US 2007 O120430A1

(19) United States

(12) Patent Application Publication (10) Pub. No.: US 2007/0120430 A1
Kurosawa (43) Pub. Date: May 31, 2007
(54) FLYWHEEL ELECTRIC GENERATOR Publication Classification
(75) Inventor: Keiji Kurosawa, Chiba (JP) (51) Int. Cl.
HO2K 7/18 (2006.01)
Correspondence Address: HO2K 7/02 (2006.01)
BANNER & WITCOFF, LTD. HO2K 47/00 (2006.01)
1100 13th STREET, N.W. (52) U.S. Cl. ........................... 310/74; 310/113; 290/1 R:
SUTE 12OO 322/4
WASHINGTON, DC 20005-4051 (US)
(73) Assignees: Jiro KATO, Nagoya (JP); Value Sup- (57) ABSTRACT
pers Developer Corporation, Noda- A flywheel electric generator comprises a star-up motor, a
flywheel rotary shaft rotated by the motor, a flywheel
(21) Appl. No.: 11/474,466 rotating by coupling with the rotary shaft, a plurality of
permanent magnets disposed at Substantially equal spaces of
(22) Filed: Jun. 26, 2006 center angles on outer circumferential sections of the fly
wheel, a pair of electromagnets arranged fixedly at positions
(30) Foreign Application Priority Data on a diameter line of the flywheel so as to face the permanent
magnets and an electronic generator rotationally driven by
Nov. 30, 2005 (JP)...................................... 2005-346OO2 the rotary shaft.
Patent Application Publication May 31, 2007 Sheet 1. Of 7 US 2007/0120430 A1
Fig.1
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Fig.2
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Fig.3
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Fig.4

O 2 4 6 8 10 12 14 16 18 20 22
DISTANCE IN ROTATING DIRECTION(mm)
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Fig.5
Patent Application Publication May 31, 2007 Sheet 6 of 7 US 2007/0120430 A1
Fig.6

3OHz-600rpm

X-26
Patent Application Publication May 31, 2007 Sheet 7 of 7 US 2007/0120430 A1

Fig. 7 (PRIOR ART)

