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BACKGROUND OF THE INVENTION
The present invention relates to a direct current motor provided with a
plurality of armature windings disposed around a disc-shaped or
cylindrical coreless armature.
Conventionally, a number of motors of the type with an armature core having
a plurality of armature windings formed in a lap winding or wave winding
manner are widely used. However, when the conventional armature windings
are employed in the coreless type motor, various shortcomings are
encountered as will be explained by referring to FIGS. 1 and 2. FIGS. 1
and 2 are expanded views of armature windings in the case where
conventional armature winding formed in a wave winding manner are employed
in a coreless motor. More specifically, FIG. 1 is an expanded view of a
wave winding armature comprising five armature coils, provided with a
field magnet with six magnetic poles. The filed magnet 1 has magnetic
poles 1-1, 1-2, . . . , and 1-6, magnetized alternately to N and S with 60
degree angular intervals. A commutator 3 comprises commutator segments
3-1, 3-2, 3-3, 3-4, and 3-5, with 72 degree angular intervals (6/5 the
magnetic pole width). An armature 2 is a cross-connected normal winding,
with the angular intervals of the electrically conductor portion
contributing to the generation of torque in each armature coil set equal
to the magnetic pole width. Armature coils 2-1, 2-2, 2-3, 2-4 and 2-5 are
each disposed with an equal pitch of an angular interval of 72 degrees
(6/5 the magnetic pole width), without being superimposed on each other.
Each armature coil is subjected to wave winding connection. The connecting
portions of the armature coils 2-1 and 2-3, the armature coils 2-3 and
2-5, of the armature coils 2-5 and 2-2, of the armature coils 2-2 and 2-4,
and of the armature coils 2-4 and 2-1 are respectively connected to
commutator segments 3-2, 3-4, 3-1, 3-3 and 3-5. To brushes 4-1 and 4-2 is
supplied power from D.C. power source positive and negative poles 5-1 and
5-2, respectively. The brushes 4-1 and 4-2 are disposed with 180 degree
angular intervals (3/1 the magnetic pole width). In the configuration as
shown in FIG. 1, electric current flows in the direction of the arrow, and
torque is generated in each armature coil, so that the armature 2 and the
commutator 3 are respectively rotated in the directions of the arrows A
and B and work as commutator motor. In the example as shown in FIG. 1, the
number of the armature coils is so small that the switching of armature
current is performed 10 times per revolution (except the singular point)
and therefore good commutating characteristics cannot be obtained. Due to
the poor commutating characteristics, reverse torque is generated and the
operation efficiency and the starting torque are reduced. Furthermore,
since the number of armature coils present between the positive pole and
the negative poles of the D.C. power source is extremely small, this
cannot be used as direct current motor for high voltage. Furthermore,
sparking frequently takes place and short-circuit troubles are apt to
occur. As a result, the life of the motor is shortened. In order to
improve on the above-mentioned shortcomings, it has been proposed to
construct the armature coils in multiple layers. Referring to FIG. 2, this
will now be explained. FIG. 2 is an expanded view of a wave winding
armature comprising 15 armature coils, provided with a field magnet with
six magnetic poles. The field magnet 1 is exactly the same as that
explained in FIG. 1. A commutator 7 comprises commutator segments 7-1,
7-2, . . . , 7-15, with 24 degree angular intervals (2/5 the magnetic pole
width). An armature 6 is constructed of a cross-connected normal
triple-superimposed wave winding coil, in which the angular intervals of
the conductor portions thereof contributing to the generation of torque in
each armature coil are equal to the magnetic pole width. The armature
coils 6-1, 6-2, . . . , 6-15 are arranged, superimposing on each other, in
multiple layers, with an equal pitch of 24-degree angular intervals (2/5
the magnetic pole width). Each armature coil is subjected to wave winding
connection. The respective connecting portions of the armature coils 6-1
and 6-7, of the armature coils 6-7 and 6-13, of the armature coils 6-13
and 6-4, of the armature coils 6-4 and 6-10, and of the armature coils
6-10 and 6-1 are connected to commutator segments 7-4, 7-10, 7-1, 7-7 and
7-13. The respective connecting portions of the armature coils 6-2 and
6-8, of the armature coils 6-8 and 6-14, of the armature coils 6-14 and
6-5, of the armature coils 6-5 and 6-11, and of the armature coils 6-11
and 6-2 are connected to commutator segments 7-5, 7-11, 7-2, 7-8 and 7-14.
