28 is supported
by the rear arm 23 on the left hand side via a shaft 29 for
pivotal movement in the rear of the footstep 27. This side
stand 28 is urged by a return spring 31 toward a retracted position.
A drive unit including an axial gap type electric motor
32 that is connected to drive the rear wheel 25 is incorporated
within the rear end 23a of the rear arm 23.
Now, a structure of an axial gap type electric motor and
an operation thereof that are the basis of the present invention
is described, and then a structure of the axial gap type electric
motor 32 and an operation thereof according to a first embodiment
of the present invention is described.
(Basic structure of axial gap type electric motor)
Fig. 2 is a cross-sectional view, showing a structure of
the axial gap type electric motor (hereunder, simply can be
called electric motor) that is the basis of the present invention,
together with a structure around the rear end 23a of the rear
arm 23. Incidentally, Fig. 2 is a cross-sectional view taken
along the line A-A of Fig. 1 (partial side view) . However,
the rear wheel 25 is not shown.
In Fig. 2, a drive unit 33 is incorporated within a space
defined inside of a gear cover 34 attached to a right side (in
Fig. 2, recto) of the rear end 20a of the rear arm 23. The
drive unit 33 includes the electric motor, a planetary geared
speed reducer 35, a controller 36 and so forth together unitarily
built in.
As shown in Fig. 2, the electric motor includes a rotor
38 supported by bearings 37a, 37b at the rear end 20a of the
rear arm 23 for rotation about a center axis BO of the bearings
37a, 37b; and a generally annular (or doughnut-like shaped)
stator 39 fixed to an inside surface of the rear end 23a of
the rear arm to oppose to the rotor 38.
As shown in Fig. 2, the rotor 38 has a rotor side yoke
41 (41a-41e) which has a generally gambrel-like shape convex
toward the rear end 23a of the rear arm 23.
That is, the rotor side yoke 41 includes a annular section
41a opposing to the stator 39; a tapered section 41b extending
generally in a truncated cone shape toward the rear end 23a
of the rear arm 23 from an inner circumferential periphery of
the annular section 41a; a first cylindrical section 41c convexly
extending along the center axis BO toward the rear end 23a of
the rear arm 23 from a terminal end of the tapered section 41b;
a annular section 41d extending in a radial direction of the
rotation toward the center axis BO from a terminal end (in Fig.
2, bottom end) of the cylindrical section 41c; and a second
cylindrical section 41e convexly extending along the center
axis BO toward the rear end 23a of the rear arm 23 from an inner
circumferential periphery of the annular section 41d.
The second cylindrical section 41e is supported by the
bearings 37a, 37b for rotation about the center axis BO to form
a rotational shaft of the rotor 38. Thus, a rotational center
of a rotational shaft 43 of the rotor 38 corresponds to the
center axis BO of the bearings 37a, 37b.
Also, the rotor 38 has a plurality of field magnets 42
fixedly positioned on a stator side opposing surface of the
annular section 41a of the rotor side yoke 41. These field
magnets 42 are located annularly and coaxially about the center
axis BO and circumferentially along the annular section 41a.
The field magnets 42 are positioned in such a manner that the
N pole and the S pole alternately appears. Alternatively, the
field magnets 42 can be made from a single magnet member having
the N pole and the S pole alternately magnetized, both of which
are formed with dielectric body portions that are permanently
polarized along the same circumferential surface of a disk or
ring.
A toothed rotational shaft 43 is fixedly attached to a
rear wheel side end of the second cylindrical section (rotational
shaft) 41e of the rotor 38 to extend coaxially with the rotor
38 (the second cylindrical section (rotational shaft) 41e) .
This toothed rotational shaft 43 rotates together with the rotor
38.
On the other hand, the planetary geared speed reducer 35
is coupled with the toothed rotational shaft 43 and is built
in the tapered section 41b of the rotor side yoke 41. The planetary
geared speed reducer 35 and the electric motor (the rotor 38
and the stator 39) overlap with each other in a width direction
of the vehicle.
The planetary geared speed reducer 35 is coupled with a
rear axle 44 which extends coaxially with the toothed rotational
shaft 43, and has a function to reduce a speed of the rotation
of the electric motor (rotation of the second cylindrical section
(rotational shaft) 41e), and transmit the rotation to the rear
axle 44 through the toothed rotational shaft 43.
A nut 45 is detachably screwed onto the tip 44a of the
rear axle 44 projecting from the gear cover 34 for the rear
axle 44. The rear wheel 25 shown in Fig. 1 is fastened by the
nut 45 that is screwed under a condition that the rear wheel
25 is put on the rear axle 44 to be fixedly attached to the
rear axle 44.
Fig. 3 is an illustration, showing a structure of the stator
39 of the electric motor and the circumference thereof looked
from the side of the rear wheel 25. That is, in Fig. 3, the
front side of the illustration corresponds to a right hand side
of the vehicle body of the electromotive two-wheeled vehicle
1, the left side of the illustration corresponds to a lower
side of the vehicle body, the upper side of the illustration
corresponds to a rear side of the vehicle body, and the lower
side of the illustration corresponds to a front side of the
vehicle body.
In Fig. 3 (see Fig. 2 also), the stator 39 is fixedly
positioned at the rear end 23a of the rear arm 23, and includes
a stator side yoke 4 6 that has a lamination layer structure
in which, for example, circular steel sheets are laminated in
the center axis direction. The stator side yoke 46 has a reversed
C shape around the center axis BO. In other words, the stator
side yoke 46 is shaped as a circle one portion of which is cut
away.
The stator side yoke 4 6 of the stator 39 has generally
rectangular tooth receiving openings, which number is multiples
of three, circumferentially extending. The stator 39 has teeth
47 fixedly positioned in the respective tooth receiving openings
with a lower portion (in Fig. 3, the side end of the sheet)
of each tooth 47 inserted into the respective recess, and the
teeth 47 are circumferentially arranged on the stator side yoke
46 at regular intervals (circumferential pitches).
Each tooth 47 is a lamination layer of steel sheets, and
is placed such that a top end (in Fig. 3, side surface of the
recto) thereof is spaced apart from the respective field magnets
42 of the rotor 38 in the axial direction of the rotational
shaft 43 to oppose to the field magnet 42.
Additionally, the circumferential pitch means an angle
defined between line segments; one of which extends from a center
of the opposing surface of the tooth 47 that opposes to the
corresponding f ieldmagnet 42 to the center axis BO of the bearings
37a and 37b along the upper surface; and another one of which
extends from a center of the opposing surface of the neighboring
tooth 47 that opposes to the corresponding field magnet 42 to
the center axis BO of the bearings 37a and 37b along the upper
surface.
The stator side yoke 46 that fixedly holds the teeth 47
is shaped as the circle which center is consistent with the
center axis BO of the bearings 37a and 37b and one portion of
which is cut away, as described above. Thus, the teeth 47,
which number is multiples of three, is arranged along the circular
configuration which one portion is cut away. Thereby, teeth
of three phases (U phase, V phase and W phase) corresponding
to the cut-away portion of the circle are omitted. Hereunder,
the cut-away portion of the circle is called a teeth omitted
portion 48.
Also, the stator 39 includes a coil 49 (see Fig. 2) wound
around each tooth 47; a molded section 51 in which the respective
teeth 47 and the coils 49 are molded with resin or the like;
and a plurality of flanges 52 formed on an circumferential outer
surface of the molded section 51.
Each flange 52 has a bolt hole for attaching the molded
section 51 including the teeth 47 and the coils 4 9 to the rear
end 23a of the rear arm 23. Bolts inserted into the bolt holes
are screwed onto the rear end 23a of the rear arm 23 to fixedly
position the stator 39 on the rear end 23a of the stator 39.
Also, an inverter 54 which can supply electric power to
the stator 39 by being electrically connected to the stator
39 is fixed to the teeth omitted portion 48 through an elastic
material, which is not shown, made of rubber or the like. Further,
an encoder substrate 55 is placed in the teeth omitted portion
48. This encoder substrate 55 and the inverter 54 are
electrically coupled with each other through a wire harness
56 that is covered with a flexible coating (a flexible substrate
or the like can replace the harness).
Magnetic pole detecting elements 57a, 57b and 57c such
as a Hall sensor, for example, are mounted on the encoder substrate
55. The magnetic pole detecting elements 57a, 57b and 57c are
placed at positions where those elements detect a moment when
each electrical angle of the U phase, V phase and W phase of
the electric motor becomes 180 degrees (for example, a coil
current is the maximum).
Fig. 4 is a perspective view, showing a schematic structure
of the major part of the stator 39 of Fig. 3 together with the
rotor 38 placed to oppose to the stator 39 and the rotational
shaft 43 thereof. Additionally, the coil 49 shown in Fig. 2;
the molded portion 51 shown in Figs. 2 and 3; and the flanges
52, the inverter 54, the encoder substrate 55 shown in Fig.
3; and so forth are omitted from Fig. 4.
As shown in Fig. 4, on the stator side yoke 46, the respective
recesses 58 each of which is formed in a generally rectangular
shape and in which the respective tooth 47 is inserted and fixed
are arranged in the circular configuration, the portion of which
is cut away at the circular pitches. A pair of shorter side
inner surfaces 58a, 58b of each insert hole are adapted to direct
to the center axis BO.
Further, a steel sheet portion next to each insert hole
and positioned between a circumferential outer surface 46a of
the stator side yoke 46 and an inner side surface 58b located
closer to the circumferential outer surface 4 6a is cut to make
a slit 59 extending radially such that each insert hole
communicates outside.
The respective teeth 47, three of which form one set of
the U phase, V phase and W phase to which a two-pole/three-phase
alternating current is applied, are sequentially positioned
on the stator side yoke 46 except for the teeth omitted portion
48. Even number of the field magnets 42 having the polar pair
of the N pole and the S pole are disposed on the rotor 38 at
regular intervals corresponding to the intervals of the set
of the three phases.
Of course, as described above, the field magnets 42 can
be formed from a single magnet member having the N pole and
the S pole alternately magnetized, both of which are formed
with dielectric body portions that are permanently polarized
along the same circumferential surface of a disk or ring.
That is, for example, the field magnets 42 are positioned
in such a manner that either four field magnets 42 each having
a polar pair, or one field magnet having four polar pairs oppose
to a range involving arrangement intervals of six teeth 47 at
all times. Also, the field magnets 42 are positioned in such
a manner that either six field magnets 42 each having a polar
pair, or one field magnet having six polar pairs oppose to a
range involving arrangement intervals of nine teeth 47 at all
times.
Incidentally, Fig. 4 shows fifteen teeth 47 in total.
Originally, the stator can have 18 teeth 47; however, three
of them are omitted to place the encoder substrate 55 of Fig.
3 there.
