Stepping motor

Abstract

To provide a stepping motor which can improve simpleness of structure and ease of manufacture.SOLUTION: There is provided an axial gap type stepping motor comprising first and second stators sandwiching a rotor. The first and second stators are in the same structure, and the first stator comprises: a first coil; and a plurality of first electromagnetic steel members which are columnar and long in one direction comprising 1A and 2A portions by bending. The plurality of first electromagnetic steel members are arranged so that the plurality of 1A portions radially spread at equal angular intervals at a predetermined angle from a rotational shaft and that magnetic fluxes generated in the first coil flow to the plurality of 2A portions. Similarly, the second stator comprises a plurality of second electromagnetic steel members, and each of the plurality of 1A portions in the plurality of first electromagnetic steel members deviates from each of a plurality of 1B portions in the plurality of second electromagnetic steel members in a circumferential direction by an angle half of the predetermined angle.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an axial gap type stepping motor. [Background technology]

[0002] A stepping motor is a motor that can rotate intermittently at a fixed rotation angle in response to a drive control signal (pulse signal). Since the rotation angle can be determined from the number of drive control signals, it can be positioned without a sensor. Like other types of motors, stepping motors are classified into radial gap types, in which the gap between the stator and rotor is located in the radial direction, and axial gap types, in which the gap between the stator and rotor is located in the axial direction. Compared to radial gap stepping motors, axial gap stepping motors have the advantage that they can be made larger in diameter to increase the opposing area and thus more easily produce high torque, and can be made smaller by adopting a flatter shape. An axial gap stepping motor like this is disclosed, for example, in Patent Document 1.

[0003] The stepping motor disclosed in Patent Document 1 comprises a stator having a plurality of flat air-core coils arranged on a first magnetic thin plate so that they can be electrically connected, and a rotor having a plurality of permanent magnets arranged on a second magnetic thin plate rotatably supported on the stator, the permanent magnets being positioned opposite the plurality of air-core coils across a predetermined gap. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-320941 Summary of the Invention [Problem to be solved by the invention]

[0005] However, like other types of motors, stepping motors are also desired to have a simple structure and be easy to manufacture. The stepping motor disclosed in Patent Document 1 requires multiple air-core coils for each rotation angle, which makes the structure more complex and difficult to manufacture. For example, if the rotation angle is increased from 90 degrees to 45 degrees to improve spatial resolution, the number of air-core coils doubles, which makes the structure more complex and difficult to manufacture.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a stepping motor that can be further improved in terms of simplicity of structure and ease of manufacture. [Means for solving the problem]

[0007] After extensive investigation, the inventors have found that the above object can be achieved by the present invention described below. That is, a stepping motor according to one aspect of the present invention comprises a first stator having a first coil, a second stator having a second coil, and a rotor that is axially disposed between the first and second stators and rotates while magnetically interacting with the first and second stators, wherein the first stator comprises a plurality of first electromagnetic steel members that are bent to have 1A and 2A portions and that are elongated in one direction, and the second stator comprises a plurality of second electromagnetic steel members that are bent to have 1B and 2B portions and that are elongated in one direction, and the plurality of first electromagnetic steel members are arranged such that the plurality of 1A portions of the plurality of first electromagnetic steel members are radially spread at equal angular intervals from a rotation axis, Furthermore, the plurality of first electromagnetic steel members are arranged so that magnetic flux generated by the first coil flows through the plurality of 2A portions of the plurality of first electromagnetic steel members, the plurality of second electromagnetic steel members are arranged so that the plurality of 1B portions of the plurality of second electromagnetic steel members extend radially from the rotation axis at equal angular intervals of the predetermined angle, and so that magnetic flux generated by the second coil flows through the plurality of 2B portions of the plurality of second electromagnetic steel members, and the plurality of first electromagnetic steel members and the plurality of second electromagnetic steel members are arranged so that each of the plurality of 1A portions of the plurality of first electromagnetic steel members is circumferentially offset from each of the plurality of 1B portions of the plurality of second electromagnetic steel members by an angle that is half the predetermined angle.

[0008] Such a stepping motor does not require changing the number of first and second coils according to the angle of one rotation, and only requires providing columnar first and second electromagnetic steel members according to the angle of one rotation, thereby further improving the simplicity of the structure and ease of manufacturing.

