U.S. patent number RE46,850 [Application Number 14/852,244] was granted by the patent office on 2018-05-15 for electric wire for high frequency, high volume and large current.
This patent grant is currently assigned to Goto Denshi Co., Ltd.. The grantee listed for this patent is GOTO DENSHI CO., LTD.. Invention is credited to Taiki Goto, Yoshihide Goto, Youichi Miura.
United States Patent |
RE46,850 |
Goto , et al. |
May 15, 2018 |
Electric wire for high frequency, high volume and large current
Abstract
An electric wire contains a conductive wire having at least a
groove structured on the surface of the conductive wire, and an
additional wire to be filled into the groove. The groove is
provided on an outer surface of the conductive wire along a
longitudinal direction of the conductive wire. The additional wire
is inserted in the groove.
Inventors: |
Goto; Yoshihide (Sagae,
JP), Goto; Taiki (Sagae, JP), Miura;
Youichi (Sagae, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
GOTO DENSHI CO., LTD. |
Sagae-shi, Yamagata |
N/A |
JP |
|
|
Assignee: |
Goto Denshi Co., Ltd.
(Sagae-shi, Yamagata, JP)
|
Family
ID: |
43897917 |
Appl.
No.: |
14/852,244 |
Filed: |
September 11, 2015 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
12925690 |
Oct 26, 2010 |
8878068 |
Nov 4, 2014 |
|
|
Foreign Application Priority Data
|
|
|
|
|
Oct 26, 2009 [JP] |
|
|
2009-245345 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01B
7/0009 (20130101); H01F 27/303 (20130101); H01B
7/0009 (20130101); H01B 7/30 (20130101); H01F
27/303 (20130101); H01B 7/30 (20130101); H01F
5/06 (20130101) |
Current International
Class: |
H01B
5/08 (20060101); H01F 27/30 (20060101); H01B
7/30 (20060101); H01B 5/00 (20060101); H01B
7/00 (20060101) |
Field of
Search: |
;174/15.6,21R,24,97,100,116,113R,115,116R,117R,113C,119R,126.1,126.2,128.1
;336/199,208 ;310/196,201 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
H05-15218 |
|
Feb 1993 |
|
JP |
|
2006-172838 |
|
Jun 2006 |
|
JP |
|
2008-053143 |
|
Mar 2008 |
|
JP |
|
Primary Examiner: Nguyen; Minh T
Attorney, Agent or Firm: Masuvalley & Partners
Claims
What is claimed is:
1. An electric wire comprising: a conductive wire, which has
substantially a quadrilateral cross-sectional shape; and an
insulator placed along a longitudinal direction of the conductive
wire at a corner of the quadrilateral; a groove provided along the
longitudinal direction of the conductive wire at the corner of the
quadrilateral; wherein the insulator is placed in the groove.
2. The electric wire of claim 1, wherein a width of the insulator
is less than one third of a width of the conductive wire.
3. The electric wire of claim 1, wherein the insulator is made of a
synthetic resin.
4. The electric wire of claim 1, wherein insulators are placed at
all corners of the quadrilateral.
5. The electric wire of claim 1, further comprising: an additional
wire inserted in the conductive wire along the longitudinal
direction of the conductive wire; wherein the additional wire
comprises a conductive member; wherein the conductive wire and the
conductive member are made of different materials; and wherein the
conductive member is in contact with the conductive wire.
6. A coil comprising the electric wire of claim 1, the electric
wire being wound on a bobbin so that a corner of a quadrilateral is
adjacent to a corner of a next quadrilateral in a cross sectional
view.
.Iadd.7. The electric wire of claim 1, wherein a thickness of the
insulator at the corner of the quadrilateral is larger than a
thickness of the insulator at a side of the
quadrilateral..Iaddend.
.Iadd.8. An electric wire comprising: a single conductive wire
having substantially a quadrilateral cross-sectional shape; and an
insulating layer placed along a longitudinal direction of said
single conductive wire, covering at least one corner of said
quadrilateral, wherein a thickness of the insulating layer at the
corner is thicker than a thickness of the insulating layer at a
side of said quadrilateral, and wherein said thickness of the
insulator at the corner is less than one third of the thickness of
said single conductive wire..Iaddend.
.Iadd.9. The electric wire of claim 8, wherein the insulating layer
covers entirely an outer surface of the conductive wire, covering
all corners and all sides of the quadrilateral..Iaddend.
.Iadd.10. The electric wire of claim 8, wherein the insulating
layer is made of synthetic resin..Iaddend.
.Iadd.11. The electric wire of claim 8 further comprises a groove
disposed along the longitudinal direction of the conductive wire at
one corner of the quadrilateral, wherein the insulating layer
covers the groove..Iaddend.
.Iadd.12. The electric wire of claim 11, wherein the groove is
provided at all corners of the quadrilateral and the insulating
layer covers entirely an outer surface of the conductive wire,
including all corners and all sides of the
quadrilateral..Iaddend.
.Iadd.13. A coil comprising the electric wire of claim 8, the
electric wire being wound on a bobbin so that a corner of a
quadrilateral is adjacent to a corner of a next quadrilateral in a
cross sectional view..Iaddend.
Description
TECHNICAL FIELD
This application claims priority under 35 U.S.C. .sctn. 119 from
Japanese patent application Serial No. 2009-245345, filed Oct. 26,
2009, entitled "Electric wire for high frequency, high voltage and
large current", which is incorporated herein by reference in its
entirety.
The present invention relates to an electric wire, which is optimal
to apply a high-frequency current or high-voltage large current, or
optimal to flow a current at a high temperature.
