JPH08163853A - Stepping motor - Google Patents

Abstract

PURPOSE: To increase the holding torque greatly at the time on non-conduction through a simple structure by providing at least two salient teeth as the auxiliary poles being disposed oppositely to the tubular surface of a permanent magnet and disposing each salient pole oppositely to the subsequent N and S poles of the permanent magnet. CONSTITUTION: A magnetic circuit A1 passing through the pole teeth 12, 13 constituting a first row is established through stator cores 3a1, 3a2 and a housing 1 made of a magnetic material. A magnetic circuit B1 passing through the pole teeth 14, 15 constituting a second row is established through stator cores 3b1, 3b2 and the housing 1 made of a magnetic material. Furthermore, a magnetic circuit C1 is established through a salient tooth 10a and a second housing 10. When at least two salient teeth 10a are provided continuously to one pole of the permanent magnet, the magnetic circuit C1 is established and the holding torque can be increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepping motor, and more particularly to a PM type stepping motor capable of increasing a holding torque of a rotor with a simple structure.

[0002]

2. Description of the Related Art In a conventionally known PM type step motor, a permanent magnet formed on the outer circumference of a rotor establishes a magnetic circuit together with the stator core when the stator core is not excited by an exciting coil wound around the stator core and the stator core is not energized. The magnetic circuit moves the rotor to a magnetically stable position, and a holding torque is generated between the rotor and the stator core. When such a step motor is used in, for example, a valve adjustment or suspension damping force adjustment actuator that controls the intake air amount of the engine, the holding torque that holds the rotor stationary so that the rotor does not rotate when the step motor is stopped is very important. Will be things.

Therefore, in recent years, a step motor has been devised which is capable of increasing the holding torque of the rotor and adjusting the generation of the maximum holding torque with respect to the rotation angle of the rotor. For example, the step motor described in Japanese Patent Application Laid-Open No. 60-16363, filed by the applicant of the present application in advance, can be cited. In this step motor, the number of teeth that is twice the number of poles of the permanent magnet is provided at the position facing the permanent magnet, and the step motor is not affected by the exciting coil made of a magnetic material.
Is provided with a stator core. The torque generated by the magnetic circuit formed in the second stator core is combined with the torque generated by each stator core to increase the holding torque of the rotor. As shown in FIG. 37, the second stator core 100 is provided with protrusions 101, which is twice as many as the number of poles of the permanent magnet on the outer circumference of the rotor, and two protrusion teeth are arranged so as to face each of the N pole and the S pole. It is used as a compensating pole for holding torque generation when power is not supplied. Since the configuration is described in detail in the above publication, detailed description is omitted.

FIG. 38 shows a model diagram of a magnetic circuit magnetized by a permanent magnet when the step motor having the second stator core 100 is de-energized. The magnetomotive force generated by the permanent magnets formed on the outer circumference of the rotor acts on the pole teeth 21 to 24 formed on each of the stator cores 90a1, 2, 90b1 and 2 that are formed by stacking two stator cores. Each magnetic circuit A3,
B3 is established. Here, the pole teeth 21 are the stator core 90.
a1 to the pole teeth 22 to the stator core 90a2 to the pole teeth 23
Is the stator core 90b1 and the pole teeth 90 are the stator core 1
5b2 respectively. Further, the magnetomotive force also acts on the respective protrusions 101 of the second stator core 100 to establish the magnetic circuits c3 and d3. The holding torque of the rotor is generated from the combination of these magnetic circuits A3, B3, C3, D3.

FIGS. 39 (a) to 39 (e) show the torque generation state of each magnetic circuit A when the step motor is not energized.
3, B3, C3, and D3 are shown separately, and FIG. 39 (f) shows what kind of holding torque the rotor has by each of such torques. The horizontal axis is the rotation angle of the rotor,
The vertical axis represents the generated torque and shows the variation of the holding torque between the four step angles.

The combined torque of the torque A4 generated by the magnetic circuit A3 shown in FIG. 39 (a) and the torque B4 generated by the magnetic circuit B3 shown in FIG. 39 (b) is as shown in FIG. 39 (c). This combined torque is the torque A4, B described above.
Compared with 4, the cycle in which the maximum torque is generated is halved. However, by adding the torque C4 generated by the magnetic circuit C3 shown in FIG. 39 (d) and the torque D4 generated by the magnetic circuit D3 shown in FIG. 39 (e) to the combined torque, the maximum torque shown in FIG. 39 (f) is obtained. Figure 3 shows the holding torque
It can be increased compared to the maximum torque of the combined torque shown in 9 (c). In this way, the holding torque of the rotor is increased when the step motor is not energized so that the rotor or the shaft does not rotate due to vibration of the step motor or the like.

[0007]

However, in order to further increase the holding torque of the rotor when the step motor having the conventional structure is not energized, the special plate pressure formed on the second stator core is used. It is necessary to increase or increase the size of the permanent magnet of the rotor to strengthen the magnetic force. When this method is adopted, there are problems such as an increase in size of the step motor and an increase in cost. In addition, increasing the size of the permanent magnets causes the rotor to become heavier, which leads to a reduction in the performance of the step motor.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a step motor in which the holding torque at the time of non-energization is greatly increased as compared with the conventional one with a simple structure.

[0009]

In order to solve the above problems, a step motor according to the present invention has an N pole and an S pole on the outer peripheral surface.
The rotor is provided with a cylindrical permanent magnet in which poles are alternately magnetized, and is rotatably supported by a rotor, and a pole tooth disposed opposite to the permanent magnet with a predetermined gap therebetween. A plurality of hollow core-shaped stator cores having a circumferential portion,
An exciting coil wound around the stator core to magnetize the pole teeth of the stator core when energized to rotate the rotor, and to generate a holding torque by being magnetized to the permanent magnet when the exciting coil is de-energized. To
At least two projecting teeth serving as auxiliary poles that are arranged so as to face the cylindrical surface of the permanent magnet, and each of the projecting teeth is a continuous north pole and south pole of the permanent magnet. It is characterized in that they are arranged facing each other.

A stepping motor may be adopted in which the number of the protruding teeth is equal to the number of magnetic poles of the permanent magnet. Further, a step motor may be adopted in which the protruding teeth are formed with a substantially constant interval between the adjacent protruding teeth. A step motor may be adopted in which the width of the protruding teeth in the circumferential direction with respect to the permanent magnet is formed to be smaller than the width of each magnetic pole of the permanent magnet.

Further, a stepping motor may be adopted in which the projecting teeth are arranged so as to face each other in the vicinity of the center with respect to the cylindrical width of the permanent magnet. A second stator core that is arranged in parallel with the plurality of magnetic stator cores and is formed of a magnetic material into a hollow disk shape is provided, and the protruding teeth are integrally formed on an inner circumferential portion of the second stator core. You may make it employ | adopt the stepper motor characterized by the above.

Further, a stepping motor may be adopted in which the protruding teeth are integrally formed on at least one of the plurality of stator cores. Also,
The plurality of stator cores includes a first row of pole teeth formed by two stator cores arranged such that pole teeth facing in opposite directions are meshed with each other, and a stator row formed by another two stator cores. Two pole tooth groups, and the second stator core is disposed between the stator core having the pole tooth groups forming the first row and the stator core having the pole tooth groups forming the second row. A characteristic stepping motor may be adopted.

Further, the respective pole teeth in the pole tooth group forming the first row and the pole tooth group forming the second row are arranged such that their circumferential positions with respect to the outer surface of the permanent magnet deviate from each other by a predetermined amount. And the projecting teeth of the second stator core are arranged at an intermediate position between the closest pole teeth in the same direction in the pole tooth group forming the first row and the pole tooth group forming the second row. Alternatively, a stepping motor may be adopted.

Further, the respective pole teeth of the pole tooth group forming the first row and the pole tooth group forming the second row are arranged such that their circumferential positions with respect to the outer surface of the permanent magnet are displaced from each other by a predetermined amount. And the protruding teeth of the second stator core are arranged at an intermediate position between the pole teeth of the first row and the pole teeth of the second row facing in opposite directions. Alternatively, a stepping motor may be adopted.

Further, the respective pole teeth of the pole tooth group forming the first row and the pole tooth group forming the second row are arranged such that their circumferential positions with respect to the outer surface of the permanent magnet are displaced from each other by a predetermined amount. And the projecting teeth of the second stator core are aligned with the respective pole tooth positions of either one of the pole tooth group forming the first row and the pole tooth group forming the second row. It is also possible to adopt a stepping motor characterized in that

The plurality of stator cores includes a first row of pole teeth formed by two stator cores arranged so that pole teeth facing in opposite directions are meshed with each other.
Similarly, the second formed by the other two stator cores
A pair of pole teeth, and the projecting tooth is one of the two stator cores including the pole tooth group forming the first row, and the stator tooth arranged closer to the pole tooth group forming the second row. , One of the two stator cores including the pole teeth group forming the second row and one of the stator cores arranged in a portion close to the pole teeth group forming the first row is integrally formed with at least one of the stator cores. You may make it employ | adopt the step motor characterized by the above.

The plurality of stator cores includes a first row of pole teeth formed by two stator cores arranged so that pole teeth facing in opposite directions are meshed with each other.
Similarly, the second formed by the other two stator cores
A pair of pole teeth, and the projecting tooth is one of the two stator cores including the pole tooth group forming the first row, and the stator tooth arranged closer to the pole tooth group forming the second row. , The two stator cores having the pole teeth group forming the second row and the stator core arranged closer to the pole teeth group forming the first row and the other stator core, which are distributed to the respective two stator cores. You may make it employ | adopt the stepper motor characterized by being integrally formed.