[0009] In another aspect, in the above-mentioned stepping motor, the first electromagnetic steel member is formed from a plurality of bundled first electromagnetic steel wires, and the second electromagnetic steel member is formed from a plurality of bundled second electromagnetic steel wires.

[0010] In such a stepping motor, the first and second electromagnetic steel members are formed by bundling wire rods together, which reduces the so-called eddy currents that occur in each of the first and second electromagnetic steel members compared to when the first and second electromagnetic steel members are formed integrally from electromagnetic steel, thereby contributing to improved responsiveness.

[0011] In another aspect, in the above-mentioned stepping motor, the first stator further comprises a plurality of first non-magnetic members, and the second stator further comprises a plurality of second non-magnetic members, each of the plurality of first non-magnetic members being arranged between a plurality of 1A portions formed by a plurality of 1A portions in the plurality of first electromagnetic steel members, and each of the plurality of second non-magnetic members being arranged between a plurality of 1B portions formed by a plurality of 1B portions in the plurality of second electromagnetic steel members.

[0012] Such a stepping motor includes a first non-magnetic member between the 1A portions and a second non-magnetic member between the 1B portions, so that the first and second electromagnetic steel members can be appropriately fixed in position. [Effects of the Invention]

[0013] The stepping motor according to the present invention can further improve the simplicity of its structure and ease of manufacture. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a perspective view illustrating a configuration of a stepping motor according to an embodiment. [Figure 2] FIG. 2 is a plan view illustrating a configuration of a rotor in the stepping motor. [Figure 3] FIG. 10 is a diagram showing, as an example, a simulation result of magnetic flux density in the stepping motor. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, one or more embodiments of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the disclosed embodiments. In addition, components with the same reference numerals in each drawing indicate the same components, and their description will be omitted as appropriate. In this specification, when referring to a general term, a reference numeral without a subscript is used, and when referring to an individual component, a reference numeral with a subscript is used.

[0016] Fig. 1 is a perspective view illustrating the configuration of a stepping motor according to an embodiment. Fig. 2 is a plan view illustrating the configuration of a rotor in the stepping motor. Fig. 2A shows a rotor according to a first embodiment, and Fig. 2B shows a rotor according to a second embodiment. Fig. 3 is a diagram illustrating, as an example, simulation results of magnetic flux density in the stepping motor.

[0017] As shown in FIG. 1, the stepping motor 100 in this embodiment includes a first stator 1A, a second stator 1B, and a rotor 2 (2a, 2b).

[0018] The rotor 2 is a disk-shaped member disposed between the first and second stators 1A and 1B in the axial direction and rotates while magnetically interacting with the first and second stators 1A and 1B. The rotor 2 includes a plurality of permanent magnets (not shown in FIG. 1) arranged sequentially in the circumferential direction with their magnetic poles (south and north poles) facing the same direction. A through-hole is formed in the center of the rotor 2 for inserting a rod-shaped rotating shaft (not shown) serving as the output shaft. The rotating shaft is inserted through the through-hole and fixedly connected to the rotor 2. More specifically, the rotor 2 may be, for example, a rotor 2a of a first embodiment shown in FIG. 2A, or a rotor 2b of a second embodiment shown in FIG. 2B. The rotor 2 may also include a plurality of permanent magnets arranged sequentially in the circumferential direction with their magnetic poles (south and north poles) alternating.

[0019] The rotor 2a of the first embodiment includes four first through fourth permanent magnets 21a-1 to 21a-4 and four first through fourth intermediate members 22a-1 to 22a-4. Each of the first through fourth intermediate members 22a-1 to 22a-4 is a fan-shaped member with a central angle of 90 degrees, and a top portion (a portion forming the central angle) is cut out in a fan shape to form a through opening 23a for inserting the rotation shaft. Each of the first through fourth intermediate members 22a-1 to 22a-4 is made of a non-magnetic material such as aluminum or resin. Each of the first through fourth permanent magnets 21a-1 to 21a-4 is columnar and has approximately the same length as the side length (radial length) of the first through fourth intermediate members 22a-1 to 22a-4 and approximately the same thickness as the thickness of the first through fourth intermediate members 22a-1 to 22a-4. The cross-sectional shape of the first to fourth permanent magnets 21a-1 to 21a-4 may be any shape, such as a circle or a polygon, but is preferably a square prism, since when the rotor 2 faces the first stator 1A on one side and faces the second stator 1A on the other side, the area of ​​each opposing surface of the first to fourth permanent magnets 21a-1 to 21a-4 is maximized.