US 2007/O120430 A1 May 31, 2007

FLYWHEEL ELECTRIC GENERATOR of its own rotations. The electric generator 51 supplies an
excitation power source to the exciting device 58 from the
CROSS-REFERENCE TO RELATED bus-bar 53 through a breaker 54c (refer to, for instance,
APPLICATIONS Japanese Patent Application KOKAI Publication No. 2001
0001. This application is based upon and claims the 258294).
benefit of priority from the prior Japanese Patent Application 0008. With respect to a structure of a fly wheel electric
No. 2005-346002, filed on Nov.30, 2005, the entire contents generator, in a conventional flywheel electric generator,
of which are incorporated herein by reference. other than one, in which a flywheel is attached to a usual
salient pole type electric generator to operate it by using a
BACKGROUND OF THE INVENTION usual bearing in the atmosphere, a technique using a mag
netic shaft composed of a levitating magnet and a levitating
0002 The present invention relates to a flywheel electric bulk made of a high-temperature Superconductor positioned
generator utilizing rotational kinetic energy of a flywheel. facing the levitating magnet in a sealed container and
0003. The flywheel electric generator is an electric gen operating the flywheel electric generator by setting Sur
erator to discharge kinetic energy stored in the flywheel rounding atmospheric pressure of the rotor in the sealed
coupled to a rotor of the electric generator, as electric power. container to a range within 0.1 atm to 0.4 atm is disclosed
That is, the flywheel electric generator employs a system by (refer to, for instance, Japan Patent Application KOKAI
which electric energy is converted into rotational energy of Publication No. 6-303738).
an object having large inertia moment to store it. In general, 0009. In such a conventional flywheel electric generator,
the flywheel electric generator is often utilized to supply the heavier the weight of the flywheel becomes, the larger an
electric power to a load in need of pulse-like large electric energy storage quantity becomes and, on the other hand, the
power.
larger a mechanical loss at the bearing, etc., becomes.
0004 For instance, a nuclear fusion system confining Therefore, in the case of use of a usual bearing for the
plasma by means of a magnetic field Supplies electric power flywheel electric generator, a requirement for a large output
of several hundreds of thousands kw in a short time such as causes a large mechanical loss at the bearing and certainly
several seconds sometimes, so that it is disagreeable to causes a reduction in efficiency as the flywheel electric
directly obtain such pulse-like electric power from a electric generator.
power system because the influence on the power system is 0010. As disclosed in the latter patent document given
too considerable. Therefore, such a field of the electric above, the technique, in which the magnetic shaft composed
power system employs the flywheel electric generator. The of the levitating magnet and the levitating bulk made of the
flywheel electric generator operates in Such a cycle that it high-temperature Superconductor positioned facing the levi
increases the number of rotations of an electric generator tating magnet is used in the sealed container, needs a
over a time interval of several minutes to store the kinetic large-scaled device for operating the high-temperature
energy in the flywheel, and discharges the kinetic energy Superconductor Sufficiently.
stored in the flywheel in supplying the electric power to a
load to result in a decrease in the number of the rotations of 0011. As mentioned above, the system for housing the
the electric generator. flywheel electric generator in the sealed container is not
0005 Usually, a conventional flywheel electric generator preferable because the whole of the system becomes com
directly couples an electric motor for driving to an electric plex and large and the system takes a great deal of time in
generator. An output from the electric generator indepen working maintenance and inspection and in re-starting there
after.
dents from the electric power system and the flywheel
electric generator also varies the number of rotations of the BRIEF SUMMARY OF THE INVENTION
electric generator with the power Supply to the load, so that
a frequency also varies in Synchronization with the number 0012. The present invention is invented on the basis of
of rotations thereof. the foregoing situation, and an object of the invention is to
0006 FIG. 7 shows a configuration view of a control provide a flywheel electric generator capable of obtaining an
device of such conventional flywheel electric generator. A output with efficiency even in the atmosphere.
flywheel electric generator 51 is driven by an electric motor 0013 A flywheel electric generator according to an
for driving 52 to store the kinetic energy in the flywheel embodiment of the present invention includes a start-up
electric generator 51. The electric motor 52 is connected to motor; a flywheel rotary shaft which is rotated by the
a receiving-power-end bus-bar 53 of the electric power start-up motor; a flywheel which rotates by coupling with
system through a breaker 54a and controlled by a Scherbius the flywheel rotary shaft; a plurality of permanent magnets
device 55 on the basis of the number of rotations from a which are disposed at a Substantially equal distance on outer
means 56 for detecting the number of rotations. The Scher circumferential sections of the flywheel; a pair of electro
bius device 55 conducts secondary exciting control of the magnets arranged at fixed positions on both sides of the
electric motor 52 to regenerate a part of secondary electric flywheel along its diameter direction so as to face the
power generated on a secondary side to the bus-bar 53 permanent magnets; and an electric generator which is
through a breaker 54b. rotationally driven by the flywheel rotary shaft.
0007 To supply the electric power from the flywheel 0014. In the flywheel electric generator described above,
electric generator 51 to a load 57, the electric generator 51 the flywheel is composed of two pieces of circular plates
is excited by an exciting device 58 to generate the electric which are arranged separately in parallel to each other and
power and supplies it to the load 57 to decrease the number a plurality of Support plates which are disposed so as to
US 2007/O120430 A1 May 31, 2007

