Electrical rotary machine

An electrical rotary machine or motor having one rotor on which a plurality of stages of pole teeth corrresponding in number to the number of phases are formed, with magnetic flux being supplied thereto through individual annular exciting coils corresponding in number to the number of the phases for rendering the motor to operate in polyphases.

The present invention relates to an electrical rotary machine and more 
particularly, to an improved electrical rotary machine having polyphase 
construction with only one rotor. 
Conventionally, there have been various types of two-phase electrical 
rotary machines, for example, those including two rotors fixed on a rotary 
shaft in a concentric relation therewith, and corresponding sets of 
stators and annular exciting coils arranged also in concentric relation to 
the rotors at suitable electrical angles either in simply parallel 
relation to each other or in symmetrically parallel relation to each 
other, or those having the annular exciting coils in common, most of which 
arrangements have been proposed by the present inventor and disclosed, for 
example, in Japanese Patent laid open Publications Nos. 50/114519 and 
50/114520. 
The conventional electrical rotary machines or motors of the above 
described type, although superior in output efficiency and frequency 
response with other merits of their own, still have such disadvantages 
that two rotors are inevitably required therefor, which arrangement makes 
it necessary in the assembling of the rotary machines to fix the rotors to 
the rotary shaft, with the angle of the pole teeth between the two rotors 
being maintained extremely accurately, thus not only requiring much time 
in the assembling process, but increasing the possibilities for producing 
defective products. Furthermore, employment of the two rotors tends to 
increase the thickness of the motors in an axial direction of the rotors, 
thus hampering reduction in size of such motors. 
Accordingly, an essential object of the present invention is to provide an 
electrical rotary machine having one rotor on which a plurality of stages 
of pole teeth corresponding in number to the number of the phases are 
formed, with magnetic flux being supplied thereto through individual 
annular exciting coils corresponding in number to the number of the phases 
for rendering the rotary machine to operate in polyphases. 
Another important object of the present invention is to provide an 
electrical rotary machine of the above described type which is accurate in 
functioning and simple in construction with consequent facilitation of 
assembling process thereof for reduction in manufacturing cost. 
A still further object of the present invention is to provide an electrical 
rotary machine of the above described type which is compact in size and 
whose concept is readily applicable to various types of motors, depending 
on the end uses. 
According to a preferred embodiment of the present invention, the 
electrical rotary machine or motor includes a rotary shaft, one rotor 
which has pole teeth formed thereon in a plurality of stages corresponding 
in number to the phases and which is fixed to said rotary shaft in a 
concentric relation therewith, a plurality of annular exciting coils 
corresponding in number to the phases and provided at one side of the 
rotor in position corresponding to the pole teeth at each stage of the 
rotor, a magnetic stator concentric with the rotary shaft and magnetized 
radially to provide north and south poles alternating at equal angular 
spacings which correspond to the pole teeth of each stage of the rotor, 
and member for causing magnetic flux from each of the annular exciting 
coils to form magnetic loops individually flowing through the pole teeth 
at each stage of the rotor, by which arrangement, construction of the 
motor, especially, of the rotor is much simplified, with consequent 
facilitation in the manufacturing process thereof. Furthermore, the motor 
can be made compact in size through employment of one rotor, with 
substantial elimination of disadvantages inherent in the conventional 
electrical rotary machines.

Referring to FIGS. 1 to 4, there is shown in FIG. 1 a two-phase electric 
motor M employing one rotor according to one embodiment of the present 
invention. The motor M includes a rotary shaft 2 rotatably supported by a 
first bearing 3 and a second bearing 4, and having a boss member 5 of a 
soft magnetic material fixed to the central portion thereof, to which boss 
member 5, a rotor 6 is secured in a concentric relation therewith. The 
rotor 6 is made of an annular iron piece of a soft magnetic material, and 
formed with an inner periphery and an outer periphery bent to extend along 
the shaft 2, while the same rotor 6 is fixed at the inner periphery 
thereof to the boss member 5 to form a rotor assembly, thus the rotor 6 
having a circular flat body portion 6.sub.1 which lies in a radial plane 
perpendicular to the axis of the shaft 2 and an extension 6.sub.2 
extending in a direction parallel to the axis of the rotary shaft 2 from 
the outer peripheral edge of the circular portion 6.sub.1 as shown in FIG. 
2. The flat body portion 6.sub.1 is provided with a plurality of slits or 
grooves 6a of high magnetic reluctance formed in L-shape and radially 
disposed reversing alternatingly in a circumferential direction to form 
pole teeth 6b and 6c, while the extension 6.sub.2 is also 
circumferentially divided into a plurality of pole teeth 6e and 6f at 
equal angular spacings by similar slits or grooves 6d corresponding in 
number to the grooves 6a in the circular body portion 6.sub.1 as in FIG. 