Further, the respective pole teeth of the pole tooth group forming one row and the pole tooth group forming the second row are arranged such that their circumferential positions with respect to the outer surface of the permanent magnet are displaced from each other by a predetermined amount. The projecting teeth are arranged integrally with an intermediate position stator core between the closest pole teeth facing the same direction in the pole tooth group forming the first row and the pole tooth group forming the second row. A characteristic stepping motor may be adopted.

Further, the respective pole teeth of the pole tooth group forming the first row and the pole tooth group forming the second row are arranged such that their circumferential positions with respect to the outer surface of the permanent magnet deviate from each other by a predetermined amount. And the projecting teeth are arranged on the stator core at an intermediate position between the nearest pole teeth facing in opposite directions in the pole tooth group forming the first row and the pole tooth group forming the second row. A characteristic stepping motor may be adopted.

Further, the respective pole teeth of the pole tooth group forming the first row and the pole tooth group forming the second row are arranged such that their positions in the circumferential direction with respect to the outer surface of the permanent magnet deviate from each other by a predetermined amount. And the projecting teeth are formed on the stator core so as to coincide with the respective pole tooth positions of either one of the pole tooth groups forming the first row and the pole tooth group forming the second row. Alternatively, a step motor may be adopted.

Further, a stepping motor may be adopted in which the protruding teeth are formed in a curved surface at a portion facing the permanent magnet. Further, by increasing or decreasing an area of a portion of the protruding tooth facing the permanent magnet, the magnitude of the holding torque generated by the protruding tooth is set to an arbitrary value. It may be adopted.

Further, the amount of holding torque generated by the projecting teeth is set to an arbitrary value by setting the gap between the tip of the projecting teeth and the cylindrical surface of the permanent magnet to be a predetermined distance. Alternatively, a step motor may be used. Further, the pole teeth formed on the plurality of stator cores may have a comb tooth shape, and a step motor may be adopted.

[0023]

The operation of the step motor constructed as described above will be described below. In the step motor according to the first aspect of the present invention, at least two protruding teeth that generate a holding torque are arranged so as to face one magnetic pole of the permanent magnet one by one. As a result, the at least two protruding teeth are magnetized by the permanent magnets when the step motor is de-energized, and the magnetic circuit is established. Due to the establishment of this magnetic circuit, a torque for holding the rotor is generated. The torque for holding the rotor is also generated by the pole teeth formed on the stator core, but the torque by the pole teeth is extremely weak except for the step motor that employs a permanent magnet having a very strong magnetic force. Therefore, as described above, the torque generated by the protruding teeth is combined with the torque generated by the pole teeth, so that a large holding torque can be obtained.

Further, the number of the protruding teeth may be the same as the number of N and S of the permanent magnets. In this case, since the number of magnetic circuits formed is greater than that in the first aspect, a larger holding torque can be generated. Even in this case, the number of protruding teeth is 1 for each magnetic pole of the permanent magnet.
Must be formed. Further, as described in claim 3, if the formation interval of the protruding teeth is made constant, the magnetic flux density in each magnetic circuit is made uniform, and the holding torque can be efficiently increased.

When the protruding teeth are formed near the center of the cylindrical width of the permanent magnet as described in claim 5, a stronger holding torque can be obtained. This is because the magnetomotive force of the magnet is weakened at both ends of the width of the permanent magnet, and the protruding teeth cannot be strongly magnetized. Further, as in claim 6, the second stator core may be provided, and the protruding teeth may be provided on the inner circumferential portion. Also in this case, each protruding tooth
At least one magnetic pole of the permanent magnet is formed, and when the step motor is not energized, the permanent magnet is magnetized from the tips of the protruding teeth. Then, a magnetic circuit is established between the adjacent protruding teeth and the permanent magnet that pass through the inside of the second stator core. Thereby, the holding torque can be matched.

Further, the projecting teeth may be integrally formed on at least one of the stator cores. In this case, the magnetic circuit is established if, for example, all the protruding teeth are formed on one stator core,
A magnetic circuit that passes through the protruding teeth that receive the magnetomotive force from the permanent magnet and the inside of the stator core on which the protruding teeth are formed is established. Further, for example, when the projecting teeth are distributed and formed on the two stator cores as described in claim 13, the magnetic circuit may pass between the stator cores arranged in contact with each other. . When the protruding teeth are arranged on each stator core as described above, these protruding teeth are arranged near the center of the cylindrical width of the permanent magnet, so that a strong holding torque can be efficiently exerted.

Further, when the second stator core having the same number of projecting teeth as the number of magnetic poles of the permanent magnet is arranged, the phase of each projecting tooth with respect to the pole teeth is set as claimed in claim 9 or 10. When set to, for example, when the two-phase excitation of the step motor is performed, the maximum holding torque can be efficiently increased. Further, the energization stop position and the non-energization stop position of the step motor can be matched. Even when the protruding teeth are formed integrally with the stator core,
If the protruding teeth are arranged as described in claims 14 and 15, 2
The same effect can be obtained in the stepping motor driven by the phase excitation method.

Further, when the protruding teeth are arranged as described in claims 11 and 16, in the one-phase excitation step motor, the rotor stop position when energized and the rotor stop position when not energized are provided. Can be forced to match. That is, in the one-phase excitation type step motor, the stop position (angle) when energized and the stop position (angle) due to the torque generated by the pole teeth when de-energized are deviated, but the protruding teeth are larger than the torque generated by the pole teeth. Since the torque due to is larger than a certain amount, it is possible not only to increase the holding torque but also to make the stop angles uniform when these torques are combined.

According to the seventeenth to nineteenth aspects, the magnitude of the torque that can be generated by the protruding teeth can be adjusted, and the maximum holding torque obtained by combining the torques can also be adjusted by the step motor. Can be adjusted to suit your needs. When the portion of the protruding tooth facing the permanent magnet is a curved surface, a large magnetomotive force from the permanent magnet can be received, and a large maximum holding torque can be obtained.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A step motor according to the present invention will be described below with reference to the drawings. A first embodiment of the present invention will be described with reference to FIGS. 1 to 5. FIG. 1 is a configuration diagram showing a configuration of a step motor according to the present invention, and is a cross-sectional view showing a configuration of a stepping motor, which is a feature of the present invention, formed on a second stator core and arranged to face a permanent magnet. Also, FIG.
FIG. 2 is a sectional view taken along line AA in FIG. 1.

First, based on FIG. 1, the step motor 5
The structure of 0 is shown. The first housing 1 formed of a magnetic material in the shape of a cup and the second housing 2 formed in the shape of a disk are fixed to each other by screws (not shown) or the like to form a housing. Bearings 6 and 7 are fixed to the inside of the housing, respectively.
The rotor 4 is rotatably supported by the shaft 7. A permanent magnet 5 is provided on the outer peripheral portion of the rotor 4. Also,
A shaft 8 having the same central axis as the rotor 4 is fixed.
On the outer side of the rotor 4, stator cores 3a1, 2, 3b1, 2 serving as stator poles are fixed to the inner surface of the first housing 1 with a space 11 therebetween. Pole teeth 12 to 15 are formed on the inner peripheral surfaces of the stator cores 3a1, 2 and 3b1 and 2 that face the rotor 4, as will be described later with reference to FIG. Inside the stator cores 3a1, 2, 3b1, 2 an exciting coil 9 for exciting each of the stator cores 3a1, 2, 3b1, 2 insulated by an insulating member (not shown).
A and 9b are wound. Stator cores 3a1, 2,
A second stator core 10 made of a magnetic material is provided between 3b1 and 3b1. The second
The stator core 10 of each of the stator cores 3a1, 2 and 3b
1 and 2 may be arranged in parallel with each other and may be arranged so as to face the permanent magnets 5, for example, the stator cores 3a1 and 3a.
It may be provided in contact with either of b2.

As shown in FIG. 2, protruding teeth 10a are formed on the inner circumferential portion of the hollow disk-shaped second stator core 10 which faces the permanent magnets 5. This protruding tooth 10a
Are formed at the same intervals as the number of magnetic poles formed on the permanent magnet 5. That is, in the prior art, FIG.
7 to 39, the number of the protruding teeth 10 is half the number of the protruding teeth of the second stator core in the step motor.
a is formed. Further, the surface of the protruding tooth 10a facing the permanent magnet is a curved surface, which is advantageous in that a large holding torque is generated in view of the following points.
That is, since the magnetic flux from the permanent magnet 5 normally enters perpendicularly to the facing surface of the protruding tooth 10a, the facing surface of the protruding tooth 10a is formed into a curved surface, so that the magnetic flux from a wide portion of the cylindrical surface of the permanent magnet 5 is generated. This is because they can be affected. In FIG. 2, the second stator core 1
One projecting tooth 10a is provided for each of the N and S poles of the permanent magnet 5 at equal intervals on the inner circumferential portion of 0.
It is not limited to this. That is, it is also possible to dispose only the protruding teeth 10a formed in the E portion of FIG. 2 and eliminate the other protruding teeth. That is, if at least two projecting teeth 10a are arranged facing the N and S poles of the permanent magnet 5 that are continuous, the holding torque of the step motor 50 can be increased. Therefore, for example, two protruding teeth 10a are continuously arranged for each pole of the permanent magnet 5, and
The two protruding teeth 10a may be arranged continuously on the opposite side of the disk center of the stator core 10 for each pole of the permanent magnet 5.