Thus, the electric motor is constructed in such a manner
that the field magnets 42 each having 12 polar pairs exist to
oppose to a range involving arrangement intervals of fifteen
teeth 47 (including the omitted portion for three teeth) all
the times, whether odd number of field magnets 42 are used or
one field magnet is used.
(Drive principle of axial gap type electric motor)
Next, a drive principle of the axial gap type electric
motor constructed as described above is described.
Figs. 5(a) to (f) are illustrations for describing the
drive principle of the axial gap type electric motor. In Fig.
5(a), the arrow "a" indicates a rotational direction of the
rotor 38, while the arrow "b" indicates the plus direction of
magnetic fluxes, when a direction of the magnetic fluxes coming
from the N pole field magnet 42 (hereunder, simply called magnet
42) is decided to be plus, and a direction of the magnetic fluxes
coming from the S pole magnet 42 is decided to be minus. However,
all the fluxes do not go right downward as indicated by the
arrow "b," and some of them go obliquely downward. The arrow
"b" thus is given to mean that generally the magnetic fluxes
go downward.
Also, the arrow "c" indicates the plus direction of magnetic
fluxes, when a direction of magnetic fluxes having the N polarity,
which are generated in the coils 49 wound around the respective
teeth 47 of the stator 39 with a current being supplied to the
coils 49 and exited by the teeth 47 (47u, 47v and 47w) that
are core members, is decided to be plus, and a direction of
magnetic fluxes having the S polarity is decided to be minus.
However, all the fluxes do not go right downward as indicated
by the arrow wb," and some of them go obliquely downward. The
arrow "b" thus is given to mean that generally the fluxes go
downward.
Also, in Figs. 5(a) to (f), the teeth 47 of the U phase
are indicated by reference numeral 47u, the teeth 47 of the
V phase by 47v, and the teeth 47 of the W phase by 47w.
Fig. 5(a) shows a condition under which the N pole magnets
42 are positioned right above the U phase teeth 47u, while the
S pole magnets 42 are positioned between the respective V phase
teeth 47v and the respective W phase teeth 47w.
Under this condition, a current toward the coils 4 9 of
the U phase teeth 47u is shut down, no magnetic flux is generated
in the teeth 47u, and only the magnetic fluxes from the N pole
magnets 42 flow through the teeth 47u.
A current that can generate magnetic fluxes having the
S polarity flows through the coils 49 of the V phase teeth 47v,
and the teeth 47v excites the S pole magnetic fluxes. The excited
S pole magnetic fluxes of the teeth 47v repel the S pole magnets
42, i.e., the same pole magnets, in the direction of the arrow
On the other hand, a current that can generate N pole magnetic
fluxes flows through the coils 49 of the W phase teeth 47w,
and the teeth 47w excite the N pole magnetic fluxes. The excited
N pole magnetic fluxes of the teeth 47w attract the S pole magnets
42, i.e., the opposite pole magnets, in the direction' of the
arrow "a."
The rotor 38 rotates in the direction of the arrow "a"
by the torque toward the direction of the arrow "a" caused by
the force of repulsion and the force of attraction, and transfers
to a condition shown in Fig. 5(b) . That is, the N pole magnets
42 are positioned between the respective U phase teeth 47u and
the respective V phase teeth 47v, while the S pole magnets 42
are positioned right above the W phase teeth 47w.
Under this condition, the direction of the current is changed
to generate N pole magnetic fluxes in the coils 4 9 of the U
phase teeth 47u. The teeth 47u excite the Npole magnetic fluxes,
and the excited N pole magnetic fluxes repel the N pole magnets
42, i.e., the same pole magnets, in the direction of the arrow
On the other hand, the direction of the current is changed
to generate S pole magnetic fluxes in the coils 49 of the V
phase teeth 47v. The teeth 47u excite the S pole magnetic fluxes,
and the excited S pole magnetic fluxes attract the N pole magnets
42, i.e., the opposite pole magnets, in the direction of the
arrow "a."
Also, the current toward the coils 49 of the W phase teeth
47w is shut down, no magnetic flux is generated in the teeth
47w, and only the magnetic fluxes from the S pole magnets 42
flow through the teeth 47w.
Also under this condition, the rotor 38 rotates in the
direction of the arrow "a" by the torque toward the direction
of the arrow "a" caused by the force of repulsion and the force
of attraction, and transfers to a condition shown in Fig. 5(c) .
Relationships between the teeth 47 and the magnets 42 under
the condition are the same as those which shown in Fig. 5(a).
However, each relationship between the respective tooth 47
and the respective N pole and S pole magnets 42 is shifted one
by one in the direction of the arrow "a."
That is, the N pole magnets 42 are positioned right above
the V phase teeth 47v, while the S pole magnets 42 are positioned
between the respective W phase teeth 47w and the respective
U phase teeth 47u which is one of the neighboring sets of the
three phases.
The current of the teeth 47v, the teeth 47w and the neighboring
teeth 47u and the polarity of the magnetic fluxes generated
in the coils 49 under the condition of Fig. 5(c) is the same
as the current of the teeth 47u, the teeth 47v and the teeth
47w of sets of the three phases and the polarity of the magnetic
fluxes generated in the coils 49 under the condition of Fig.
5(a), respectively.
That is, under the condition, the torque in the direction
of the arrow "a" is generated by the repulsive force and the
attractive force, and the rotor 38 rotates in the direction
of the arrow "a" by the torque and transfers to a condition
shown in Fig. 5(d). The relationships between the teeth 47
and the magnets 42 under the condition is the same as those
which shown in Fig. 5(b). However, also under this condition,
each relationship between the respective tooth 47 and the
respective one of the N pole and S pole magnets 42 is shifted
one by one in the direction of the arrow "a."
That is, the N pole magnets 42 are positioned between the
respective V phase teeth 47v and the respective W phase teeth
47w, while the S pole magnets 42 are positioned right above
the U phase teeth 47u which is one of the neighboring sets of
the three phases.
The current of the teeth 47v, the teeth 47w and the neighboring
teeth 47u and the polarity of the magnetic fluxes generated
in the coils 49 under the condition of Fig. 5(d) is the same
as the current of the teeth 47u, the teeth 47v and the teeth
47w of the sets of the three phases and the polarity of the
magnetic fluxes generated in the coils 49 under the condition
of Fig. 5(b), respectively.
Hereunder, similarly, the rotor 38 transfers to a condition
of Fig. 5(e), and further transfers to a condition of Fig. 5(f) .
The Npole magnets, 42 thus are positioned between the respective
W phase teeth 47w and the respective teeth 47u of the sets of
the three phases. One drive relationship, which is shown on
the left hand side of Fig. 5(a), between one set of the three
phases including the U phase teeth 47u, V phase teeth 47V and
W phase teeth 47w and the pair of N pole magnet 42 and S pole
magnet ends.
Continuously, again, as shown in Fig. 5(a), another drive
relationship between another one set of the three phases including
the U phase teeth 47u, V phase teeth 47V and W phase teeth 47w
and another pair of N pole magnet 42 and S pole magnet neighboring
the pair of N pole magnet 42 and S pole magnet, the foregoing
relationship of which has ended, and positioned upstream of
the former pair starts as shown in Figs 5(a) to (f).
Additionally, in the description of Figs. 5 (a) to (f),
the positioning relationships between the magnets 42 and the
teeth 47 are divided into six stages for easy understanding.
Actually, however, as the applied current to the coils 49,
a current depicting a sine curve is sequentially applied to
three teeth 47 of each set of the three phases neighboring each
other at regular phase differences. The direction and magnitude
of the magnetic fluxes generated in the coils 49 by the applied
current vary because the magnets 42 of the rotor rotate.
Also, respective distances between the N pole and S pole
magnets 42 in an actual arrangement are shorter than those which
are shown in Figs. 5(a) to (f), and one tooth 47 can oppose
to both of the N pole magnet 42 and the S pole magnet 42.
Additionally, if a single magnet having multiple polar pairs
is used instead of the odd number of magnets 42, the N pole
and the S pole contact with each other without having no space
therebetween.
The relationship shown in Figs. 5(a) to (f) is sequentially
shifted in the rotational direction to one another among all
the sets of the three phases of the teeth 47 and the pairs of
two magnets 42 in association with neighboring teeth and magnets.
That is, two teeth of the set of three phases of teeth 47 and
one tooth of the neighboring set of three phases of teeth 47
makes a next set of three phases, and one magnet of the pair
of two magnets 42 and one of the neighboring pair of two magnets
42 makes a next pair of magnets.
The current for changing the directions of the magnetic
fluxes of the coils is changed under the control of the inverter
54, and a timing of current application is given also under
the control of the inverter 54 based upon the detection of
rotational positions of the N pole magnet 42 and the S pole
magnet 42 by the magnetic pole detectinq elements 57a, 57b and
57c shown in Fig. 3.
As thus described, in the axial gap type motor, magnetiq
circuits are made between the rotor 38 and the stator 39, and
the excitation of the respective teeth 47 of the stator 39 is
sequentially changed corresponding to the N pole and S pole
of the magnets 42 of the rotor 38 via the coils wound around
the respective teeth 47, thereby rotating the rotor 38 using
the repulsive force and the attractive force of the magnets
42 of the rotor 38 against the excitation of the respective
teeth 47.
Fig. 6 is an illustration, showing that one tooth 47 opposes
to both of the N pole magnet 42 and the S pole magnet 42 in
an actual arrangement in such a manner that the N pole magnet
42 and the S pole magnet 42 are positioned close to each other.
In this illustration, the arrow "a" again indicates the
rotational direction of the rotor 38. Also, a direction of
the magnetic fluxes flowing between the N pole magnet 42 and
the S pole magnet is indicated by arrows G1, G2 and G3. Further,
this condition is the same as the condition occurring
transitionally when the conditions shown in Figs. 5(a) to (f)
are shifted to one another.
In Fig. 6, a current flows through the coil 49 wound around
the tooth 47 on the stator 39 counterclockwise in a top plan
view as indicated by an arrow E. Therefore, magnetic fluxes
generated in the coil 4 9 and excited by the tooth 47 flow as
indicated by an arrow G4, and cross the magnetic fluxes flowing
between the N pole magnet 42 and the S pole magnet 42. On this
occasion also, the N pole magnet 42 repels and the S pole magnet
42 attracts to generate the torque in the rotor 38 in the direction
of the arrow "a."
In Fig. 6, when the magnets 42 move to other positions
relative to the tooth 47, and the magnet 42 on the left hand
side is replaced by the N pole magnet and the magnet on the
right hand side is replaced by the S pole magnet, the direction
of the current that is given to the tooth 47 is reversed from
the direction indicated by the arrow E, i.e., the direction
is changed to the clockwise direction in view of the top side
of the illustration.
By the way, in the electric motor having the basic structure
described above, the rotational power thereof does not become
larger than a certain limit because of a structural restriction