2. Bridge portions Ca and Cb, and Ca' and Cb' across the ends of the 
respective neighboring grooves 6a and 6d are formed sufficiently narrow to 
provide magnetic saturation for enabling possible short circuits of 
magnetic flux therethrough to be neglected i.e., to provide high magnetic 
reluctance between the adjacent pole teeth, while keeping sufficient 
mechanical strength for bridging the adjacent pole teeth 6b and 6c, and 
also 6e and 6f. Accordingly, the respective pole teeth 6b and 6c on the 
circular body portion 6.sub.1 of the rotor 6 are in the same electrical 
phasial positions or staggered by an electrical angle of 90.degree. with 
respect to the pole teeth 6e and 6f on the extension 6.sub.2 of the rotor 
6. The number of the pole teeth 6b and 6c is the same as that of the pole 
teeth 6e and 6f. It should be noted here that although the pole teeth 6b, 
6c, 6e and 6f are formed at equal angular spacings in FIG. 2, some of them 
may be omitted. Depending on necessity, one of the set of pole teeth 6b 
and 6c and the set of pole teeth 6e and 6f may be ordinary pole teeth 
which are not magnetized in opposite polarities simultaneously. 
Between a washer 8 and the first bearing 3, there is provided a first yoke 
7 of a soft magnetic material, to which yoke 7, a disk-shaped first casing 
member 9 of a similar soft magnetic material and a first annular exciting 
coil 10 are secured, while a cylindrical second yoke 11 of a soft magnetic 
material is fixed to the first casing member 9. A second casing member 12 
made of a soft magnetic material is fixed at its inner periphery to the 
second bearing 4, with an outer periphery of the casing member 12 being 
bent to extend in the axial direction of the rotary shaft 2 so as to fit 
around the first casing member 9. In the space defined by the second 
casing member 12, the first casing member 9 and the second yoke 11, there 
is disposed a second annular exciting coil 13, while in the space 
surrounded by the second casing member 12 and the rotor 6, a permanent 
magnet stator 14 made of a hard magnetic material such as barium ferrite, 
strontium ferrite, alnico or the like is fixedly mounted with the recess 
of the cup-shaped rotor 6 overlying the top and side thereof as shown in 
FIG. 1. 
The permanent magnet stator 14 of an annular shape has faces 14.sub.1 and 
14.sub.2 each magnetized to provide north and south poles alternating at 
equal angular spacings at positions confronting the pole teeth 6b and 6c 
and the pole teeth 6e and 6f, respectively. Each pole on the magnetized 
upper face 14.sub.1 is aligned with respective pole on the magnetized 
peripheral face 14.sub.2 in the radial direction and is magnetized in a 
polarity same as or opposite to the polarity of the aligned pole on the 
upper face 14.sub.2. The second yoke 11 is provided between the exciting 
coils 10 and 13 to form two separate alternating magnetic circuits by the 
exciting coils 10 and 13. The peripheral edge 14a of the magnet stator 14 
at the side of the second casing member 12 is bevelled as shown for 
reducing magnetic interference at the extension 6.sub.2 of the rotor 6. In 
the second bearing 4, a steel ball 15 rotatably supports one end of the 
rotary shaft 2, while an output gear 1 is secured to the other end of the 
shaft 2 extending through the first bearing 3. A bush 16 is fitted in an 
opening formed in the second casing member 12 in a position adjacent to 
the first casing member 9 for passing leads 17 and 18 from the first and 
second annular exciting coils 10 and 13 therethrough. 
The extension 6.sub.2 of the rotor 6 and accordingly the pole teeth 6e and 
6f may be formed in the same plane as the circular portion 6.sub.1 of the 
rotor 6. In this case, the permanent magnet stator 14 is magnetized at 
positions facing the pole teeth 6b and 6c and the pole teeth 6e and 6f, 
respectively and the annular exciting coils 10 and 13 are disposed 
concentrically with the rotary shaft 2 at positions facing the pole teeth 
6b and 6c and the pole teeth 6e and 6f, respectively, opposite to the 
magnetized faces 14.sub.1 and 14.sub.2 of the stator 14 with reference to 
the rotor 6. 
