JPH11235001A - Permanent magnet stepping motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a permanent magnet stepping motor in which drive windings are wound on salient poles so as not to create a dead space. SOLUTION: This stepping motor is provided with a cylindrical permanent magnet rotor 25 having a cylindrical shaft 24 as a rotating shaft and multiple poles of N and S magnetized alternately at an equal interval in the circumferential direction, a stator yoke 21 with salient poles 40 arranged at an equal interval in the circumferential direction surrounding the permanent magnet rotor 25, and drive winding mounting parts 41 each protruding from salient pole 40 in the shaft direction of the rotor 25 and around which drive windings 22a to 22h are wound. Furthermore, the protruding ends of the neighboring winding mounting parts 41 are each jointed with a yoke plate 43.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a permanent magnet (PM) stepping motor using a multi-pole magnetized permanent magnet as a rotor.

[0002]

2. Description of the Related Art FIG. 6 shows a conventional stepping motor having four-phase winding salient pole type magnetic poles. In FIG. 6, 2
Numeral 5 denotes a permanent magnet rotor having a cylindrical shape and N-poles and S-poles alternately multipole magnetized on the outer peripheral surface. In this example, the rotating shaft 2
4 and a permanent magnet rotor (hereinafter referred to as a rotor) 25
Rotates about a central axis perpendicular to the plane of the paper. The stator includes a stator yoke 21 in which a drive winding is wound around eight salient poles 30, and a yoke case 21a that fixedly supports the stator yoke 21. The mechanical rotation angle corresponding to the magnetic pole pitch angle of the rotor 25 (this is called a mechanical angle) is 180 °, and the magnetic flux flowing into the stator yoke 21 changes by one cycle. This one cycle change is 360
The rotation angle of the rotor 25 measured in degrees is called an electrical angle. According to this expression, the salient poles 30 are arranged by being shifted by 45 degrees in electrical angle.

[0003] If the origin at which the magnetic flux distribution generated when a current is applied to the drive winding (solenoid winding) 22a is measured by an electrical angle is 0 °, if the current is applied to the drive winding 22b in the same direction, the electrical angle is reduced. A magnetic flux distribution of 45 ° occurs. At this time, if the drive winding 22a is a 0 ° winding, the drive winding 22b is 4 °.
5 °, drive winding 22c is 90 °, drive winding 22d is 13
5 °, the drive winding 22e is 180 °, and the drive winding 22f is 2
The drive winding 22g is a 270 ° winding, and the drive winding 22h is a 315 ° winding. By switching the drive windings driven in this order, the rotor 25 advances by the magnetic pole pitch.

In such a motor, the stator yoke 21 is generally assembled by fusing the base of each salient pole 30 to the inner surface of the yoke case 21a by a high-density energy beam such as a laser beam, and then fixing the salient pole 30 Are inserted around the center axis of the yoke case 21a from the center axis side of the yoke case 21a, and the windings are sent out and supplied to the needles and rotated around the salient poles 30 to drive around the salient poles 30. The windings 22a to 22h are wound.

[0005]

However, a needle is inserted between the narrow salient poles 30 from the center side in the yoke case 21a, and the driving winding is wound around the salient poles 30. However, there is a problem in that a winding machine having a special mechanism must be used, and the cost of the motor increases accordingly.

Further, since the inside of the yoke case 21a is narrow and has low visibility, even when the above-mentioned special winding machine is used, in order to keep the density of the winding, the accuracy of winding and the like constant, the driving winding is required. There is a problem that the feed speed and the winding speed of the wires 22a to 22h must be set to low speeds.

If the drive windings 22a to 22h are wound around the axis of the salient pole 30 as the center of rotation of the needle, the drive winding 2 wound around the adjacent salient pole 30 may be used.
Even when the outer surfaces 2a to 22h are set so as not to contact each other, a dead space A is formed between the drive windings wound around the adjacent salient poles 30, 30 which cannot contribute to the enhancement of the magnetic force at all. As a result, there is a problem that the volume of the yoke case 21a is wasted.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a permanent magnet type stepping motor in which a winding can be easily attached without using a special winding machine. It is in.