in its rotational speed. If converted into a speed of a motorcycle,
approximately 20 km per hour is a limit in order to obtain a
torque that is necessary for the vehicle, shown in Fig. 1, to
run. However, it is understood that the data can vary in
accordance with diameters of tires, gear ratios of drive gear
systems, specifications of motors and so forth.
Fig. 7 is an illustration to describe reasons for the limit
of the rotational speed of a normal electric motor. Fig. 7
shows positioning conditions of the N pole magnet 42, the V
phase tooth 47v and others around them shown in Fig. 5(c).
Additionally, Fig. 7 only shows the coil 49 for the V phase
tooth 47v, and omits the coils for the other teeth. As described
with reference to Fig. 5, no current is applied to the coil
49 when the magnet 42 is positioned right above the tooth 47.
In Fig. 7, the rotor 38, the stator 39, and teeth 47 (47u,
47v and 47w) are made of a soft magnetic material. Because
a distance "d" between the opposing surfaces of the magnet 42
and the tooth 47 is extremely small, a space magnetic reluctance
is low. Thus, the magnetic fluxes flowing between the N pole
magnet 42 (N) and S pole magnet 42 (S) are divided into two
portions, and one of them becomes a magnetic flux flow 61 while
another one of them becomes a magnetic flux flow 62 to flow
through the magnetic poles of the magnets 42, the rotor 38,
the teeth 47 and the stator 39.
Thus, larger magnetic fluxes involving the foregoing two
of the magnetic flux flows 61 and 62 both of which merge together
pass through the coil 49 of the tooth 47v via the tooth 47v
positioned within the coil 49.
While the rotor 38 rotates in the direction of the arrow
"a," a current is generated in the coil 49 according to the
Faraday's electromagnetic induction law, because the fluxes
passing through the coil 49 cross the coil 49. The current
generated in the coil 49 in turn generates magnetic fluxes having
the S polarity from the coil 49.
That is, the S pole magnetic fluxes generated in the coil
49, i.e., in the tooth 47, by the current generated in the coil
49 functions to attract the N pole magnet 42 (N).
In other words, resistive force (magnetic reluctance)
affects the rotation of the rotor 38. The faster the rotation
of the rotor 38, the faster the speed of the magnetic fluxes,
which involves the foregoing two of the magnetic flux flows
61 and 62 merging together in the coil 49, crossing the coil
49. The faster the speed of the magnetic fluxes crossing the
coil 49, the larger the current generated in the coil 49. The
larger the current generated in the coil 49, the larger the
amount of the magnetic fluxes generated in the tooth 47v by
the current to increase the magnetic reluctance of the rotor
38.
Before long, the increased magnitude of the rotational
power of the rotor 38 and the magnetic reluctance reach the
balance with each other. This balance condition is the limit
of the rotational speed described above. Of course, the limit
can goes up with an increase of the electric supply. However,
it is not a good plan because the consumption of the electricity
increases in geometric progression.
As a method of improving the weak point of the rotational
characteristic of the axial gap type electric motor to increase
the rotational power, i.e., a method of shifting the rotational
condition to a low torque high speed rotation from the high
torque.low speed rotation, a field magnet weakening control
method is known.
Fig. 8 is an illustration, schematically showing the field
magnet weakening control method. Under the condition such that
no current is applied to the coil 49 when the N pole magnet
42 (as to S pole magnet 42, the same) is positioned right above
the tooth 47 as described with reference to Fig. 7, a large
resistance affects the rotation of the rotor 38 when the rotational
speed increases.
As shown, however, if a moderate current is applied to
the coil 49 in the direction indicated by the arrow E when the
N pole magnet is positioned right above the tooth 47 (as to
S pole magnet 42, reverse direction), magnetic fluxes having
the N polarity are generated in the direction indicated by the
arrow G4 (as to S pole magnet 42, reverse direction).
The magnetic fluxes generated by this coil function to
weaken the N pole magnetic fluxes that go to the tooth 47 from
the N pole magnet 42 as indicated by the arrow G2. That is,
because the magnetic fluxes function to weaken the magnetic
flux flows 61 and 62 shown in Fig. 7, the magnetic reluctance
decreases and the rotational power becomes large, corresponding
to the weaken magnetic flux flows. Namely, the low torque high
speed rotation can be realized.
In the field magnet weakening control method, a new current
having a phase that is inconsistent with the phase of the
alternating current applied to the tooth 47 having three phases,
which are the U phase, V phase and W phase, applied at a moment
when the electromagnets 42 shown in Fig. 5 position right above
the teeth 47and the current becomes zero, that is, a current
that generates magnetic fluxes in the direction of weakening
the magnetic fluxes going to the coils from the electromagnets
42 at the moment when the current becomes zero is further added
to a current for rotating (for generating torque) to be applied
to the coil. That is, a current that does not contribute to
the rotational torque itself is newly applied.
Additionally, it is described above that, as a method to
realize the low torque and high speed rotation of the electric
motor, there is another method to enlarge the opposing distances
of the rotor and the stator in the rotational direction, i.e.,
to enlarge the magnetic gaps between the rotor and the stator.
However, the inventors of the present invention noticed
that the flow of the magnetic flux flow was unstable in the
magnetic gaps between the rotor and the stator. The present
invention originates from the inventors' notice of the fact
that the flow of the magnetic flux flow is unstable in the magnetic
gaps.
The inventors found out portions at which the flow of the
magnetic flux flow was in good order, and further found that
the flow of the magnetic flux flow can be controlled if variable
magnetic gaps are made there. As a result, it becomes practicable
to improve controllability of the output characteristic.
Hereunder, this is described.
(Structure and Operation of Axial gap Type Electric Motor
According to first embodiment of the present invention)
Next, based upon the basic structure and the drive principle
of the foregoing axial gap type electric motor, a structure
and an operation of an axial gap type electric motor according
to a first embodiment of the present invention is described.
Fig. 9 is a cross sectional view, showing an axial gap
type electric motor according to the first embodiment together
with the structure around the rear end of the rear arm.
Additionally, in Fig. 9, the same constructive portions as those
shown in Fig. 2 are assigned with the same reference numerals
and symbols as those used in Fig. 2.
Fig. 10 is a perspective exploded view of the axial gap
type electric motor according to the first embodiment. Hereunder,
with reference to Figs. 9 and 10, the structure of the axial
gap type electric motor (hereunder, simply called electric motor)
of the present embodiment is described.
First, the electric motor 70 of the present embodiment
has a rotor 71. The rotor 71 is constructed so as to rotate
about an axis of a rotational shaft 72, like a disk. The rotor
71 has the same structure as the rotor 38 shown in the basic
structure of Figs. 2 and 4.
That is, in Fig. 10, the rotor 71, the rotational shaft
72, a rotor side yoke 73,. a annular section 74, a tapered section
75, a first cylindrical section 76, a annular section 77, a
second cylindrical section 78, and field magnets 79 are the
same as the rotor 38, the rotational shaft 41e, the rotor side
yoke 41, the annular section 41a, the tapered section 41b, the
first cylindrical section 41c, the annular section 41d, the
second cylindrical section (rotational shaft) 43, and the field
magnets 42, respectively, shown in Figs. 2 and 4.
A stator (statbr section) 88 is disposed to oppose to the
rotor 71 (more specifically, a surface where a plurality of
field magnets 79 are disposed) . The stator 88 is divided into
two portions, a first stator section 83 and a second stator
section 87.
The first stator section 83 includes a first stator core
80 having a plurality of first teeth 81 retained by a retainer
(not shown) . The first teeth 81 are disposed in such a manner
that one end surface 81a of each first tooth 81 opposes to the
rotor 72 in an axial direction. Each tooth 81 has a winding
82 wound around a circumferential side surface 81c except for
both end surfaces (81a, 81b).
Additionally, the first teeth 81 is formed in such a manner
that the end surface 81a of each tooth 81 opposing to the rotor
71 is larger than an opposite end surface 81b. Thus, with regard
to spaces between neighboring first teeth 81 and 81, one of
the spaces existing between the end surfaces 81a opposing to
the rotor 71 is made narrow, and the other space between the
opposite surfaces 81b is made broad.
Each first tooth 81 having the respective winding 82 is
molded together with the winding 82 to form the respective first
stator section 83 which whole configuration is circular.
Additionally/ a drive current control for generating torque
that is applied to respective windings (coils) 82 of the first
teeth 81 of the first stator section 83 is the current control
that uses the same method as that described with reference to
Fig. 5, i.e., the basic drive method that does not include the
field magnet weakening control, and the torque of the electric
motor is generated under the drive current control.
Also, the second stator section 87 itself forms a second
stator core (87) with second teeth 84 which number is the same
as the number of the first teeth 81 retained by a retainer 85.
Each second tooth 84 of the second stator section 87 has one
end portion 84a that is positioned to oppose to the opposite
end surface 81b that oppositely exists relative to the end surface
81a of the first tooth 81 of the first stator section 83 that
opposes to the rotor 71.
Another end 84b of each second tooth 84 is press-fitted
into respective one of multiple tooth receiving openings 86
that are formed on the annular retainer 85 to be fixed.
The second teeth 84 and the retainer 85 having the second
teeth 84 press-fitted and fixed to the tooth receiving openings
86 together form the second stator section 87. Also, preferably,
the second teeth 84 and the retainer 85 are unitarily molded.
Those are molded in this embodiment/ accordingly. However,
the mold is not shown in Fig. 10.
Fig. 11 is a perspective view, showing a condition under
which the electric motor 70 having the structure described above
is completely assembled, together with a rotation control system.
Additionally, in Fig. 11, the same components as those shown
in Fig. 10 are assigned with the same reference numerals as
those used in Fig. 10. Also, the molds of the first stator
section 83 and the second stator 87 are not shown in Fig. 11.
Further, slits 89 which are omitted in Fig. 10 (see slits 59
of Fig. 4) are indicated in the retainer 85 of the second stator
section 87 shown in Fig. 11.
As shown in Fig. 11, the rotor 71, the first stator section
83 and the second stator section 87 of the electric motor 70
shown in the exploded view of Fig. 10 are positioned in order
along the rotational axis direction to be slightly spaced apart
from one another.
The first stator section 83 is, as called such, fixed to
the rear end 23a of the rear arm 23 shown in Fig. 2 by an engaging
section formed at the molded portion, although not shown. To
the contrary, the second stator section 87 is not completely
fixed and can pivot somewhat relative to the first stator 83,