In the electric motor of the above described construction, when a 
commercial frequency voltage is applied to the first and second annular 
exciting coils 10 and 13 respectively, alternating magnetic flux is 
produced by electric current flowing therethrough. The magnetic flux 
developed by the first annular exciting coil 10 forms a magnetic circuit 
including the first casing member 9, the first yoke 7, the boss member 5 
of the rotor 6, the circular flat body portion 6.sub.1 of the rotor 6 and 
the second yoke 11, while the magnetic flux produced by the second annular 
exciting coil 13 also forms a magnetic circuit including the first casing 
member 9, the second yoke 11, the peripheral extension 6.sub.2 of the 
rotor 6 and the second casing member 12. Accordingly, in a given half 
cycle of the power supply voltage, if the magnetic flux arising from the 
first annular exciting coil 10 flows, for example, through the flat body 
portion 6.sub.1 of the rotor 6 towards the boss member 5, with the 
magnetic flux due to the second annular exciting coil 13 flowing, for 
example, through the extension 6.sub.2 of the rotor 6 toward the second 
casing member 12, the pole teeth 6b and 6c of the flat body portion 
6.sub.1 of the rotor 6 are simultaneously magnetized in north and south 
polarities, while the pole teeth 6e and 6f of the extension 6.sub.2 are 
also magnetized simultaneously in south and north polarities as shown in 
FIG. 2, thus the rotor 6 initiating rotation through magnetic interference 
between the magnetic poles formed in the rotor 6 and the magnetic poles of 
the magnet stator 14. 
The two-phase electric motor of the above described fundamental 
construction may be applied to a two-phase synchronous motor, a reversible 
motor and a pulse motor, the detailed construction for each of which 
motors will be described hereinbelow with reference to FIGS. 5(a) to 13. 
(1) Two-phase synchronous motor: The pole teeth 6b and 6c of the flat body 
portion 6.sub.1 and the pole teeth 6e and 6f of the extension 6.sub.2 of 
the rotor 6 are formed in relative positions where the electrical angle 
therebetween is kept at 0.degree., while the first and second annular 
coils 10 and 13 are connected in parallel with respect to the power source 
(FIG. 4). Since the areas of the pole teeth 6b and 6c of the rotor 6 are 
not the same as those of the pole teeth 6e and 6f, variable resistors 
R.sub.1 and R.sub.2 are connected in series to the exciting coils 10 and 
13 respectively for controlling the magnetic fields produced by the 
exciting coils 10 and 13, thereby to match the magnetic interferences 
between the pole teeth 6b and 6c and the magnetized face 14.sub.1 and 
between the pole teeth 6e and 6f and the magnetized face 14.sub.2 to each 
other. 
Referring to FIGS. 5(a) to 5(e), in a stationary position, the rotor 6 is 
located in such a position that the magnetic circuit from the respective 
north poles to the south poles on the upper face 14.sub.1 and the 
peripheral face 14.sub.2 of the magnet stator 14 contains a minimum 
magnetic reluctance, so that the pole teeth 6b and 6c, and 6e and 6f are 
positioned midway between adjacent north and south poles of the magnet 
stator 14 to stride over the latter as shown in FIG. 5(a). 
It should be noted here that since the rotor 6 is positioned over the 
magnet stator 14, with the upper flat face 14.sub.1 and the peripheral 
face 14.sub.2 of the magnet stator 14 facing the corresponding flat body 
portion 6.sub.1 and the peripheral extension 6.sub.2 of the rotor 6, the 
relation therebetween is shown in a simplified form in diagrams of FIGS. 
5(a) to 5(e), and that similar diagrams shown hereinbelow are simplified 
in the same manner. 
Upon application of commercial frequency voltages to the first exciting 
coil 10 and the second exciting coil 13, currents flowing therethrough are 
of the same phase, with the corresponding two magnetic circuits 
established thereby being exactly in the same electrical condition. In 
this instance, if the pole teeth 6b and 6e of the rotor 6 are magnetized 
in north polarity and the pole teeth 6c and 6f of the same rotor 6 are 
magnetized in south polarity, the pole teeth 6b and 6e are repelled by the 
north poles of the permanent magnet 14 and attracted by the adjacent south 
poles thereof, while the pole teeth 6c and 6f are repelled by the south 
poles of the permanent magnet 14 and attracted by the adjacent north poles 
thereof to run said rotor 6 in a direction of an arrow A. The pole teeth 
6b and 6e, and 6c and 6f advance to the respective positions as shown in 
FIG. 5(b) before the given half cycle of the power supply frequency has 
been over, gaining a moment of inertia. In the following half cycle, the 
pole teeth 6b and 6e assume a south polarity and the pole teeth 6c and 6f 
assume a north polarity as shown in FIG. 5(c) and advance to the position 
of FIG. 5(c) through strong magnetic interferences between the confronting 
magnetic faces. Likewise, said pole teeth 6b and 6e, and 6c and 6f advance 
to the positions of FIG. 5(d) and then to the positions of FIG. 5(e), 
making the rotation surely and positively synchronizing with the power 
supply frequency. 
In case the reversed polarities are induced in the pole teeth at the start, 
the rotor 6 run in the reverse direction. 