BACKGROUND OF THE INVENTION
Electric vehicles are being put to practical use. It is known that
some electric vehicles equip motors that have coils, through which
high-frequency currents, such as 200 kHz, flow. Since, this type of
motors consumes a lot of electric power, high-voltage large current
needs to flow through the coils. However, the motors are driven by
electricity supplied from batteries. Thus, there has been a need to
reduce electric consumptions of motors. However, it is well known
that loss of a high-frequency current is large while the current is
flowing through a conducting wire because the current gathers
around a surface of the conducting wire due to the skin effect.
Therefore, the effective resistance of the conducting wire
increases and the loss of electric power also increases. Worse
thing is that the temperature of the motor become high such as 100
to 200.degree. C. while the motor is running. Resistances of the
traditional electric wires become undesirably high at such
temperatures. Thus, higher voltage must be applied to the motor to
generate the same mechanical force. This leads a large electric
power consumption of the motor.
Litz wires have been commonly used to reduce the electric loss by
the skin effect. The litz wire is constituted with bundled plural
small-diametered wires, each of which is coated by an insulator.
Thereby, the surface area of the litz wire is enhanced. However,
since the litz wire is a bundle of the small wires, it is difficult
to make the size and shape of the coils precisely homogeneous
because the litz wire crumples up while being wound into the coil.
Therefore, characteristics and performances of the coils made from
the litz wire are not consistent. In addition, since it is
difficult to wind the litz wire densely, it is difficult to make a
coil from the litz wire that has high performance with a small
size. Worsely, since each conducting wire constituting the litz
wire has a small diameter, the litz wire is not suitable to apply a
high-voltage large current. In order to make the litz wire capable
of conducting a high-voltage large current, each conducting wire
must have a large diameter. This leads the size of the motor to be
large. This adds a weight to an electric vehicle and increases its
electric power consumption.
To conquer such problems, there is a conducting wire that has
grooves on its outer surface along the longitudinal direction
(Japan published utility model application JP H05-15218). This wire
has an increased surface area. When a high frequency current is
applied to, this wire regulates the increase of effective
resistance of the conducting wire caused by the skin effect.
However, resistances of this wire still become large when the
temperature becomes high. Thus, this wire is still not sufficient
to reduce the electric consumption of the motors.
Recently cordless inductive power supply system has been getting
popular to charge batteries of cellular phones. This system is also
expected to be a future charging method for electric vehicles. This
system enables to charge a battery without connecting a wire. The
cordless inductive power supply system is composed of a transmitter
and a receiver. To charge, a high-frequency high-voltage current is
applied to the transmitter. When the receiver is close enough (but
not in contact or wired), an electric power is transmitted to a
receiver and a battery connected to the receiver is charged. To
maximize the transmission efficiency, electric properties of
electric wires such as impedance and inductance in the transmitter
and receiver are critical. Currently, manufacturers produce the
inductive power supply systems by their own format. Thus, in order
to produce compatible transmitters and receivers, electric wires
must be modified for each manufacturer. However, it costs a lot to
develop electric wires for each manufacturers. Thus, an electric
wire whose electric properties is easily attenuated is desired.
SUMMARY OF THE INVENTION
One aspect of the present invention is an electric wire containing
a conductive wire and an additional wire. The additional wire is
inserted in the conductive wire along a longitudinal direction of
the conductive wire.
Another aspect of the present invention is an electric wire
containing a conductive wire and an insulator. The conductive wire
has substantially a quadrilateral cross-sectional shape. The
insulator is placed along a longitudinal direction of the
conductive wire at a corner of the quadrilateral.
Another aspect of the present invention is an electric wire
containing a conductive wire. A resistance of the conductive wire
at 200.degree. C. is at most 1.42 times larger than a resistance of
the conductive wire at 50.degree. C.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 depicts a perspective view of a first embodiment of an
electric wire.
FIG. 2 depicts a perspective view of the first embodiment of the
electric wire in which additional electric wires are inserted into
a conductive wire.
FIG. 3 depicts a perspective view of a first modification example
of the first embodiment.
FIG. 4 depicts a perspective view of the first modification example
in which an additional electric wire is inserted into a conductive
wire.
FIG. 5 depicts a perspective view of a second modification example
of the first embodiment.
FIG. 6 depicts a perspective view of the second modification
example in which additional electric wires are inserted into a
conductive wire.
FIG. 7 depicts a perspective view of a second embodiment of an
electric wire.
FIG. 8 depicts a perspective view of a first modification example
of the second embodiment.
FIG. 9 depicts a transverse cross-sectional view of a second
modification example of the second embodiment.
FIG. 10 depicts a transverse cross-sectional view of a third
modification example of the second embodiment.
FIG. 11 depicts a transverse cross-sectional view of a fourth
modification example of the second embodiment.
FIG. 12 depicts a transverse cross-sectional view of a fifth
modification example of the second embodiment.
FIG. 13 depicts a transverse cross-sectional view of a third
embodiment of an electric wire.
FIG. 14 depicts a transverse cross-sectional view of a first
modification example of the third embodiment.
FIG. 15 depicts a transverse cross-sectional view of a second
modification example of the third embodiment.
FIG. 16 depicts a transverse cross-sectional view of a third
modification example of the third embodiment.
FIG. 17 depicts a transverse cross-sectional view of a fourth
embodiment of an electric wire.
FIG. 18 depicts an enlarged longitudinal cross-sectional view of a
coil containing the electric wire shown in FIG. 17.
FIG. 19 depicts a transverse cross-sectional view of a first
modification example of the fourth embodiment.