which is described below.
As shown in Fig. 11, a pivot mechanism for the second stator
section 87 is constructed in such a manner that a toothed portion
for gear engagement 90 formed at a portion of a circumferential
side surface of the retainer 85 of the second stator section
87 engages with a small diameter gear ,of speed reduction gears
91 of a rotation control system.
A large diameter gear of the speed reduction gears 91 engages
with a small diameter gear of speed reduction gears 92 in the
next stage, and a large diameter gear of the speed reduction
gears 92 engages with a small diameter gear of speed reduction
gears 93 in the third stage. A large diameter gear of the speed
reduction gears 93 engages with a worm gear 95 fixedly attached
to the tip of a rotational shaft of an electric motor 94.
The motor 94 is connected to a drive pulse voltage output
terminal, which is not shown, of a controller 97 to which electric
power for driving circuits is supplied from a power source 96.
An axis of the rotation of the motor 94 in the right and reverse
directions is changed to extend at right angles to its original
direction by the worm gear 95. Also, the rotation is reduced
in speed and is transmitted to the large diameter gear of the
speed reduction gears 93. The rotation is reduced through three
stages, corresponding to gear ratios between the reduction gears
93, 92 and 91 in order, and then transmitted to the toothed
portion 90 for gear engagement that is formed on the retainer
85 of the second stator section 87.
Thereby, the second stator section 87 is constructed to
be slightly movable in the rotational direction of the rotor
71 relative to the first stator section 83. That is, the second
stator section 87 can continuously, intermittently and
reciprocally move with a narrow pivot angle. In other words,
the second stator section 87 can move steplessly, intermittently,
and slightly in both the right and reverse directions along
the rotational direction of the rotor 71.
Figs. 12(a), (b) and (c) are illustrations for describing
the pivot angle and the operation of the reciprocal movement
made by the second stator section 87 along the rotational direction
of the rotor 71 relative to the first stator section 83.
Additionally, in Figs. 12(a), (b) and (c), in order to simply
show transitional conditions of the second teeth 84 of the second
stator section 87 relative to the first teeth 81 of the first
stator section 83, the windings 82, the slits 89 and the toothed
portion 90 for gear engagement, the rotation control system
etc. shown in Fig. 11 are omitted in the illustrations.
Fig. 12(a) shows a positional relationship of the second
teeth 84 of the second stator section 87 relative to the first
teeth 81 of the first stator section 83, occurring when the
high torque low speed rotation is made. In this embodiment,
the position in this positional relationship is the reference
position.
With the pivotal movement of the second stator section
87 described above, the second teeth 84 can pivot (reciprocal
movement) in a narrow angular range along the rotational direction
of the rotor 71 indicated by the arrow "a," from the reference
position shown in Fig. 12(a), i.e., a position at which each
second tooth 84 right opposes to the respective first tooth
81, to the maximum movable position shown in Fig. 12(c), i.e.,
a right center position between the respective first teeth 81
and 81, by way of a midway position shown in Fig. 12(b).
Additionally, the midway position shown in Fig. 12(b) is a certain
and any position in the stepless and intermittent pivotal
movement.
Figs. 13(a) and (b) are illustrations for describing the
principle of the rotation control of the electric motor 70 in
this embodiment made in a range from a high torque low speed
rotation to a low torque high speed rotation.
Additionally, in order to simply show, the windings 82
wound around the respective teeth 81 and the mold are omitted
in Figs. 13(a) and (b) . Similarly, the mold of the second teeth
84 and the retainer 84 is omitted in the illustrations.
Also, Fig. 13 (a) shows the high torque low speed rotational
condition shown in Fig. 12(a) under which each second tooth
84 right opposes to the respective first tooth 81. Fig. 13(b)
shows the low torque high speed rotational condition shown in
Fig. 12(c) under which each second tooth 84 exists at the right
center position between the respective first teeth 81 and 81.
Also, Fig. 13(a) shows a condition under which the ith
magnet 79i of the rotor 71 right opposes to the ith first tooth
81i of the first stator 83 on the stator side, and the ith second
tooth 84i of the second stator section 87 on the stator side
right opposes to the first tooth 81i. That is, Fig, 13(a) shows
the same condition as that shown in Fig. 12(a).
Further, Fig. 13(b) shows a condition under which the
positional relationship between the magnet 7 9i of the rotor
71 and the first tooth 81i of the first stator section 83 is
not changed, and the second tooth 84i of the second stator section
87 is placed at the right center position between the respective
first teeth 81i and 81i+l of the first stator section 83. That
is, Fig. 13(b) shows the same condition as that shown in Fig.
12(c).
In Fig. 13(a), the annular section 74 of the rotor side
yoke 73, the first teeth 81 (811-1, 81i, 81i+l) of the first
stator section 83, the second teeth 84 (84i-l, 84i, 84i+l) of
the second stator section 87 and the retainer 85 all belonging
to the rotor 71 have strong permeability. Also, the opposing
surfaces of the magnets 79 (79i-l, 79i, 79i+l) and the first
teeth 81, and the opposing surfaces of the first teeth 81 and
the second teeth 84 are extremely close to eachother, respectively.
Thus, a magnetic reluctance "h" between the opposing surfaces
of the magnets 79 (791-1, 79i, 79i+l) and the first teeth 81,
and a magnetic reluctance "k" between the opposing surfaces
of the first teeth 81 and the second teeth 84 are small. .
Additionally, as described above, the end surface 81a of
each first tooth 81 opposing to the rotor 71 is formed to be
larger than the other end surface 81b thereof. Thus, between
the respective neighboring f jlrst teeth 81, a magnetic reluctance
"j" is made between the end surfaces 81a opposing to the rotor
71 extremely smaller than a magnetic reluctance made between
the other surfaces; however, this "j" is larger than the magnetic
reluctance wh" with the rotor 71. That is, there is a relationship
(h ^f k Thus, the magnetic fluxes generated between the magnet
79i (decided to be N pole) and the neighboring magnet 79i-l
(S pole, accordingly) hardly permeates through the portions
having the magnetic reluctance "j," and form a strong magnetic
flux flow 98a that permeates through the portions having the
magnetic reluctance "h, " the first tooth 81i, the portions having
the magnetic reluctance "k," the second tooth 84i, the retainer
85, the second tooth 84i-l, the retainer 85, the portions having
the magnetic reluctance "k, " the first tooth 81i-l, the portions
having the magnetic reluctance "h," and the annular section
74.
Further, the magnetic fluxes generated between the magnet
79i (N pole) and the other neighboring magnet 79i+l (S pole)
hardly permeates through the portions having the magnetic
reluctance wj," and form a strong magnetic flux flow 98b that
permeates through the portions having the magnetic reluctance
"h," the first tooth 81i, the portions having the magnetic
reluctance "k," the second tooth 84i, the retainer 85, the second
tooth 84i+l, the retainer 85, the portions having the magnetic
reluctance "k," the first tooth 81i+l, the portions having the
magnetic reluctance "h," and the annular section 74.
These phenomena occur even though the magnet 79i is not
the N pole magnet but the S pole magnet except that the magnetic
fluxes go in the reverse direction, and similarly a strong magnetic
flux flow is made that flows through the associated magnet 79,
first tooth 81, second tooth 84, retainer 85 and annular section
74.
It is described above that the strong magnetic fluxes cause
the magnetic reluctance that can soon bring in the limit against
the transition of the electric motor 70 to the low torque high
speed rotation from the high torque low speed rotation without
taking any measure. Also, it is described above that there
is the field magnet weakening control to make the limit come
late.
However, in the present embodiment, as shown in Fig. 11
and Figs. 12(a), (b) and (c) , the second teeth 84 can pivot
(reciprocal movement) in the narrow angular range along the
rotational direction of the rotor 71 indicated by the arrow
"a" from the reference position at which each second tooth 84
right opposes to the respective first tooth 81 to the maximum
movable position located at the right center position between
the respective first teeth 81 and 81.
Now, suppose that the second teeth 84 pivot to the maximum
movable position shown in Fig. 13(b) from the reference position
shown in Fig. 13(a) . On this occasion, a magnetic reluctance
f
"m," which is larger than the magnetic reluctance wk" under
the right opposing condition, is made between the opposing
surfaces of each first tooth 81 and the respective second tooth
84. Further, because each second tooth 84 is positioned in
the configuration to project from the retainer 85, a magnetic
reluctance "n," which is larger than the magnetic reluctance
"m" made with the second tooth 84, is made.
That is, there is a relationship "m The magnetic reluctance "n" is negligible compared with the
magnetic reluctance "m." Thus, under the condition shown in
Fig. 13(b), it is almost true that the magnetic reluctance made
between each second tooth and the opposite end surface 81b of
the respective first tooth oppositely positioned relative to
the end surface 81a opposing to the rotor 71 is "m, " when the
second tooth 84 moves to the right center position between each
first tooth 81 and the other neighboring first tooth 81.
As described above, the end surface 81a of each first tooth
81 opposing to the rotor 71 is formed to be larger than the
other end surface 81b thereof. Thus, between the respective
neighboring first teeth 81, the magnetic reluctance "j" made
between the end surfaces 81a opposing to the rotor 71 extremely
small, and under the condition shown- in Fig. 13(b), the
relationship (j "j" and the magnetic reluctance "m."
That is, it is true that a distance (magnetic reluctance
"j") defined between the end surface 81a of each first tooth
81 opposing to the rotor 71 and the end surface 81a of the other
neighboring first tooth 81 is smaller than the minimum distance
(magnetic reluctance "m") defined between each second tooth
and the opposite end surface 81b oppositely positioned relative
to the end surface 81a of the first tooth opposing to the rotor
71.
By being brought into this condition, i.e., the condition
under which the relationship among the magnetic reluctances
of the respective members ish in Fig. 13(b), the magnetic fluxes made between the magnet 79i
(N pole) and the other neighboring magnet 79i-l (S pole) form
a weak magnetic flux flow 99a that does not flow to the second
tooth 84i-l or to the retainer 85 from the first tooth 81i,
due to the magnetic reluctance V and the magnetic reluctance
"n," but permeates through the first tooth 81i, the portions
having the magnetic reluctance "j," the first tooth 81i-l and
the annular section 74.
Also, the magnetic fluxes made between the magnet 79i (N
pole) and the other neighboring magnet 79i+l (S pole) form a
weak magnetic flux flow 99a that does not flow to the second
tooth 84i+l or to the retainer 85 from the first tooth 81i,
due to the magnetic reluctance "m" and the magnetic reluctance
"n," but permeates through the first tooth 81i, the portions
having the magnetic reluctance "j," the first tooth 81i+l, and
the annular section 74.