(2) Reversible synchronous motor: The pole teeth 6b and 6c of the circular 
flat body portion 6.sub.1 and the pole teeth 6e and 6f of the extension 
6.sub.2 of the rotor 6 are so formed that the respective pole teeth are 
staggered from each other by an electrical angle of 96.degree. to 
120.degree., while the first exciting coil 10 and the second exciting coil 
13 are connected as shown in FIG. 6. Stated illustratively, the exciting 
coils 10 and 13 are coupled in parallel with each other and connected to 
the A.C. power supply through a switch means SW and a capacitor C is 
connected between the exciting coils 10 and 13, with variable resistors R3 
and R4 being connected in series to the exciting coils 10 and 13 
respectively for similar purpose in the two-phase synchronous motor 
mentioned earlier. The waveforms of currents flowing through said exciting 
coils 10 and 13 are shown in FIG. 7, in which (I) represents a waveform of 
a current flowing through the first exciting coil 10, (II) a waveform of a 
current flowing through the second exciting coil 13 when the switch SW is 
in a position of a solid line and (III) a waveform of a current flowing 
through said second exciting coil 13 when the switch SW is switched to a 
position of a dotted line of FIG. 6, from which it is seen that the phase 
of the current flowing through the exciting coil to which the capacitor C 
is connected is leading. 
When the switch SW is in the position shown by the solid line in FIG. 6, 
the current of waveform (I) flows through the first exciting coil 10 and 
the current of waveform (II) flows through the second exciting coil 13 as 
mentioned above. In the instance of (I-O) in FIG. 7, the current flowing 
through the first exciting coil 10 is positive, with the pole teeth 6b and 
6c of the rotor 6 being magnetized, for example, in north and south 
polarities, respectively. On the other hand, the current flowing through 
the second exciting coil 13 is negative and a north and a south polarity 
are induced respectively in the pole teeth 6e and 6f on the peripheral 
face 6.sub.2 of the rotor 6 as shown in FIG. 8(a). 
In a rest position, the pole teeth 6b and 6c of the rotor 6 are positioned 
over the north and the south poles on the upper face 14.sub.1 of the 
permanent magnet 14, respectively and the pole teeth 6e and 6f of the 
rotor 6 are positioned midway between adjacent north and south poles on 
the peripheral face 14.sub.2 of the permanent magnet stator 14. Under this 
condition, a repelling force is exerted on the flat body portion 6.sub.1 
of the rotor 6. This repelling force, however, does not act to determine 
the rotational direction since the pole teeth 6b and 6c are positioned 
centrally over the poles of the permanent magnet 14. On the other hand, 
both of a repulsion force and an attraction force are exerted on the rotor 
6 because its pole teeth 6e and 6f rest approximately midway between the 
poles on the peripheral face 14.sub.2 of the magnet 14. Due to these 
forces exerted on said rotor 6, the rotor 6 starts to rotate in a 
direction of an arrow B and gains a moment of inertia. 
The pole teeth 6e and 6f of the rotor 6 then advance to positions crossing 
the south poles and the north poles on the peripheral face 14.sub.2 of the 
permanent magnet 14, respectively, until at a phasic position of (II-O) of 
FIG. 7, the current (II) flowing through the second exciting coil 13 has 
become positive, inverting the polarities of the pole teeth 6e and 6f on 
the extension 6.sub.2 of the rotor 6 to south and north, respectively as 
shown in FIG. 8(b). Said rotor 6, therefore, is subjected to repulsion 
between the peripheral face 14.sub.2 of the permanent magnet 14 and the 
pole teeth 6e or 6f. At this time, however, a maximum positive current 
still flows through the first exciting coil 10 and the pole teeth 6b and 
6c on the flat body portion 6.sub.1 of the rotor 6 are kept in a north and 
a south polarity stronger than those of the second exciting coil 13. 
Accordingly, the rotation is further made in the direction of arrow B due 
to the magnetic interference between the flat body portion 6.sub.1 of the 
rotor 6 and the upper face 14.sub.1 of the permanent magnet 14 as shown in 
FIG. 8(b). When the pole teeth 6e and 6f on the extension 6.sub.2 of the 
rotor 6 pass the center of the respective poles on the peripheral face 
14.sub.2 of the permanent magnet 14, they get repulsion force to afford 
the rotor assembly a large rotational torque in cooperation with the 
attracting force of the pole teeth 6b and 6c on flat body portion 6.sub.1 
of the rotor 6. At phasic positions of (I-1), (II-1) and (I-2), of FIG. 7 
also, the rotor assembly is brought into positions of FIGS. 8(c), 8(d) and 
8(e), respectively through analogous magnetic operation. Thus, the rotor 
assembly continues to run in the direction of arrow B through every 
inversion in the polarities of the pole teeth 6b and 6c or 6e and 6f of 
the rotor 6 depending upon the inversion in the polarities of the currents 
flowing through the first exciting coil 10 and the second exciting coil 
13. 