FIG. 20 depicts a transverse cross-sectional view of a second
modification example of the fourth embodiment.
FIG. 21 depicts a transverse cross-sectional view of a third
modification example of the fourth embodiment.
FIG. 22 depicts a transverse cross-sectional view of a fourth
modification example of the fourth embodiment.
FIG. 23 depicts a transverse cross-sectional view of a fifth
modification example of the fourth embodiment.
FIG. 24 is a graph showing a relation of temperature and ratio of
resistance measured on the electric wire of an example.
FIG. 25 is a graph and region showing a relation of temperature and
ratio of resistance on an electric wire.
DETAILED DESCRIPTION OF THE INVENTION
Below, best modes of the present invention are explained with the
drawings.
<First Embodiment>
As shown in FIG. 1, an electric wire 0 is composed of a conductive
wire 1. On an outer surface of the conductive wire 1, grooves 2 are
formed in a longitudinal direction I. Furthermore, the conductive
wire 1 is covered by an insulator sheath 4.
In this embodiment, additional electric wires 3 are arranged to be
inserted into the grooves 2. A cross-sectional shape of the
additional electric wire 3 fits to that of the groove 2. The
additional electric wire 3 is composed of a conductive member 3A.
The conductive member 3A is covered by an insulator sheath 5.
The conductive wire 1 has a substantially circular cross-sectional
shape. The conductive wire 1 is preferably made of copper,
aluminum, silver or iron. In this embodiment, the conductive wire 1
is made of a conductive material containing copper. Since copper
has a high conductivity, it efficiently reduces the electrical
loss. Iron offsets an undesirable Eddy current. Thus, when the
electric wire 0 containing iron is used for a coil, it can generate
a larger magnetic power. The optimal diameter .PHI. of the
conductive wire 1 is 0.2 mm -50 mm.
On the outer surface of the conductive wire 1, the plural grooves 2
are provided. In the case of FIGS. 1 and 2, eight grooves 2 are
provided. In the first embodiment, a cross-sectional shape of the
groove 2 is substantially elliptic. This elliptic shape increases
the surface area of the conductive wire 1. Thereby, the effective
resistance and electric power loss by the conductive wire 1 is
reduced. Therefore, the electric wire 0 is optimal for conducting a
high-frequency current regardless of the size of the load.
Furthermore, in the cross-sectional view, a bottom shape of the
groove 2 is round. When the additional electric wire 3, whose
cross-sectional shape is circular, is used for the electric wire 0,
the round shape improves the adherence of the additional electric
wire 3 to the groove 2. In this embodiment, an angle ".alpha." at a
junction formed by a top end of the groove 2 and an end of the
outer surface of the conductive wire 1 is less than 90.degree..
This arrangement effectively prevents the additional electric wire
3 from coming out of the groove 2. As shown in FIG. 1, in this
embodiment, a width D of the outer surface of the conductive wire 1
between the grooves 2 is smaller than a width W of the grooves 2.
This configuration makes portions of the conductive wire 1 between
the grooves 2 more flexible. Thus, the additional electric wires 3
can be more easily inserted into the grooves 2.
The insulator sheath 4 covers the conductive wire 1. The insulator
sheath 4 is preferably made of synthetic resin or rubber. These
materials provide an excellent electric insulation even if the
insulator sheath 4 is made thinner. Furthermore, these materials
add water repellency and elasticity. Thus, the insulator sheath 4
made of these materials enables tighter insertion of the additional
electric wires 3 into the groove 2.
A cross-sectional shape of the additional electric wire 3 is
circular. In this embodiment, since the bottom of the groove 2 has
a round shape, the additional electric wire 3, whose outer surface
is round, fits well to the groove 2, and hence the adhesiveness
between the additional electric wire 3 and the groove 2 is
improved. As shown in FIG. 2, it is preferable that a width of the
groove 2 is substantially the same as a diameter of the additional
electric wire 3. This arrangement efficiently prevents the
additional electric wire 3 from coming out from the groove 2.
Furthermore, it is preferable that a depth of the groove 2 is
substantially the same as the diameter of the additional electric
wire 3. This makes the outer surface of the electric wire 0
smoother. Hence, the electric wire 0 can be wound more densely to
form a coil. The conductive member 3A of the additional electric
wires 3 is preferably made of copper, aluminum, silver or iron. In
this embodiment, the conductive member 3A is made of a conductive
material containing aluminum. Since aluminum is relatively more
flexible, it is easier to put the additional electric wire 3 into
the groove 2. Furthermore, like this embodiment, if the material of
the conductive member 3A and the material of the conductive wire 1
are different, it is easy to adjust or modify electrical
characteristics of the electric wire 0 by adding or removing the
additional electric wires 3. When the conductive member 3A is made
of iron, it is easier to offset an undesirable Eddy current
generated in the electric wire 0.
The insulator sheath 5 covers the conductive member 3A. The
insulator sheath 5 is preferably made of synthetic resin or rubber.
These materials provide an excellent electric insulation even if
the insulator sheath 5 is made thinner. Furthermore, these
materials add water repellency and elasticity. Thus, the insulator
sheath 4 made of these materials enables tighter insertion of the
additional electric wire 3 into the groove 2. It is preferable that
the insulator sheath 4 and the insulator sheath 5 are made of the
same material. This arrangement improves the adherence of the
insulator sheath 4 and the insulator sheath 5.
In order to insert the additional electric wire 3 into the groove
2, the additional electric wire 3 put over the groove 2 is pressed
toward the center R of the conductive wire 1 along the longitudinal
direction by a pressing means such as a roller. Thereby, shapes of
the insulator sheath 4 and the insulator sheath 5 are changed by
their elasticity so that the shape of the additional electric wire
3 and the shape of the groove 2 fit to each other. As shown in FIG.
