JPH08317623A - Longitudinal-coil type stepping motor - Google Patents

Abstract

PURPOSE: To provide the longitudinal-coil type stepping motor, wherein enlargement of a frame, increase in inertial mass of a rotor, degradation in accuracy and increase in costs of manufacturing process and parts are suppressed, and the increase of the output based on the reduction of the leakage flux between stator cores is realized. CONSTITUTION: Claw-pole (claw-shaped induction pole) type stator core is provided. In the stator core, the claw-shaped induction poles are made to protrude from the inner-surface edges of a pair of side plate parts 72, which surround a phase coil and constitute a part of a ring-shaped yoke (yoke), and the outer surface edges of both side plate parts 72 are coupled with a cylinder part 71 magnetically and mechanically. The mutually neighboring side plate parts 72 of the neighboring stator core 7 have opening parts 9 for reducing the leakage of magnetic flux, which are arranged at the mutually different positions in the circumferential direction. Therefore, the leakage flux leaking between pair of the mutually neighboring side plate parts 72 can be decreased to a large extent. The effective magnetic flux acting on the magnetic pole of a rotor is increased by that amount, and the output 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 cascade coil type stepping motor (hereinafter also simply referred to as a stepping motor) using a so-called claw pole (claw-shaped induction pole).

[0002]

2. Description of the Related Art FIG. 5 shows a stator core of a cascade coil type stepping motor using claw poles. The stator cores 1a and 1b adjacent to each other are cylindrical portions 11a, which are arranged at the outer peripheral sides of the phase coils (not shown),
21a and side plate portions 11b, 11 extending inward in the radial direction with the phase coil sandwiched from both axial ends of the cylindrical portions 11a, 21a.
c, 21b, 21c and side plate portions 11b, 11c, 21
Claw-shaped induction pole 1 projecting from the radially inner ends of b and 21c toward the inner circumferential side of the phase coil while maintaining a predetermined pitch in the circumferential direction.
1d and 21d.

Japanese Utility Model Laid-Open No. 1-64983 discloses a cascade coil type stepping motor using a claw-shaped induction pole.
It is proposed that the side plates of adjacent stator cores be provided with steps that drop in the axial direction, and an air gap is formed between the side plates by the amount of this step, thereby reducing the leakage flux between the stator cores. Further, in order to reduce the leakage magnetic flux, a spacer is also provided between the side plate portions of the stator cores adjacent to each other.

[0004]

However, in the conventional stepping motor in which the spacer or the step is provided, the leakage flux is significantly reduced (the magnetic resistance of the leakage flux path is increased when the axial length of the spacer or the step is not sufficiently increased). ) Was not obtained, and as a result, there was a drawback that the size of the stepping motor was increased. Further, the increase in the axial length of the rotor also causes a serious problem of increasing the inertial mass of the rotor.

Further, there is a drawback that the steps are formed or the cost of parts is increased due to the step forming step and the adoption of thick spacers. Further, in the conventional stepping motor having the step, there is a problem that the axial dimension due to the springback, the burr, etc. and the accuracy of the air gap between the rotor and the claw-shaped induction pole are reduced. Explaining this springback further, when the side plate portion is displaced in the axial direction by the springback, the axial overlap dimension between the claw-shaped induction pole and the outer peripheral surface of the rotor and the air gap dimension between the two will change. To derive the problem.

The present invention has been made in view of the above problems, and it suppresses an increase in physique, an increase in inertial mass of a rotor, a decrease in accuracy, and an increase in manufacturing process and component costs, while suppressing leakage flux between stator cores. It is an object of the present invention to provide a tandem coil type stepping motor that realizes an increase in output due to reduction.

[0007]

The first structure of the present invention is as follows.
A plurality of stator cores each having a phase coil and sequentially arranged adjacent to each other in the axial direction, and a plurality of stator cores rotatably arranged on the inner peripheral side of the stator core and sequentially controlling the energization pattern of each phase coil to provide a predetermined angle. Each of the stator cores has a cylindrical portion disposed on the outer peripheral side of the phase coil, and radially inwardly sandwiches the phase coil from both axial ends of the cylindrical portion. Cascade coil including a pair of side plate portions and a claw-shaped induction pole projecting from a radially inner end of the pair of side plate portions toward the inner peripheral side of the phase coil while maintaining a predetermined pitch in the circumferential direction. In the stepping motor, the pair of adjacent side plates of the pair of adjacent stator cores are provided with openings for reducing magnetic flux leakage, which are arranged at different positions in the circumferential direction. A tandem coil type stepping motor according to claim.