couple the two pieces of the circular plates with one another DETAILED DESCRIPTION OF THE
on circumferential sections thereof, and the plurality of INVENTION
permanent magnets are Supported on the plurality of the
Support plates, respectively. 0031 Hereinafter, embodiments of the present invention
will be described with reference to the drawings in detail.
0.015 Further, in the flywheel electric generator, the FIG. 1 is an exemplary side elevation view showing a
flywheel rotary shaft is coupled with the start-up motor and schematic configuration of a flywheel electric generator
the electric generator, respectively, through a first and a regarding an embodiment of the present invention, and FIG.
second clutches. 2 is its exemplary plan view.
0016 Further, in the flywheel electric generator, the 0032. A flywheel electric generator 1 of the embodiment
facing Surfaces of the permanent magnets and the electro includes three stages of angle structures 2, 3 and 4 which are
magnets are arranged at prescribed inclination angle. arranged at each position of an upper stage, a middle stage
0017 Further, in the flywheel electric generator, the and a lower stage in a vertical direction, respectively. The
inclination angle is not more than 30° each. upper stage angle structure 2 is formed, as shown in FIG. 2,
of three arms 2a which are coupled so that they form a planar
0018 Further, in the flywheel electric generator, the shape of a triangle. An upper stage bearing 5 is Supported
inclination angle is approximately 22.5° each. with three arms 2a through three bearing Support arms. 5a at
0019. Further, in the flywheel electric generator, the first the central part of the upper stage angle structure 2. The
and second clutches are electromagnetic clutches. middle stage angle structure 3 is also has the approximately
same structure as that of the upper angle structure 2. That is,
0020) Further, in the flywheel electric generator, the the middle stage angel structure 3 is formed, as partly shown
permanent magnets of an even number are arranged on the in FIG. 3, of three arms 3a which are coupled with one
outer circumferential sections of the flywheel. another so that its planar shape becomes a triangle. A middle
stage bearing 6 is Supported by the three arms 3a through
0021 And further, in the flywheel electric generator, a three bearing Support arms 6a at the central part of the
minimum gap between the facing Surfaces of the electro middle stage angel structure 3. The lower stage angel
magnets and the permanent magnets is 1 mm. structure 4 is also has the approximately same structure as
0022. Additional objects and advantages of the invention that of the upper angle structure 2. That is, the lower stage
will be set forth in the description which follows, and in part angel structure 4 is also formed, as a partly shown in FIG.
will be obvious from the description, or may be learned by 3, of three arms 4a which are coupled with one another so
practice of the invention. The objects and advantages of the that its planner shape becomes a triangle. A lower stage
invention may be realized and obtained by means of the bearing 7 is supported by the three arms 4a through three
instrumentalities and combinations particularly pointed out bearing Support arms 7a at the central part of the lower stage
hereinafter. angle structure 4.
0033. The tops of the angle structures 2, 3 and 4 are fixed
BRIEF DESCRIPTION OF THE SEVERAL with three fixing poles 8 formed in a vertically elected state
VIEWS OF THE DRAWING on leg bases 9, respectively, and the angle structures 2.3 and
0023 The accompanying drawings, which are incorpo 4 of the three stages are integrally coupled with one another.
rated in and constitute a part of the specification, illustrate 0034) The flywheel 11 is fixed to a flywheel rotary shaft
embodiments of the invention, and together with the general 11a pivoted by an upper stage bearing 5 disposed at the
description given above and the detailed description of the upper stage angle structure 2 and by a middle stage bearing
embodiments given below, serve to explain the principles of 6 disposed at the middle stage angle structure 3 by use of a
the invention. hub 12. The rotary shaft 11a is extended downward from the
0024 FIG. 1 is an exemplary schematic side elevation middle stage bearing 6 and its lower end is coupled with a
first electromagnetic clutch 13. The first electromagnetic
view showing an embodiment of a flywheel electric genera clutch 13 is also coupled with a first pulley rotary shaft 14a.
tor of the present invention; Thus, the flywheel rotary shaft 11a and the first pulley rotary
0.025 FIG. 2 is an exemplary schematic horizontal plan shaft 14a are coupled or separated in accordance with
view of the flywheel electric generator shown in FIG. 1; opening/closing of the first electromagnetic clutch 13, and as
a result, electric power is transmitted or shut off.
0026 FIG. 3 is an exemplary horizontal cross sectional
view of the flywheel shown in FIG. 1; 0035. The first pulley 14 is coupled with a start-up motor
16 fixed on the lower surface of the middle stage angel
0027 FIG. 4 is an exemplary graph indicating measured structure 3 through a transmission belt 15. The transmission
torque of a stepping motor shown in FIG. 3; belt 15, accordingly, transmits the electric power from the
0028 FIG. 5 is an exemplary partly enlarged view of the start-up motor 16 to the first pulley 14. The start-up motor
stepping motor shown in FIG. 3; 16 is, for example, a two-pole motor of 2.2 kW using an
inverter and its number of rotations is 3,400 rpm.
0029 FIG. 6 is an exemplary explanatory view used for 0036) The flywheel 11 is a basket-shaped rotor in which
calculating torque in operating the flywheel electric genera
tor; and two metallic circular plates 11b are supported in parallel to
each other with a plurality of sheets of iron-made support
0030 FIG. 7 is an exemplary block diagram showing an plates 17. Here, the support plates 17 are formed, for
example of use of a conventional flywheel electric generator. instance, by 18 sheets thereof and arranged at Substantially
US 2007/O120430 A1 May 31, 2007