2, it is desirable that the additional electric wire 3 does not
project over the outer surface of the conductive wire 1. In other
word, it is desirable that the entire wire 3 fits inside of the
groove 2. This enables the electric wire 0 to be aligned neatly. In
addition, this secures the insulation of the conductive wire 1 and
the additional electric wire 3. Therefore, the conductive wire 1
and the additional electric wire 3 can conduct high-frequency
current and high-voltage current stably and efficiently. In other
embodiment, the additional electric wire 3 may be adhered to the
groove 2 by an adhesive. In other embodiment, the additional
electric wire 3 may be welded to the groove 2 by high-frequency
wave or by ultrasonic wave. Furthermore, in other embodiment, an
additional insulator sheath 5 may be filled in a gap between the
additional electric wire 3 and the groove 2 after the additional
electric wire 3 is inserted into the groove 2.
The electric wire 0 of the first element has the structure
described above. Since the grooves 2 are provided on the outer
surface of the conductive wire 1 along the longitudinal direction
I, the surface area of the conductive wire 1 increases and the
effective resistance and the electrical power loss decrease.
Therefore, the electric wire 0 can optimally conduct currents to or
in a motor in an automobile, a battery of a cellular phone, a
transformer for an organic electroluminescent device or a light
emission diode devices, and cordless inductive power supplies,
regardless of the size of the load.
Furthermore, in the first embodiment, the plural grooves 2 are
provided on the outer surface of the conductive wire 1 along the
longitudinal direction I. Since the groove 2 has an substantially
elliptic cross-sectional shape, the conductive wire 1 has a small
transverse cross-sectional area and is compact. However, the
surface area of the conductive wire 1 is enhanced and its effective
resistance is reduced. Hence, the electrical power loss by the
conductive wire 1 is reduced.
In order to supply a current to a high load such as a motor of an
automobile through the electric wire 0, a diameter of the
conductive wire 1 does not have to be large unlike litz wire.
Because the surface area of the conductive wire 1 is large, the
conductive wire 1 can transmit a high-frequency current and a
high-voltage large current stably without being large-diametered.
Since the diameter .PHI. of the conductive wire 1 does not have to
become large, the motor can be compact and it contributes to reduce
the weight of an automobile.
In this embodiment, since the conductive wire 1 is made of a
conductive material containing copper, the effective resistance of
the conductive wire 1 is reduced and its electrical power loss is
reduced. Thus, the conductive wire 1 can transmit the
high-frequency current efficiently.
In this embodiment, since the conductive wire 1 is covered by the
insulator sheath 4 made of synthetic resin or rubber, the
conductive wire 1 is well electrically insulated.
By putting the additional electric wires 3 in the grooves 2,
characteristics of the electric wire 0 is modified. When it is
necessary to use cords, plugs and terminals specified by auto
manufacturers to charge batteries of cars, by using the electric
wire 0, it is possible to make the current capacities and supplied
currents constant and to make the charging time constant.
Therefore, by using the electric wire 0, it is not necessary to
prepare several kinds of chargers. The electric wire 0 can provide
the same advantage for charging batteries of cellular phones when
plug cord terminals and chargers are specified by the
manufacturers.
Furthermore, by inserting the additional electric wires 3 into the
grooves 2, the total surface area of the electric wire 0 can be
increased. Therefore, the effective resistance of the electric wire
0 decreases and the electric power loss is also reduced. Therefore,
the electric wire 0 can optimally transmit high-frequency currents
or high-voltage large currents for motors of automobiles and
cellular phones, regardless of the size of the load.
In the embodiment 1, the additional electric wires 3 are put in all
the grooves 2. However, all the grooves 2 do not have to be filled
with the additional electric wires 3. The number of the additional
electric wires 3 put into the grooves 2 are adjusted based on
necessity. Since the electric wire 0 is easy to change the number
of the additional electric wires 3, it is easy to adjust the
electric properties of the electric wire 0 such as impedance and
inductance. Therefore, the electric properties of the electric wire
0 are easily set for cordless inductive power supply systems
provided by various manufacturers.
Since the additional electric wires 3 are covered by the insulator
sheaths 5 made of synthetic resin or rubber, the additional
electric wires 3 are well electrically insulated. Therefore, the
electric wire 0 has an excellent insulation characteristic as a
whole, and thus the electric wire 0 has a high safe-profile.
<First Modification Example> and <Second Modification
Example>
FIGS. 3 and 4 show a first modification example of the first
embodiment. In the first modification example, one groove 2 is
provided on an outer surface of the conductive wire 1, whose
cross-sectional shape is substantially circular, along the
longitudinal direction I. One additional electric wire 3 is
inserted into the groove 2. FIGS. 5 and 6 show a second
modification example of the first embodiment. In the second
modification example, two grooves 2 are provided on an outer
surface of the conductive wire 1 along the longitudinal direction I
so that both are positioned as bilaterally symmetric. Two
additional electric wires 3 are inserted into the grooves 2.
Even in these modification examples, the surface area of the
conductive wire 1 is enhanced. Thus, even though its
cross-sectional area is small and the conductive wire 1 is compact,
its effective resistance and its electrical power loss are reduced.