Thus, the magnetic fluxes from the magnets 79 do not cross
the windings 82, which is not shown, of the respective first
teeth 81, and the magnetic reluctances against the rotation
of the rotor 71 in its rotational direction, generated by these
magnetic fluxes crossing the windings 82, disappear. The rotor
can rotate in a high speed, accordingly.
Also, similarly, the magnetic fluxes from the magnets 79
do not flow into the windings of the respective first teeth
81. Thus, the torque to be generated between the electrified
first teeth 81 and the magnets 79 and then given to the rotor
71 is lowered. That is, the low torque high speed operation
is realized.
As thus described, simply, the second teeth reciprocally
move between the position at which the second teeth right oppose
to the first teeth and the other position at which the second
teeth are placed midway to the neighboring first teeth. The
entire structure thus can be compact.
Now, a space making the magnetic reluctance, i.e., a gap
(" j, ""k, ""in, ""n" and so on) that causes the magnetic reluctances
is described. The gap that causes the magnetic reluctance is
defined as a magnetic reluctance space of air or the equivalent.
The gap that causes the magnetic reluctance (hereunder, simply
called gap), is further described.
Figs. ; 14(a) to (e) are illustrations for describing
differences between a contact area which varies a magnetic
reluctance between two members and a gap. Generally, it is
known that, when a magnetic flux flow coming from a magnet.is.
going to flow between the two members made of a magnetic material,
if any portion is ensured to be a flow route for the magnetic
fluxes, the magnet does not provide any surplus magnetic fluxes.
When the two members are completely separated by a gap,
the magnet tries to make the magnetic fluxes flow by any means,
and the magnetic fluxes start to flow from a portion that gives
the easiest route, i.e., from the narrowest gap.
Fig. 14(a) shows a condition under which two magnetic members
101 and 102 configured as the letter L in their cross sections
are tightly coupled with each other. A vertical cross section
of the major portion of the magnetic member 101 has an area
A, while a vertical cross section of a projection of the magnetic
member 101 has an area B. Also, a vertical cross section of
the major portion of the magnetic member 102 has an area D,
while a vertical cross section of a projection of the magnetic
member 102 has an area D-B. A horizontal cross section of the
respective projections has an area C, which is the same as one
another.
Now, the following conditions are given: area A = area
D = area C = 200S, and area B = 50S. Also, it is decided that
magnetic fluxes 103 coming from a magnet out of the illustration
flow to the magnetic member 102 from the magnetic member 101.
Suppose that, as shown in Fig. 14(b), the two magnetic
members 101 and 102 move to be relatively separated from one
another by the respective distances a and b (a = b) at the area
B portion of the vertical cross section and the area D-B portion
of the vertical cross section while the area C portions of the
horizontal surfaces are in slide contact with each other.
Upon this movement, because a space of the distance b is
made between the two magnetic members 101 and 102, the magnetic
flux flow flowing into the major portion of the magnetic member
101 having the areaA=200S becomes saturatedat the areaBportion,
and reduces to the magnetic flux flow that flows through the
area B=50S. This magnetic flux flow 103 flows into the magnetic
member 102 via the sliding surfaces C1 (area C1 = 150S, B C1) .
Next, suppose that, as shown in Fig. 14 (c) , the two magnetic
members 101 and 102 further move to be relatively separated
from one another by the respective distances 2a and 2b at the
area B portion of the vertical cross section and the area D-B
portion of the vertical cross section while the area C portions
of the horizontal surface are in slide contact with each other.
In this situation, the magnetic flux flow becoming saturated
at the area B portion also reduces to the magnetic flux flow
that flows through the area B=50S, and flows into the magnetic
member 102 via the sliding surfaces C2 (area C2 = 100S, B C2) .
That is, no magnetic reluctance changes between conditions
of Fig. 14(b) and Fig. 14(c). Specifically, the spaces that
separate the two magnetic members 101 and 102 by the distances
a, b or 2a, 2b in the magnetic flux direction are not spaces
for causing the magnetic reluctance, because the magnetic
reluctance does not change (is not varied), even though the
distances change. Namely, the spaces are not gaps.
Further, suppose that, as shown in Fig. 14(d), the two
magnetic members 101 and 102 further move to be relatively
separated from one another by the respective distances 3.5a
and 3.5b at the area B portion of the vertical cross section
and the area D-B portion of the vertical cross section while
the area C portions of the horizontal surface are in slide contact
with each other.
On this occasion, each area C portion of the respective
horizontal surface has a sliding surface area C3=25S. That
is, the following relationship is given: B > C3. Thus, the
magnetic flux flow 103 is saturated at the sliding surface C3,
and the magnetic flux flow corresponding to the area 25S flows
into the magnetic member 102.
That is, the magnetic reluctance between the two magnetic
members 101 and 102 changes for the first time when the area
of the sliding surface C becomes smaller than the area B of
the vertical cross section of the projection of the magnetic
member 101. In other ;words, the magnetic reluctance changes
depending on the change of each area of the sliding surfaces
between the two members.
The change of the magnetic reluctance shown in Figs. 14 (c)
and (d) is not caused by the changes of the separating distances
between the two members (the changes 2a and 2b to 3. 5a and 3. 5b),
but by the change of the area of the sliding surface C (the
change of C2 to C3) . Namely, the separating distances 3.5a and
3.5b that have changed still do not cause the gaps.
Also, Fig. 14 (e) shows a condition under which the two
magnetic members 101 and 102 are relatively separated from one
another by the respective distances 5a and 5b at the area B
portion of the vertical cross section and the area D-B portion
of the vertical cross section so that the sliding surfaces C3
are completely released from the abutting function to be separated
by the distance C4.
As described above, when the two members are completely
separated by a gap, the magnetic flux flow of the magnet flows
through a portion that gives the easiest route, i.e., through
a portion having the narrowest distance C4 . Namely, the magnetic
reluctance is generated at the portion having the distance C4,
and the distance C4 is a magnetic reluctance gap. That is,
the magnetic reluctance varies in accordance with the change
of the distance C4.
In other words, the distance C4 is a gap to vary the magnetic
reluctance; however, the distances 5a and 5b are not spaces
to vary the magnetic reluctance, i.e., those are not gaps.
Any portion that is described as a gap in this embodiment is
the portion that defines the distance C4 discussed above.
In the present embodiment, as thus described, the stator
is divided into at least two portions, and one portion is moved
at right angles to the rotational direction of the rotor, i.e.,
to the direction of the magnetic flux flow that flows into each
core around which the respective winding is wound from the rotor
to form the variable gaps, to thereby greatly change the output
characteristic of the rotary electrical machine without consuming
the electric power that does not contribute to the torque.
Figs. 15(a) and (b) show a structure of the major part
of an alternative (first one) of the axial gap type electric
motor in the first embodiment.
Fig. 15(a) shows a condition that is the same as the condition
shown in Fig. 13(a), under which each first tooth 83 of the
first stator section 83 right opposes to the respective second
tooth 84 of the second stator section 87. From this condition,
each second tooth 84 in this embodiment obliquely moves downward
to be separated from the respective first tooth 81 as indicated
by the two-headed arrow "e" of the illustration.
That is, as shown in Fig. 15(b) , the second stator section
87 moves in a direction parallel to the rotational direction
of the rotor 71 that exists out of the illustration and also
moves in a direction perpendicular to the rotational direction
of the rotor 71.
Thus, a distance, between each first tooth 81 of the first
stator section and the respective second tooth 84 of the second •
stator section 87 and in the direction perpendicular to the
rotational direction of the rotor 71, changes from a distance
"p" shown in Fig. 15(a) to a distance "p'" shown in Fig. 15
(b) (p' > p) .
That is, a magnetic reluctance gap between each first tooth
83 and each second tooth 84 is larger than that in the structure
shown in Fig. 13(b). Therefore, the output characteristic of
the electric motor can vary on a larger scale.
Figs. 16(a) to (d) show a structure of the major part of
another alternative (second one) of the axial gap type electric
motor in the first embodiment.
As shown in Figs. 16(a) and (b), each first tooth 104 has
a protruding portion 104-1 abutting on a side surface of the
respective second tooth 105 at an end surface that opposes to
one end surface of the second tooth 105.
Each first tooth 104 therefore prohibits the respective
second teeth 105 from moving rightward beyond the right opposing
positions shown in Fig. 16 (b).
In this embodiment, also each second tooth 105 not only
moves in the direction parallel to the rotational direction
of the rotor 71 that exists out of the illustration but also
moves in the direction perpendicular to the rotational direction
of the rotor 71. That is, each second tooth 105 obliquely moves
downward to be separated from the respective first tooth 81.
Fig. 16(c) shows an alternative in which each second tooth
105 moves horizontally as indicated by the arrow "f," while
Fig. 16(d) shows another alternative in which each second tooth
105 obliquely moves downward as indicated by the arrow "g."
In this alternative, also a magnetic reluctance gap between
each first tooth 104 and each second tooth 105 is larger than
that in the structure shown in Fig. 13 (b) . Therefore, the output
characteristic of the electric motor can vary on a larger scale.
(Structure and operation of axial gap type electric motor
according to second embodiment of the present invention)
Figs. 17(a) to (d) show a structure of the major part of
an axial gap type electric motor in a second embodiment.
As shown in Figs. 17(a) and (c), each first tooth 106 in
this embodiment is formed in such a manner that a portion lower
than an end portion 106-1 facing the annular section 74 of the
rotor 71 includes a winding-possessing-portion 106-2 having
a winding 107 positioned around it and a non-winding-possessing
portion 106-3 having no winding positioned around it.
In this connection, as shown in Figs. 17(b) and (c), each
second tooth 108 is divided into an inner tooth portion 109
corresponding to the winding-possessing-portion 106-2 of the
respective first tooth 106 and an outer tooth portion 110
corresponding to the non-winding-possessing-portion 106-3 of
the each first tooth 110.
The inner tooth portion 109 of each second tooth 108 is
placed at an inner side (side close to the center axis) of the
annular retainer 111, while the outer tooth portion 110 is placed
at an outer side of the retainer 111 and at a middle position
between two neighboring tooth portions 109.
A condition shown in Fig. 17 (c) is the same as the condition
shown in Fig. 13(a), because the winding-possessing-portion
106-2 of each first tooth 106 and the inner tooth portion 109