According to a second aspect of the present invention, in addition to the first configuration, the opening formed in one of the pair of side plate portions adjacent to each other of the pair of adjacent stator cores is formed in the other side. It is characterized in that it is displaced by 1/2 pitch in the circumferential direction with respect to the formed opening.
The third configuration of the present invention is the same as the first configuration,
It is characterized in that the opening is formed so as to extend to the cylindrical portion.

[0009]

The cascade coil stepping motor of the present invention has a so-called claw pole (claw-shaped induction pole) type stator core, and the phase coils are wound around the outer peripheral surface of the rotor at a predetermined distance. Claw-shaped induction poles are circumferentially arranged at a predetermined pitch between the phase coil and the outer peripheral surface of the rotor. The claw-shaped induction pole is projected from the inner peripheral ends of a pair of side plate parts that surround the phase coil and constitutes a part of an annular yoke (yoke), and the outer peripheral ends of both side plate parts are cylindrical parts. Magnetically and mechanically coupled.

When the phase coils are energized, the claw-shaped induction poles are magnetized through the effective magnetic circuit (effective magnetic flux path) passing through the side plate portion, the cylindrical portion, and the side plate portion, and the stator magnetic field that interacts with the magnetic poles on the outer peripheral surface of the rotor. To form. Further, a part of the magnetic flux passing through the side plate portion leaks to the side plate portion of the adjacent stator core, and the effective magnetic flux that should act on the magnetic pole of the rotor that should originally act decreases by that amount.

In this structure, since the pair of side plate portions adjacent to each other of the pair of adjacent stator cores are provided with the openings for reducing the magnetic flux leakage, which are arranged at different positions in the circumferential direction, these side plate portions are adjacent to each other. The leakage magnetic flux leaking between the pair of side plate portions can be significantly reduced, and the effective magnetic flux acting on the magnetic poles of the rotor can be increased by that amount, and the output torque can be increased.

According to a second structure of the present invention, in the above first structure, an opening formed in one of a pair of side plate portions adjacent to each other of a pair of adjacent stator cores is formed in the other side. It is displaced by 1/2 pitch in the circumferential direction with respect to the opening. In other words, an unreasonable increase in the opening area to a certain extent leads to a decrease in the effective magnetic flux. In this way, the overlapping of the openings adjacent to each other is minimized, so that the leakage magnetic resistance of one opening is reduced. It is possible to effectively utilize the effect of increasing the magnetic flux, and it is possible to increase the leakage magnetic flux reduction amount while preventing reduction of the effective magnetic flux.

In the third structure of the present invention, since the opening is formed so as to extend to the cylindrical parts in the first structure, the leakage magnetic flux leaking between the cylindrical parts can be further reduced. , The effective magnetic flux can be increased. In this preferred embodiment, the magnetic path cross-sectional area of the effective magnetic flux of the side plate portion and the magnetic path cross-sectional area of the effective magnetic flux of the cylindrical portion are made equal to each other, or the magnetic path cross-sectional area of the effective magnetic flux of the side plate portion is equal to that of the cylindrical portion. It is preferably larger than the magnetic path cross-sectional area of the effective magnetic flux.

[0014]

1 is a partial sectional view in the axial direction of a stepping motor according to this embodiment, FIG. 2 is a perspective view of the stator core thereof, and FIG. 3 shows. This stepping motor is a column-coil PM type stepping motor using claw poles, and four stators 1 to 4 each have a non-magnetic spacer 5 made of a ring-shaped resin plate sandwiched in a housing (not shown). The stators 1 to 4 are arranged in cascade in the axial direction.
A rotary shaft 60, to which four rotors 6 each made of a permanent magnet are fitted and fixed, is rotatably supported by the housing on the inner peripheral side thereof.

Each of the stators 1 to 4 will be described below with reference to FIG. Since the stators 1 to 4 have the same structure, common constituent elements of the stators 1 to 4 are designated by common reference numerals. The stators 1 to 4 include a stator core 7 including a left core 7a and a right core 7b formed by press-molding a soft iron plate, preferably an electromagnetic silicon steel plate, and a phase coil wound around a bobbin 80 and accommodated in the stator core 7. 8 and. Each of the left core 7a and the right core 7b has a cylindrical cylindrical portion 71, a side plate portion 72 extending radially inward from an axial outer end of the cylindrical portion 71, and a radial inner end of the side plate portion 72. It is composed of a claw-shaped induction pole 73 that first extends radially inward and then axially extends, is covered by the same phase coil 8 from both axial sides, and the axial inner ends of both cylindrical portions 71 are butted against each other. .