It is another object of the present invention to provide a permanent magnet type stepping motor configured so that a driving winding can be attached to a salient pole so that there is no dead space.

[0010]

In order to achieve the above object, a permanent magnet type stepping motor according to the first aspect of the present invention uses a cylindrical shaft as a rotating shaft and alternately alternates NS at equal intervals in a circumferential direction. A multi-pole magnetized cylindrical permanent magnet rotor, and a stator yoke surrounding the permanent magnet rotor and having salient poles arranged at equal intervals in a circumferential direction, wherein the stator yoke includes the respective salient poles. Further, the mounting portion of the drive winding is formed so as to protrude along the axial direction of the rotor, and the drive winding is attached by winding around the drive winding mounting portion,
The protruding ends of adjacent winding attachment portions are connected by a yoke plate.

According to a second aspect of the present invention, in the permanent magnet type stepping motor according to the first aspect of the present invention, the driving winding is connected to the winding attaching portion from a projecting end side. It is characterized in that it is wound into a coil in advance so as to be fitted and attached.

Further, in the permanent magnet type stepping motor of the invention according to claim 3 of the present application, in the permanent magnet type stepping motor according to claim 2, each of the coils is mounted on the winding mounting portion. It is characterized in that it is wound in a substantially fan shape so as to form a gap along the radial direction of the rotor between the adjacent coils in the state.

Still further, in the permanent magnet type stepping motor according to the invention according to claim 4 of the present application, the above-described claim 1 is provided.
4. The permanent magnet type stepping motor according to any one of the first to third aspects, wherein the yoke plate is formed in a ring shape in which the projecting end faces of the respective wire winding attachment portions are connected along the circumferential direction of the rotor.

According to a fifth aspect of the present invention, in the permanent magnet type stepping motor according to the first aspect of the present invention, the yoke case for supporting the stator yoke is made of resin. And the stator yoke is integrally molded with the yoke case.

That is, if each of the salient poles is provided with a drive winding attaching portion which is formed so as to protrude in the axial direction of the rotor, and around which the drive winding is attached in a wound shape. ), The drive winding can be easily attached even with a general winding machine. If the drive winding is wound in advance and formed into a coil (claim 2), the drive winding coil can be fitted and attached. In any case, the attachment is performed from the protruding end side of the winding attachment portion, so that even if the inside of the yoke case is narrow, visibility and workability are good, and efficient attachment is possible.

In particular, when the drive winding is formed in advance in the coil (claim 2), the working efficiency can be remarkably improved as compared with the case where the drive winding is wound in the yoke case.
In addition, the winding density and the number of turns for each salient pole can be made constant. For this reason, when the coil is used for the attachment in advance, not only the attachment time can be shortened, but also the torque fluctuation of the rotor caused by the difference in the winding quality can be suppressed.

After the drive winding is wound, the projecting ends of the drive winding mounting portions of adjacent salient poles are connected to each other by a yoke plate (claim 1), whereby these two salient poles are magnetically connected. It becomes one electromagnet. For this reason, a stronger magnetic force acts on the permanent magnetic pole of the rotor than before. In this case, when the yoke plate is formed in an annular shape so as to connect the protruding end surfaces of the respective wire machine winding mounting portions (claim 4), the number of mounting steps can be reduced, and the cost can be reduced. Become.