The respective connecting portions of the armature coils 6-3 and 6-9, of
the armature coils 6-9 and 6-15, of the armature coils 6-15 and 6-6, of
the armature coils 6-6 and 6-12, and of the armature coils 6-12 and 6-3
are connected to commutator segments 7-6, 7-12, 7-3, 7-9 and 7-15. As
mentioned previously, since the armature 6 is of the cross-connected
normal triple wave winding type, there are disposed three pairs of
brushes. A positive pole 5-1 and a negative pole 5-2 of DC power source
respectively supply power to the brushes 4-1 and 4-2. A positive pole 5-3
and a negative pole 5-4 of DC power source respectively supply power to
the brushes 4-3 and 4-4. A positive pole 5-5 and a negative pole 5-6 of DC
power source respectively supply power to the brushes 4-5 and 4-6. The
angular intervals of those brushes are 60 degrees (the magnetic pole
width). In the configuration shown in FIG. 2, electric current flows in
the direction of the arrow and torque is generated in each armature coil,
so that the armature 6 and the commutator 7 respectively rotate in the
directions of the arrows A and B and constitute a commutator motor. In the
commutator motor shown in FIG. 2, the armature coils are superimposed in
multiple layers and, therefore, the armature is thick. That thickness of
the armature significantly reduces the effective magnetic field of the
field magnet which passes through the armature. As a result, the motor
efficiency and starting torque are decreased. In order to eliminate those
shortcomings, the prior art effort has been directed to decreasing the
thickness of the conductor portions contributing to the generation of
torque. However, this process for decreasing the thickness of the
conductor portions is performed by press molding, and accordingly is often
accompanied by such defects as breaking and short-circuiting of the
armature coils. Further, since the phase relationship between the armature
coils cannot be positively held in the desired state at the time the coils
are arranged, correct phase relationship between the windings is liable to
be distorted. Accordingly, such prior art DC motors are costly and cannot
be mass produced.
Another prior art technique used for conventional cylindrical coreless DC
motors, for avoiding superimposition of the opposite edge portions of the
armature coils on each other, requires that the insulated wire be wound in
alignment, turn by turn, alternately at an angle of about 180 degrees, so
that a cylindrical armature is formed, with the entire width of winding,
or part thereof slanting with respect to the rotating axis. This
technique, however, also is costly and cannot be used for mass-production.
Further, in Japanese Patent Publication Sho 44-4450, there is disclosed a
DC motor having armature coils with .+-.1 magnetic pole for a field magnet
with 4 or more magnetic poles, and commutator segments, the number of
which is two times the number of the armature coils.
In the case where a field magnet with 4 magnetic poles is employed, the
motor efficiency and the starting torque are high. However, in the case
where a field magnet with 6 or more magnetic poles is employed and the
number of commutator segments is two times the number of the armature
coils, reverse torque is generated and, accordingly, the motor efficiency
and the starting torque are significantly decreased.
SUMMARY OF THE INVENTION
The above-described drawbacks in the prior art motors have been
successfully eliminated by the present invention.
A primary object of the present invention is to provide a DC motor with
high efficiency, which is simplified in structure, suitable for mass
production and inexpensive, and from which the above-described
conventional shortcomings are eliminated.
Another object of the present invention is to provide a DC motor of the
type described above, with the commutator thereof reduced in thickness,
and with the commutating characteristics thereof improved, capable of
attaining high torque and high motor efficiency.
In order to attain these objects, the present invention provides a DC motor
provided with m(2n.+-.1) armature coils for a field magnet with 2mn
magnetic poles (where m is an integer of 1 or more and n is an integer of
3 or more), and with power supply control means capable of switching the
armature current 2mn(2n.+-.1) times per revolution of the amature.
These and other objects of the invention will become apparent from the
following description of embodiments thereof when taken together with the
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings,
FIG. 1 and FIG. 2 are expanded views of conventional field magnets and wave
winding armatures.
FIG. 3 is an explanatory view of the construction of a commutator motor
according to the present invention.
FIGS. 4, 5 and 6 are expanded views of examples of field magnets and
armatures for use in a commutator motor according to the present
invention.
FIG. 7(a) is an expanded view of the field magnets shown in FIGS. 4, 5 and
6.
FIGS. 7(b), 7(c) and 7(d) are respectively expanded views of the armatures
shown in FIG. 4, FIG. 5 and FIG. 6.
FIGS. 8, 9 and 10 are expanded views of examples of field magnets and
armatures for use in a commutator motor according to the present
invention.
FIG. 11(e) is an expanded view of the field magnets shown in FIGS. 8, 9 and
10.
FIGS. 11(b) and 11(c) are respectively expanded views of the armatures
shown in FIG. 9 and FIG. 10.
FIGS. 12, 13 and 14 are expanded views of examples of field magnets and
armatures for use in a commutator motor according to the present
invention.
