JP2007116852A - Stepping motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stepping motor which gives low load on a shaft and facilitate processing of a rotor magnet including polarization as well as diameter reduction. <P>SOLUTION: Claw poles are provided on a roughly cylindrical rotor magnet polarized in the axial direction. At the same time, a plurality of claw-pole type coil yokes are arranged so as to be symmetrical to the axial direction, and the claw poles are used a pair, thus attaining diameter reduction for low load on the shaft and stable stepping drive. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a small stepping motor having a small step angle.

The driving mechanism of the stepping motor currently used is the one that has a PM type drive structure using a cylindrical rotor magnet that is multipolarly magnetized in the circumferential direction in the rotor portion, and is magnetized in the axial direction. It is roughly classified into an HB type drive structure using a cylindrical rotor magnet.

Among the above two drive structures, the PM type is superior in terms of simplicity of individual component shapes, and the HB type is superior in terms of the ease of magnetizing the rotor magnet, and drive structures suitable for each application have been used. .

As a stepping motor using a general PM type drive structure, a stator having a cylindrical rotor magnet as a movable part and a field coil wound around a yoke having comb-like protrusions corresponding to the magnetic poles of the rotor There is a stepping motor used to rotate the rotor by a predetermined angle (see FIG. 4). As an invention relating to such a motor, there is already a stepping motor represented by Japanese Patent Laid-Open No. 64-1464 (hereinafter referred to as Patent Document 1), which has a structure in which two stators are provided in two upper and lower coils, respectively. It is configured to rotate by a quarter with respect to the magnetic pole.

The above-mentioned patent document 1 is characterized by a component configuration in which the side plate for supporting the motor shaft is eliminated from the stepping motors used so far. By adopting such a configuration, Patent Document 1 simplifies the component configuration of the stepping motor, lowers the cost during assembly, and reduces the number of components and improves the volume efficiency.

In Patent Document 1, a positioning projection is provided on a stator to which a coil is attached, and the projection of the yoke can be arranged at an appropriate position during assembly.

Furthermore, it is possible to increase the coil volume corresponding to the reduced component volume due to the improvement in volume efficiency, and it is possible to maintain a high torque even when the size is reduced.

In addition, it has a structure in which the bobbin bearing portion is supported by a substrate to which the motor is attached, and a large moment can be transmitted to the output side shaft during driving.

As described above, in Patent Document 1, the bobbin that winds the field coil and the bobbin bearing that supports the rotating shaft are integrated, thereby reducing the number of components and increasing the volume (number of turns) of the field coil. Have gained.

However, the above-mentioned Patent Document 1 corresponding to the flat type has a structure in which the rotor magnet is magnetized in multiple poles, so that it is necessary to reduce the number of magnetic poles when the motor is downsized, and it is difficult to maintain the step angle. was there.

Furthermore, there is a problem that it is difficult to reduce the component cost by using a rotor magnet magnetized with multiple poles.

In order to solve the above problems, Japanese Patent No. 3363786 (hereinafter referred to as Patent Document 2) has been filed and registered.

In Patent Document 2, a cylindrical rotor magnet magnetized in the axial direction is characterized in that magnetic pole grooves and protrusions are alternately formed at substantially the same pitch in the circumferential direction.

With the above shape, the magnetic pole groove and the protrusion can be handled as different magnetic poles, and the same effect can be obtained as in the case of multipolar magnetization in the circumferential direction only by magnetization in the axial direction.

As a result, Patent Document 2 solves the problem of reduction in the number of magnetic poles accompanying the reduction in diameter, which the conventional PM type stepping motor represented by Patent Document 1 has.

In the embodiment, as shown in Patent Document 1, not only the stator is concentrically formed around the rotor magnet, but also a stepping motor in which the stator is arranged on both sides of the rotor is presented. As a result, the number of turns of the field coil can be maintained, and the number of turns of the coil and the diameter of the rotor magnet can be ensured without waste with respect to the thickness dimension.

Furthermore, the arrangement in the substrate shape is not limited to the cylindrical shape by adopting the rectangular arrangement, and by reducing the number of poles of the stator and increasing the number of turns of the coil, the overall apparatus is thinned while maintaining the torque. Yes.

JP-A 64-1464 Japanese Patent No. 3363786

However, in Patent Document 2, because of its structure, the rotation angle becomes a quarter of the protrusion, and it becomes difficult to process the rotor magnet when the diameter is reduced. There is no problem.