an equal angular space of around 20° on the peripheral edges couples the second pulley 23 with an electric generator
of each circular plate 11b. Each plate-like permanent magnet pulley 27 fixed to a rotary shaft of an electric generator 26.
18 is fixed on a surface of the sheet at an approximately The electric generator 26 rotating in accordance with the
central Section in a vertical direction of each Support plate rotation of the electric generator pulley 27 has, for instance,
17. a rated power of 7.5 kw, an AC frequency of 30 Hz and the
number of rotations of 600 rpm.
0037 FIG. 3 is the horizontal cross sectional view of the
flywheel 11 shown in FIG.1. As shown in FIG. 3, each plate 0043. Next to this, operations of the electric generator 26
surface of the support plates 17 is not perpendicular to each having the flywheel 11 configured as mentioned above will
radius direction of the flywheel 11 and arranged with an be described by dividing them into three steps.
inclination thereto. Each plate surface of the plate-like 0044) (Step 1: Start-Up Step)
permanent magnets 18 fixed on each plate surface of the
Support plates 17 is also arranged with an inclination to the 0045. The electric generator 26 closes the first clutch 13
radius direction. The inclination angle is around 67.5° at the to star-up the rotation of the start-up motor 16 in a state with
cross angle between the radius direction of the flywheel 11 the second clutch 22 opened therein, then, transmits its
and the plate Surface of the permanent magnet 18, and torque to the first pulley rotary shaft 14a through the
around 22.5° at the cross angle between a tangent direction transmission belt 15 and the first pulley 14 to rotate it. At this
of a circle forming the outer circumference of the flywheel moment, the first clutch 13 having closed, the first pulley
11 and the plate surface of the permanent magnet 18. rotary shaft 14a and the flywheel rotary shaft 11a are
coupled with each other. The rotation of the first pulley
0038 A pair of electromagnets 19 is arranged at fixed rotary shaft 14a is thereby transmitted to the flywheel rotary
positions on both sides of the flywheel 11 along its diameter shaft 11a to rotate it and further rotate the flywheel 11 fixed
direction so as to face the permanent magnet 18. to the flywheel rotary shaft 11a.
0.039 FIG. 5 is a partly enlarged view showing a posi 0046 (Step 2: Flywheel Rotation Step)
tional relationship between the permanent magnet 18 fixed
to the outer circumferential section of the flywheel 11 and 0047. After starting up the rotation of the flywheel 11, the
the electromagnet 19 disposed to face the permanent magnet electric generator 26 opens the first clutch 13 to disconnect
18. The permanent magnet 18 has a shape of which the the flywheel rotary shaft 11a from the rotary shaft 14a of the
horizontal cross sectional shape is a rectangular with a long first pulley 14. In this state, the pair of electromagnets 19 is
side 18a and a short side 18b, and each corner 18c at which supplied with pulse currents by a pulse signal generator,
the sides 18a and 18b are crossed is arranged on an outer which is not shown in the drawings. The pulse currents are
circumferential edge C of the flywheel 11. Here, the rotating applied at timing right after each permanent magnet 18 has
direction of the flywheel 11 is indicated by an arrow A. The passed through the position facing each electromagnet 19 by
long side 18a is arranged with an inclination so as to be the rotations of the flywheel 11. As the result of the excita
closer to a central side rather than the outer circumferential tion caused by the pulse signals from the electromagnets 19,
edge C toward the rotating direction. The inclination angle repulsive force generated between the electromagnets 19
is experimentally confirmed that the above-described angle and the permanent magnets 18 further applies torque to the
is preferable therefor. flywheel 11 in the rotating direction thereof.
0040. On the other hand, the pair of electromagnets 19 is 0048 FIG. 4 is a graph showing a result of measurement
disposed at positions facing the permanent magnets 18 of relationships between relative positions of the permanent
which are fixed on the outer circumferential sections of the magnets 18 against the electromagnets 19 disposed on the
flywheel 11 with prescribed gaps. The electromagnets 19 are flywheel 11 and the torque (knockout force). During the
respectively disposed, as shown in FIG. 3, on the opposite measurement, each plate face of the permanent magnet 18 is
sides on a diameter line (not shown) crossing the flywheel disposed in a state in which it is not inclined to the radius
11. Not shown in the figure, the pair of electromagnets 19 is direction of the flywheel 11 but orthogonal thereto and each
Supported with fixing poles 18 fixing the angle structures 2. opposing gap between the permanent magnet 18 and the
3 and 4 at the circumferences of the flywheel 11. electromagnet 19 in the radius direction is kept at 1 mm. The
lateral axis of FIG. 4 indicates the distance (mm) between
0041. With the arrangement given above, each of the the permanent magnet 18 and electromagnet 19 in the
permanent magnet 18 and the electromagnet 19 form a rotating direction of the flywheel 11 in a range of 0 to 20
magnetic circuit for a motor. In other words, the magnet 18 mm, and the longitudinal axis indicates the torque (kg) at the
forms a rotor, the pair of electromagnets 19 forms a stator, stepping motor.
and the Supplying a pulse signal to the pair of electromagnets
19 forms a stepping motor (pulse motor). The stepping 0049. As cleared from FIG. 4, the torque of the stepping
motor drives the flywheel 11, for instance, at a time when the motor reaches a maximum value of around 8 kg when the
number of rotations is 400 rpm. distance between the permanent magnet 18 and the electro
magnet 19 in the rotating direction is around 8 mm. The
0042. In the lower section of the first pulley 14, a break maximum torque is generated as pulling force when the
disk 21 operating as a disk break is fixed to the first pulley distance between the permanent magnet 18 and the electro
rotary shaft 14a, and a second electromagnetic clutch 22 is magnet 19 becomes 8 mm before the permanent magnet 18
coupled to the lower end of the rotary shaft 14a. The passes through the position facing the electromagnet 19
opposed end of the second electromagnetic clutch 22 is fixed (entrance side), and as reaction force when the distance
to a pulley rotary shaft 23a of which the lower end is pivoted between the permanent magnet 18 and the electromagnet 19
by a lower stage bearing 7. A second pulley 23 is fixed to the becomes 8 mm after the permanent magnet 18 passes
second pulley rotary shaft 23a. A transmission belt 25 through the position facing the electromagnet 19 (exit side).
US 2007/O120430 A1 May 31, 2007