FIG. 15(a) is an expanded view of the field magnets shown in FIGS. 12, 13
and 14.
FIGS. 15(b) and 15(c) are respectively expanded views of the armatures
shown in FIG. 13 and FIG. 14.
FIG. 16 is an explanatory view of a semiconductor motor according to the
present invention.
FIG. 17 is an expanded view of the field magnet and armature employed in
the semiconductor motor shown in FIG. 16.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 3 is a sectional view of a commutator motor with a disc-shaped
commutator. In the figure, a bearing 12 is fixed to a casing 10 made of
press-formed soft steel. Further, a casing 9 made of press-formed soft
steel is secured to the casing 10 by screws 18, forming a magnetic circuit
therebetween. A bearing 11 is fixed to the casing 9. A rotating shaft 8 is
supported by the bearings 11 and 12. One end of the rotating shaft 8 is in
pressure contact with the casing 10. A cylindrical field magnet 13, with
magnetic poles N and S thereof magnetized in the axial direction of the
rotating shaft 8, is secured to the casing 10. To the rotating shaft 8,
there are fixed an armature 14 and a commutator 15 serving as power supply
control means for the armature 14, which are molded integrally. The
armature 14 is located in a field air gap between the casing 9 and the
field magnet 13. Reference numeral 17 indicates a brush support for
supporting brushes 16 which are in contact with the commutator 15, which
serves as power supply control means.
Referring to FIGS. 4 to 15, embodiments of the above-described commutator
motor provided with a disc-shaped commutator, to which the present
invention is applied, will now be explained.
Referring to FIG. 4, there is shown an expanded view of an embodiment of a
DC motor comprising a field magnet with 6 (=2mn) magnetic poles, 5
(=m(2n-1)) armature coils and 15 (=mn(2n-1)) commutator segments, where
m=1 and n=3. In this embodiment, only the commutator segments are
increased in number in comparison with the example shown in FIG. 1, while
the number of the armature coils is decreased in number in comparison with
the example shown in FIG. 2. As shown in FIG. 7(a), a field magnet 19 is
provided with magnetic poles 19-1, 19-2, . . . , 19-6, magnetized
alternately to N and S with 60 degree angular intervals in the axial
direction of the rotating shaft. The field magnet 19 corresponds to the
field magnet 13 shown in FIG. 3. A commutator 21, which serves as power
supply control means for the armature, comprises commutator segments 21-1,
21-2, . . . , 21-15, with 24 degree angular intervals (2/5 the magnetic
pole width) 3 (=mn) commutator segments, which are separated by 120 degree
(=360/mn) angular intervals (2/1 the magnetic pole width), are each
electrically short-circuited by electrically conductive short-circuit
members. The communtator segments 21-1, 21-6 and 21-11 are short-circuited
with each other. Likewise, the communtator segments 21-2, 21-7 and 21-12
are short-circuited with each other; the communtator segments 21-3, 21-8
and 21-13 are short-circuited with each other; the communtator segments
21-4, 21-9 and 21-14 are short-circuited with each other; and the
communtator segments 21-5, 21-10 and 21-15 are short-circuited with each
other. The commutator 21 corresponds to the commutator 15 shown in FIG. 3.
In an armature 20, armature coils 20-1, 20-2, 20-3, 20-4 and 20-5 are
arranged as shown in FIG. 7(b) and those armature coils are integrally
molded. Each armature coil is arranged adjacent to each other, without
overlapping on each other, with an equal pitch of 72 degree angular
intervals (6/5 the magnetic pole width). The angular intervals of the
conductor portions (in the case of the armature coil 20-1, its conductor
portions are portions 20-1-a and 20-1-b ), which conductive portions
contribute to the generation of torque, are set at 60 degrees so as to be
equal to the magnetic pole width. This corresponds to the armature 14
shown in FIG. 3.
Referring back to FIG. 4, one end of the armature coil 20-1 is connected to
the commutator segment 21-2, and the other end of the armature coil 20-1
is connected to the commutator segment 21-3. Likewise, the opposite ends
of the armature coil 20-2 are each connected to the commutator segments
21-5 and 21-6; the opposite ends of the armature coil 20-3 are each
connected to the commutator segments 21-8 and 21-9; the opposite ends of
the armature coil 20-4 are each connected to the commutator segments 21-11
and 21-12; and the opposite ends of the armature coil 20-5 are each
connected to the commutator segments 21-14 and 21-15. This connection mode
is different from the wave winding connection mode or the lap winding
connection. However, its characteristics in terms of motor are exactly the
same as those of the other connection modes. This applies to other
embodiments according to the present invention, which will be described
later. Therefore, only one connection method will be explained. Reference
numerals 22-1 and 22-2 represent brushes which serves as electric power
supply control means. To the brushes 22-1 and 22-2 is power supplied from
a positive pole 23-1 and a negative pole 23-2 of DC power source. The
angular intervals of the brushes 22-1 and 22-2 are 180 degrees (3/1 the
magnetic pole width). However, 60 (=360/2mn) degree angular intervals
(equal to the magnetic pole width) or 300 degree angular intervals (5/1
the magnetic pole width) can be equivalently adopted.