FIG. 4 shows the pole teeth 1 formed on each stator core 3a1, 2, 3b1, 2 in the first embodiment.
The model figure which shows the positional relationship of 2, 13, 14, 15 and the protruding tooth 10a is shown. The positional relationship shown in FIG. 4 is the stop angle of the shaft 8 (rotor 4) when energized and the stop angle of the shaft 8 when not energized when the step motor 50 is energized by the one-phase excitation method. Are set to match. The step motor 50
The energization stop angle in (1) means a predetermined angle capable of controlling the rotation angle of the shaft 8.

As shown in FIG. 4, the row formed by the pole teeth constitutes the first row by the pole teeth 12, 13 formed on the stator cores 3a1, 3a2, and is also formed on the stator cores 3b1, 3b2. The pole teeth 14 and 15 form a second row. In a step motor, the pole teeth 12 and 13 forming the first row and the pole teeth 14 and 1 forming the second row are usually used.
5 has a predetermined positional difference (deviation between each other), and is set to the following difference in the embodiment of the present invention. That is, with reference to the pole teeth 12 and 13 forming the first row,
Positions shifted by a quarter of the positional difference between the positions of the pole teeth 20a and the positions of the pole teeth 20b in the first row, in other words, the pole teeth 20a.
And a position shifted by a half of the position difference between the pole teeth 21a,
A second row of pole teeth 14, 15 is arranged. Therefore, when viewed from the pole teeth 21a in the first row, the pole teeth 30a and 31a in the second row are the positions of the pole teeth 20a and the pole teeth 2a.
Position difference of 1/4 of 0b, in other words pole teeth 20a
Is set to a position having a half position difference from the position of the pole teeth 21a.

As can be seen from FIG. 4, the protruding teeth 10a formed on the second stator core 10 are formed at the same positions as the pole teeth 14 and 15 forming the second row at equal intervals.
The operation and effect of the step motor according to the first embodiment configured as described above will be described below. When the step motor 50 is not energized, each stator core 3a1,
2, 3b1 and 2 are simply magnetic materials. However, due to the magnetomotive force of the permanent magnet of the rotor 2, the stator core 3a
A magnetic circuit is established in 1, 2, 3b1 and 2. A method of forming a large number of patterns can be considered for forming the magnetic circuit. A magnetic circuit is also established in the second stator core 10 via the protruding teeth 10a. An example of each magnetic circuit is shown in FIG.
This will be described with reference to the model diagram of FIG.

First, the pole teeth 12 and 13 forming the first row
The magnetic circuit A1 via the stator cores 3a1, 3a
2 and the housing 1 formed of a magnetic material. Also, the pole teeth 14, 15 forming the second row
The magnetic circuit B1 through the stator cores 3b1, 3b
2 and the housing 1 formed of a magnetic material. Further, the magnetic circuit C1 is established in the second stator core 10 via the protruding teeth 10a. Here, as can be seen from FIG. 5 which will be described later, in a step motor which is usually aimed at lowering the price, since the permanent magnet 5 does not have a magnet having a strong magnetic force but a ferrite magnet or the like, The combined torque of the magnetic circuits A1, B1 formed by the teeth 12, 13, 14, 15 is very small,
The torque generated by the magnetic circuit C1 by the protruding teeth 10a is much larger. Therefore, the holding torque of the step motor 50 can be increased by establishing at least one magnetic circuit C1. That is, as described above with reference to FIG.
If at least two magnetic poles are continuously provided, the magnetic circuit C1 is established and the holding torque can be increased. Note that the magnetic circuit is not limited to this pattern, and various other patterns are conceivable, for example, via each pole tooth,
A magnetic circuit may be established between the first row and the second row. The rotor 2 moves so that the magnetic circuit thus established is in a stable state, and the rotor 4 and the stator core 4 to
A holding torque is generated between the holding torque and 7. At this time, the holding torque is established by combining the generated torque generated by the pole teeth 12 to 15 and the auxiliary torque generated by each protruding tooth 10a, as will be described later with reference to FIG.

When the step motor 50 is not energized,
The generated torque generated by the pole teeth 12 to 15, the auxiliary torque generated by the protruding teeth 10a, and the holding torque obtained by combining them will be described below with reference to FIG. As described above, the torque generated by the pole teeth 12, 13, 14, 15 formed on the stator cores 3a1, 2, 3b1, 2 is generated as shown in FIG.
This generated torque has a smaller value than the auxiliary torque generated by the protruding teeth 10a described later. This generated torque is applied to the pole teeth 12 to 15 when the stepping motor 50 in which power is not supplied to the exciting coils 9a and 9b is not energized.
Is generated by being magnetized by the permanent magnet of the rotor. The generated torque is a combination of the torque generated by the magnetic circuit A1 described in FIG. 3 and the torque generated by the magnetic circuit B1. When the step motor 50 is not energized, the stop angle of the rotor 4 due to the generated torque, that is, the stop angle of the shaft 8 stops at the rotation angle β. However, the rotation angle β is the energization stop position when the step motor 50 is energized and driven by the two-phase excitation. Therefore, the protruding teeth 10a
The non-energized stop position of the step motor 50 is forcibly set by the auxiliary torque generated by the step motor 50 to be set to the stop position V when the step motor 50 is energized and driven by the one-phase excitation. That is, it is adjusted to the stop position when the excitation coils 9a and 9b are energized, and is made to coincide with the holding position of the rotor 4 when energized.

To that end, a torque larger than the generated torque is generated to some extent by the protruding teeth 10a, and the stop angle due to the torque becomes the rotation angle V. Therefore, the protruding teeth 10a set and arranged as described above are provided with an auxiliary torque such that the stop angle of the shaft 8 becomes P.
It occurs as shown in (b). In addition, this protruding tooth 10a
When the step motor in the above-described conventional art has the protruding teeth twice the number of poles of the permanent magnet, the cycle of the auxiliary torque is due to the auxiliary torque generated by the protruding teeth. The frequency of occurrence of the stop angle is halved. However, the magnitude of this auxiliary torque is much larger than the auxiliary torque (combination of the magnetic circuits C3 and D3 in FIG. 39) generated by the protruding teeth in the conventional step motor. . It should be noted that the fact that the number of the protruding teeth 10a is smaller than that of the conventional one means that the second stator core 1 is simply
Needless to say, it is very advantageous when punching with a press, etc., even from the viewpoint of manufacturing process of No. 0.

The combination of the generated torque thus generated and the auxiliary torque is the holding torque shown in FIG. 5 (c). The maximum holding torque in this holding torque is increased by the amount of the auxiliary torque generated by the projecting teeth 10a by combining the generated torque with a large auxiliary torque, and becomes a value capable of sufficiently holding the shaft 8 when not energized. ing. Here, the stop position of the stator cores 3a1, 2, 3b1, 2 at this holding torque, that is, the stop angle of the step motor 50 becomes the angle of the rotation angle Y because the auxiliary torque is somewhat larger than the generated torque. . Here, the rotation angle Y matches the stop angle V in FIG. 5A, but the frequency of occurrence thereof is half the stop angle V. As described above, if the generation cycle of the maximum holding torque becomes long, the stable position of the shaft 8 becomes rough when the step motor 50 is not energized, and it may not be possible to stop the shaft 8 at an arbitrary stop angle.
Further, even when the step motor 50 is energized, there is a possibility that fine control by the step motor 50 cannot be performed. However, these include the number of magnetic poles of the permanent magnet 5 and one of the pole teeth of the stator cores 3a1, 2, 3b1, 2.
By increasing the number of 2 to 15 and the number of the projecting teeth 10a in the second stator core 10, it is possible to reduce the one-step angle and thereby reduce the frequency of occurrence of the stop angle of the rotor 4 and deal with it.

As described above, according to the first embodiment, the step motor 5 having the maximum holding torque increased with a simple structure.
0 can be provided. In addition, as shown in FIG.
When disposing the second stator core 10 on the step motor 50, the protruding teeth 1 formed on the second stator core 10
0a may be arranged at the same position as the pole teeth 12 and 13 forming the first row.

The auxiliary torque generated by the protruding teeth 10a set in this way is as shown in FIG. 7B, and the stop angle of the shaft 8 at this auxiliary torque is Q.
Is. Further, as compared with the first embodiment, the position where the protruding teeth 10a are arranged is displaced as described above, so that the stop angle Q of the shaft 8 is displaced by one cycle of the generated torque.

When such generated torque and auxiliary torque are combined, a holding torque as shown in FIG. 7 (c) is produced. Here, the stop angle of the shaft 8 at this holding torque, that is, the stop angle of the rotor 4 is larger to some extent in the auxiliary torque than in the generated torque. Become. Here, the stop angle Z matches the rotation angle V in FIG. 7A, but the frequency of occurrence thereof is half the rotation angle V, as in the first embodiment.

Even if the positions of the protruding teeth 10a are set in this way, the maximum holding torque can be increased as in the first embodiment. Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 8 is a model diagram showing the positional relationship between the pole teeth 12, 13, 14, 15 formed on the stator cores 3a1, 2, 3b1, 2 and the protruding teeth 10a in the second embodiment. In this second embodiment,
Similar to the first embodiment, the second stator core 10 is disposed and the protruding teeth 10a are formed on the disk-shaped inner circumferential portion, and the positional relationship shown in FIG. When the motor 50 is energized by two-phase excitation, the stop angle of the shaft 8 (rotor 4) when energized and the stop angle of the shaft 8 when de-energized are set to match.