In case the switch SW is turned to the position of the dotted line, the 
current of waveform (III) of FIG. 7 flows through the second exciting coil 
13 as mentioned before. At the phasic position of (I-0) of FIG. 7, the 
current flowing through the first exciting coil 10 is being turned to be 
positive and the current flowing through the second exciting coil 13 is 
positive so that north and south poles are induced in the pole teeth 6b 
and 6c on the flat body portion 6.sub.1 of the rotor 6, respectively and 
south and north poles in the pole teeth 6e and 6f on the extension 6.sub.2 
of the rotor 6, respectively as shown in FIG. 9(a). 
As a result, the rotor 6 begins to rotate in a direction of an arrow C 
(opposite to the direction of FIG. 8) by the attraction between the 
extension 6.sub.2 of the rotor 6 and the peripheral face 14.sub.2 of the 
permanent magnet 14. When the pole teeth 6b and 6c of the rotor 6 are then 
brought, to any extent, into positions offset from the north poles and the 
south poles on the upper face 14.sub.1 of the permanent magnet stator 14, 
respectively, repulsion is exerted therebetween to act to continue the 
rotation in the direction of arrow C in cooperation with the above 
mentioned attraction, imparting a moment of inertia to the rotor 6. 
Likewise, the rotor 6 makes further rotation in a manner analogous with 
the case of FIG. 8 as shown in FIGS. 9(b ) to 9(e). Thus, the present 
reversible motor is capable of selectively reversing its rotation by 
operation of the switch means SW. 
(3) Pulse motor: The pole teeth 6b and 6c of the circular flat body portion 
6.sub.1 and the pole teeth 6e and 6f of the extension 6.sub.2 of the rotor 
6 are so arranged that an electrical angle between the respective pole 
teeth is 90.degree., while intermediate taps 10b and 13b are provided on 
the first exciting coil 10 and the second exciting coil 13, respectively 
to form substantially four exciting coils as shown in FIG. 10. Input 
signals to be applied across the taps of the first exciting coil 10 and 
the second exciting coil 13 are selected through a drive circuit 19, to 
which drive circuit 19, an electric power and a control signal are applied 
through terminals 20 and 21. Variable resistors R5 and R6 are inserted in 
the taps 10b and 13b for similar purpose as in the two-phase synchronous 
motor mentioned earlier. Said drive circuit 19 is adapted to produce 
exciting pulse signals to be applied to the first exciting coil 10 and the 
second exciting coil 13 as shown in FIG. 11 in response to the control 
signal applied through the terminals 21. In FIG. 11, (I) represents a 
waveform of a pulse voltage to be applied across the taps 10a and 10b of 
the first exciting coil 10, (II) a waveform of a pulse voltage to be 
applied across the taps 10b and 10c of the coil 10, (III) a waveform of a 
pulse voltage to be applied across the taps 13a and 13b of the second 
exciting coil 13 and (IV) a waveform of a pulse voltage to be applied 
across the taps 13b and 13c of the coil 13. Upon application of these 
pulse voltages to the first exciting coil 10 and the second exciting coil 
13, the pole teeth 6b and 6c and the pole teeth 6e and 6f of the rotor 6 
are magnetized as shown in Table I. Table I is based upon the case where 
positive pulse voltages are applied. Then, in case negative pulse voltages 
are applied, the polarities induced become reverse. 
Table I 
______________________________________ 
energization polarities induced 
conditions of in pole teeth 
exciting coils 
6b 6c 6e 6f 
______________________________________ 
10b - 10a + ON 
N S -- -- 
10b - 10c + ON 
S N -- -- 
13b - 13a + ON 
-- -- N S 
13b - 13c + ON 
-- -- S N 
______________________________________ 
In FIG. 11, operational regions are expressed on the abscissa and critical 
points in operation are represented by a, b, c, d -----. Said critical 
points form respective operational regions such as region a - b, region b 
- c, region c - d, region d - a' and so on. 
The operations of the exciting coils and the magnetized conditions of the 
pole teeth are summarized in the following based upon Table I. 
In region a - b (FIG. 11): at the point a, a positive pulse voltage starts 
to be applied across the taps 10b and 10a of the first exciting coil 10 to 
induce north and south poles in the pole teeth 6b and 6c on the flat body 
portion 6.sub.1 of the rotor 6, respectively while a positive pulse 
voltage is being applied across the taps 13b and 13c of the second 
exciting coil 13, magnetizing the pole teeth 6e and 6f on the peripheral 
face 6.sub.2 of the rotor 6 in south and north polarities, respectively 
until the point b. 