Alternative construction is that electrically conductive members for
connecting the commutator segments to each other are omitted, and 2mn
brushes are arranged so as to slide on the commutator with an angle of
360/2mn degrees and the adjacent brushes are each connected to the
positive and negative poles of the DC power source so as to supply power
to the armature coils. In the present embodiment, the following
modification exhibits exactly the same characteristics as those of the
embodiment in which the aforementioned electrically conductive members are
employed and the brushes 22-3, 22-4, 22-5 and 22-6 are unnecessary: Of 6
(=2mn) brushes 23-1, 23-2, . . . , 23-6, the brushes which are positioned
with 60 (=360/2mn) degree angular interval are connected to the positive
pole and negative pole of the DC power source and are disposed so as to be
capable of sliding on the commutator 21 in such a manner that power is
supplied from the positive pole 23-1 of the DC power source to the brushes
23-1, 23-3 and 23-5, and from the negative pole 23-2 to the brushes 23-2,
23-4 and 23-6. This modification can be applied to other embodiments which
will be described hereinafter.
In the configuration as shown in FIG. 4, electric current flows in the
direction of the arrow and torque is generated in each armature coil, so
that the armature 20 and the commutator 21 are respectively rotated in the
directions of the arrows A and B. The switching of armature current is
performed 30 (=2mn(2n-1)) times per revolution of the armature 20, and
torque is successively generated. Thus, the armature 20 and the commutator
21 work as commutator motor.
In the case of the commutator motor, the abovementioned number of the
switching of armature current is the number when the angular intervals of
the brushes are extremely small. This case does not necessarily correspond
to the embodiment shown in FIG. 4. The point where the brushes come into
contact with two commutator segments is referred to as singular point. The
switching point does not include that singular point. The definitions of
the singular point and the switching point apply to other embodiments
which will be explained hereinafter.
Referring to FIGS. 5 and 6, there is shown an expanded view of an
embodiment of a DC motor according to the present invention, comprising a
field magnet with 6 (=2mn) magnetic poles, 7 (=m(2n+1)) armature coils and
21 (=mn(2n+1)) commutator segments, where m=1 and n=3. The field magnet 19
is the same as that shown in FIG. 4. A commutator 25 comprises commutator
segments 25-1, 25-2, . . . , 25-21, with about 17.1 degree angular
interval (2/7 the magnetic pole width). 3 (=mn) commutator segments, which
are separated by 120 degree (=360/mn) angular intervals (2/1 the magnetic
pole width), are each electrically short-circuited by electrically
conductive short-circuit members. Specifically, the commutator segments
25-1, 25-8 and 25-15 are short-circuited with each other. Likewise, the
commutator segments 25-2, 25-9 and 25-16 are short-circuited with each
other; the commutator segments 25-3, 25-10 and 25-17 are short-circuited
with each other; the commutator segments 25-4, 25-11 and 25-18 are
short-circuited with each other; the commutator segments 25-5, 25-12 and
25-19 are short-circuited with each other; the commutator segments 25-6,
25-13 and 25-20 are short-circuited with each other; and the commutator
segments 25-7, 25-14 and 25-21 are short-circuited with each other. The
commutator 25 corresponds to the commutator 15 shown in FIG. 3. In an
armature 24 shown in FIG. 5, armature coils 24-1, 24-2, . . . , and 24-7
are arranged as shown in FIG. 7(c) and those armature coils are integrally
molded. Each armature coil is arranged adjacent to each other, without
overlapping on each other, with an equal pitch of about 51.4 degree
angular intervals (6/7 the magnetic pole width). In this arrangement, the
angular intervals of the conductor portions (in the case of the armature
coil 24-1, its conductor portions are portions 24-1-a and 24-1-b ), which
conductive portions contribute to the generation of torque, are slightly
smaller than the magnetic pole width as shown in FIG. 5. Due to the
smaller angular intervals, this motor has a shortcoming that reverse
torque is generated. This shortcoming, however, can be eliminated by
conventional countermeasures, such as by (i) making the magnetic pole
width substantially equal to the angular intervals of the conductor
portions contributing to generation of torque in each armature coil or by
(ii) increasing the angular intervals of the brushes. This countermeasure
can be applied to other embodiments which will be described later. An
armature 26 shown in FIG. 6 comprises armature coils 26-1, 26-2, . . . ,
26-7, which are arranged as shown in FIG. 7(d) and are molded integrally.