As shown in FIG. 8, one of the protruding teeth 10a is the position of a predetermined pole tooth 21a in the first row of pole teeth 12 and the position of a predetermined pole tooth 30a in the second row of pole teeth 15a. Is formed at an intermediate position. In addition, the position of the predetermined pole tooth 20a in the pole tooth 13 and the predetermined pole tooth 3 in the pole tooth 14
One protruding tooth is also formed at an intermediate position from the position of 1b.
Similarly, one protruding tooth is formed at an intermediate position between the position of the polar tooth 21b adjacent to the polar tooth 21a in the polar tooth 12 and the position of the polar tooth 30b adjacent to the polar tooth 30a in the polar tooth 15. Further, one protruding tooth is formed at an intermediate position between the position of the pole tooth 20b adjacent to the pole tooth 20a in the pole tooth 13 and the position of the pole tooth 31c adjacent to the pole tooth 31b in the pole tooth 14. As can be seen from this, in the second embodiment, the respective pole teeth 1 forming the first row and the second row are arranged.
One of the protruding teeth is formed at an intermediate position between the nearest pole teeth of 2 to 15 facing in the same direction. That is, the nearest pole tooth facing the same direction as the pole tooth 21a is 30a, and the nearest pole tooth of the pole tooth 31b is 20a.
Is. The protruding teeth 10a formed at such positions are
The protrusion teeth 10a adjacent to each other are formed on each stator core with a constant interval.

The operation and effect of the second embodiment having the above structure will be described below. It should be noted that detailed description will be omitted for points that overlap with the effects of the above-described embodiment. The torques generated by the protruding teeth 10a and the pole teeth 12 to 15 that are set and arranged as described with reference to FIG. 8 and the holding torque that is a combined torque thereof will be described with reference to FIG.

The generated torque generated by each pole tooth 12 to 15 is the same as that in the first embodiment, and as shown in FIG. 9 (a), the shaft 8 is de-energized at the rotation angle β. Also,
The auxiliary torque generated by the protruding teeth 10a is shown in FIG.
As shown in (b), the stop angle N of the shaft 8 is set to the pole teeth 1
It occurs at the same angle as the stop angle β due to the generated torque of 2 to 15. The frequency of occurrence of the stop angle N at this time is half the stop angle β due to the torque generated by the pole teeth.

Therefore, the holding torque obtained by combining the torque generated by the pole teeth 12 to 15 and the auxiliary torque by the protruding teeth 10a is as shown in FIG. 9C, and the stop angle of the rotor 2 is the rotation angle W. Here, each rotation W is the step motor 5
It can be seen that it coincides with the stop angle β when 0 is driven by two-phase excitation. As described above, even when the step motor 50 is driven by two-phase excitation, when the second stator core 10 is arranged, the positions of the projecting teeth 10a are set as described above, the same as the first embodiment. Similarly, it is possible to increase the maximum holding torque.

When the step motor 50 is operated by two-phase excitation, the positions of the protruding teeth 10a may be set as shown in FIG. That is, the protruding tooth 10 is located at an intermediate position between the pole tooth 20a and the pole tooth 30a in FIG.
Set a. Similarly, the intermediate position between the pole teeth 21a and 31a, the pole tooth 21b and the pole tooth 31b, the pole tooth 20b and the pole tooth 3
Set to an intermediate position with 0b. That is, each of the pole teeth 12 to 15 in the first row and the second row is formed with one protruding tooth at an intermediate position between the closest pole teeth facing in the same direction.

The torque generated by the protruding teeth 10a and the pole teeth 12 to 15 which are set and arranged as shown in FIG. 10 and the holding torque which is the combined torque thereof will be described with reference to FIG. As in the above-described embodiments, the generated torque generated by the pole teeth 12 to 15 causes the step motor 50 to stop de-energizing at the rotation angle β, as shown in FIG.
In addition, as shown in FIG. 11B, the auxiliary torque generated by the protruding teeth 10a set as described above is as shown in FIG.
The same output as the auxiliary torque described in (b) is exerted, but with the auxiliary torque in FIG. 11 (b), the stop angle O of the step motor 50 is the auxiliary torque shown in FIG. 9 (b). The generated torque is deviated from the stop angle N of the step motor 50 by one cycle. This is shown in FIG.
This is because the installation positions of the protruding teeth 10a described in detail in FIG. 8 and FIG. 8 are deviated from each other by exactly one cycle.

Therefore, here, the holding torque obtained by combining the generated torque and the auxiliary torque is as shown in FIG. 11C, and the stop angle of the shaft 8 is X. However,
This is because the reference position of the stop angle deviates from the step motor 50 and does not adversely affect the efficacy. That is, even if the protruding teeth 10a are set in this manner, it is possible to obtain the same effect as that of the second embodiment.

Next, the third embodiment of the present invention will be described with reference to FIG.
This will be described below with reference to FIGS. In the above-described embodiments, the second stator core 10 is provided and the projecting teeth 10a that are arranged to face the outer peripheral surface of the permanent magnet 5 are formed on the inner circumferential surface of the second stator core 10. In the embodiment, the protruding tooth 10a as the auxiliary pole is replaced by the pole tooth 1
It is formed integrally with the stator cores 3a2, 3b1 having the 2,2.

FIG. 12 shows the auxiliary electrode 10 in the third embodiment.
FIG. 13 is a configuration diagram showing the configuration of the stator cores 5 and 6 integrally formed with each other, and FIG. 13 is a model diagram showing a basic pattern of the positional relationship between each pole tooth and the protruding tooth 10a formed as shown in FIG. . First, the positional relationship between the pole teeth 12 and 13 in the first row, the pole teeth 14 and 15 in the second row, and the auxiliary pole 10 will be described with reference to FIG. Also in the third embodiment, the pole teeth 13 and 12 forming the first row and the pole teeth 14 and 15 forming the second row have the same positional difference as in the above-described first embodiment. Further, in the third embodiment, the number of poles of the protruding teeth 10a is equal to the number of magnetic poles of the permanent magnet in the stator core, and the shaft 8 is energized when the step motor 50 is energized by two-phase excitation. The position of the projecting tooth 10a is set so that the stop angle of No. 2 and the stop position of the shaft 8 when not energized are matched.

As can be seen from FIG. 13, the protruding teeth 10a
Are formed in the same number as the total number of the pole teeth 12 and 13 forming the first row, in other words, the same number as the total number of the pole teeth 14 and 15 forming the second row. That is, the same number as the number of magnetic poles of the permanent magnet 5 is formed, and the protruding teeth 10a are formed. One of the protruding teeth 10a is the position of the predetermined pole tooth 21a in the first row pole tooth 12 and the predetermined pole tooth 3 in the second row pole tooth 15 is.
It is formed at a position intermediate to the position of 0a. Also, pole teeth 1
One auxiliary pole is also formed at an intermediate position between the position of the predetermined pole tooth 20a in 3 and the position of the predetermined pole tooth 31b in the pole tooth 14. Similarly, the pole tooth 21a of the pole tooth 12 is
One protruding tooth is formed at an intermediate position between the position of the pole tooth 21b adjacent to the pole tooth 21b and the position of the pole tooth 30b adjacent to the pole tooth 30a in the pole tooth 15. Further, one protruding tooth is formed at an intermediate position between the position of the pole tooth 20b adjacent to the pole tooth 20a in the pole tooth 13 and the position of the pole tooth 31c adjacent to the pole tooth 31b in the pole tooth 14. As can be seen from this, in the third embodiment, the auxiliary pole is located at an intermediate position between the closest pole teeth facing in the same direction among the pole teeth 12 to 15 forming the first row and the second row. Will be formed one by one. That is, the nearest pole tooth facing the same direction as the pole tooth 21a is 30a, and the nearest pole tooth of the pole tooth 31b is 20a. The protruding teeth 10a formed at such positions are formed on the respective stator cores with the intervals between the adjacent protruding teeth 10a being constant.

FIG. 14 shows a structural model diagram when the protruding teeth 10a positioned as described in detail with reference to FIG. 13 are separately formed on the two stator cores 3a2 and 3b1. In FIG. 14, the polar tooth 21a and the polar tooth 3 in FIG.
0a is formed integrally with the stator core 3a2, and the protruding tooth 10a1 is formed at an intermediate position between the pole tooth 20a and the pole tooth 31b. The protruding tooth 10a1 is formed integrally with the stator core 3b1. . Similarly, pole teeth 2
1b and pole tooth 30b
a1 is integrally formed with the stator core 3a2 and has pole teeth 20b.
Tooth 10a2 formed at an intermediate position between the tooth and the pole tooth 31c
Is integrally formed with the stator core 3b1. in this way,
Projection tooth 1 positioned as described in FIG.
0a are alternately one by one and the stator cores 3a2 and 3b
1 is integrally formed.