of each second tooth 108 right oppose to each other. Also,
because the non-winding-possessing-portion 106-3 and the outer
tooth portion 110 are placed at the outer side of the circular
arrangement and are alternately positioned, the magnetic gap
is extremely large, and they nearly do not affect the magnetic
flux flow.
To the contrary, a condition shown in Fig. 17(d) is the
same as the condition shown in Fig. 13 (b) regarding a positioning
relationship between the winding-possessing-portion 106-2 of
each first tooth 106 and the inner tooth portion 109 of each
second tooth 108a. Each non-winding-possessing portion 106-3
and the respective outer tooth portion 110 right oppose to each
other.
That is, the magnetic fluxes of each field magnet 79 reflux
through the respective non-winding-possessing portion 106-3
and outer tooth portion 110 and the retainer 111, and nearly
do not flow through the winding-possessing-portion 106-2 of
each first tooth 106. Namely, the magnetic fluxes of each
winding-possessing-portion 106-2 can be shut off stronger than
the embodiment shown in Fig. 13(b).
Additionally, in the first and second embodiments, the
opposing surfaces of the rotor and the stator, and the opposing
surfaces of the stator sections, which are the two portions
of the divided stator, are arranged to extend parallel to
(horizontally in the illustrations) the rotational surface of
the rotor; however, the opposing surfaces of those components
are not limited to such parallel arrangement.
Figs. 18(a) and (b) show a further alternative wherein
the opposing surfaces of the rotor and the stator, and the opposing
surfaces of the stator sections, which are the two portions
of the divided stator, extend slantwise.
In the alternative shown in Figs. 18(a) and (b) , the
respective opposing surfaces of the field magnets 113 retained
by the retainer 112, the first teeth 114, and the second teeth
116 retained by the retainer 115 extend upward outward relative
to the center 117 of the rotor 112 in its radial direction.
With this alternative structure, the same actions and effects
can be obtained as those in the first and second embodiments.
(Structure of radial gap type electric motor according to third
embodiment of the present invention)
Fig. 19 is a cross sectional view, showing a structure
of a radial gap type electricmotor according to a third embodiment.
Additionally, in the illustration, in order to simply show
the third embodiment in comparison with the first embodiment,
components having the same functions are assigned with the same
reference numerals as those assigned in Fig. 10.
As shown in the illustration, this radial gap type electric
motor includes a cylindrical rotor 73 rotating about an axis
of a rotational shaft (indicated by a rotational center 117
in the illustration), and a first stator core 83 positioned
inside of the cylindrical rotor 73 and having a plurality of
first teeth 81 respective one end surfaces of which oppose to
the rotor 73 and a winding 82 is wound around a circumferential
side surface of each first tooth 81 except for both the end
surfaces 81a and 81b.
The electric motor further includes a second stator core
87 having a plurality of second teeth 84. Each second tooth
84 has one end surface 84a positioned to oppose to the one end
surface of the first tooth 81 that oppositely exists relative
to the other end surface opposite the rotor 73. The second
tooth has also the other end surface 84b retained in a retainer
85.
In this radial gap type electric motor, the second stator
core 87 moves at right angles to a direction of flow of magnetic
fluxes that are generated, when the magnetic windings 82 of
the first stator core 83 are electrified, to permeate through
the respective first teeth 81, i.e., clockwise or
counterclockwise in the illustration. Therefore, the same field
magnet control as that described with reference to Figs. 13(a)
and (b) can be practicable.
(Structure of radial gap type electric motor according to fourth
embodiment of the present invention)
Fig. 20 is a cross sectional view, showing a structure
of a radial gap type electric motor according to a fourth
embodiment.
Additionally, also in the illustration, in order to simply
show the fourth embodiment in comparison with the first embodiment,
components having the same functions are assigned with the same
reference numerals and symbols as those assigned in Fig. 10.
As shown in the illustration, this radial gap type electric
motor includes a columnar or cylindrical rotor 73 rotating about
a rotational shaft 72, and a first stator core 83 positioned
outside of the rotor 73 in its radial direction and having a
plurality of first teeth 81 respective one end surfaces of which
oppose to the rotor 73 and a winding is wound around a
circumferential side surface of each first tooth 81 except for
both the end surfaces 81a and 81b.
The electric motor further includes a second stator core
87 having a plurality of second teeth 84. Each second tooth
84 has one end surface 84a positioned to oppose to the one end
surface 81b of the first tooth 81 that oppositely exists relative
to the other end surface 81a opposite the rotor 73. The second
tooth has also the other end surface 84b retained in a retainer
85.
In this radial gap type electric motor, the second stator
core 87 moves at right angles to a direction of flow of magnetic
fluxes that are generated when the magnetic windings 82 of the
first stator core 83 are supplied with the electric power and
permeates through the respective first teeth,81, i.e., clockwise
or counterclockwise in the illustration. Thus, the same field
magnet control as that described with reference to Figs. 13(a)
and (b) can be practicable.
(Structure of axial gap type electric motor according to fifth
embodiment of the present invention)
Fig. 21 is a perspective view, showing the major part of
an axial gap type electric motor according to a fifth embodiment.
This illustration only shows a rotor of the axial gap type
electric motor of this embodiment.
As shown in Fig. 21, first, the rotor 120 of this embodiment
includes a plurality of field magnets 122 fixedly positioned
on a annular section 121 of a rotor yoke of a first rotor section
120-1.
Next, the rotor 120 includes a second rotor section 120-2
constructed in such a manner that magnetic members 123 which
number is the same as the number of the field magnets 122 are
disposed on a rotary retainer which is not shown to nearly slidably
contact with a rotational surface of each filed magnet 122,
and the second rotor section 120-2 coaxially engages with the
first rotor section 120-1 and rotates together with the first
rotor section 120-1.
A stator that is positioned to oppose to the rotor 120
has the same structure as that of the stator 39 shown in Figs.
3 and 4.
In this axial gap type electric motor of this embodiment,
when it makes a low speed high torque rotation, as shown in
Fig. 21, the first rotor section 120-1 and the second rotor
section 120-2 are positioned in such a manner that the respective
field magnets 122 and the magnetic members 123 entirely overlap
with each other to rotate in phase.
Thereby, magnetic fluxes of the field magnets 122 are
controlled to gather in the respective magnetic members 123
and then flow into teeth of the stator.
Fig. 22 is an illustration, showing a relationship of
displacement of the rotational phase between the first rotor
section 120-1 and the second rotor section 120-2 when the rotor
120 makes a high speed low torque rotation in the structure.
Fig. 22 shows a condition under which the displacement of the
rotational phase between the first rotor section 120-1 and the
second rotor section 120-2 is the maximum.
The first rotor section 120-1 and the second rotor section
120-2 can move relative to each other between the condition
under which the phases are consistent with one another as shown
in Fig. 21 and the condition under which the phases are displaced
within 15 degrees from one another as shown in Fig. 22.
Under the condition that the phases are displaced with
15 degrees as shown in Fig. 22, a magnetic gap between each
field magnet 122 and the respective magnetic member 123 becomes
extremely large at large portions in a width direction of the
rotational shaft, except for a relatively small gap partially
formed at end portions located close to the rotational center.
Thus, almost the entire magnetic flux flow of each field magnet
122 flow through the neighboring field magnet 122 via the annular
section 121 to reflux.
The magnetic flux flow that flows into the magnetic member
123 through the small gap formed at the portions close to the
rotational center is an extremely small portion of the entire
magnetic flux flow. Also, the magnetic gap between each magnetic
member 123 and the respective toothof the stator becomes extremely
large at large portions in the width direction of the rotational
shaft, except for a relatively small gap partially formed at
end portions located close to the rotational center.
Thus, the magnetic flux flow that slightly flows into each
magnetic member 123 from the respective field magnets 122 does
not flow through the tooth of the stator. Thereby, the drive
condition during the high speed low torque rotation can be
realized.
In other words, by suitably positioning the first rotor
section and the second rotor section to control the displacement
of the rotational phase from the state shown in Fig. 22 to the
state shown in Fig. 23, an amount of the flux linkage is controlled.
The relationship between the rotational speed and the rotational
torque thus can be controlled without wastefully using the
electric power.
(Structure of axial gap type electric motor according to sixth
embodiment of the present invention)
Fig. 23 is an illustration, showing a structure of the
major part of the axial gap type electric motor according to
a sixth embodiment.
This illustration only shows a rotor of the axial gap type
electric motor of this embodiment.
As shown in Fig. 23, first, the rotor 124 of this embodiment
includes a plurality of magnet members 126 fixedly positioned
on an annular section 125 of a rotor yoke of a first rotor section
124-1.
Next, the rotor 120 includes a second rotor section 124-2
constructed in such a manner that magnetic-member-Combined type
magnets 129 which number is the same as the number of the magnetic
members 126 are disposed on a rotary retainer (not shown) to
nearly slidably contact with a rotational surface of each magnetic
member 126, and the second rotor section 124-2 coaxially engages
with the first rotor section 124-1 and rotates together with
the first rotor section 124-1.
Each magnetic-member-combined type magnet 129 is formed
in such a manner that a magnetic member 127 disposed to oppose
to the respective magnetic member 126 and a field magnet 128
disposed to oppose to the stator (not shown) are piled with
each other.
A stator that is positioned to oppose to the rotor 124
has the same structure as that of the stator 39 shown in Figs.
3 and 4.
In this axial gap type electric motor of this embodiment,
when it makes a low speed high torque rotation, as shown in
Fig. 23, the first rotor section 124-1 and the second rotor
section 124-2 are positioned in such a manner that the respective
magnetic members 126 and the magnetic-member-combined type
magnets 129 entirely overlap with each other to rotate in phase.
Thereby, the magnetic fluxes coming from one magnetic pole
of each field magnet 128 are gathered and the flow thereof is
adjusted by the combined type magnetic member 12 7 and the magnetic
member 126 positioned thereabove and opposing to the combined
type magnetic member 127, and then the magnetic fluxes are again
gathered and the flow thereof is again adjusted by the annular
section 125, the neighboring magnetic member 126 and the magnetic
member 127 positioned opposite and below the magnetic member