Therefore, the electric wire 0 can optimally transmit
high-frequency currents or high-voltage large currents for motors
of automobiles and cellular phones, regardless of the size of the
load. Furthermore, the electric wire 0 can conduct high-frequency
and high-voltage current stably without making the wire diameter
.PHI. large unlike the litz wire. Therefore, the electric power
consumption of the motor can be reduced and the size of the motor
can be made smaller. Thus, it prevents an automobile from being
heavier. When it is necessary to use cords, plugs and terminals
specified by auto manufacturers to charge batteries of cars, by
using the electric wire 0, it is possible to make the current
capacities and supplied currents constant and to make the charging
time constant. Therefore, by using the electric wire 0, it is not
necessary to prepare several kinds of chargers. The electric wire 0
can provide the same advantage for charging batteries of cellular
phones when plug cord terminals and chargers are specified by the
manufacturers.
<Second Embodiment>
FIG. 7 shows a second embodiment of the present invention. In the
second embodiment, a cross-sectional shape of the conductive wire 1
is substantially square. And, a transverse cross-sectional shape of
the groove 2 is substantially half ellipse. FIG. 8 shows a first
modification example of the second embodiment. In the first
modification example, a cross-sectional shape of the conductive
wire 1 is substantially square. Furthermore, a transverse
cross-sectional shape of the groove 2 is substantially square.
Likewise, a transverse cross-sectional shape of the additional
electric wire 3 is also substantially square. If the transverse
cross-sectional shape of the additional electric wire 3 is
quadrilateral, it is easier to make the outer surface of the
electric wire 0 flat after the additional electric wire 3 is
inserted into the groove 2. In this respect, it is desirable that
the height of the additional electric wire 3 is the almost same as
the depth of the groove 2. In addition, it is desirable that the
width of the additional electric wire 3 is almost the same as the
width of the groove 2. This arrangement more efficiently prevents
the additional electric wire 3 from coming off from the groove 2.
In this embodiment, an angle ".alpha." at a junction formed by a
top end of the groove 2 and an end of the outer surface of the
conductive wire 1 is substantially 90.degree.. This angle still
makes it harder for the additional electric wires 3 to come off
from the grooves 2. In the first modification example, an angle
".beta." at a junction formed by a side wall of the groove 2 and a
bottom surface of the groove 2 is also substantially 90.degree..
This angle has a good balance between easily inserting the
additional electric wire 3 into the groove 2 and between preventing
the additional electric wire 3 from coming off from the groove 2.
As shown in FIG. 8, in the first modification example, a width W of
the outer surface of the conductive wire 1 between the grooves 2 is
smaller than a width D of the grooves 2. A conductive wire 1, whose
cross-sectional shape is rectangular, can be produced for example
by referring Japan patent JP 3523561 and JP 3390746.
In the second embodiment, since the conductive wire 1 has an
substantially square shape, a larger number of the grooves 2 can be
formed on the outer surface of the conductive wire 1 and hence a
larger number of the additional electric wires 3 can be put on the
electric wire 0. Therefore, the electric wire 0 can conduct even a
larger current. Furthermore, since the electric wire 0 has a square
shape, it can increase a fill factor. In other words, the electric
wires 0 can fill a space more densely with reduced dead spaces.
Since the groove 2 has an substantially elliptic cross-sectional
shape, the surface area of the conductive wire 1 is enhanced with a
reduced cross-sectional area. The electrical characteristics of the
electric wire 0 are easily altered by adding the additional
electric wires 3 to the conductive wire 1. When it is necessary to
use cords, plugs and terminals specified by auto manufacturers to
charge batteries of cars, by using the electric wire 0, it is
possible to make the current capacities and supplied currents
constant and to make the charging time constant. Therefore, by
using the electric wire 0, it is not necessary to prepare several
kinds of chargers. The electric wire 0 can provide the same
advantage for charging batteries of cellular phones when plug cord
terminals and chargers are specified by the manufacturers.
FIG. 9 shows a second modification example of the second
embodiment. FIG. 10 shows a third modification example of the
second embodiment. FIG. 11 shows a fourth modification example of
the second embodiment. FIG. 12 shows a fifth modification example
of the second embodiment. The conductive wires 1 of the second to
fifth examples have rectangular transverse cross-sectional shapes.
In the second modification example shown in FIG. 9, one groove 2,
whose transverse cross-sectional shape is substantially half
ellipse, is provided on each short-edge side of the conductive wire
1 in cross-sectional view. And, an additional electric wire 3,
which has a circular transverse cross-sectional shape, is inserted
into each groove 2. In the third modification example shown in FIG.
10, three grooves 2, whose transverse cross-sectional shapes are
substantially half ellipse, are provided on one long-edge side of
the conductive wire 1 in cross-sectional view. And, an additional
electric wire 3, which has a circular transverse cross-sectional
shape, is inserted into each groove 2. In the fourth modification
example shown in FIG. 11, one groove 2, whose transverse
cross-sectional shape is substantially square, is provided on each
short-edge side of the conductive wire 1 in cross-sectional view.
And, an additional electric wire 3, which has a square transverse
cross-sectional shape, is inserted into each groove 2. In the fifth
modification example shown in FIG. 12, three grooves 2, whose
transverse cross-sectional shapes are substantially square, are
provided on one long-edge side of the conductive wire 1 in
cross-sectional view. And, an additional electric wire 3, which has
a square transverse cross-sectional shape, is inserted into each
groove 2.
The conductive wires 1 of the second to fifth examples have same
advantages as those of the first embodiment. Furthermore, the
conductive wires 1 of the second to fifth examples have larger fill
factor than the conductive wire 1 of the first embodiment. The
electric wires 0 shown in FIGS. 9 and 11 are particularly flexible
when bent toward the long edge of the electric wire 0 (right and
left direction in FIGS. 9 and 11). When the electric wire 0 shown
in FIGS. 10 and 12 are placed on an object so that the outer
surface of the conductive wire 1 on which the grooves 2 are formed
touches a surface of the object, the additional electric wires 3
becomes extremely stable so as not to come out from the grooves
2.