Furthermore, shafts currently used in small motors have a minimum diameter of 0.3 to 0.7 mm, and the above-mentioned coil yoke uses these shafts for two stepping motors. Then, since only one magnetic pole is used at a time, the magnetic force acting on the shaft through the rotor portion is biased to one side during driving, and a load is applied to the shaft.

In addition, due to the structure in which the shaft hole is provided in the rotor magnet, the diameter of the rotor magnet is limited by the shaft diameter when the diameter of the entire apparatus is reduced.

In order to solve the above-described problems, an object of the present invention is to provide a stepping motor that has a small load on a shaft during driving, can easily process a rotor magnet including magnetization, and can easily reduce the diameter.

In order to solve the above-mentioned problem, in the invention of claim 1, a substantially cylindrical rotor magnet magnetized in the height direction is provided inside,
A magnet yoke having a cylindrical side wall with the height direction of the rotor magnet as an axis and provided with convex portions at equal intervals in the circumferential direction of the cylinder as a rotor portion,
A claw pole type stator provided with a field coil is arranged along the rotor magnet axial direction so that the inner wall of each claw pole is close to the outer periphery of the convex part of the rotor side wall, and with the magnet magnetic pole surface as a boundary. Arrange multiple to be symmetrical,
It is characterized in that the stators at the symmetrical positions are used as a set during driving.

The invention according to claim 2 is the invention according to claim 1, wherein the magnet yoke is used as a rotating shaft.

In Claim 3, the convex part on the thin board which consists of magnetic bodies was provided in the circumferential direction at equal intervals on the side wall of the substantially cylindrical rotor magnet magnetized in the rotating shaft direction and penetrating the shaft. Having a rotor part,
A claw pole type stator provided with a field coil is arranged along the rotor magnet axial direction so that the inner wall of each claw pole is close to the outer periphery of the convex part of the rotor side wall, and with the magnet magnetic pole surface as a boundary. Arrange multiple to be symmetrical,
It is characterized in that the stators at the symmetrical positions are used as a set during driving.

According to the first aspect of the present invention, it is possible to obtain a stepping motor that is easy to assemble, has a small number of component structures, and maintains the step angle even when the entire apparatus is reduced in size.

As described above, the PM type stepping motor represented by Patent Document 1 applies a multi-pole magnetized rotor magnet by alternately applying a current to the stator coils provided at both ends of the rotor magnet. A rotating structure is used.

On the other hand, the stepping motor of the present invention provides a magnetic projection due to the unevenness of the magnet yoke by providing a magnet yoke having a plurality of projections on a cylindrical rotor magnet magnetized in the axial direction. By alternately performing step driving between the stator provided at the boundary portion of the protrusion and the stator provided at the end portions of both poles, it is possible to suppress the bias of the force when the diameter is reduced and to drive with less load on the shaft.

Also, instead of providing irregularities directly on the rotor magnet, magnetic irregularities can be formed relatively easily even with a reduced diameter structure by providing irregularities using a magnet yoke, and the magnet yoke can be replaced. This makes it possible to easily change the step angle.

Furthermore, by providing the stator yoke on the boundary surface, not only both ends of the rotor magnet but also an intermediate region thereof can be used.

According to the second aspect of the present invention, when the diameter is reduced, the shaft hole is not provided in the rotor magnet, and the magnet yoke is directly used as the rotating shaft, so that it is not necessary to provide the shaft hole in the rotor magnet. It is possible to reduce the diameter of the magnet.

According to the third aspect of the present invention, the diameter of the rotor portion including the rotor magnet and the magnet yoke is kept small by removing the inner peripheral portion of the magnet yoke and directly attaching the protrusion made of a magnetic material to the rotor magnet. In addition, the same effect as that of the motor according to the first aspect can be obtained.

Similarly to the first aspect of the present invention, the coil yoke is always driven on both the S pole side and the N pole side to obtain a drive state without bias.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 and FIG. 2 show components and a side sectional view of a stepping motor used in the first embodiment used in the present invention.