In region b - c: the first exciting coil 10 is kept energized across the 
taps 10b and 10a until the point c, while the second exciting coil 13 is 
newly applied across the taps 13b and 13a with a positive pulse voltage to 
induce north and south poles in the pole teeth 6e and 6f on the extension 
6.sub.2 of the rotor 6, respectively. 
In region c - d: a pulse voltage is newly applied across the taps 10b and 
10c of the first exciting coil 10 to magnetize the pole teeth 6b and 6c on 
the flat body portion 6.sub.1 of the rotor 6 in south and north poles, 
respectively while the second exciting coil 13 is kept energized across 
the taps 13b and 13a until the point d. 
In region d - a': the first exciting coil 10 are kept energized across the 
taps 10b and 10c until the point a' while the second coil 13 are newly 
applied across the taps 13b and 13c with a positive pulse voltage to 
magnetize the pole teeth 6e and 6f on the extension 6.sub.2 of the rotor 6 
in south and north polarities, respectively. 
Thus, through these operational regions two of the four exciting coils are 
in an energized condition and through repitition of the operation as 
mentioned above, the rotor 6 continue to run. These operations are further 
summarized in Table II. 
Table II 
______________________________________ 
conditions of polarities 
exciting coils induced in 
operational 
10b- 10b- 13b- 13b- pole teeth 
region 10a 10c 13a 13c 6b 6c 6e 6f 
______________________________________ 
a - b + - - + N S S N 
b - c + - + - N S N S 
c - d - + + - S N N S 
d - a' - + - + S N S N 
a' - b' + - - + N S S N 
b' - c' + - + - N S N S 
______________________________________ 
The rotational operation of the thus magnetized pole teeth 6b and 6c, and 
6e and 6f of the rotor 6 is explained hereunder referring to the operation 
diagram of FIGS. 12(a) to 12(e), the pulse voltage as shown in FIG. 11 and 
the magnetized condition of the pole teeth as shown in Table II. 
FIG. 12(a) shows a condition before the point a of FIG. 11 wherein the pole 
teeth 6b and 6c on the flat body portion 6.sub.1 of the rotor 6 are 
magnetized in south and north, respectively, while the pole teeth 6e and 
6f on the extension 6.sub.2 of the rotor 6 are magnetized in south and 
north, respectively. In this condition, the pole teeth 6b and 6c get a 
repulsion and an attraction force in the rightward direction as viewed in 
FIG. 12 and on the other hand, the pole teeth 6e and 6f of the rotor 6 
receive a repulsion and an attraction force in the leftward direction. 
Accordingly, the rotor 6 fixed to the boss member 5 are in a dynamically 
balanced position and can not move in either direction, keeping the rotary 
shaft 2 to stand still. 
In the region a - b of FIG. 11, a pulse voltage is applied across the taps 
10b and 10a of the first exciting coil 10 at the point a and a pulse 
voltage is still applied across the taps 13b and 13c of the second 
exciting coil 13. The pole teeth 6b and 6c on the flat body portion 
6.sub.1 of the rotor 6, then, change their polarities to those in the 
parentheses in FIG. 12(a). As a result, the flat body portion 6.sub.1 of 
the rotor 6 advances in the leftward direction through the attraction by 
the upper face 14.sub.1 of the permanent magnet 14, while the extension 
6.sub.2 of the rotor 6 rotates in the same direction due to the replusion 
by the peripheral face 14.sub.2 of said permanent magnet 14 by 1/2 pole 
pitch of the permanent magnet 14. The rotor 6 then reaches dynamically 
balanced position and stalls in the positions as shown in FIG. 12(b). 
In the region b - c, the second exciting coil 13 are de-energized between 
the taps 13b and 13c but energized by a pulse voltage newly applied across 
the taps 13b and 13a, while the first coil 10 is still energized across 
the taps 10b and 10a at the point b. The polarities of the pole teeth 6e 
and 6f on the extension 6.sub.2 of the rotor 6 are then changed to those 
in the parentheses as shown in FIG. 12(b). Accordingly, the flat body 
portion 6.sub.1 of the rotor 6 runs in the leftward direction due to the 
attraction by the permanent magnet 14, while the extension 6.sub.2 of the 
rotor 6 rotates in the same direction due to the repulsion by said 
permanent magnet 14 by further 1/2 pole pitch of the permanent magnet 14 
to dynamically balanced stable positions where the rotor 6 stalls as shown 
in FIG. 12(c). 
In the region c - d, the first exciting coil 10 is de-energized between the 
taps 10b and 10a but energized by a pulse voltage newly applied across the 
taps 10b and 10c at the point c, while the second exciting coil 13 is 
still energized across the taps 13b and 13a at the point c so that the 
pole teeth 6b and 6c on the flat body portion 6.sub.1 of the rotor 6 
changes their polarities to those in the parentheses as shown in FIG. 
