JPS61199455A - Stepping motor - Google Patents

Abstract

PURPOSE:To increase the torque of a motor by engaging a spacer made of a nonmagnetic material with a rotor shaft, and integrally mounting a permanent magnet and a rotor yoke for holding the magnet on the outer periphery, thereby increasing the effective magnetic flux. CONSTITUTION:A ring-shaped spacer 12 made of a nonmagnetic material is engaged with the periphery of a rotor shaft 11. Yokes 13a, 13b and a permanent magnet 15 disposed between the yokes are mounted on the outer periphery of the spacer 12. Sub salient poles 14a, 14b are formed at the ends of the yokes 13a, 13b, and opposed to the poles of a stator, not shown. Thus, the effective magnetic flux between the yokes 13a and 13b is increased to increase the torque of a motor, and the assembling steps are decreased to reduce the cost.

Description

[Detailed Description of the Invention] Industrial Application Field Invention C: Frothopy disk drive device,...-
This invention relates to a thin stepping motor that can be used as an actuator in information terminal devices such as disk drive devices.Conventional TechnologyIn recent years, with the rapid spread of computers, a large number of information terminals have also been used. It is becoming popular. For this reason, devices are being made thinner as a design measure to make them easier to use for the general public. Accordingly, the actuators used in these devices are also required to be thinner. Therefore, stepping motors, which are often used in information terminals, are no exception, and thin ones of the type shown in FIG. 2 are used. The conventional structure will be explained below using FIG. 2 as an example. FIG. 2 shows the structure of a conventional thin stepping motor. In Figure 2, 1 is a stator yoke, 2 is an excitation winding applied to the stator yoke 1, 3 is a frame, 4 is a rotor shaft, 5a is a 5-bid rotor yoke, 6 is a permanent magnet, and 7 is a rotating This is a bearing that rotatably supports the child shaft 4 with respect to the stator yoke 1 via the frame 3.

In the above configuration, the stator yoke 1' has salient poles 12L.
+ 1 b+ IC! 1 (hereinafter referred to as the first phase) is applied to the first excitation winding (hereinafter referred to as the first phase), and the excitation winding (hereinafter referred to as the third phase) is applied to the same salient pole so as to have the opposite polarity. ), and the salient pole 18 T 1 f ,
An excitation winding (hereinafter referred to as the second phase) provided as a 141hi set and an excitation winding (hereinafter referred to as the fourth phase) in which the excitation winding is set to 0 (hereinafter referred to as the fourth phase) with an opposite pattern are provided. The permanent magnet 6 constituting the twisted rotor is magnetized into two poles in the axial direction.

Here, when the first phase is energized, the salient poles 1fL and 10 become N poles, and the salient pole IJ1d is wound so as to become the S pole, and when the third phase is energized, the salient poles 1a and 1a are wound.

1C is an S pole, and salient poles 1b and 1d are N poles. Assuming that when electricity is applied to the twisted second phase, salient poles 1el and 1g become N poles,
Salient poles 1f and 1h are wound so that they become S poles, and when the fourth phase is energized, salient poles 161 1 glsl: S poles, salient poles 1f,
1h becomes the north pole. Since the permanent magnet 6 of the shunted rotor is magnetized with two poles in the axial direction as described above, the rotor yoke 5a
If is the N pole, then the rotor yoke 5b is the S pole.○ The recessed stator salient poles 1a to 1h and the rotor yoke are provided with side salient poles 8 and 9, respectively. The eight side salient poles provided on the rotor yoke 5a and those provided on the rotor yoke 5b are the same magnetic poles. The side salient poles 8a of the rotor yoke 6a and the side salient poles 8b of the rotor yoke 6b are shifted in pitch. For the following explanation, the rotor yoke 52L is assumed to be an S pole, and the rotor yoke 6b is assumed to be an N pole.

Regarding the stepping motor configured as above,
The operation will be explained below. Now, when the first phase is energized, salient poles 1a and 10 become N poles and 1b.

Since 1d becomes the S pole, the side salient pole 8a of the rotor yoke 5a opposes the salient poles 1B and 1c, and the side salient pole 8b of the rotor yoke 5b opposes the salient poles 1b and 1a, resulting in a stable state. Become. At this time, the side salient poles of the salient poles 1e+ 1fr 1g+ 1b and the rotor side salient poles are set so that a deviation in % side salient pole pitch occurs. Therefore, when the state is switched from the state in which the first phase is excited to the state in which the second phase is excited, the rotor rotates by the distance of this % salient pole pitch and enters the next stable state. In this way, the third and fourth phases are excited, and the first phase is excited again.
By repeating the phase excitation, the stepping motor having the structure shown in FIG. 2 rotates with the salient pole pitch as a unit step. Here, FIG. 3 shows a conventional rotor structure. In Fig. 3, a 4-piece rotor shaft, 5a and 5b are rotor yokes, and 6-
1.6-2 is a permanent magnet, sa and sb are rotor yoke 6a
, 5b, respectively. Now, as mentioned above, the permanent magnetic field of the rotor is polarized with two poles in the direction of 1.
, sb, but at this time the side salient poles 8a, 8
The magnetic flux flowing from b to stator 1 contributes to torque generation.
This becomes what is called effective magnetic flux. This amount of magnetic flux is the permanent magnet 6-1
．． As mentioned above, this was generated from 6-2.