[0020] The first through fourth permanent magnets 21a-1 through 21a-4 and the first through fourth intermediate members 22a-1 through 22a-4 are sequentially arranged in the circumferential direction so as to form the through-opening 23a and to have the same orientation, in the order of first permanent magnet 21a-1, first intermediate member 22a-1, second permanent magnet 21a-2, second intermediate member 22a-2, third permanent magnet 21a-3, third intermediate member 22a-3, fourth permanent magnet 21a-4, and fourth intermediate member 22a-4, and are fixedly connected to each other at their side edges, for example, with an adhesive. The first permanent magnet 21a-1 is also fixedly connected to the fourth intermediate member 22a-4 at its side edge, for example, with an adhesive.

[0021] The rotor 2b of the second embodiment includes four permanent magnets, first through fourth, 21a-1 through 21a-4. Each of the first through fourth permanent magnets 21a-1 through 21a-4 is a fan-shaped member with a central angle of 90 degrees, and the top portion (the portion forming the central angle) is cut out in a fan shape to form a through opening 23b for inserting the rotating shaft. The first through fourth permanent magnets 21b-1 through 21b-4 are sequentially arranged in the circumferential direction in the order of first permanent magnet 21a-1, second permanent magnet 21a-2, third permanent magnet 21a-3, and fourth permanent magnet 21a-4, so as to form the through opening 23b and so that the magnetic poles are oriented in the same direction. The first permanent magnet 21b-1 is also fixedly connected to the fourth permanent magnet 21b-4 at its side edge, for example, by adhesive.

[0022] The first stator 1A includes a first coil 11A, a plurality of first electromagnetic steel members 12A, and a plurality of first non-magnetic members 13A, while the second stator 1B includes a second coil 11B, a plurality of second electromagnetic steel members 12B, and a plurality of second non-magnetic members 13B. The first stator 1A and the second stator 1B are arranged so as to be plane-symmetric with respect to the rotor 2, but because they have the same structure, the following description will mainly focus on the first stator 1A, and the reference numbers for the configuration of the second stator 1B corresponding to the reference numbers for the first stator 1A will be followed by the reference numbers for the configuration of the second stator 1B in parentheses, thereby substituting for the description of the second stator 1B and omitting the description of the second stator 1B.

[0023] The first coil 11A (11B) is formed by winding a strip-shaped long conductor member with an insulating material (not shown) interposed therebetween such that the width direction of the conductor member is along the axial direction of the first coil 11A (11B), and is a coil having a so-called single pancake structure. Such a strip-shaped long conductor member is in a sheet shape, a ribbon shape or a tape shape, and the thickness (length in the thickness direction) t with respect to the width (length in the width direction) W is less than 1 (0 < t / W < 1). With such a configuration, since the strip-shaped conductor member is arranged along the magnetic flux direction generated in the first coil 11A (11B), so-called eddy currents in the first coil 11A (11B) can be reduced. The first coil 11A (11B) is electrically connected to a drive power source (not shown) via a control circuit (not shown). Incidentally, the first coil 11A (11B) may be formed by winding an insulated long conductor wire.

[0024] The plurality of first electromagnetic steel members 12A (12B) are each a columnar member that is long in one direction and includes first A and second A portions 121A (121B), 122A (122B) by bending. In the example shown in FIG. 1, the first A portion 121A (121B) and the second A portion 122A (122B) are bent at approximately 90 degrees. The plurality of first electromagnetic steel members 12A (12B) are each formed of electromagnetic steel. For example, the plurality of first electromagnetic steel members 12A (12B) are each formed of a plurality of first electromagnetic steel wires bundled with a binder such as an adhesive or resin. The cross-sectional shape of the plurality of first electromagnetic steel members 12A (12B) may be an arbitrary shape such as a circular shape or a polygonal shape, but when the first stator 1A (1B) faces the rotor 2, the area of each opposing surface in each of the plurality of first electromagnetic steel members 12A (12B) is maximized, so it is preferably a quadrangular prism. In the example shown in FIG. 1, the stepping motor 100 includes 12 first electromagnetic steel members 12A (12B), but the number of first electromagnetic steel members 12A (12B) is appropriately determined based on, for example, the rotation angle for one time according to specifications and the like.