In the above embodiments, one additional electric wire 3 was
provided in one groove 2. In other embodiment, plural additional
electric wires 3 may be provided in one groove 2. Furthermore, such
additional electric wires 3 may be bundled. Such configuration
realizes high fill factor, and such electric wire 0 does not have
to be large-diametered to conduct high-frequency large current
unlike litz wire. Accordingly, such electric wire 0 can transmit a
high-frequency current and a high-voltage large current stably
without big electric power loss. Since the diameter 1 of the
conductive wire 1 does not have to become large, the motor can be
compact and it contributes to reduce the weight of an
automobile.
By putting the additional electric wires 3 in the grooves 2,
characteristics of such electric wire 0 can also be modified. When
it is necessary to use cords, plugs and terminals specified by auto
manufacturers to charge batteries of cars, by using the electric
wire 0, it is possible to make the current capacities and supplied
currents constant and to make the charging time constant.
Therefore, by using the electric wire 0, it is not necessary to
prepare several kinds of chargers. The electric wire 0 can provide
the same advantage for charging batteries of cellular phones when
plug cord terminals and chargers are specified by the
manufacturers.
In the above embodiments, the conductive wire 1 was made of copper
and the conductive member 3A was made of aluminum. In other
preferred embodiment, the conductive wire 1 can be made of silver
or aluminum and the conductive member 3A can be made of copper.
Such electric wire 0 also provides excellent conductivity of
high-frequency current. In addition, it is easy to adjust the
electric property of the electric wire 0. In other embodiment, the
conductive wire 1 can be formed from copper, aluminum or silver.
Also, the conductive member 3A can be formed from copper, aluminum
or silver. Furthermore, the conductive wire 1 and the conductive
member 3A may be made of other conductive materials.
In the above embodiments, cross-sectional shapes of the conductive
wires 1 were substantially circular, square or rectangular.
However, such shapes can be modified to be any shape including any
quadrilateral shape. Cross-sectional shapes of the grooves 2 in the
above embodiments were substantially half ecliptic or square.
However, such shapes can be modified to be any shape. Also,
cross-sectional shapes of the additional electric wires 3 can be
any shape other than circular or square. Furthermore, the numbers
of the grooves 2 and the additional electric wires 3 can be set any
numbers other than the above embodiments. Likewise, size or
diameter .PHI. of the conductive wire 1, the groove 2 and the
additional electric wire 3 can be modified upon actual use.
<Third Embodiment>
Here, the same explanations as in the previous embodiments are
omitted and the different things are mainly explained. FIG. 13
shows a third embodiment of the electric wire. As shown in this
figure, an electric wire 0 is composed of a conductive wire 1. The
conductive wire 1 has an approximately circular cross-sectional
shape. On the conductive wire 1, grooves 2 are formed along the
longitudinal direction of the conductive wire 1.
In the grooves 2, additional wires 3 are inserted. Thus, the
additional wires 3 are also provided in the conductive wire 1 along
the longitudinal direction of the electric wire 1. The additional
wire 3 is composed of a conductive member 3A. In this embodiment,
the conductive member 3A is directly in contact with the conductive
wire 1. Furthermore, in this embodiment, the conductive wire 1 and
the conductive member 3A are made of different materials. The
inventor discovered that if the additional wire 3 composed of a
different material from a material constituting the conductive wire
1 is embedded in the conductive wire 1, the electric wire 0
obtained has a property that the resistance of the electric wire 0
increases less gradually than traditional conductive wires. In
other word, an increase of the resistance of the conductive wire 0
is suppressed when the temperature of the conductive wire 0
increases. Therefore, the conductive wire 0 of this embodiment has
relatively lower resistance at a high temperature such as 100 to
200.degree. C. Thus, for example, in the case a motor is made with
the electric wire 0, after a temperature of the motor rises, the
motor can generate the same power with a lower voltage. In other
word, electric power consumption of the motor containing the
electric wire 0 is lower after the motor temperature rises.
Therefore, an electric vehicle equipped with a motor containing the
electric wire 0 can drive a longer distance than an electric
vehicle equipped with a traditional motor. Although the reason why
the increase of the resistance of the electric wire 0 is suppressed
is unknown, the inventor speculates that the electricity may
selectively flow at the best place in the electric wire 0 according
to the temperature.
To obtain the above advantage better, it is preferable that the
conductive wire 1 and the conductive member 3A are made of
materials containing copper or aluminum as long as both are made of
different materials. It is more preferable that the conductive wire
1 is made of a material containing aluminum and the conductive
member 3A is made of a material containing copper. The inventor
discovered that the resistance increase according to the
temperature rise is most effectively suppressed when the materials
of the conductive wire 1 and the conductive member 3A are this
combination.
In other embodiment, the conductive member 3A may be coated with a
conductive material different from the material constituting the
conductive member 3A. This can also decrease the resistance of the
electric wire 0. As a coating material, silver is suitable.
Silver-plated copper wire is particularly suitable as a conductive
member 3A.
As shown in FIG. 13, the conductive wire 1, in which the additional
wires 3 are embedded, is coated with an insulator sheath 4.
In order to use the electric wire 0 for a motor that becomes a high
temperature, it is optimal that the electric wire 0 fulfils
following property. First, a resistance of the electric wire 0 at
200.degree. C. is at most 1.42 times larger than a resistance of
the electric wire at 50.degree. C. Electric power consumption of a
motor containing such wire doesn't increase very much even after
the temperature of the motor becomes high. Although not limited,
the lower limit of the resistance may be set as 1.00 times larger.