The claw-shaped induction pole 73 of the left core 7a is a minute air gap (radial air gap) provided in the radial direction.
Faces the magnetic pole surface 61 of the rotor 6 and the claw-shaped induction pole 73 of the right core 7b faces the magnetic pole surface 62 of the rotor 6 with a minute air gap (radial air gap) provided in the radial direction therebetween. ing. The magnetic pole surfaces 61 and 62 are oppositely magnetized in the circumferential direction at the same pitch, and the polarities of the magnetic pole surfaces 61 and 62 are opposite at the same angular position in the circumferential direction. Also, the claw-shaped induction poles 73 and 4 of the four stator cores 7 are
The circumferential relative spatial relationship with the magnetic poles of each rotor is shifted in a predetermined order, and the stepping rotation of the rotor is possible by sequentially energizing each phase coil 8, but the operation itself of the stepping motor is Since this is well known, further description will be omitted.

The structure which characterizes this embodiment will be described below. Openings 9 for reducing the leakage flux are provided in the side plate portions 72 of the left core 7a and the right core 7b. The openings 9 have a fan shape (a truncated cone shape) that is long in the circumferential direction, and a plurality of openings 9 are arranged at a constant pitch in the circumferential direction. Further, in this embodiment, the opening 9 of the left core 7a and the opening 9 of the right core 7b have an opening position of ½ in the circumferential direction as shown in FIGS.
The pitch is off. δ is an axial gap between the stator cores 7 secured by the spacer 5.

With this configuration, the supporting column portion 72a of the side plate portion 72 formed in the pair of circumferentially adjacent openings 9 and the supporting column portion 72a of the adjacent side plate portion 72 in the circumferential direction are spaced by 1/2 pitch. Since it shifts, the permeability of the leakage flux path μ
In addition, each right core 7b can be molded by a common mold, and each left core 7a can also be molded by a common mold, and it is not necessary to increase the number of parts. (Other Embodiment) Another embodiment is shown in FIG. In this embodiment, the opening 9a is formed so as to straddle both the side plate portion 72 and the cylindrical portion 71. By doing so, the leakage magnetic flux can be further reduced.

The circumferential angular position of the opening 9a of the right core 7b and the circumferential angular position of the opening 9a of the left core 7a may be equal. In this case, the odd-numbered stator cores 7 may be assembled by shifting the odd-numbered stator cores 7 in the circumferential direction by half the pitch of the opening 9a.

[Brief description of drawings]

FIG. 1 is an axial partial sectional view of a cascade coil type stepping motor of this embodiment.

FIG. 2 is a perspective view of a stator core 7 shown in FIG.

3 (a) is a view of the stator core 7 of FIG. 1 in the axial direction, and FIG. 3 (b) is a view of the radial direction thereof in the radial direction.

FIG. 4 is a perspective view of a stator core 70 according to another embodiment.

FIG. 5 is a perspective view of a stator core of a conventional cascaded coil type stepping motor.

[Explanation of symbols]

8 is a phase coil, 7 is a stator core, 7a is a left core 7a,
7b is a right core, 6 is a rotor, 71 is a cylindrical portion, 72 is a side plate portion, 73 is a claw-shaped induction pole, and 9 is an opening.

Claims (3)

[Claims] 1. A plurality of stator cores, each of which has a phase coil and is sequentially disposed adjacent to each other in the axial direction, and a plurality of stator cores rotatably disposed on the inner peripheral side of the stator core and having an energization pattern of each of the phase coils. The stator core includes a rotor that rotates by a predetermined angle by sequential control, and each of the stator cores has a cylindrical portion disposed on the outer peripheral side of the phase coil and a diameter that sandwiches the phase coil from both axial ends of the cylindrical portion. A pair of side plate portions extending inward, and a claw-shaped induction pole projecting from the radially inner ends of the pair of side plate portions toward the inner peripheral side of the phase coil while maintaining a predetermined pitch in the circumferential direction. And a pair of side plates of the pair of adjacent stator cores, which are adjacent to each other, are provided at different positions in the circumferential direction to reduce magnetic flux leakage. A columnar coil type stepping motor comprising: 2. The opening formed in one of the pair of side plate portions adjacent to each other of the pair of adjacent stator cores is 1/2 in the circumferential direction with respect to the opening formed in the other side. The cascade coil stepping motor according to claim 1, wherein the stepping motor is pitch-displaced. 3. The cascade coil stepping motor according to claim 1, wherein the opening is formed so as to extend to the cylindrical portion.