Each armature coil is arranged with an equal pitch of about 51.4 degrees
(6/7 the magnetic pole width), partly overlapping on each other. In this
arrangement, the angular intervals of the conductor portions (in the case
of the armature coil 26-1, its conductor portions are portions 26-1-a and
26-1-b), which conductor portions contribute to the generation of torque
in each armature coil, are 60 degrees, which is equal to the magnetic pole
width. The armatures 24 and 26 correspond to the armature 14 shown in FIG.
3.
Referring back to FIGS. 5 and 6, one end of each of the armature coils 24-1
and 26-1 is connected to the commutator segment 25-2, and the other end of
each of the armature coils 24-1 and 26-1 is connected to the commutator
segment 25-3. Likewise, the opposite ends of the armature coils 24-2 and
26-2 are respectively connected to the commutator segments 25-5 and 25-6;
the opposite ends of the armature coils 24-3 and 26-3 are respectively
connected to the commutator segments 25-8 and 25-9; the opposite ends of
the armature coils 25-4 and 26-4 are respectively connected to the
commutator segments 25-11 and 25-12; the opposite ends of the armature
coils 24-5 and 26-5 are respectively connected to the commutator segments
25-14 and 25-15; the opposite ends of the armature coils 24-6 and 26-6 are
respectively connected to the commutator segments 25-17 and 25-18; and the
opposite ends of the armature coils 24-7 and 26-7 are respectively
connected to the commutator segments 25-20 and 25-21.
The angular intervals and others of the brushes 22-1 and 22-2 are the same
as those explained by referring to FIG. 4. n+
In the configuration as shown in FIGS. 5 and 6, electric current flows in
the direction of the arrow and torque is generated in each armature coil,
so that the armatures 24 and 26 and the commutator 25 are respectively
rotated in the directions of the arrows A and B. The switching of armature
current is performed 42 (=2mn(2n=1)) times (except the singular point) per
revolution, and torque is successively generated. Thus, the armatures 24
and 26 and the commutator 25 work as commutator motor.
Referring to FIG. 8, there is shown an expanded view of an embodiment of a
DC motor according to the present invention, comprising a field magnet
with 8 (=2mn) magnetic poles, 7 (=m(2n-1)) armature coils and 28
(=mn(2n-1)) commutator segments, where m=1 and n=4. As shown in FIG.
11(a), a field magnet 27 is provided with magnetic poles 27-1, 27-2, . . .
, and 27-8, magnetized alternately to N and S with 45 degree angular
intervals in the axial direction of the rotating shaft. The field magnet
27 corresponds to the field magnet 13 shown in FIG. 3. A commutator 29
comprises commutator segments 29-1, 29-2, . . . , and 29-28 arranged with
about 12.9 degree angular intervals (2/7 the magnetic pole width). 4 (=mn)
commutator segments, which are separated by 90 degree (=360/mn) angular
intervals (2/1 the magnetic pole width), are each electrically
short-circuited by electrically conductive short-circuit members.
Specifically, the commutator segments 29-1, 29-8, 29-15 and 29-22 are
short-circuited with each other. Likewise, the commutator segments 29-2,
29-9, 29-16 and 29-23 are short-circuited with each other; the commutator
segments 29-3, 29-10, 29-17 and 29-24 are short-circuited with each other;
the commutator segments 29-4, 29-11, 29-18 and 29-25 are short-circuited
with each other; the commutator segments 29-5, 29-12, 29-19, and 29-26 are
short-circuited with each other; the commutator segments 29-6, 29-13,
29-20, and 29-27 are short-circuited with each other; and the commutator
segments 29-7, 29-14, 29-21 and 29-28 are short-circuited with each other.