As can be seen from FIG. 1, the stepping motor of this embodiment corresponds to the cylindrical rotor magnet 8 magnetized in the axial direction, the two magnet yokes 7a and 7b attached to the magnet, and the uneven portions of the magnet yoke. Four coil yokes 4a to 4d having comb-tooth portions, field coils 5a, 5b and 6 wound inwardly and outwardly with respect to the coil yokes, and a boss 3 fitted to a non-recessed portion of the magnet yoke 7. And the bearing 2, and the case 1 and the cover 9 having a cylindrical cross section for housing the above-described components.

In addition, as can be seen from the side sectional view of FIG. 2, in this embodiment, the rotor portion is circumferentially formed with respect to the uneven portion of the rotor portion by the rotor magnet 8 and the two magnet yokes 7 attached to the magnet 8. The stator portions are respectively composed of coil yokes 4a to 4d in which comb teeth are arranged with a phase difference of 1/4 each, and field coils 5a, 5b, and 6 are wound around the outer periphery. By applying a current to 5a, 5b, and 6, mutual magnetic force is generated between the comb tooth tips of each of the coil yokes 4a to 4d and the magnet yoke, and the structure is driven by a predetermined angle. It has become.

Since the above-described drive structure is used, the stepping motor of this embodiment eliminates the need to provide a shaft hole in the rotor magnet 8, and the overall diameter of the apparatus can be reduced by using the rotor unit integrally with the rotating shaft. It is said.

Further, during driving, each coil yoke 4a and 4d, 4b and 4c is applied as a set to apply a current, thereby reducing the load applied to the rotor part and obtaining stable step driving.

In addition to the above advantages, in this embodiment, the rotor magnet 8 is sandwiched from both sides by the magnet yokes 7a and 7b during assembly, and the rotor magnet 8 is provided inside the magnet yoke 8. It has a structure that can be assembled.

Further, from the same technical point of view as the present embodiment, the rotor portion is composed of a rotor magnet 8, a shaft 11, and a claw pole 10 made of a magnetic body attached to the rotor magnet 8, as shown in FIG. It is also possible to match the inner diameter of 2 with the shaft 11.

By using the structure shown in FIG. 3 for the rotor portion, it is possible to reduce the burden on the shaft 11 provided through the magnet while driving the stepping motor while ensuring the outer diameter of the rotor magnet 8.

Further, since the outer diameter of the rotor magnet 8 can be made larger than that of the structure of the rotor portion shown in FIG. 2, the magnetic force of the rotor magnet 8 is also increased, and the torque is higher than that of the stepping motor using the structure of FIG. It can be driven by.

As described above, by using the stepping motor shown in the above-described embodiment, it is possible to provide a stepping motor that has a small load on the shaft, can be easily processed with a rotor magnet including magnetization, and can be easily reduced in diameter. .

Component perspective view in an embodiment of the present invention Side sectional view in an embodiment of the present invention Rotor used in the embodiment of the present invention General stepping motor drive principle

Explanation of symbols

1 Case 2 Bearing 3 Boss 4a, 4b, 4c, 4d Coil yoke 5a, 5b Field coil (outside arrangement)
6 Field coil (inside arrangement)
7a, 7b Magnet yoke 8 Rotor magnet 9 Cover 10 Claw pole 11 Shaft 21 Rotor 22 Stator

Claims (3)

Has a substantially cylindrical rotor magnet magnetized in the height direction inside,
A magnet yoke having a cylindrical side wall with the height direction of the rotor magnet as an axis and provided with convex portions at equal intervals in the circumferential direction of the cylinder as a rotor portion,
A claw pole type stator provided with a field coil is arranged along the rotor magnet axial direction so that the inner wall of each claw pole is close to the outer periphery of the convex part of the rotor side wall, and with the magnet magnetic pole surface as a boundary. Arrange multiple to be symmetrical,
A stepping motor using a pair of stators at the symmetrical positions during driving.
2. The stepping motor according to claim 1, wherein the magnet yoke is used as a rotating shaft.
On the side wall of a substantially cylindrical rotor magnet that is magnetized in the direction of the rotation axis and that penetrates the shaft, there is a rotor portion that has convex portions on a thin plate made of a magnetic material provided at equal intervals in the circumferential direction. ,
A claw pole type stator provided with a field coil is disposed along the rotor magnet axial direction so that the inner wall of each claw pole comes close to the outer periphery of the convex part of the rotor side wall, and with the magnet magnetic pole surface as a boundary. Arrange multiple to be symmetrical,
A stepping motor characterized by using a set of stators at the symmetrical positions as a set during driving.