126. Afterwards, the magnetic fluxes flow through the magnetic
member 127 and the combined type field magnet 128.
The magnetic fluxes coming from the other magnetic pole
of each field magnet 128 flow into each tooth of the stator
opposing to the field magnet 128 positioned therebelow, and
flow through the neighboring tooth via the stator side yoke.
That is, the magnetic fluxes of each field magnet 128 flow
through the respective combined magnetic member 127 and magnetic
member 126, the annular section 125, the neighboring magnetic
member 126, the magnetic member 127 opposing to the magnetic
member 126, the combined type field magnet 128 combined with
the magnetic member 127, the tooth of the stator, the stator
side yoke, the neighboring tooth, and the combined type field
magnet 128 opposing to this neighboring tooth to reflux through
the coil wound around the tooth of the stator.
This condition is the same as the condition of the flow
of the magnetic flux flow shown in Fig. 13(a). Thereby, the
drive condition during the low speed high torque rotation is
made can be realized.
Fig. 24 is an illustration, showing a relationship of
displacement of the rotational phase between the first rotor
section 124-1 and the second rotor section 124-2 when the rotor
120 makes a high speed low torque rotation in the structure.
Fig. 24 shows a condition under which the displacement of the
rotational phase between the first rotor section 120-4 and the
second rotor section 120-4 is the maximum.
i
In this embodiment, the first rotor section 124-1 and the
second rotor section 124-2 can move relative to each other between
the condition under which the phases are consistent with one
another as shown in Fig. 23 and the condition under which the
phases are displaced within 15 degrees from one another as shown
in Fig. 24.
Under the condition that the phases are displaced with
15 degrees as shown in Fig. 24, a magnetic gap between each
magnetic member 127 and the respective magnetic member 126 is
extremely large. Thus, almost the magnetic flux flow of each
magnetic member 127 does not flow into the magnetic member 126,
i.e., the magnetic flux flow is under the shut out condition.
This condition is slightly different from the condition
shown in Fig. 13(b); however, the condition under which the
gap becomes larger at a portion where the magnetic flux flow
has been gathered and adjusted before, and the magnetic flux
is shut out not to flow through the tooth of the stator side
yoke is the same as the condition of Fig. 13(b) . Thereby, the
drive condition during the high speed low torque rotation is
made can be realized.
In other words, by suitably positioning the first rotor
section 124-1 and the second rotor section 124-2 to control
the displacement of the rotational phase from the state shown
in Fig. 23 to the state shown in Fig. 24, an amount of the flux
linkage is controlled. The relationship between the rotational
speed and the rotational torque thus can be controlled without
wastefully using the electric power.
WE CLAIM
1. A rotary electrical machine (70) comprising:
a rotor rotational about an axis of a rotating shaft (72) in a first rotational
direction; and
a stator (88) disposed so as to oppose to the rotor (71),
wherein one of the rotor (71) and the stator (88) is divided into at least
two portions (83, 87) in the axial direction, a first portion (83) of the at
least two portions (83, 87) being movable at least in a rotational direction
or a reverse rotational direction of the first rotational direction relative to a
second of the at least two portions (83, 87) in such a manner that a gap
between the first portion (83) and the second portion (87) forms a
magnetic resistance that is variable,
the first portion (83) being a first stator core (80) having a first set of
teeth (81), each tooth of the first set of teeth (81) having an end surface
(81a) opposite the rotor (71) and a second end surface (81b) facing away
from the end surface (81a), each tooth (81) of the first set of teeth having
a winding (82) wound around a circumferential side surface (81c) thereof,
and
the second portion (87) being a second stator core (87) having a second
set of teeth (84), the second set of teeth (84) having end portions (84a)
facing the second end surfaces (81a) of the first set of teeth (81).
2. The rotary electrical machine as claimed in claim 1, wherein the
movement of the first portion relative to the second portion is a reciprocal
movement within a predetermined angle.
3. The rotary electrical machine as claimed in claim 1, wherein a rotational
angle of the first portion relative to the second portion is less than a pitch
angle that is defined by two adjacent teeth of the second set of teeth.
4. The rotary electrical machine as claimed in claim 1, wherein the first
portion and the second portion are rotors,
the first portion being a first rotor section having a first set of magnetic
members, each magnetic member of the first set of magnetic members
having an end surface that opposes the stator and a second end surfaces
that faces away from the end surface, and
the second portion being a second rotor section having a second set of
magnetic members with end portions disposed opposite the second end
surfaces of the first set of magnetic members.
5. The rotary electrical machine as claimed in claim 4, wherein a rotational
angle of the first portion relative to the second portion is less than a pitch
angle defined by two adjacent magnetic members of the second set of
magnetic members.
6. A rotary electrical machine comprising:
a rotor having an annular section rotational in a first direction about an
axis of a rotating shaft;
a first stator core having a first set of teeth, each tooth of the first set of
teeth having a portion with one end surface positioned opposite the
annular section and a second end surface facing in a direction generally
opposite the one end surface, each tooth of the first set of teeth having a
winding wound around a circumferential side surface of said portion; and
a second stator core having a second set of teeth, the second set of teeth
having end portions positioned opposite the respective second end
surfaces of the first set of teeth of the first stator core, the rotor, first
stator core and second stator core positioned axially along the axis of the
rotating shaft and proximate each other such that at least a portion of
each tooth of the first set of teeth is positionable axially opposite the
annular section of the rotor and axially opposite at least one tooth of the
second set of teeth of the second stator core,
wherein the second stator core is movable at least in the first direction or
in a reverse rotational direction.
7. The rotary electrical machine as claimed in claim 6, wherein the second
stator core is movable in the first direction or the reverse rotational
direction of the rotor and also movable in an axial direction of the rotor.
8. The rotary electrical machine as claimed in claim 6, wherein each tooth of
the first set of teeth has a protruding portion at the second end surface
thereof configured to abut a side surface of each tooth of the second set
of teeth.
9. The rotary electrical machine as claimed in claim 6, wherein each tooth of
the first set of teeth is divided into a first portion which has a winding on
a circumferential surface thereof and a second portion which has no
winding on a circumferential surface thereof, and the second set of teeth
include teeth corresponding to the first portion of each tooth of the first
set of teeth, and other teeth corresponding to the second portion of each
tooth of the first set of teeth.
10. The rotary electrical machine as claimed in claim 6, wherein respective
opposing surfaces of the rotor and the first set of teeth are formed to
obliquely extend in such a manner that an inner side of the opposing
surface of the rotor that is positioned radially closer to the axis of a
rotating shaft is thicker than an outer side thereof.
11. The rotary electrical machine as claimed in claim 6, wherein, when the
second set of teeth are positioned directly opposite the first set of teeth, a
magnetic resistance between one tooth of the first set of teeth and one
tooth of the directly opposing second set of teeth is smaller than a
magnetic resistance between adjacent teeth of the first set of teeth, and,
when the second set of teeth move so that the one tooth of the second
set of teeth is placed at a position between adjacent teeth of the first set
of teeth, a magnetic resistance between one tooth of the second set of
teeth and the adjacent teeth of the first set of teeth is larger than a
magnetic resistance between the adjacent teeth of the first set of teeth.
12. The rotary electrical machine as claimed in claim 11, wherein the
magnetic resistances are adjustable by a distance between the adjacent
teeth of the first set of teeth, or a distance between the one tooth of the
first set of teeth and the one tooth of the second set of teeth.
13.The rotary electrical machine as claimed in claim 6, comprising a
movement drive force transmitting mechanism for moving the second
stator core in the first direction or in the reverse rotational direction.
14.The rotary electrical machine as claimed in claim 6, wherein the
movement of the second stator core relative to the first stator core is a
reciprocal movement within a predetermined angle in the first direction or
in the reverse rotational direction.
15.The rotary electrical machine as claimed in claim 6, wherein the
movement of the second stator core relative to the first stator core is an
intermittently rotational movement in the first direction.
16. The rotary electrical machine as claimed in claim 6, wherein the first set of
teeth and the-windings are unitarily molded together.
17. The rotary electrical machine as claimed in claim 6, wherein the second
set of teeth and the windings are unitarily molded together.
18. A rotary electrical machine comprising:
a rotor having an annular section rotational in a first direction about an
axis of a rotating shaft;
a first stator core having a first set of teeth, each tooth of the first set of
teeth having a portion with one end surface positionable opposite the
annular section and a second end surface facing in a direction generally
opposite the one end surface, each tooth of the first set of teeth having a
winding wound around a circumferential side surface of said portion; and
a second stator core having a second set of teeth, the second set of teeth
having end portions positionable opposite the respective second end
surfaces of the first set of teeth of the first stator core,
wherein the second stator core is movable at least in the first direction or
in a reverse rotational direction, and wherein the second stator core is
also movable in an axial direction of the rotor.
19. A rotary electrical machine comprising:
a rotor having an annular section rotational in a first direction about an
axis of a rotating shaft;
a first stator core having a first set of teeth, each tooth of the first set of
teeth having a portion with one end surface positionable opposite the
annular section and a second end surface facing in a direction generally
opposite the one end surface, each tooth of the first set of teeth having a
winding wound around a circumferential side surface of said portion; and
a second stator core having a second set of teeth, the second set of teeth
having end portions positionable opposite the respective second end
surfaces of the first set of teeth of the first stator core, each tooth of the
first set of teeth has a protruding portion at the second end surface
thereof configured to abut a side surface of each tooth of the second set
of teeth,
wherein the second stator core is movable at least in the first direction or
in a reverse rotational direction.