The commutator 29 corresponds to the commutator 15 shown in FIG. 3. In an
armature 28, armature coils 28-1, 28-2, . . . , and 28-7 are arranged with
exactly the same angular intervals as explained by referring to FIG. 7(c)
and those armature coils are integrally molded. Each armature coil is
arranged adjacent to each other, without overlapping on each other, with
an equal pitch of about 51.4 degree angular intervals (8/7 the magnetic
pole width). In this arrangement, the angular intervals of the conductor
portions (in the case of the armature coil 28-1, its conductor portions
are portions 28-1-a and 28-1-b), which conductor portions contribute to
the generation of torque in each armature coil, are slightly smaller than
the magnetic pole width as shown in FIG. 8. One end of the armature coil
28-1 is connected to the commutator segment 29-2, and the other end of the
armature coil 28-1 is connected to the commutator segment 29-3. Likewise,
the opposite ends of the armature coil 28-2 are each connected to the
commutator segments 29-6 and 29-7; the opposite ends of the armature coil
28-3 are each connected to the commutator segments 29-10 and 29-11; the
opposite ends of the armature coil 28-4 are each connected to the
commutator segments 29-14 and 29-15; the opposite ends of the armature
coil 28-5 are each connected to the commutator segments 29-18 and 29-19;
the opposite ends of the armature coil 28-6 are each connected to the
commutator segments 29-22 and 29-23; and the opposite ends of the armature
coil 28-7 are each connected to the commutator segments 29-26 and 29-27.
Reference numerals 22-1 and 22-2 represent brushes, to which power is
supplied from a positive pole 23-1 and a negative pole 23-2 of DC power
source, respectively. The angular intervals of the brushes 22-1 and 22-2
are 135 degrees (3/1 the magnetic pole width). However, 45 (=360/2mn)
degree angular intervals (equal to the magnetic pole width), 225 degree
angular intervals (5/1 the magnetic pole width) or 315 degree angular
intervals (7/1 the magnetic pole width) can be equivalently adopted.
In the configuration as shown in FIG. 8, electric current flows in the
direction of the arrow, and torque is generated in each armature coil, so
that the armature 28 and the commutator 29 are respectively rotated in the
directions of the arrows A and B. The switching of armature current is
performed 56 (=2mn(2n-1)) times (except the singular point) per
revolution, so that torque is successively generated. Thus, the armature
28 and the commutator 29 work as commutator motor.
Referring to FIGS. 9 and 10, there is shown an expanded view of an
embodiment of a DC motor according to the present invention, comprising a
field magnet with 8 (=2mn) magnetic poles, 9 (=m(2n+1)) armature coils and
36 (=mn(2n+1)) commutator segments, where m=1 and n=4. The field magnet 27
is the same as that shown in FIG. 8. A commutator 31 comprises commutator
segments 31-1, 31-2, . . . , and 31-36 arranged with 10 degree angular
intervals (2/9 the magnetic width). 4 (=mn) commutator segments, which are
separated by 90 degree (=360/mn) angular intervals (2/1 the magnetic pole
width), are each electrically short-circuited by electrically conductive
short-circuit members. Specifically, the commutator segments 31-1, 31-10,
31-19 and 31-28 are short-circuited with each other. Likewise, the
commutator segments 31-2, 31-11, 31-20 and 31-29 are short-circuited with
each other; the commutator segments 31-3, 31-12, 31-21 and 31-30 are
short-circuited with each other; the commutator segments 31-4, 31-13,
31-22 and 31-31 are short-circuited with each other; the commutator
segments 31-5, 31-14, 31-23, and 31-32 are short-circuited with each
other; the commutator segments 31-6, 31-15, 31-24, and 31-33 are
short-circuited with each other; the commutator segments 31-7, 31-16,
31-25 and 31-34 are short-circuited with each other; the commutator
segments 31-8, 31-17, 31-26, and 31-35 are short-circuited with each
other; and the commutator segments 31-9, 31-18, 31-27, and 31-36 are
short-circuited with each other. The commutator 31 corresponds to the
commutator 15 shown in FIG. 3. In an armature 30, armature coils 30-1,
30-2, . . . , and 30-9 are arranged as shown in FIG. 11(b) and those
armature coils are integrally molded. Each armature coil is arranged
adjacent to each other, without overlapping on each other, with an equal
pitch of 40 degree angular intervals (8/9 the magnetic pole width). In
this arrangement, the angular intervals of the conductor portions (in the
case of the armature coil 30-1, its conductor portions are portions 30-1-a
and 30-1-b), which conductor portions contribute to the generation of
torque in each armature coil, are slightly smaller than the magnetic pole
width as shown in FIGS. 9 and 10. An armature 32 shown in FIG. 10
comprises armature coils 32-1, 32-2, . . . , 32-9 which are arranged as
shown in FIG. 11(c) and are molded integrally. Each armature coil is
arranged with an equal pitch of 40 degrees (8/9 the magnetic pole width),
partly overlapping on each other. In this arrangement, the angular
intervals of the conductor portions (in the case of the armature coil
32-1, its conductor portions are portions 32-1-a and 32-1-b), which
conductor portions contribute to the generation of torque in each armature
coil, are 45 degrees, which is equal to the magnetic pole width. The
armatures 30 and 32 correspond to the armature 14 shown in FIG. 3.