Problems to be Solved by the Invention However, in the above configuration, the magnetic flux generated from the permanent magnet 6-1 shown in FIG. Rotor yoke 5a, 51
) flows through the opposing surface 9 of the magnetic flux, so-called leakage flux, which leads to a decrease in torque.

Here, even in the case where the permanent magnets 6=2 shown in FIG. 6(b) are configured, leakage magnetic flux flows through the opposing surfaces 10 of the rotor yokes 6a+6b. As the stepping motor becomes thinner, the distance between the opposing surfaces 9 or 10 becomes smaller, and therefore the magnetic resistance of this part becomes lower, and the ratio of leakage magnetic flux to the effective magnetic flux becomes larger, which increases the motor torque. This has the problem of becoming increasingly disadvantageous in terms of generation.

In view of the above-mentioned problems, the present invention reduces the leakage magnetic flux among the magnetic flux generated from the rotor magnet, and distributes sufficient effective magnetic flux between the side salient poles and the stator without increasing the volume of the permanent magnet. The present invention provides a stepping motor with good torque characteristics.

Means for Solving the Problems In order to solve the above problems, the rotor in the stepping motor of the present invention includes a rotor shaft, a spacer made of a non-magnetic material fixed to the rotating shaft, and a spacer fixed to the spacer. It includes a rotor yoke and a permanent magnet positioned between the rotor yoke.

The above-mentioned configuration allows the magnetic flux to be emitted from the permanent magnets.Since the spacer is non-magnetic, this spacer part does not become a path for the leakage flux, and the leakage flux between the rotor yokes is different from that in the conventional case. It decreases as the ratio (-) and the effective magnetic flux can be made sufficiently large.

Example: Refer to the drawings for a rotor according to an example of the present invention.
Pilgrimage and enlightenment.

FIG. 1 shows a rotor of a stepping motor in an embodiment of the present invention. In FIG. 1, there are 11 rotor shafts, 12 is a ring-shaped spacer made of a non-magnetic material fixed to the rotor shaft 11, and 13a, 13b are spacers 1.
A pair of rotor yokes is fixed to the rotor yoke 2, and side salient poles 14a and 14b are provided on the outer peripheral portion, respectively. Permanent magnets are provided at positions l~ on the radially outer side of the 14 spacers 12, and the trochanter yokes 13a, 13t) of the negative set are clamped and fixed at VrC. Note that the structure of the stator is the same as the conventional example.

The operation of the stepping motor rotor constructed as described above in (7) will be explained below with reference to FIG. 1. The magnetic flux generated by the permanent magnet 15 passes through the rotor yokes 13a and 13b and passes through the side salient poles 14? L, 14b and enters the stator similar to that shown in FIG. 2, becoming an effective magnetic flux. At this time, the opposing surfaces of the rotor yokes 13a and 13b are the first
This is only the portion shown in C in the figure, and only the magnetic flux flowing in this portion becomes leakage magnetic flux. Since the spacer 12 made of non-magnetic material is installed in a portion where a large amount of leakage magnetic flux has conventionally flowed, there is almost no leakage magnetic flux passing through this portion.

As shown in J- below, according to this embodiment, by providing the spacer 12 fixed to the rotor shaft 11, the rotor yoke 1
The leakage magnetic flux between the side salient poles 14a and 13b can be reduced, and a sufficient amount of effective magnetic flux can be obtained from the side salient poles 14a and 14b to the stator.

Note that the spacer 12 can also be molded integrally with the rotor shaft 11, the permanent magnet 16, and the rotor yokes 13a and 13b using resin or the like.

``Better than the effect of the invention'': The present invention provides a non-magnetic spacer fixed to the rotor shaft (from C, the effective magnetic flux generated from the rotor is increased without changing the area of the permanent magnet) As a result, the torque characteristics of the motor can be completely improved.

This non-magnetic part can be easily created by resin molding, etc., and can also be used as a fixing means for the rotor yoke and permanent magnets. can do.

[Brief explanation of drawings]

Fig. 1 θ is a cross-sectional view of the rotor of the stepping motor according to the embodiment of the present invention, Fig. 2 (2L) l (b) is a vertical cross-sectional view and a transverse cross-sectional view showing the structure of a conventional stepping motor, and Fig. 3 ( FIGS. 1A and 2B are cross-sectional views showing the structure of a rotor of a conventional stepping motor. 1... Stator yoke, 2... Stator winding, 11... Rotor shaft, 12... Spacer,
13a, 13b...Rotor yoke, 14a, 1
4b...Rotor yoke, 16...Permanent magnet.

Claims (1)

[Claims] The rotor includes a stator provided with excitation windings and a rotor rotatably held with an air gap maintained relative to the stator, and the rotor includes a rotor shaft and a rotor fixed to the rotor shaft. a spacer made of a non-magnetic material, a set of rotor yokes fixed to the spacer, and a rotor yoke located between the rotor yokes,
A stepping motor comprising a permanent magnet located radially outward with respect to the spacer.