Here, when the drive winding is wound in advance to form a coil, a uniform gap along the radial direction of the rotor is provided between adjacent coils in a state where the coil is attached to the drive winding attachment portion. When the coil is viewed from the protruding end side of the drive winding mounting portion, the outer surface of the coil on the rotor side forms a short arc along the permanent magnetic pole of the rotor, while the outer surface of the coil on the opposite side is the yoke case 21a. If it is formed in a substantially fan shape so as to form an elliptical arc along the inner peripheral surface of the coils (claim 3), the coils 42a to 42
The above-mentioned dead space A can be eliminated, the number of coil turns and the winding density can be increased, and the magnetic force of each salient pole can be increased simply by inserting d into each winding attachment portion 41 and attaching it. Alternatively, since the number of coil turns can be freely adjusted within the dead space, if the number of coil turns is adjusted so that the torque of the rotor 25 becomes the same as that of the conventional motor, a motor having the same performance can be reduced in size and weight. Can be manufactured.

In order to apply the coil insertion structure to the salient poles of the conventional step motor and to insert the coil from the rotor side, a large number of salient poles projecting toward the center become obstacles. It is desirable to mount the coil from a direction along the axial direction of the rotor because the performance is significantly reduced.

Further, a yoke case for supporting the stator yoke is formed of resin, and the stator yoke is molded integrally with the yoke case.
The number of processes and man-hours are reduced, and significant cost reduction is achieved.

[0021]

An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a plan sectional view of an essential part of an embodiment of the present invention, and shows a permanent magnet type four-phase stepping motor having eight salient poles 40. In this example, the rotor 25 is multipolar magnetized by NS alternately at equal intervals in the circumferential direction, and the salient poles 40 are arranged on the inner peripheral surface of the yoke case 21a accommodating the rotor 25 around the rotor 25. It is fixed and supported at a mechanical angle of 45 °. Each of the salient poles 40 has a substantially central portion between a tip end on the rotor 25 side and a base fixedly supported by the yoke case 21a.
5 is integrally formed and provided so as to protrude along the axial direction of 5, and drive windings (solenoid windings) 22a to 22h are attached to the drive winding attachment 41. I have.

The drive windings 22a to 22h are attached by winding with a general winding machine or by driving the windings 22a to 22h.
Is formed in advance by winding and forming the coils 42a to 42d, and the coils 42a to 42d are fitted into the winding mounting portion 41.
1, that is, from the direction along the axial direction of the rotor 25, the visibility and workability are good, and the mounting efficiency is improved as compared with the conventional case. Here, in the present embodiment, in order to make the quality of the drive windings 22a to 22h attached to the winding mounting part 41 as a whole and to make the rotation of the motor as smooth as possible, Coils 42a to 42
d is attached.

The coils 42a to 42d to be attached are shown in FIG.
3, the outer surface of the coil on the rotor 25 side is a short arc along the permanent magnet of the rotor 25, and the outer surface of the coil on the opposite side is a yoke case when viewed from the protruding end side of the winding attachment portion 41. In a state of being formed in a substantially fan-like shape that forms an elliptical arc along the inner peripheral surface of the coil 21a, and attached to each salient pole 40, a slight uniform space is formed between adjacent coils along the radial direction. It is the size that is formed. Therefore, such coils 42a to 42a
The dead space A in FIG. 6 is eliminated only by attaching 42d, and the number of coil turns and the density can be increased by the amount of the dead space. Therefore, a strong magnetic force corresponding to the increase in the number of coil turns is applied to the permanent magnetic pole of the rotor 25. Can work,
It is possible to improve torque performance and the like as much as possible. Alternatively, the number of turns (size) of the coil and the inner diameter of the yoke case 21a can be appropriately changed according to the range of the dead space A. Can be formed small and lightweight.

FIG. 3 shows that the magnetic force acting on the permanent magnetic pole of the rotor 25 is strengthened by connecting the protruding ends of the adjacent drive winding attaching portions 41 to each other and connecting them magnetically with a yoke plate 43. An example is specifically shown. That is, the adjacent drive winding attachment portions 41, 41 are combined into one set and connected by the yoke plate 43 for each set, or the annular yoke plate 43 that bridges over the protruding end of each drive winding attachment portion 41. Thereby, all the drive winding attachment portions 41 are connected along the circumferential direction.