Referring back to FIGS. 9 and 10, one end of each of the armature coils
30-1 and 32-1 is connected to the commutator segment 31-2, and the other
end of each of the armature coils 30-1 and 32-1 is connected to the
commutator segment 31-3. Likewise, the opposite ends of the armature coils
30-2 and 32-2 are respectively connected to the commutator segments 31-6
and 31-7; the opposite ends of the armature coils 30-3 and 32-3 are
respectively connected to the commutator segments 31-10 and 31-11; the
opposite ends of the armature coils 30-4 and 32-4 are respectively
connected to the commutator segments 31-14 and 31-15; the opposite ends of
the armature coils 30-5 and 32-5 are respectively connected to the
commutator segments 31-18 and 31-19; the opposite ends of the armature
coils 30-6 and 32-6 are respectively connected to the commutator segments
31-22 and 31-23; the opposite ends of the armature coils 30-7 and 32-7 are
respectively connected to the commutator segments 31-26 and 31-27; the
opposite ends of the armature coils 30-8 and 32-8 are respectively
connected to the commutator segments 31-30 and 31-31; and the opposite
ends of the armature coils 30-9 and 32-9 are respectively connected to the
commutator segments 31-34 and 31-35.
The angular intervals and others of the brushes 22-1 and 22-2 are the same
as those explained by referring to FIG. 8.
In the configuration as shown in FIGS. 9 and 10, electric current flows in
the direction of the arrow and torque is generated in each armature coil,
so that the armatures 30 and 32 and the commutator 31 are respectively
rotated in the directions of the arrows A and B. The switching of armature
current is performed 72 (=2mn(2n+1)) times (except the singular point) per
revolution, and torque is successively generated. Thus, the armatures 30
and 32 and the commutator 31 work as commutator motor.
Referring to FIG. 12, there is shown an expanded view of an embodiment of a
DC motor according to the present invention, comprising a field magnet
with 10 (=2mn) magnetic poles, 9 (=m(2n-1)) armature coils and 45
(=mn(2n-1)) commutator segments, where m=1 and n=5. As shown in FIG.
15(a), a field magnet 33 is provided with magnetic poles 33-1, 33-2, . . .
, and 33-10, magnetized alternately to N and S with 36 degree angular
intervals in the axial direction of the rotating shaft. The field magnet
33 corresponds to the field magnet 13 shown in FIG. 3.
A commutator 25 comprises commutator segments 35-1, 35-2, . . . , and 35-45
arranged with 8 degree angular intervals (2/9 the magnetic pole width). 5
(=mn) commutator segments, which are separated by 72 degree (=360/mn)
angular intervals (2/1 the magnetic pole width), are each electrically
short-circuited by electrically conductive short-circuit members.
Specifically, the commutator segments 35-1, 35-10, 35-19, 35-28 and 35-37
are short-circuited with each other. Likewise, the commutator segments
35-2, 35-11, 35-20, 35-29 and 35-38 are short-circuited with each other;
the commutator segments 35-3, 35-12, 35-21, 35-30 and 35-39 are
short-circuited with each other; the commutator segments 35-4, 35-13,
35-22, 35-31 and 35-40 are short-circuited with each other; the commutator
segments 35-5, 35-14, 35-23, 35-32 and 35-41 are short-circuited with each
other; the commutator segments 35-6, 35-15, 35-24, 35-33 and 35-42 are
short-circuited with each other; the commutator segments 35-7, 35-16,
35-25, 35-34 and 35-43 are short-circuited with each other; the commutator
segments 35-8, 35-17, 35-26, 35-35 and 35-44 are short-circuited with each
other; and the commutator segments 35-9, 35-18, 35-27, 35-36 and 35-45 are
short-circuited with each other. The commutator 35 corresponds to the
commutator 15 shown in FIG. 3. In an armature 34, armature coils 34-1,
34-2, . . . , and 34-9 are arranged with exactly the same angular
intervals as explained by referring to FIG. 11(b) and those armature coils
are integrally molded. Each armature coil is arranged adjacent to each
other, without overlapping on each other, with an equal pitch of 40 degree
angular intervals (10/9 the magnetic pole width). In this arrangement, the
angular intervals of the conductor portions (in the case of the armature
coil 34-1, its conductor portions are portions 34-1-a and 34-1-b), which
conductor portions contribute to the generation of torque in each armature
coil, are slightly smaller than the magnetic pole width as shown in FIG.