In the embodiment of the invention, however, as shown in 0057 With modification of Formula 1, the following
FIG. 5, each plate surface of the permanent magnet 18 is Formula 2 is satisfied where unit conversions are 1 kg=9.80
inclined to the radius direction of the flywheel 11, and the Nm, and NM=0.101972 kgm.
pulse currents are applied at the timing right after the T=(60,000/21)H/N (Formula 2)
permanent magnet 18 has passes through the position oppo
site to the electromagnet 19 by the rotation of the flywheel 0.058. The Formula 2 is modified as follows: where the
11. In other words, if the pulse currents for the electromagnet output from the start-up motor 16 is 2.2 kW and the number
19 are applied at the exit side, the electric generator 26 can of rotations of flywheel rotary shaft 11a is 400 rpm
continuously operate the torque also to the side 18b of the TA(Nm)=(60,000/21)2.2/400
permanent magnet 18 after operating the torque to the side 0059. With performing a unit conversion from Nm into
18a of the outer circumferential side of the permanent kg, the following formula is satisfied.
magnet 18. The operation results in enabling the electric
generator 26 to apply a strong knockout force to the per
manent magnet 18. This fact is also confirmed experimen TA (kg) = (974x2.2) f 400
tally.
= 5.36 kg. m
0050. After the rotating speed of the flywheel 11 has
reached a sufficient speed, even when the electric generator
26 stops applying the pulse currents to the electromagnet 19,
the flywheel 11 keeps the rotations by itself over a prescribed 0060. Therefore, the torque TA from the start-up motor
time interval by inertia. 16 of the flywheel rotary shaft 11a becomes 5.36 kg.m.
0051 (Step 3: Power Generation Step) 0061 (b) Torque (TB) from the Stepping Motor formed
on the Outer Circumferential Section of the Flywheel 11
0052. When the flywheel 11 reaches the prescribed num 0062 Since the diameter of the flywheel 11 is 1.5 m, the
ber of rotations, the electric generator 26 brings both first torque (knockout force) by the repulsive force from the
and second clutches 13 and 22 into closed states. The
operations of two clutches 13 and 22 produce coupling permanent magnet 18 and the electromagnet 19 to the
among the flywheel rotary shaft 11a, the first pulley rotary flywheel 11 is 8 kg, and the electromagnets 19 are disposed
shaft 14a and the second pulley rotary shaft 23a with one at two spots, respectively, the torque TB from the stepping
another. The coupling results in the transmission of the motor is expressed as follows:
rotations of the flywheel 11 to the second pulley rotary shaft
23a through the flywheel rotary shaft 11a and the first pulley 0063. Accordingly, the torque (TF) from the flywheel
rotary shaft 14a to make the second pulley rotary shaft 23a rotary shaft 11a is expressed as follows:
rotate. The rotations of the second pulley rotary shaft 23a
makes the second pulley 23 rotate and further makes the
electric generator pulley 27 rotate through the transmission 0064. Next, in a calculation of the torque (TG) of the
belt 25. The electric generator pulley 27 being fixed to the electric generator 26 by the torque (TF) of the flywheel
rotary shaft of the electric generator 26, the electric genera rotary shaft 11a, because the number of the rotations of the
tor 26 generates the electric power. The electric generator 26 electric generator 26 is 600 rpm, the torque (TG) is obtained
can be stopped by operating the break disk 21. as follow:
0053 Successively, the torque acting on the flywheel TG=17.36/(600/400)=11.57 kg'm
rotary shaft 11a in operating the flywheel electric generator 0065. On the other hand, performing a single calculation
1 will be described by referring to the explanatory view of of the torque (TH) of the rotary shaft of the electric generator
the flywheel electric generator of the present invention 26 by use of Formula 2, because the output from the electric
shown in FIG. 6. In FIG. 6, two clutches 13 and 22 are in a generator 26 is 67 kw and the number of rotations thereof is
state of closing in generating the electric power. Thus, each 600 rpm, the torque (TH) is obtained as follows:
of the rotary shafts 11a, 14a and 23a being possible to be
regarded as a single shaft, the clutches 13 and 22 are omitted
from FIG. 6. 0066. Here, comparing the torque (TG) of the rotary shaft
of the electric generator 26 obtained from the torque (TF) of
0054) The torque (TF) of the flywheel rotary shaft 11a the flywheel rotary shaft 11a to the torque (TH) singly
becomes the sum of the torque (TA) from the start-up motor calculated by use of Formula 2, the relationship between the
16 and the torque (TB) from the stepping motor formed on torques (TG) and (TH) is expressed as follows:
the outer circumferential section of the flywheel 11. Here
inafter, the torque (TF), (TA) and (TB) will be explained in TG=11.57 kgmaTH=10.87 kg'm
turn. 0067. That is to say, the flywheel 11 applies, to the
0055 (a) Torque (TA) from the Start-up Motor 16 of the electric generator 26, torque not smaller than the rated power
Flywheel Rotary Shaft 11a of the electric generator 26. Consequently, it has become
obvious that the flywheel electric generator 1 can increase
0056. The following Formula 1 is satisfied for the rela the generated electric power which is output from the
tionship among the torque (TF), (TA) and (TB) where the electric generator 26.
number of rotations of the start-up motor 16 is N (rpm), a 0068 The present invention is not limited to the specific
torque is T (Nm) and rated electric power is H (kw). details and representative embodiments shown and
H={T(2TN)/60}/1,000 (Formula 1) described herein, this invention may be modified in various
US 2007/O120430 A1 May 31, 2007