In any case, a pair of adjacent salient poles constitute a single electromagnet, and the rotor 25
Thus, a stronger magnetic force can be applied.
In this embodiment, the magnetic connection is made by the latter annular yoke plate 43 in order to reduce the number of steps, and the magnetic characteristics are further improved by laminating a magnetic shield layer (not shown) on the outer surface of the yoke case 21a. I have.

FIG. 4 is a schematic view showing a process of assembling the stator.

In this example, a rotor (rotor) 25, a yoke plate 43, an FPC (flexible printed circuit) 4
5 are produced in separate processes and integrated in this assembly process. That is, after the coils 42 a to 42 d are attached to the drive winding attaching portion 41, a through hole is provided between the coils 42 a to 42 d and the yoke plate 43 to allow the projecting end of the drive winding attaching portion 41 to pass therethrough. The stator yoke 21 is formed by interposing an FPC (flexible printed circuit) 45 having 46, and the stator yoke 21 is set at a predetermined position of a mold (not shown). The coil 42
It is preferable that a to 42d are connected to the FPC 45 in advance and are integrally attached.

After the setting, the mold is filled with a non-magnetic, preferably lightweight and corrosion-resistant resin material, more preferably a synthetic resin material, and after a predetermined aging, the integral molding is completed.

After the integral molding, the yoke case 21a
The rotor 25 is inserted into the yoke case 21a through the opening 21b.
Into one end 2 of the rotating shaft 25 on the bottom shaft support 21c.
After the rotor 5a is rotatably supported, a flange (front flange) 44 is fitted and fixed to the opening 21b of the yoke case 21a from the other end 25b side of the rotor 25, and a shaft supporting portion 44a of the flange 44 and the bottom shaft supporting portion 21c. Thus, the rotor 25 is rotatably supported and the assembly of the stator yoke 21 is completed.

In this assembly, the yoke case 2
The integration of the stator 1a and the stator yoke 21 is sufficient if at least the inner surface of the yoke case 21a and the base of the drive winding attaching portion 41 are integrally molded, but the yoke plate 43, the FPC 45, and the coils 42a to
42d is also integrally molded at the same time, and the stator yoke 2
It is also possible to increase the integration with the device 1 and to cope with rough handling.

The electrical connection between the coils 42a to 42d and the drive power supply is made through the FPC 45.
The electrical connection with the PC 45 is made by the drive windings 22a and 22b,
The drive windings 22c and 22d, the drive windings 22e and 22f, and the drive windings 22g and 22h are connected in series so that the torque generated when a drive current flows through each of the drive windings 22c and 22d forms a four-phase. To be.

Then, the end of winding of the first coil and the start of winding of the second coil are connected in series so that two adjacent coils are wound in the same direction.

FIGS. 1B, 1C and 1D show permanent magnet rotors 26, 27 and 28 which can be used in place of the rotor 25, respectively. 6B, the permanent magnet rotor 26 is magnetized with 6 poles, the permanent magnet rotor 27 shown in FIG. 2C is magnetized with 10 poles, and the permanent magnet rotor 28 shown in FIG. Have been. When the permanent magnet rotor 26 is used, the interval between a pair of adjacent salient poles 40 is 135 electrical degrees. Also in this case, the winding end of the first coil and the winding start of the second coil are connected to form a series.
When the permanent magnet rotor 27 is used, the interval between the pair of salient poles is 225 degrees in electrical angle. Also in this case, the winding end of the first coil and the winding start of the second coil are connected to form a series. Further, when the permanent magnet rotor 28 is used, 1
The interval between the pair of salient poles is 315 ° in electrical angle. In this case, the end of winding of the first coil and the start of winding of the second coil are connected in series.

With the above arrangement, the distance between the four-phase drive windings shifted by 90 ° in electrical angle and the adjacent pair of salient poles is 45 °.
° or 135 ° or 225 ° or 315 °
Is realized. Each of these stepping motors satisfies the condition that the fourth-order high frequency component of the detent torque can be canceled inside the motor.