The structure of the stator cores 3a2, 3b1 in which the protruding teeth 10a are alternately formed integrally as shown in FIG. 14 is shown in FIG.
This will be explained in Section 2. As shown in FIG. 12, protruding teeth 10a1 and 10a1 formed on each stator core 3a2 and 3b1.
Since a2 has a portion that overlaps with the arrangement position of each pole tooth 12 and 14, a cutout portion 40 is provided at the base portion of each pole tooth 12 and 14. By providing the cutout portion 40, each protruding tooth 10a
1, 10a2 project so as to face the permanent magnet 5 of the rotor 4 without buffering the pole teeth 12, 14. The height of the protruding tooth 10a (10a1, 10a2) from the inner circumferential surface of the stator core 3a2, 3b1 is
The heights of the pole teeth 12 and 14 are set substantially equal to each other.
Further, in the third embodiment, the stator core 3a1
And 3b2 can be formed in the same shape,
The stator core 3a having the protruding teeth 10a in this way
A step motor 50 capable of increasing a holding torque as described later is provided only by providing two combinations of 2, 3b1 and stator cores 13, 15 in which the protruding teeth 10a are not formed. You can Further, the protruding teeth 10a are arranged to face the permanent magnet 5 of the rotor 4 as shown in FIG.
That is, the protruding teeth 10 a are arranged in a one-to-one correspondence with the one magnetic pole N, S of the permanent magnet 5, respectively.
The interval between a is constant. In addition, this protruding tooth 10
The facing surface facing the permanent magnet 5 of a is a curved surface.
When the opposing surfaces are curved in this way, the magnetic flux in a wide area of the permanent magnet 5 can be received at a right angle, which is advantageous for increasing the holding torque.

The operation and effect of the third embodiment constructed as described above will be described below. It should be noted that detailed description will be omitted for points that overlap with the effects of the above-described embodiments. FIG. 16 shows torques generated by the projecting teeth 10a and the pole teeth 12 to 15 that are set and arranged as described in detail with reference to FIGS.
Will be explained.

The generated torque generated by each pole tooth 12 to 15 is the same as that in the above-described embodiments, and as shown in FIG. 18 (a), the shaft 8 is de-energized at the rotation angle β. Further, as shown in FIG. 16B, the generation cycle of the auxiliary torque generated by the protruding teeth 10a is twice the generation cycle of the generated torque by the pole teeth 12 to 14, and therefore, the protruding teeth 10a. The stop angle N of the shaft 8 due to the auxiliary torque generated by is half the frequency of the stop angle β due to the torque generated by the pole teeth 13 to 15. Further, this auxiliary torque is a torque that is somewhat larger than the generated torque.

Therefore, the holding torque obtained by synthesizing the torque generated by the pole teeth 12 to 15 and the auxiliary torque by the protruding teeth 10a is as shown in FIG. 16C, and the stop angle of the rotor 4 is the rotation angle W. As described above, in the third embodiment, the total number of the protruding teeth 10a formed on the stator cores 3a2 and 3b1 is the same as that of the above-described embodiments.
The number is the same as the number of poles, and is half of the total number of protruding teeth that the step motor in the related art has.

Next, a fourth embodiment of the present invention will be described with reference to FIG.
7 and FIG. 18 will be described below. In the fourth embodiment, in the arrangement pattern of the protruding teeth 10a described in FIG. 13, the stator cores 3a2 and the second cores in the first row are
This is an example in which the distribution pattern for distributing the projecting teeth 10a to the stator core 3b1 in the row is changed.

That is, in the third embodiment, the protruding teeth 10a are formed separately as described above with reference to FIG. 14, but in the fourth embodiment, the protruding teeth 1a are formed as follows.
0a is formed and arranged. In the fourth embodiment, FIG.
The auxiliary pole formed at the intermediate position between the pole tooth 21a and the pole tooth 30a in FIG.
, Which are integrally formed with the stator core 3a2, are formed integrally with the stator core 3a2 as the protruding teeth 10a1. Similarly, the pole teeth 21
b and the pole teeth 30b are formed at intermediate positions between the pole teeth 20b and the pole teeth 31b.
The protruding teeth formed at the intermediate position with respect to c are the stator core 3a.
2 is integrally formed. As described above, in the fourth embodiment, the protruding teeth 10a whose positions are set as described in FIG. 13 are alternately formed one by one integrally with the stator cores 3a2 and 3b1. In the fourth embodiment, when the projecting teeth 10a are arranged in this way, the distribution pattern of the projecting teeth 10a to each stator core is as shown in FIG.
It is the opposite of the sorting pattern in.

The structure of each of the stator cores 12 and 14 in which the protruding teeth 10a are integrally formed in this manner will be described with reference to FIG. As shown in FIG. 17, the protruding teeth 10a1 formed integrally with the stator core 3a2 are formed on the left side of the pole teeth 12, and the height of the protruding teeth 10a1 from the inner peripheral surface of the stator core 5 is almost the same as that of the pole teeth 12. is there. The protruding teeth 10a2 integrally formed with the stator core 3b1 are also formed in the same manner. That is, the stator core 3a2 and the stator core 3b1 are formed in the same shape.

It goes without saying that the step motor 50 in the fourth embodiment in which the projecting teeth 10a are integrally formed on the stator cores 3a2, 3b1 in this way also exerts the same effect as the above embodiments. Nor. Next, a fifth embodiment of the present invention will be described below with reference to FIGS. First, the positional relationship between the pole teeth 12 to 15 and the protruding teeth 10a in the fifth embodiment will be described with reference to FIG. The positional difference between the pole teeth 12 and 13 forming the first row and the pole teeth 14 and 15 forming the second row is set in the same manner as in the above-described first embodiment.

As can be seen from FIG. 20, in the fifth embodiment as well, similar to the above-described embodiments, the number of the projecting teeth 10a is the same as the total number of the projecting teeth 12 and 13 forming the first row, in other words, the permanent magnet. The same number as the total number of the magnetic poles N and S of 5 is formed. One of the protruding teeth 10a is formed at an intermediate position between the position of the predetermined pole tooth 21a of the first row pole tooth 12 and the position of the predetermined pole tooth 31a of the second row pole tooth 14a.
Also, one protruding tooth 10a is formed at an intermediate position between the position of the predetermined pole tooth 20a on the pole tooth 13 and the position of the predetermined pole tooth 30b on the pole tooth 15. Similarly, one protruding tooth 10a is formed at an intermediate position between the position of the pole tooth 21b adjacent to the pole tooth 21a in the pole tooth 12 and the position of the pole tooth 31b adjacent to the pole tooth 31a in the pole tooth 14. . Further, the pole tooth 2 adjacent to the pole tooth 20a in the pole tooth 13
One protruding tooth 10a is formed at an intermediate position between the position of 0b and the position of the polar tooth 30b adjacent to the polar tooth 30a in the polar tooth 15. As can be seen from this, in the fifth embodiment, the respective pole teeth 12 to 1 forming the first row and the second row.
One of the protruding teeth 10a is formed at an intermediate position between the pole teeth facing in the opposite direction in the step 5. The protruding teeth 10a formed at such positions are formed on the respective stator cores with the intervals between the adjacent protruding teeth 10a being constant.

FIG. 21 shows a structural model diagram in which the protruding teeth 10a positioned as described with reference to FIG. 20 are separately arranged on the two stator cores 3a2 and 3b1. As shown in FIG. 21, the protruding tooth 10a1 formed at the intermediate position between the pole tooth 21a and the pole tooth 31a in FIG. 20 is integrally formed with the stator core 3a2. Further, the protruding tooth 10a2 formed at the intermediate position between the pole tooth 20a and the pole tooth 30a is the stator core 3b1.
Are formed integrally with each other. Similarly, the pole teeth 21b and the pole are 3
The protruding tooth 10a1 formed at the intermediate position of 1b is integrally formed with the stator core 3a2, and the protruding tooth 10a formed at the intermediate position between the pole tooth 20b and the pole tooth 30b.
2 is formed integrally with the stator core 3b1. Thus, every other protruding tooth 10a in FIG. 21 is formed integrally with the stator core 3a2 and the stator core 3b1.

The structure of the stator cores 3a2 and 3b1 in which the protruding teeth 10a are integrally formed as described with reference to FIG. 21 will be described with reference to FIG. As shown in FIG. 19, the protruding teeth 10a1 formed on the stator core 3a2 are
There is a part where the formation positions overlap. Therefore,
A recess 41 is formed at the base of the pole tooth 12, and a protruding tooth 10a1 is formed so as to face the permanent magnet 5 of the rotor 4 without buffering the pole tooth 12. In addition, the stator core 3b
The protruding tooth 10a2 formed in No. 1 is formed between the pole teeth 14. Further, as can be seen from the figure, in the fifth embodiment, the stator core 3a2 and the stator core 3b1 cannot be formed in the same shape. This point is disadvantageous as compared with the above-described embodiments.

The operation and effect of the step motor 50 of the fifth embodiment thus formed will be described below. It should be noted that detailed description will not be given of effects and advantages overlapping with the above-described embodiments. The torque generated by the protruding teeth 10a and the pole teeth 12 to 15 that are set and arranged as described with reference to FIGS. 19 and 21 and the holding torque that is the combined torque thereof will be described with reference to FIG.

The generated torque generated by each pole tooth 12 to 15 is the same as that in the above-described embodiments, and as shown in FIG. 22 (a), the step motor 50 is de-energized at the rotation angle β. . In addition, as in the fourth embodiment, as shown in FIG. 22B, the auxiliary torque generated by the protruding teeth 10a has a generation cycle thereof as shown in FIGS.
The cycle is twice as long as the cycle generated in the step motor of No. 9. In addition, the stop angle O of the step motor 50 by the auxiliary torque in the fifth embodiment is the same as the step motor 5 by the auxiliary torque shown in FIG. 16 in the third embodiment.
Compared with the stop angle N of 0, it is shifted by a half cycle. this is,
The arrangement position of the protruding teeth 10a in the fifth embodiment and the third
This is because when compared with the arrangement position of the projecting tooth 10a in the embodiment, it is just shifted by a half cycle.