12. One end of the armature coil 34-1 is connected to the commutator
segment 35-3, and the other end of the armature coil 34-1 is connected to
the commutator segment 35-4. Likewise, the opposite ends of the armature
coil 34-2 are each connected to the commutator segments 35-8 and 35-9; the
opposite ends of the armature coil 34-3 are each connected to the
commutator segments 35-13 and 35-14; the opposite ends of the armature
coil 34-4 are each connected to the commutator segments 35-18 and 35-19;
the opposite ends of the armature coil 34-5 are each connected to the
commutator segments 35-23 and 35-24; the opposite ends of the armature
coil 34-6 are each connected to the commutator segments 35-28 and 35-29;
the opposite ends of the armature coil 34-7 are each connected to the
commutator segments 35-33 and 35-34; the opposite ends of the armature
coil 34-8 are each connected to the commutator segments 35-38 and 35-39;
and the opposite ends of the armature coil 34-9 are each connected to the
commutator segments 35-43 and 35-44.
Reference numerals 22-1 and 22-2 represent brushes, to which power is
supplied from a positive pole 23-1 and a negative pole 23-2 of DC power
source, respectively. The angular intervals of the brushes 22-1 and 22-2
are 180 degrees (5/1 the magnetic pole width). However, 36 (=360/2mn)
degree angular intervals (equal to the magnetic pole width), 108 degree
angular intervals (3/1 the magnetic pole width), 252 degree angular
intervals (7/1 the magnetic pole width) or 324 degree angular intervals
(9/1 the magnetic pole width) can be equivalently adopted.
In the configuration as shown in FIG. 12, electric current flows in the
direction of the arrow, and torque is generated in each armature coil, so
that the armature 34 and the commutator 35 are respectively rotated in the
directions of the arrows A and B. The switching of armature current is
performed 90 (=2mn(2n-1)) times (except the singular point) per
revolution, so that torque is successively generated. Thus, the armature
34 and the commutator 35 work as commutator motor.
Referring to FIGS. 13 and 14, there is shown an expanded view of an
embodiment of a DC motor according to the present invention, comprising a
field magnet with 10 (=2mn) magnetic poles, 11 (=m(2n+1)) armature coils
and 55 (=mn(2n+1)) commutator segments, where m=1 and n=5. The field
magnet 33 is the same as that shown in FIG. 12. A commutator 37 comprises
commutator segments 37-1, 37-2, . . . , and 37-55 arranged with about 6.5
degree angular interval (2/11 the magnetic pole width). 5 (=mn) commutator
segments, which are separated by 72 degree (=360/mn) angular intervals
(2/1 the magnetic pole width), are each electrically short-circuited by
electrically conductive short-circuit members. Specifically, the
commutator segments 37-1, 37-12, 37-23, 37-34 and 37-45 are
short-circuited with each other. Likewise, the commutator segments 37-2,
37-13, 37-24, 37-35 and 37-46 are short-circuited with each other; the
commutator segments 37-3, 37-14, 37-25, 37-36 and 37-47 are
short-circuited with each other; the commutator segments 37-4, 37-15,
37-26, 37-37 and 37-48 are short-circuited with each other; the commutator
segments 37-5, 37-16, 37-27, 37-38 and 37-49 are short-circuited with each
other; the commutator segments 37-6, 37-17, 37-28, 37-39 and 37-50 are
short-circuited with each other; the commutator segments 37-7, 37-18,
37-29, 37-40 and 37-51 are short-circuited with each other; the commutator
segments 37-8, 37-19, 37-30, 37-41 and 37-52 are short-circuited with each
other; the commutator segments 37-9, 37-20, 37-31, 37-42 and 37-53 are
short-circuited with each other; the commutator segments 37-10, 37-21,
37-32, 37-43 and 37-54 are short-circuited with each other; and the
commutator segments 37-11, 37-22, 37-33, 37-44 and 37-55 are
short-circuited with each other. The commutator 37 corresponds to the
commutator 15 shown in FIG. 3. In an armature 36, armature coils 36-1,
36-2, . . . , and 36-11 are arranged as shown in FIG. 15(b) and those
armature coils are integrally molded. Each armature coil is arranged
adjacent to each other, without overlapping on each other, with an equal
pitch of about 32.7 degree angular intervals (10/11 the magnetic pole
width). In this arrangement, the angular intervals of the conductor
portions (in the case of the armature coil 36-1, its conductor portions
are portions 36-1-a and 36-1-b), which conductor portions contribute to
the generation of torque in each armature coil, are slightly smaller than
the magnetic pole width as shown in FIGS. 13 and 14. An armature 38 shown
in FIG. 14 comprises armature coils 38-1, 38-2, . . . , and 38-11 which
are arranged as shown in FIG. 15(c) and are molded integrally. Each
armature coil is arranged with an equal pitch of about 32.7 degree (10/11
the magnetic pole width), partly overlapping on each other. In this
arrangement, the angular intervals of the cond | | |