FIG. 5 is a diagram for explaining the principle of cancellation of the fourth-order high-frequency component. In the figure, reference numeral 3 denotes a part of the permanent magnet magnetic poles which are multipole magnetized at equal intervals alternately with NS.
The pitch at which the pair of magnetic poles is magnetized is an electrical angle of 36.
0 °. In this example, an armature having a four-phase drive winding wound around eight salient poles, using a drive winding (coil) attached to a pair of adjacent salient poles as one winding, is used as a basic unit. It is constituted as.

In the figure, 1-1 and 1-2 are a pair of salient poles. When the salient pole 1-1 is at a position of 0 electrical angle, the salient pole 1-2 is at a position of 315 °. It is arranged as it is.
Although not shown, the salient poles 1-2 may be arranged so as to be at 45 °, 135 °, or 225 ° when the salient poles 1-1 are at 0 ° in electrical angle. The winding 2-1 and the winding 2-2 are connected in series so that the torque generated by the drive current is additive.
In order for the torque to be additive, when the interval between a pair of salient poles measured by an electrical angle is 0 ° to 180 °, two drive windings are connected so as to be wound in the same direction, and 180 ° to 360 ° In the case of °, they are connected so that they are wound in opposite directions. When the salient pole 1-1 is at the position of 0 electrical angle, the salient pole 1-2 is 4
5 ° or 135 ° or 225 ° or 315
°, the number of permanent magnet magnetic poles arranged at an angle of eight salient poles of the armature is 2, 6, 10, and
14.

The detent torque waveform of FIG. 5 shows only the fourth high frequency component of the detent torque. Since a pair of salient poles is arranged at an electrical angle of 315 °,
Detent torque due to salient pole 1-1 and salient pole 1-2
As shown in the figure, the detent torque is opposite to the detent torque and is canceled. Also, a pair of salient poles has an electrical angle of 4
Detent torques generated by a pair of salient poles are out of phase with each other even if they are arranged at the positions of 5 °, 135 °, or 225 °, and are canceled out. Generally speaking, when a pair of salient poles are arranged at an interval of a natural number multiple of 45 °, the fourth order components of the detent torque generated by each of the pair of salient poles are out of phase with each other and cancel each other out. It is. In the symmetric two-phase or four-phase stepping motor according to the embodiment of the present invention, the secondary high-frequency component of the detent torque is canceled in principle inside the motor.
It is possible to realize a stepping motor that cancels the secondary and quaternary high-frequency components of the detent torque inside the motor. Of course, the number of salient poles is not limited to the armature yoke having a total of eight salient poles described in FIG. 1, and the number of salient poles is 8 m, where m is a natural number, and the number of permanent magnet magnetic poles is m times. However, it is apparent that the electrical angle between adjacent salient poles can maintain a relationship of a natural number multiple of 45 °.

[0039]

As described in detail in the above embodiments, according to the present invention, the following excellent effects are exhibited.

(1) In the stepping motor according to the first aspect, each of the salient poles of the stator yoke is formed so as to protrude therefrom in the axial direction of the rotor, and the driving winding is wound around the periphery thereof. By providing the winding attachment part, all drive windings can be attached from the protruding end side of the winding attachment part, so visibility and workability are improved even if the inside of the yoke case is narrow. It is possible to perform the attachment efficiently and efficiently, and it is possible to easily perform the winding attachment even with a general winding machine.

Further, since the protruding ends of the drive winding mounting portions of the adjacent salient poles are connected to each other by a yoke plate, and one salient pole constitutes one electromagnet, the permanent magnet of the rotor is stronger than the conventional one. A magnetic force can be applied, and the torque performance can be improved.