Therefore, the holding torque obtained by combining the generated torque and the auxiliary torque is as shown in FIG. 22C, and the stop angle of the step motor 50 is X. However, for the step motor 50, this is merely a deviation of the reference position of the stop angle and does not adversely affect the efficacy. Further, although the stator cores 3a2 and 3b1 cannot be formed in the same shape, the effect similar to the effect described in detail in the above-described embodiments can be exerted also in the fifth embodiment except for this point.

Next, a sixth embodiment of the present invention will be described with reference to FIG. The stator core shown in FIG. 23 has a fourth
In the embodiment and the fifth embodiment, the protruding teeth 10a are distributed to the two stator cores 3a2 and 3b1,
For example, in accordance with the arrangement pattern of the protruding teeth 10a shown in FIG. 13, all the protruding teeth 10a are integrally formed on one stator core 3a2. Of course, it may be formed integrally with the stator core 3b1. Thus, when the protruding teeth 10a are integrally formed on one stator core, if the protruding teeth 10a are formed on the stator core arranged near the center of the cylindrical width of the permanent magnet 5, the magnetomotive force from the permanent magnet 5 is generated. It can receive a large amount, which is advantageous for increasing the holding torque. However, it is only necessary to generate a holding torque of a predetermined value or more, and if the holding torque that can be generated when the protruding teeth 10a are provided on the stator core 3a1 or 3b2 is sufficient to fulfill the function, the stator core 3a1 or 3b2 protruding teeth 10a are integrally formed. You may do it. In this case, the protruding tooth 10a is 1
Since the forming positions of the pole teeth 12 and the forming positions of the pole teeth 12 overlap with each other, the deforming portion 42 is formed at the base portion of the pole teeth 12 in the stator core 5. Then, the protruding tooth 10a is projected between the deformed portion 42 and each pole tooth 12.

As described above, also in the step motor 50 in which the protruding teeth 10a are integrally formed only on the stator core 3a2, the same effects as those of the above-described embodiments can be obtained. Next, a seventh embodiment according to the present invention will be described with reference to FIGS.

FIG. 24 shows the protruding tooth 10 in the seventh embodiment.
FIG. 25 is a configuration diagram showing a configuration of a stator core 3a2 integrally formed with a, and FIG. 25 is a model diagram showing a basic pattern of a positional relationship between the pole teeth 12 to 15 and the protruding teeth 10a formed as shown in FIG. Is. First, using FIG. 25,
The pole teeth 12, 13 forming the first row and the pole teeth 14, forming the second row,
The positional relationship between 15 and the protruding tooth 10a will be described. In addition, in the seventh embodiment as well, as in the above-described embodiments, the second
Pole teeth 12, 13 forming a row and pole teeth 14, 15 forming a second row
Have the same positional difference as in the first embodiment. Also,
In the seventh embodiment, the number of poles of the projecting teeth 10a is the same as the number of magnetic poles of the permanent magnet 5, the step motor 50 is energized by one-phase excitation, and the stop position of the stator core when energized, The positions of the projecting teeth 10a are set so that the stop positions of the stator core 1 when power is not applied are matched.

As can be seen from FIG. 25, the protruding teeth 10a
Is the protruding teeth 12, 13 (14,
The same number as the total number of 15), in other words, N of the permanent magnet 5,
One is formed for each S pole. 1 of the protruding teeth 10a
One is integrally formed with the stator core 3a2 at the same position as the position of the predetermined pole tooth 30a in the pole tooth 15 of the second row. Further, the projection teeth adjacent to the predetermined projection teeth are integrally formed on the stator core 3a2 at the same positions as the pole teeth 31a adjacent to the pole teeth 30a in the second row. Further, the protruding teeth formed next to it are integrally formed on the stator core 3a2 at the same positions as the pole teeth 30b adjacent to the pole teeth 31a. No protruding tooth is formed on the stator core 3b1. In addition, the protruding teeth 10 a arranged in this manner are used for the permanent magnets 5 of the rotor 4.
And are arranged to face each other as shown in FIG.

As shown in FIG. 24, the projecting teeth 10a whose arrangement position is set as shown in FIG.
Are formed integrally with each other. The structure of the stator core 5 will be described below with reference to FIG. As can be seen from FIG. 24, the protruding teeth 10a are all integrally formed with the stator core 3a2. That is, the protruding teeth 10a are formed on both lateral sides of all the pole teeth 12 formed on the stator core 3a2. The height of the protruding tooth 10a from the inner circumferential portion of the stator core 3a2 is substantially the same as the height of the pole tooth 12.

The stator core 3a constructed as described above
The operation and effect of the seventh embodiment adopting No. 2 will be described below. Note that description that overlaps with the above-described embodiments will be omitted. With reference to FIG. 27, the generated torque generated by each pole tooth 12 to 15 in the step motor 50 in the seventh embodiment, the auxiliary torque generated by the protruding tooth 10a, and the holding torque obtained by combining them will be described.

The generated torque generated by the pole teeth 12 to 15 forming the first row and the second row is as shown in FIG. 27 (a). The non-energization stop angle due to this generated torque is the rotation angle β. . However, the rotation angle β is the energization stop position when the step motor 50 is energized and driven by the two-phase excitation.
Therefore, the auxiliary torque generated by the protruding teeth 10a forces the non-energization stop position of the step motor 50,
The step motor 50 is set to the stop position V when energized by one-phase excitation.

For this purpose, a torque which is larger than the generated torque by a certain degree or more is generated, and the stop angle becomes the rotation angle V by the torque. Therefore, in the protruding teeth 10a set and arranged as described above, the stop angle of the shaft 8 is P.
An auxiliary torque that satisfies the above condition is generated as shown in FIG. When such generated torque and auxiliary torque are combined, a holding torque as shown in FIG. 27 (c) is produced. Here, the stop position of the rotor 4 at this holding torque, that is, the stop angle of the step motor 50 becomes the angle of the rotation angle γ because the auxiliary torque is larger than the generated torque to some extent or more. Here, the rotation angle γ is as shown in FIG.
Although it coincides with the stop angle V in 7 (a), the occurrence frequency is half of the stop angle V. In this way, if the non-energized stop position and the energized stop position of the step motor that is energized by the one-phase excitation method are matched, the actuator of the anti-skid controller (brake piping is connected to -When opening and closing a valve element to be shut off), the opening and closing amount when not energized and the opening and closing amount when energized can be matched, which is advantageous in drive control of the actuator.

The step motor 50 of the seventh embodiment as described above can also achieve the same effects as those of the above-described embodiments. Next, an eighth embodiment of the present invention will be described with reference to FIGS. In the eighth embodiment, the installation position pattern of the protruding teeth 10a in the eighth embodiment is changed.

That is, as shown in FIG.
0a is formed integrally with the stator core 3a2 at the same position as the pole teeth 12 and 13 forming the first row. Of course, the protruding teeth 10a may be integrally formed on the stator core 3b1. The protruding tooth 10 whose arrangement position is set in this way
As shown in FIG. 28, a is integrally formed with the stator core 3a2. The structure of the stator core 3a2 will be described below with reference to FIG.

As can be seen from FIG. 28, all the protruding teeth 10a are integrally formed on the stator core 3a2. Here, since every other protruding tooth 10a has a forming position which overlaps with the pole tooth 12, a hollow portion 43 is provided at the base portion of the pole tooth 12 to project the protruding tooth 10a. Further, the other protruding teeth are arranged on the lateral side of the pole teeth 12. These protruding teeth 1
The height of the stator tooth 0a from the inner circumferential portion of the stator core 3a2 is substantially the same as the height of the pole teeth 12.

The stator core 3a constructed as described above
The operation and effect of the eighth embodiment which adopts No. 2 will be described below. Note that description that overlaps with the above-described embodiments will be omitted. With reference to FIG. 30, the generated torque generated by the pole teeth 12 to 15, the auxiliary torque generated by the protruding teeth 10a, and the holding torque obtained by combining them in the step motor 50 according to the eighth embodiment will be described.

The generated torque generated by the pole teeth 12 to 15 forming the first row and the second row is as shown in FIG. 30 (a), which is the same as that shown in FIG. do not do. The auxiliary torque generated by the protruding teeth 10a set and arranged as described above is as shown in FIG. 30 (b), and the stop angle of the shaft 8 at this auxiliary torque is Q.
Is. Further, in comparison with the seventh embodiment, the arrangement position of the projecting teeth 10a is displaced as described above in the eighth embodiment, so the rotation angle Q of the shaft 8, that is, the step motor 5
The rotation angle Q of 0 is shifted by a half cycle.

When such generated torque and auxiliary torque are combined, a holding torque as shown in FIG. 30 (c) is produced. Here, the stop angle of the rotor 4 at this holding torque, that is, the stop angle of the step motor 50 is the rotation angle Z because the auxiliary torque is larger than the generated torque to some extent or more. Here, the stop angle Z is
Although it coincides with the rotation angle V in FIG. 30A, the frequency of occurrence thereof is half the rotation angle V.

The step motor 50 in the eighth embodiment as described above can also achieve the same effects as those of the above-described embodiments. Next, a ninth embodiment of the present invention will be described based on FIGS. 33 and 34. In the ninth embodiment, in the arrangement position setting pattern of the protruding teeth 10a in the eighth embodiment, the protruding teeth 10a are replaced by the stator core 3a.
2 and the stator core 3b1.