12(c). Accordingly, the flat body portion 6.sub.1 of the rotor 6 rotates 
in the leftward direction due to the repulsion by the upper face 14.sub.1 
of the permanent magnet 14, while the extension 6.sub.2 of the rotor 6 
rotates in the same direction through the attraction by the peripheral 
face 14.sub.2 of said permanent magnet 14 by further 1/2 pole pitch of the 
permanent magnet 14. At the positions, the rotor 6 stalls in dynamically 
balanced stable condition as shown in FIG. 12(d). 
In the region d - a', the polarities of the extension 6.sub.2 of the rotor 
6 are changed through similar operation to those in the parentheses as 
shown in FIG. 12(d) and the rotor 6 further advances by 1/2 pole pitch of 
the permanent magnet 14 to stall in dynamically balanced stable positions 
as shown in FIG. 12(e). Likewise, the rotor 6 advances in the leftward 
direction step by step by 1/2 pole pitch of the permanent magnet 14. 
In order to rotate the rotor 6 in the opposite direction, i.e., toward 
rightward direction, the pulse voltage (III) of FIG. 10 is applied across 
the taps 10b and 10a of the first exciting coil 10 and the pulse voltage 
(IV) is applied across the taps 10b and 10c, while the pulse voltage (I) 
and the pulse voltage (II) are applied across the taps 13b and 13a and the 
taps 13b and 13c, respectively. The energization operation and the 
magnetization operation under these conditions are shown in Table III and 
the resultant operation of the rotor 6 is shown in FIGS. 13(a) to 13(e). 
Table III 
______________________________________ 
conditions of polarities 
exciting coils induced in 
operational 
10b- 10b- 13b- 13b- pole teeth 
region 10a 10c 13a 13c 6b 6c 6e 6f 
______________________________________ 
a - b - + + - S N N S 
b - c + - + - N S N S 
c - d + - - + N S S N 
d - a' - + - + S N S N 
a' - b' - + + - S N N S 
c' - d' + - + - N S N S 
______________________________________ 
In the region a - b of FIG. 11, the second exciting coil 13 is de-energized 
between the taps 13b and 13c but energized by a pulse voltage applied 
across the taps 13b and 13a, while the first exciting coil 10 is energized 
by a pulse voltage applied across the taps 10b and 10c at the point a. The 
polarities of the pole teeth 6e and 6f on the extension 6.sub.2 of the 
rotor 6 are then changed to those in the parentheses as shown in FIG. 
13(a). As a result, the rotor 6 rotates in the rightward direction as 
viewed in FIG. 13 by 1/2 pole pitch of the permanent magnet 14. Then, the 
rotor 6 reaches dynamically balanced stable positions to stall there as 
shown in FIG. 13(b). 
In the region b - c, the first exciting coil 10 is energized by a pulse 
voltage applied across the taps 10b and 10a, while the second exciting 
coil 13 is energized by a pulse voltage applied across the taps 13b and 
13a at the point b. The polarities of the pole teeth 6b and 6c on the 
extension 6.sub.1 of the rotor 6 are then changed to those in the 
parentheses as shown in FIG. 13(b). Accordingly, the rotor 6 advances and 
then stalls in positions as shown in FIG. 13(c). 
In the region c - d, the second exciting coil 13 is energized by a pulse 
voltage applied across the taps 13b and 13c, while the first exciting coil 
10 is energized by a pulse voltage applied across the taps 10b and 10a at 
the point c, so that the polarities of the pole teeth 6e and 6f on the 
extension 6.sub.2 of the rotor 6 are changed to those in the parentheses 
as shown in FIG. 13(c). As a result, the rotor 6 rotates in the rightward 
direction and then stalls in the positions as shown in FIG. 13(d). 
In the region d - a', the first exciting coil 10 is energized by a pulse 
voltage applied across the taps 10b and 10c, while the second exciting 
coil 13 is energized by a pulse voltage applied across the taps 13b and 
13c at the point d. The polarities of the pole teeth 6b and 6c on the flat 
body portion 6.sub.1 of the rotor 6 are then changed to those in the 
parentheses as shown in FIG. 13(d). Then, the rotor 6 is caused to rotate 
rightwardly to the positions as shown in FIG. 13(e). Thus, the rotor 6 
continues to rotate step by step in the rightward direction through 
repitition of similar operation. 
In the light of the foregoing description, every advance operation of the 
two-phase pulse motor is effected by distributing a pulse voltage to the 
four exciting coils according to necessity through the driving circuit 19 
in response to every application of the input or control signal through 
the terminals 21. In this connection, it is to be noted that the input 
signal from the terminals 21 is not necessarily required to be a regular 
signal such as an AC sine-wave current or a constant and regular pulse 
signal. Even if the signal applied is occasionally constant or quick or 
occasionally intermittent or slow, the rotor of the present motor can 
surely advance by a pedetermined rotational angle depending upon the 
number of the input signals and stall in a position for a predetermined 
period. 