The present invention relates to a rotary electrical machine (70) comprising a
rotor rotational about an axis of a rotating shaft (72) in a first rotational
direction; and a stator (88) disposed so as to oppose to the rotor (71), wherein
one of the rotor (71) and the stator (88) is divided into at least two portions (83,
87) in the axial direction, a first portion (83) of the at least two portions (83, 87)
being movable at least in a rotational direction or a reverse rotational direction of
the first rotational direction relative to a second of the at least two portions (83,
87) in such a manner that a gap between the first portion (83) and the second
portion (87) forms a magnetic resistance that is variable, the first portion (83)
being a first stator core (80) having a first set of teeth (81), each tooth of the
first set of teeth (81) having an end surface (81a) opposite the rotor (71) and a
second end surface (81b) facing away from the end surface (81a), each tooth
(81) of the first set of teeth having a winding (82) wound around a
circumferential side surface (81c) thereof, and the second portion (87) being a
second stator core (87) having a second set of teeth (84), the second set of
teeth (84) having end portions (84a) facing the second end surfaces (81a) of the
first set of teeth (81).

Documents:

01126-kol-2005-abstract.pdf

01126-kol-2005-claims.pdf

01126-kol-2005-description complete.pdf

01126-kol-2005-drawings.pdf

01126-kol-2005-form 1.pdf

01126-kol-2005-form 2.pdf

01126-kol-2005-form 3.pdf

01126-kol-2005-form 5.pdf

1126-KOL-2005-(27-01-2012)-CORRESPONDENCE.pdf

1126-KOL-2005-(27-01-2012)-FORM 27.pdf

1126-KOL-2005-(27-01-2012)-PA.pdf

1126-KOL-2005-ABSTRACT 1.1.pdf

1126-KOL-2005-CANCELLED DOCUMENT.pdf

1126-KOL-2005-CLAIMS 1.1.pdf

1126-kol-2005-correspondence.pdf

1126-KOL-2005-DESCRIPTION COMPLETE 1.1.pdf

1126-kol-2005-examination report.pdf

1126-KOL-2005-FORM 1 1.1.pdf

1126-kol-2005-form 18.pdf

1126-KOL-2005-FORM 2 1.1.pdf

1126-KOL-2005-FORM 27.pdf

1126-kol-2005-form 3.pdf

1126-kol-2005-form 5.pdf

1126-kol-2005-gpa.pdf

1126-kol-2005-granted-abstract.pdf

1126-kol-2005-granted-claims.pdf

1126-kol-2005-granted-description (complete).pdf

1126-kol-2005-granted-drawings.pdf

1126-kol-2005-granted-form 1.pdf

1126-kol-2005-granted-form 2.pdf

1126-kol-2005-granted-specification.pdf

1126-KOL-2005-OTHER PATENT DOCUMENT.pdf

1126-KOL-2005-PETITION UNDER RULE 137.pdf

1126-kol-2005-priority document.pdf

1126-KOL-2005-REPLY TO EXAMINATION REPORT.pdf

1126-kol-2005-translated copy of priority document.pdf


Patent Number 243401
Indian Patent Application Number 1126/KOL/2005
PG Journal Number 42/2010
Publication Date 15-Oct-2010
Grant Date 13-Oct-2010
Date of Filing 09-Dec-2005
Name of Patentee YAMAHA HATSUDOKI KABUSHIKI KAISHA
Applicant Address 2500 SHINGAI, IWATA-SHI, SHIZUOKA
Inventors:
# Inventor's Name Inventor's Address
1 HARUYOSHI HINO C/O YAMAHA HATSUDOKI KABUSHIKI KAISHA 2500 SHINGAI, IWATA-SHI, SHIZUOKA 438-8501
2 KEIKO MUROTA C/O YAMAHA HATSUDOKI KABUSHIKI KAISHA 2500 SHINGAI, IWATA SHI, SHIZUOKA 438-8501
PCT International Classification Number H02K 21/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 2005-133559 2005-04-28 Japan
2 2004-357339 2004-12-09 Japan