That is, as shown in FIG. 31, the protruding tooth 10a formed at the same position as the pole tooth 12 in the first row is
Projecting teeth 10a1 integrally formed with the stator core 3a2
Has become. Further, the auxiliary pole formed at the same position as the pole tooth 13 in the first row is the projection tooth 10a2 integrally formed with the stator core 3b1. Further, the stator cores 3a2 and 3b1 integrally formed with the protruding teeth 10a arranged and set in this way are configured as shown in FIG. At this time, needless to say, the stator core 3a2 on which the protruding teeth 10a1 are formed is an abbreviation of the protruding teeth formed between the pole teeth 12 of the stator core 3a2 in the eighth embodiment. Further, in the stator core 3b1, when the protruding teeth 10a2 buffer the pole teeth 14, the notch portion 40 is provided as shown in the drawing. In the ninth embodiment, the stator core 3a2 and the stator core 3b are
The shapes of 1 are not formed in the same shape.

Further, FIGS. 33 and 34 show a tenth embodiment of the present invention. In the tenth embodiment, in the arrangement position setting pattern of the protruding teeth 10a according to the eighth embodiment, the method of allocating the protruding teeth 10a to the two stator cores 3a2 and 3b1 is the reverse of that of the ninth embodiment. It is the one. That is, as shown in FIG. 33, the protruding teeth formed at the same positions as the pole teeth 12 in the first row are the protruding teeth 10a2 integrally formed with the stator core 3b1. The protruding teeth formed at the same positions as the pole teeth 13 in the first row are the protruding teeth 10a1 formed integrally with the stator core 3a2.

Further, the protruding teeth 1 thus arranged and set.
The stator cores 5 and 6 integrally formed with
It is configured as shown in FIG. At this time, needless to say
The stator core 3a2 on which the protruding teeth 10a1 are formed is an abbreviated form of the protruding teeth formed on the cavity 43 of the pole teeth 12 of the stator core 3a2 in the ninth embodiment. Also,
In the stator core 3b1, when the protruding teeth 10a2 buffer the pole teeth 14, the notch 40 is provided as shown in the figure. In the tenth embodiment, the stator core 3a2 and the stator core 3b1 cannot be formed in the same shape.

The present invention is not limited to the above embodiment, but can be variously modified as follows. That is,
In the fourth and fifth embodiments, the projecting teeth 10a are distributed and integrally formed with the stator cores 3a2 and 3b1, but the invention is not limited to this, and the projecting teeth 10a may be integrally formed with one stator core. In addition, in the above-described embodiment, the protruding teeth 10a are provided on one or two stator cores.
However, it may be distributed to three or more stator cores. At this time, the projecting teeth 10a to be distributed may be, for example, two adjacent projecting teeth in FIG. 13 with respect to one distribution-target stator core. That is, if the projecting teeth 10a are distributed to three or more stator cores, the distance between the projecting teeth 10a is increased, so that the magnetic circuit for generating the auxiliary torque by the projecting teeth 10a is weakened (the magnetic flux density is reduced). It is possible that the holding torque cannot be generated,
By forming at least two adjacent protruding teeth 10a for each at least two stator cores, a sufficient magnetic circuit is formed between these two protruding teeth, and a large holding torque can be generated.

Further, in the above-mentioned embodiment, the protruding tooth 10a is the pole tooth 12, 14 of each stator core 3a2, 3b1.
When the formation position is buffered, the notch portion 40, the concave portion 41 or the deformed portion 42 is formed at the root portions of the pole teeth 12 and 14, respectively. However, the pole teeth 12,
By reducing the width of 14 or the width of the protruding tooth 10a itself, the cutout portion 4 as described above can be formed.
It is also possible to eliminate the need to form 0 and the like.

Further, each protruding tooth 10a has a respective pole tooth 12-1.
Although the heights of the permanent magnets 5 and the pole teeth and the gaps between the permanent magnets 5 and the protruding teeth were almost the same,
Not limited to this, it may be formed as follows.
That is, the protruding height of the protruding teeth 10a is increased to increase the rotor 4
The protruding teeth 10a may be set so as to approach the permanent magnet 5 of FIG. At this time, it is possible to increase the auxiliary torque by the protruding teeth 10a. Further, the protruding height of the protruding teeth 10a may be reduced and the protruding teeth 10a may be set to be far from the permanent magnet 5 of the rotor 4. In this case, the protruding tooth 1
It is possible to reduce the auxiliary torque due to 0a.

Further, the following method can be adopted as a method of adjusting the auxiliary torque by the protruding teeth 10a. That is, although the surface of the protruding tooth 10a facing the permanent magnet is a curved surface in the above-described embodiment, the auxiliary torque can be adjusted by forming the facing surface to be a flat surface and enlarging or reducing the area of this facing surface. Is. In this case, the auxiliary torque can be maximized when the area relationship is such that the ratio of the area of the protruding teeth 10a facing one magnetic pole to the area of one magnetic pole of the permanent magnet is a predetermined ratio. Therefore, the auxiliary torque can be adjusted by changing the area of the protruding teeth 10a and changing the ratio. In addition, protruding tooth 1
When the surface facing the permanent magnet 0a is a curved surface, the auxiliary torque can be adjusted by increasing or reducing the width of the protruding tooth 10a and expanding or contracting the area of the curved surface.

Further, the step motor 50 according to the present invention may be applied to the suspension position control actuator 60 for executing the four-wheel independent control shown in FIG. FIG. 35 shows a front view of the actuator structure of the shock absorber at that time, and FIG. 36 shows a vertical sectional view thereof. FIG.
5 shows the external appearance of a housing case 51 in which a step motor 50 and an electric circuit 53 for driving and controlling the step motor 50 are incorporated. Inside the case 51, a connector 52 for making electrical connection with the outside is also provided.

FIG. 36 is a sectional view showing the internal structure of the case 52. The electric circuit 53 is independently arranged in each step motor 50 provided corresponding to each suspension of the vehicle. The actuator 60 having such a configuration is arranged above the shock absorber in each suspension device for each wheel, and the driving force of the step motor 50 is connected to a control rod (not shown).

Here, the second stator core 10 is provided with a notch, and the terminal mounting portion 54 formed integrally with the spool for holding the exciting coil is arranged so that the electrical connection with the electric circuit 53 is prevented. There is. As described above, when the electronic control circuit 53 is made to correspond to each of the step motors 50 having a high holding torque according to the present invention and adopted for independent suspension control of four wheels, the accuracy of suspension operation can be improved. When the holding torque is strong when the suspension is not energized as described above, accurate damping force control can be performed without supplying power to the step motor 50 while maintaining the damping force of the suspension. You can avoid extra consumption.

[0094]

As described above, according to the present invention, it is possible to provide a step motor capable of increasing the holding torque of the rotor with a simple structure without sacrificing the physical size and performance. .

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the structure of a step motor according to the present invention in which a protruding tooth serving as an auxiliary pole is provided near the center of the cylindrical width of a permanent magnet.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a model diagram showing a positional relationship between the pole teeth forming the first row and the second row and the protruding teeth formed on each stator core in the first embodiment.

FIG. 4 is a model diagram showing a positional relationship between the projecting teeth and the pole teeth when the projecting teeth are distributed and formed on two stator cores in the first embodiment.

FIG. 5 is a characteristic diagram showing a generation state of each torque and a generation state of a holding torque in the step motor in the first embodiment.

FIG. 6 is a model diagram showing a positional relationship between projecting teeth and pole teeth in a step motor showing a modification of the first embodiment.

FIG. 7 is a characteristic diagram showing a generation state of each torque and a generation state of a holding torque in the step motor shown in FIG.

FIG. 8 is a model diagram showing the positional relationship between the pole teeth forming the first row and the second row and the protruding teeth formed on each stator core in the second embodiment.

FIG. 9 is a characteristic diagram showing a generation state of each torque and a generation state of a holding torque in the step motor in the second embodiment.

FIG. 10 is a model diagram showing a positional relationship between projecting teeth and pole teeth in a step motor showing a modification of the second embodiment.

FIG. 11 is a characteristic diagram showing a generation state of each torque and a generation state of a holding torque in the step motor shown in FIG.

FIG. 12 is a model diagram showing the positional relationship between the pole teeth forming the first row and the second row and the protruding teeth formed on each stator core in the third embodiment.

FIG. 13 is a model diagram showing the positional relationship between the pole teeth forming the first row and the second row and the protruding teeth formed on each stator core in the third embodiment.

FIG. 14 is a model diagram showing the positional relationship between the projecting teeth and the pole teeth when the projecting teeth are distributed and formed on two stator cores in the third embodiment.

FIG. 15 is a diagram showing a facing positional relationship between each protruding tooth and each magnetic pole of the permanent magnet formed on the rotor in the third embodiment.

FIG. 16 is a characteristic diagram showing a generation state of each torque and a generation state of a holding torque of the step motor in the third embodiment.

FIG. 17 is a configuration diagram showing a configuration of each stator core in which protruding teeth as auxiliary poles are formed between the respective pole teeth in the fourth embodiment.

FIG. 18 is a model diagram showing the positional relationship between the pole teeth forming the first row and the second row and the protruding teeth formed on each stator core in the fourth embodiment.

FIG. 19 is a configuration diagram showing a configuration of each stator core in which protruding teeth as auxiliary poles are formed between the respective pole teeth in the fifth embodiment.

FIG. 20 is a model diagram showing the positional relationship between the pole teeth forming the first row and the second row and the protruding teeth formed on each stator core in the fifth embodiment.

FIG. 21 is a model diagram showing the positional relationship between the projecting teeth and the pole teeth when the projecting teeth are distributed and formed on two stator cores in the fifth embodiment.