Moreover, when resistances of the electric wire 0 is measured at
every 10.degree. C. between 50.degree. C. and 200.degree. C. and
then ratios of resistances at the measured temperature to the
resistance measured at 50.degree. C. are plotted so that an X axis
represents the temperature in .degree. C. and a Y axis represents
the ratio of resistance, it is desirable that a slope is at most
0.0028. Resistance of such electric wire 0 doesn't increase much
even after the temperature of the electric wire 0 has become high.
The slope is obtained for example by linear regression. Although
not limited, the lower limit of the slope may be set as 0.0000.
Furthermore, when resistances of the electric wire 0 is measured at
50.degree. C. and at a certain temperature between 60.degree. C.
and 200.degree. C. and an increase of a resistance of the electric
wire in fold is plotted against the temperature, it is more
preferable that the increase of the resistance of the electric wire
is inside of a hatched area shown in FIG. 25. Such electric wire 0
has a relatively lower resistance at a high temperature. Thus, such
electric wire 0 is very suitable for a motor or an electric device
whose temperature becomes high. The following equation represents
the hatched area shown in FIG. 25. R.ltoreq.0.0028t+0.86
Here, t is a temperature in .degree. C., at which a resistance of
the electric wire is measured. R is a ratio of a resistance at the
measured temperature to a resistance measured at 50.degree. C. It
is optimal that resistances of the electric wire 0 fulfill the
above equation when the resistances of the electric wire 0 are
measured at every 10.degree. C. between 50.degree. C. and
200.degree. C. Such electric wire 0 has lower resistance in a wide
range of temperature. Therefore, electric power consumptions of a
motor containing such electric wire 0 become more consistent in a
wide range of temperature. Although not limited, the equation may
be set as `1.ltoreq.R.ltoreq.0.0028t+0.86`. It is not to mention
that the above preferred value, slope, area and equation is not
only applied to the electric wire 0 in the present embodiments but
also any other electric wire.
<Modification Examples>
FIG. 14 shows a first modification example of the third embodiment.
As shown in this figure, a conductive wire 1, grooves 2 and
additional wires 3 have square cross-sectional shapes. Square
shapes are easy to reduce dead spaces and increase contact areas.
Since the grooves 2 and the additional wires 3 have square
cross-sectional shapes, dead spaces inside of the electric wire 1
is reduced and the contact areas between the additional wires 3 and
the conductive wire 1 are increased. Furthermore, when a coil is
wound with the electric wire 0 of the first modification example,
the electric wire 0 is packed more densely. FIG. 15 shows a second
modification example of the third embodiment. An electric wire 0 of
the second modification has a rectangular cross-sectional shape.
Grooves 2 and additional wires 3 are placed on one long edge of the
rectangular. FIG. 16 shows a third modification example of the
third embodiment. An electric wire 0 of the third modification has
a rectangular cross-sectional shape. A groove 2 and an additional
wire 3 is placed on each short edge of the rectangular so that the
two grooves 2 and the two additional wires 3 face to each other.
The advantages of these electric wires 0 are the same as described
before.
<Fourth Embodiment>
FIG. 14 shows a fourth embodiment of the electric wire. Here, the
same explanations as in the previous embodiments are omitted and
the different things are mainly explained. As shown in this figure,
an electric wire 0 is composed of a conductive wire 1. The
conductive wire 1 has an approximately square cross-sectional
shape. Each corner of the conductive wire 1 is cut out along the
longitudinal direction of the conductive wire 1. Thereby, on each
corner of the conductive wire 1, a groove (cutout) 7 is formed
along the longitudinal direction of the conductive wire 1. The
groove 7 has a square cross-sectional shape. In the groove 7, an
insulator 6 is placed. In other word, the groove 7 is filled with
the insulator 6. The insulator 6 also has a square cross-sectional
shape. The outer surface of the conductive wire 1 is coated with an
insulator sheath 4.
In the case of an electric wire that has a quadrilateral
cross-sectional shape, the inventor has discovered that the
electric discharge mainly occurs at the corner of the electric wire
when the electric wires are packed densely. Then, the inventor also
discovered that if insulators are placed at the corners of the
quadrilateral along the longitudinal direction of the electric
wire, the electric discharges are effectively prevented. Thus, the
electric wire 0 of this embodiment can prevent electric discharge
effectively even when the electric wire 0 is packed densely.
Therefore, when a coil is wound with the electric wire 0, a higher
voltage can be applied to this coil.
The discharge is well prevented even if a width W1 of the insulator
6 is less than one third of a width W2 of the conductive wire 1. If
the width W1 of the insulator 6 is set less than one third of a
width W2 of the conductive wire 1, an cross-sectional area of the
conductive wire 1 doesn't have to become so small that the
conductive wire 1 can still conduct a large current. Because of the
same reason, it is also preferable that a width W1 of the groove 7
is less than one third of a width W2 of the conductive wire 1.
It is preferable that the insulator 6 is made of a synthetic resin.
Synthetic resin provides an excellent insulation even if the
insulator 6 is thin. Furthermore, synthetic resin adheres well to
many metals.
The insulator sheath 4 may be made of the same or different
material from the material of the insulator 6. However, if the
insulator sheath 4 is made of the same material as the material of
the insulator 6, adhesiveness between the insulator 6 and the
insulator sheath 4 is improved.