Referring to FIG. 14, there is shown a modification of the rotor 6 of the 
invention. In this modification, the plurality of grooves 6a and 6d 
described as formed in the circular flat body portion 6.sub.1 and the 
peripheral extension 6.sub.2 of the rotor 6 to provide the pole teeth 6b 
and 6c, and 6e and 6f thereon are replaced by corresponding triangular 
openings 6a' and rectangular openings 6d' formed in the flat body portion 
6.sub.1 ' and the extension 6.sub.2 ' of the rotor 6' respectively for 
providing similar pole teeth 6b' and 6c', and 6e' and 6a' thereon. Other 
construction and function of the rotor 6' is similar to those described 
with reference to FIGS. 1 to 13, so that detailed description thereof is 
abbreviated for brevity. 
It should be noted here that part of the pole teeth described as employed 
in the rotor of the foregoing embodiments may be omitted without 
formation, and that the same pole teeth described to be of double 
polarities may be replaced by pole teeth of single polarity magnetizable 
either in south pole or north pole. The pole teeth in the peripheral 
extension of the rotor can be formed into ones of single polarity if 
replaced, for example, by pointed teeth. 
It should also be noted that the difference in the electrical angle made 
through angular difference between the circular flat body portion and the 
peripheral extension of the rotor in the foregoing embodiments may be 
replaced by difference in electrical angle formed by staggering the 
magnetization of the north and south poles between the upper face and the 
peripheral face of the magnet stator. 
It will be understood that though a two-phase synchronous motor, reversible 
motor and pulse motor are illustratively explained above, the motor of the 
present invention may of course be applicable to multi-phase motors of 
various types, in which case, the annular exciting coils may be increased 
in number corresponding to the number of the phases employed, while the 
magnetic stator is magnetized coaxially in a centrifugal direction in a 
plurality of stages corresponding to the number of the same phases, with 
the rotor being provided with pole teeth formed coaxially in the 
centrifugal direction in a plurality of stages also corresponding to the 
number of the phases for individually forming magnetic loops developed by 
respective annular exciting coils. 
Furthermore, although self-explanatory from the foregoing description, the 
pole teeth for the rotor may either be formed in a centrifugal direction 
only on the circular flat body portion in a plurality of stages for 
forming the rotor in a disk-like configuration, or be formed in an axial 
direction of the rotor only on the peripheral extension of the rotor in a 
plurality of stages for making the rotor in a cylindrical shape, in the 
former case of which, the magnet stator may be magnetized coaxially in a 
centrifugal direction, only on the upper surface thereof, thus making it 
possible to form the motor rather thin or flat, while in the latter case, 
only the peripheral face of the magnetic stator is magnetized in the axial 
direction of the rotor in a plurality of stages, so that the motor can be 
formed in a shape rather long along the axis thereof. 
As is clear from the foregoing description, according to the present 
invention, the electrical rotary machine includes a rotary shaft, a rotor 
made of a soft magnetic material on which the pole teeth are formed in a 
plurality of stages corresponding to the number of phases and which is 
fixed to the rotary shaft in a concentric relation therewith, a plurality 
of annular exciting coils corresponding in number to the number of the 
phases and provided at one side of the rotor in position corresponding to 
the position of the pole teeth at each of the stages of said rotor, a 
magnetic stator concentric with said rotary shaft and magnetized radially 
to provide north and south poles alternating at equal angular spacings in 
positions corresponding to the pole teeth of each of the stages of the 
rotor, with the magnetic stator being disposed at the other side of the 
rotor, and member of a soft magnetic material for causing magnetic flux 
developed by each of the annular exciting coils to form magnetic loops 
individually flowing through the pole teeth of each of the stages of the 
rotor. 
Accordingly, since only one rotor is employed in the rotary electrical 
machine of the invention, the motor can be made thinner and consequently 
more compact than the two-phase motor having two rotors and can be 
manufactured more easily than the motor having two rotors because it is 
required in the latter that the angles between the pole teeth of the 
respective rotors be adjusted in the assembling of the motor, while in the 
former the pole teeth are accurately formed by molding or press 
eliminating such a necessity of adjustment, with possibilities of 
producing defective products being reduced to a large extent. 
It is another advantage of the electrical rotary machine of the invention 
that the concept thereof is readily applicable to various types of motors 
as detailed in the foregoing description, depending on the use of the 
motors. 
Although the present invention has been fully described by way of example 
with reference to the attached drawings, it is to be noted that various 
changes and modifications are apparent to those skilled in the art. 
Therefore, unless otherwise such changes and modifications depart from the 
scope of the present invention, they should be construed as included 
therein.