forms without departing from the sprit or scope of the the plurality of permanent magnets are Supported on the
general inventive concept thereof. plurality of the Support plates, respectively.
What is claimed is: 3. The flywheel electric generator according to claim 2,
1. A flywheel electric generator, comprising: wherein the flywheel rotary shaft is coupled with the start-up
motor and the electric generator, respectively, through a first
a start-up motor; and a second clutches.
a flywheel rotary shaft which is rotated by the start-up 4. The flywheel electric generator according to claim 3,
motor, wherein the facing Surfaces of the permanent magnets and
the electromagnets are arranged with a prescribed inclina
a flywheel which rotates by coupling with the flywheel tion angle.
rotary shaft; 5. The flywheel electric generator according to claim 4,
a plurality of permanent magnets which are disposed at a wherein the inclination angle is not more than 30° each.
Substantially equal distance on outer circumferential 6. The flywheel electric generator according to claim 5,
sections of the flywheel; wherein the inclination angle is approximately 22.5° each.
a pair of electromagnets arranged at fixed positions on 7. The flywheel electric generator according to claim 6,
both sides of the flywheel along its diameter direction wherein the first and second clutches are electromagnetic
clutches.
So as to face the permanent magnets; and
8. The flywheel electric generator according to claim 7.
an electric generator which is rotationally driven by the wherein the permanent magnets of an even number are
flywheel rotary shaft. arranged on the outer circumferential sections of the fly
2. The flywheel electric generator according to claim 1, wheel.
wherein 9. The flywheel electric generator according to claim 8,
the flywheel is composed of two pieces of circular plates wherein a minimum gap between the facing positions of the
which are arranged separately in parallel to each other electromagnets and the permanent magnets is approximately
and a plurality of Support plates which are disposed so 1 mm.
as to couple the two pieces of the circular plates with
one another on circumferential sections thereof, and