FIG. 18 shows a part of a coil, in which the electric wire 0 is
wound with a best arrangement. This figure shows an enlarged
longitudinal cross-sectional view of the coil. More specifically,
the electric wire 0 is wound on an outer surface of a cylindrical
bobbin 11. After the coil 10 is sectioned in a longitudinal
direction of the cylindrical bobbin 11 and one end section is
magnified, the coil 10 is seen as FIG. 18. In this figure, a right
and left direction is the longitudinal direction of the cylindrical
bobbin 11. An upward direction is the circumferential direction of
the cylindrical bobbin 11. And, a downward direction is the center
direction of the cylindrical bobbin 11. For convenience, the right
and left direction of the FIG. 18 is called longitudinal direction
and the upward and downward direction is called circumferential
direction.
As shown in FIG. 18, the electric wire 0 is arranged so that the
electric wire 0 aligns on one line in both longitudinal and
circumferential directions. In other words, the electric wire 0 is
arranged so that it forms columns and rows in cross-sectional view.
This arrangement maximizes the density of the electric wire 0. As
shown in FIG. 18, each edge of the electric wire 0 is arranged to
be on one line in both longitudinal and circumferential directions.
Thus, one corner of one square is adjacent to one corner of next
three squares. In other word, four corners come together at a
junction of a grid formed by edges of the quadrilateral. In this
arrangement, the four insulators 6 become adjacent to one another
at the junction. This arrangement effectively prevents electric
discharge from the corner of the electric wire 0. Therefore, a
higher voltage can be applied to the coil 10. Thus, a larger power
can be generated if the coil 10 is used for a motor. In addition,
since the wire density is high, the coil 10 can be compact to
obtain a sufficient inductance or to generate a sufficient magnetic
force.
<Modification Examples>
FIG. 19 shows a first modification example of the fourth
embodiment. As shown in this figure, in an electric wire 0, an
insulator 6 that fills grooves 2 and an outer surface of the
conductive wire 1 is formed together. In other word, in this
modification example, the insulator sheath 4 is united into the
insulator 6. This arrangement makes the manufacturing process of
the electric wire 0 simpler.
FIG. 20 shows a second modification example of the fourth
embodiment. An electric wire 0 of the second modification has a
rectangular cross-sectional shape. When a conductive wire 1 has a
rectangular cross-sectional shape, width W2 of the conductive wire
1 may be based on a longer edge of the conductive wire 1.
FIG. 21 shows a third modification example of the fourth
embodiment. As shown in this figure, on each corner of the
conductive wire 1, a groove 7 is formed along the longitudinal
direction of the conductive wire 1. In addition, grooves 2 are
formed on the edges of the square. The position of these grooves 2
are approximately at the middle of the edge and distant from the
corner. In the groove 7, an insulator 6 is placed. In the groove 2,
an additional wire 3 is placed. Therefore, in the electric wire 0
of this modification example, an increase of the resistance is well
suppressed at high temperature. In addition, electric discharge
from the corner of the electric wire 0 is well prevented.
Therefore, at a high temperature not only a motor containing the
electric wire 0 of this modification example can suppress the
elevation of the electric power consumption effectively, but a high
voltage can also be applied to the motor. Accordingly, such motor
can generate a larger mechanical power with a relatively lower
electric power consumption at a high temperature.
FIG. 22 shows a fourth modification example of the fourth
embodiment. As shown in this figure, all the grooves 2 and 7,
additional wires 3 and insulators 6 have square cross-sectional
shapes. Like this example, if the grooves 2 and the grooves 7 have
a similar cross-sectional shape, a process of forming grooves
becomes simpler.
FIG. 23 shows a fifth modification example of the fourth
embodiment. An electric wire 0 of the fourth modification has a
rectangular cross-sectional shape. Grooves 7 and insulators 6 are
placed at all the corners of the rectangular. Grooves 2 and
additional wires 3 are placed on one long edge of the rectangular.
The advantages of electric wires 0 are a combination of the
advantages described before.
In the above embodiments, the quadrilateral shapes are rectangular
or square. In other embodiments, a quadrilateral shape may be a
quadrilateral shape that is not rectangular or square. In other
embodiment, the insulator 6 may be placed at one, two or three
corners of the quadrilateral. In other embodiment, a
cross-sectional shape of the groove 7 and the insulator 6 may be
other shape such as circular.
<Example>
An electric wire 0 as shown in FIG. 13 was made. As a conductive
wire 1, an aluminum (Al) wire (.PHI.2 mm) was prepared. And, as
additional wires 3, copper (Cu) wires (.PHI.0.2 mm) were prepared.
On the aluminum wire, four grooves 2 were formed by a blade. Then,
the copper wires were put into the groove 2.
Then, the temperature of the electric wire 0 was slowly raised.
And, resistances of the electric wire 0 were measured between
50.degree. C. and 200.degree. C. at every 10.degree. C., applying a
direct current (DC). Then, ratios of the resistances at the
measured temperature to the resistance at 50.degree. C. were
calculated. The result is shown in FIG. 24.
As a comparison, resistances of an aluminum wire (.PHI.2 mm) and a
copper wire (.PHI.2 mm) were measured in the same way. And, ratios
of the resistances at the measured temperature to the resistance at
50.degree. C. were also calculated. The results are also shown in
FIG. 24.
As shown in this figure, the resistance of the aluminum wire, in
which the copper wires were embedded, didn't increase as much as
those of the aluminum wire and the copper wire as the temperature
of the wire rose. Therefore, it is expected that a motor containing
the electric wire 0 of this example will generate the same power
with a lower voltage than motors containing the aluminum wire or
the copper wire at a high temperature such as 100 or 200.degree.
C.
* * * * *