FIG. 22 is a characteristic diagram showing a torque generation state and a holding torque generation state of the step motor in the fifth embodiment.

FIG. 23 is a configuration diagram of a stator core according to a sixth embodiment.

FIG. 24 is a configuration diagram showing a configuration of a stator core in which projecting teeth as auxiliary poles are formed between respective pole teeth in the seventh embodiment.

FIG. 25 is a model diagram showing the positional relationship between the pole teeth forming the first row and the second row and the protruding teeth formed on each stator core in the seventh embodiment.

FIG. 26 is a diagram showing a facing positional relationship between each protruding tooth and each magnetic pole of the permanent magnet formed on the rotor in the seventh embodiment.

FIG. 27 is a characteristic diagram showing each torque generation state and holding torque generation state of the step motor in the seventh embodiment.

FIG. 28 is a configuration diagram showing a configuration of a stator core in which protruding teeth as auxiliary poles are formed between the respective pole teeth in the eighth embodiment.

FIG. 29 is a model diagram showing the positional relationship between the pole teeth forming the first row and the second row and the protruding teeth formed on each stator core in the eighth embodiment.

FIG. 30 is a characteristic diagram showing each torque generation state and holding torque generation state of the step motor in the eighth embodiment.

FIG. 31 is a model diagram showing the positional relationship between the projecting teeth and the pole teeth when the projecting teeth are distributed and formed on two stator cores in the ninth embodiment.

FIG. 32 is a structural diagram showing the structure of a stator core in which protruding teeth as auxiliary poles are formed in the ninth embodiment.

FIG. 33 is a model diagram showing the positional relationship between the projecting teeth and the pole teeth when the projecting teeth are distributed and formed on two stator cores in the tenth embodiment.

FIG. 34 is a configuration diagram showing a configuration of a stator core in which projecting teeth as auxiliary poles are formed in the tenth embodiment.

FIG. 35 is a front view of an actuator that employs a step motor according to the present invention.

FIG. 36 is a sectional view of the actuator shown in FIG. 35.

FIG. 37 is a diagram showing the relationship between the projection teeth and the permanent magnet in the conventional step motor.

FIG. 38 is a first row and a second row in the conventional step motor.
It is a model figure which shows the relationship between the pole tooth and the projection tooth which form a row, and the formation condition of a magnetic circuit.

FIG. 39 is a characteristic diagram showing a generation state of each torque and a generation state of a holding torque in the conventional step motor.

[Explanation of symbols]

 50 Step motor 1 First housing 2 Second housing 3a1, 3a2, 3b1, 3b2 Stator core 4 Rotor 5 Permanent magnet 8 Shafts 9a, 9b Excitation coil 10 Second stator core 10a Projection teeth 11 Space 12, 13 First row Polar tooth group to be formed 14 and 15 Polar tooth group to form the second row 40 Notch portion 41 Recessed portion 42 Deformed portion 43 Cavity portion

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masayuki Yano, 1-1, Showa-cho, Kariya city, Aichi prefecture, Nihon Denso Co., Ltd. (72) Kenji Tange, 1-1, Showa-cho, Kariya city, Aichi prefecture, Nihon Denso Co., Ltd. Within the corporation

Claims (20)

[Claims] 1. A rotor having a cylindrical permanent magnet having an N pole and an S pole alternately magnetized on an outer peripheral surface thereof, the rotor being rotatably supported by a rotor, and a predetermined rotor for the permanent magnet. A plurality of stator cores formed in the shape of a hollow disc having pole teeth arranged in the inner circumference of the rotor core and facing each other with a gap between the stator core and the stator core. An exciting coil to be moved, and at least an auxiliary pole arranged to face the cylindrical surface of the permanent magnet so as to generate a holding torque by being magnetized by the permanent magnet when the exciting coil is not energized. Two protruding teeth, each of the protruding teeth being a continuous N pole of the permanent magnet,
A step motor, which is arranged so as to face the S pole. 2. The step motor according to claim 1, wherein the number of the protruding teeth is equal to the number of magnetic poles of the permanent magnet. 3. The protruding teeth are formed such that a distance between the protruding teeth and an adjacent protruding tooth is substantially constant.
Step motor described in. 4. The width of the protruding tooth in the circumferential direction with respect to the permanent magnet is formed to be smaller than the width of each magnetic pole of the permanent magnet. Step motor described in. 5. The step according to any one of claims 1 to 4, wherein the protruding teeth are arranged so as to face each other in the vicinity of the center of the cylindrical width of the permanent magnet. motor. 6. A second stator core, which is arranged in parallel with a plurality of magnetic stator cores and is formed into a hollow disk shape by a magnetic material, wherein the protruding teeth are integrally formed on an inner circumferential portion of the second stator core. Claim 1 thru | or Claim 5 characterized by the above-mentioned.
Step motor according to any one of 1. 7. The step motor according to claim 1, wherein the protruding teeth are integrally formed on at least one of the plurality of stator cores. 8. The plurality of stator cores includes a first row of pole teeth formed by two stator cores arranged so that pole teeth facing in opposite directions are meshed with each other, and the other two stator cores similarly. A second pole tooth group formed by: and the second stator core between the stator core having the pole tooth group forming the first row and the stator core having the pole tooth group forming the second row. The step motor according to claim 6, wherein the step motor is arranged. 9. The pole teeth of the pole tooth group forming the first row and the pole tooth group forming the second row are arranged such that their circumferential positions with respect to the outer surface of the permanent magnet are displaced from each other by a predetermined amount. And the projecting teeth of the second stator core are arranged at an intermediate position between the closest pole teeth facing in the same direction in the pole tooth group forming the first row and the pole tooth group forming the second row. 9. The step motor according to claim 8, wherein: 10. The respective pole teeth in the pole tooth group forming the first row and the pole tooth group forming the second row are arranged such that their circumferential positions with respect to the outer surface of the permanent magnet deviate from each other by a predetermined amount. And the protruding teeth of the second stator core are arranged at an intermediate position between the closest pole teeth facing in opposite directions in the pole tooth group forming the first row and the pole tooth group forming the second row. 9. The step motor according to claim 8, wherein: 11. The respective pole teeth of the pole tooth group forming the first row and the pole tooth group forming the second row are displaced from each other in a circumferential direction with respect to the outer surface of the permanent magnet by a predetermined amount. And the protruding teeth of the second stator core are aligned with respective pole tooth positions of either one of the pole tooth group forming the first row and the pole tooth group forming the second row. The step motor according to claim 8, wherein 12. The plurality of stator cores includes a first row of pole teeth formed by two stator cores arranged so that pole teeth facing in opposite directions are meshed with each other, and the other two stator cores similarly. And a second pole tooth group formed by the second pole tooth group, wherein the protruding tooth is arranged in a portion close to the pole tooth group forming the second row in the two stator cores including the pole tooth group forming the first row. At least one of the two stator cores provided with the pole teeth group forming the second row, and the one of the two stator cores including the pole teeth group forming the second row arranged nearer to the pole teeth group forming the first row. The step motor according to claim 7, wherein the step motor is integrally formed. 13. The plurality of stator cores includes a first row of pole teeth formed by two stator cores arranged so that pole teeth facing in opposite directions mesh with each other, and two other stator cores similarly. And a second pole tooth group formed by the second pole tooth group, wherein the protruding tooth is arranged in a portion close to the pole tooth group forming the second row in the two stator cores including the pole tooth group forming the first row. Distributed to the two stator cores, one of which is arranged closer to the pole tooth group forming the first row in the two stator cores including the pole tooth group forming the second row. The step motor according to claim 7, wherein the step motor is formed integrally with each stator core. 14. The respective pole teeth of the pole tooth group forming the first row and the pole tooth group forming the second row are displaced from each other by a predetermined amount in the circumferential direction with respect to the outer surface of the permanent magnet. And the protruding teeth are arranged at an intermediate position between the closest pole teeth facing the same direction in the pole tooth group forming the first row and the pole tooth group forming the second row. The step motor according to claim 12 or claim 13. 15. The respective pole teeth of the pole tooth group forming the first row and the pole tooth group forming the second row are arranged such that their circumferential positions with respect to the outer surface of the permanent magnet are displaced from each other by a predetermined amount. And the protruding teeth are arranged at an intermediate position between the nearest pole teeth facing in opposite directions in the pole tooth group forming the first row and the pole tooth group forming the second row. The step motor according to claim 12 or claim 13. 16. The positions of the respective pole teeth in the first group of pole teeth and the second group of pole teeth in the circumferential direction with respect to the outer surface of the permanent magnet deviate from each other by a predetermined amount. And the projecting teeth are aligned with respective pole tooth positions of either one of the pole tooth groups forming the first row and the pole tooth group forming the second row. The step motor according to claim 12 or claim 13. 17. The step motor according to claim 1, wherein a portion of the protruding tooth facing the permanent magnet is formed in a curved shape. 18. The magnitude of the holding torque generated by the protruding teeth is set to an arbitrary magnitude by increasing or decreasing the area of the portion of the protruding teeth facing the permanent magnet. Claims 1 to 17
Step motor according to any one of 1. 19. The amount of holding torque generated by the protruding teeth is set to an arbitrary value by setting a gap between a tip of the protruding teeth and a cylindrical surface of the permanent magnet to be a predetermined distance. Claims 1 to 18
Step motor according to any one of 1. 20. The step motor according to claim 1, wherein the pole teeth formed on the plurality of stator cores have a comb tooth shape.