(2) In the stepping motor according to the second aspect, since the drive winding is wound in advance and formed into a coil, the drive winding coil can be fitted into the attachment portion and easily attached. The working efficiency can be remarkably improved as compared with the case where the drive winding is wound in the yoke case, and the winding density and the number of turns for each salient pole can be made as uniform as possible. For this reason, not only can the attachment time be reduced, but also torque fluctuations of the rotor due to differences in winding quality can be suppressed.

(3) In the stepping motor according to the third aspect, when the drive winding is wound in advance and formed into a coil, the rotor is inserted between adjacent coils in a state where the rotor is attached to the drive winding attachment portion. The outer surface of the coil on the rotor side as viewed from the projecting end side of the drive winding mounting portion becomes a short arc along the permanent magnetic pole of the rotor so that a uniform gap along the radial direction is formed, Since the outer surface of the coil on the opposite side is formed into a substantially fan shape that becomes an elliptical arc along the inner peripheral surface of the yoke case, dead space that has conventionally occurred can be eliminated, and the number of coil turns and the winding density can be increased. The magnetic force of the salient pole can be increased. Alternatively, since the number of coil turns can be freely adjusted within the dead space, if the number of coil turns is adjusted so that the torque of the rotor becomes the same as that of the conventional motor, a motor having the same performance can be reduced in size and weight. Can be manufactured.

(4) In the stepping motor according to the fourth aspect, the yoke plate is formed in an annular shape so as to connect the protruding end surfaces of the wire winding mounting portions, thereby reducing the number of mounting steps and cost. It becomes possible.

(5) In the stepping motor according to the fifth aspect, the yoke case for supporting the stator yoke is formed of resin, and the stator yoke is integrally molded with the yoke case. Cost reduction is achieved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a four-phase stepping motor according to an embodiment of the present invention.

FIG. 2 is a perspective view showing details of a main part of FIG. 1;

FIG. 3 is a perspective view showing a mounting state of a yoke plate according to the embodiment of the present invention.

FIG. 4 is a schematic view showing a stator assembly process of the motor.

FIG. 5 is a diagram illustrating the principle for canceling the secondary high-frequency component and the fourth high-frequency component of the detent torque inside the motor.

FIG. 6 is a schematic configuration diagram of a conventional salient pole type stepping motor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 Stator yoke 21a Yoke case 22a-22h Drive winding 24 Rotating shaft 25 Permanent magnet rotor 40 Salient pole 41 Drive winding attachment part 42a-42d Coil (drive winding) 43 Yoke plate

Claims (5)

[Claims] 1. A cylindrical shaft as a rotation axis, and N
S a multi-pole magnetized cylindrical permanent magnet rotor, and a stator yoke surrounding the permanent magnet rotor with salient poles arranged at equal intervals in the circumferential direction. At each of the salient poles, a mounting portion of the drive winding is formed so as to protrude along the axial direction of the rotor, and the drive winding is wound around the drive winding mounting portion so that the drive winding is attached thereto. A permanent magnet type stepping motor, wherein the projecting ends of the wire mounting portions are connected by a yoke plate. 2. The permanent magnet type stepping motor according to claim 1, wherein the drive winding is formed into a coil by being wound in advance so as to be fitted into and attached to the winding mounting portion from a protruding end side. A permanent magnet type stepping motor characterized in that: 3. The permanent magnet type stepping motor according to claim 2, wherein each of the coils is mounted on the winding mounting portion and a gap is formed between adjacent coils in a radial direction of the rotor. A permanent magnet type stepping motor characterized by being formed in a substantially fan shape so as to form a stepping motor. 4. The permanent magnet type stepping motor according to claim 1, wherein the yoke plate is formed in an annular shape that connects a projecting end surface of each wire winding attachment portion along a circumferential direction of the rotor. A permanent magnet type stepping motor characterized by being molded. 5. The permanent magnet type stepping motor according to claim 1, wherein a yoke case for supporting the stator yoke is formed of resin, and the stator yoke is integrally molded with the yoke case. Features a permanent magnet type stepping motor.