[0025] The plurality of first electromagnetic steel members 12A (12B) are arranged such that the plurality of first A portions 121A (121B) of the plurality of first electromagnetic steel members 12A (12B) radiate outward from the rotation axis at equal angular intervals of a predetermined angle, and such that magnetic flux generated in the first coil 11A (11B) flows through the plurality of second A portions 122A (122B) of the plurality of first electromagnetic steel members 12A (12B). More specifically, the first coil 11A (11B) is arranged on the side of one surface formed by the plurality of first A portions 121A (121B) of the plurality of first electromagnetic steel members 12A (12B) and is spaced a predetermined distance (first distance) from the one surface so that the coil axis and the rotation axis are coaxial. The first distance is designed as appropriate, for example, depending on specifications, etc. These first electromagnetic steel members 12A (12B) are arranged such that the second A portions 122A (122B) of the first electromagnetic steel members 12A (12B) are located within the air core of the first coil 11A (11B) arranged in this manner. The second A portions 122A (122B) of the first electromagnetic steel members 12A (12B) may be in contact with the first coil 11A (11B), or may be spaced apart by a predetermined distance (second distance). The second distance is designed appropriately depending on, for example, specifications. The predetermined angle is defined between the center lines extending in the radial direction of two first electromagnetic steel members 12A (12B) adjacent to each other in the circumferential direction.

[0026] The rotating shaft is inserted into an inner space formed by the plurality of second A portions 122A (122B) of the plurality of first electromagnetic steel members 12A (12B) arranged in this manner. Therefore, the rotating shaft, the plurality of second A portions 122A (122B), and the first coil 11A (11B) are arranged in this order radially outward. The plurality of second A portions 122A (122B) of the plurality of first electromagnetic steel members 12A (12B) and the rotating shaft may be in slidable contact with each other, or may be spaced apart by a predetermined distance (third distance). The third distance is designed as appropriate, for example, depending on specifications, etc.

[0027] The plurality of first non-magnetic members 13A (13B) are respectively disposed between the plurality of 1A portions formed by the plurality of 1A portions 121A (121B) of the plurality of first electromagnetic steel members 12A (12B). Each of the plurality of first non-magnetic members 13A (13B) is a plate-like member formed of a non-magnetic material such as aluminum or resin, and having the same thickness (height) as the thickness (axial height) of the plurality of 1A portions 121A (121B). As described above, the plurality of 1A portions 121A (121B) of the plurality of first electromagnetic steel members 12A (12B) are disposed so as to radially spread out at equal angular intervals of a predetermined angle from the rotation axis, and therefore the plurality of first non-magnetic members 13A (13B) are each a fan-shaped plate-like member with a central angle equal to the predetermined angle and a notch at the top. The first portions 121A (121B) of the first electromagnetic steel members 12A (12B) and the first non-magnetic members 13A (13B) that are adjacent to each other in the circumferential direction may be fixedly connected, for example, with an adhesive, etc. Alternatively, the multiple first non-magnetic members 13A (13B) may be integrally formed as a ring-shaped disk (annular disk) that extends radially and has multiple grooves that radiate out from the rotation axis at equal angular intervals of the predetermined angle, and the multiple first non-magnetic members 13A (13B) may be assembled to the multiple first A portions 121A (121B) of the multiple first electromagnetic steel members 12A (12B) by fitting each of the multiple first A portions 121A (121B) of the multiple first electromagnetic steel members 12A (12B) into each of the multiple grooves.

[0028] The first stator 1A and the second stator 1B rotatably sandwich the rotor 2 therebetween, and the plurality of first electromagnetic steel members 12A and the plurality of second electromagnetic steel members 12B are arranged such that each of the plurality of 1A portions 121A in the plurality of first electromagnetic steel members 12A is circumferentially offset from each of the plurality of 1B portions 121B in the plurality of second electromagnetic steel members 12B by an angle that is half the specified angle.

[0029] The results of a simulation of the magnetic flux density in a stepping motor 100 configured as described above are shown in Figure 3. In Figure 3, the level of magnetic flux density is indicated by the shade of brightness, with the darker the brightness (the higher the magnetic flux density). This simulation was performed using electromagnetic field analysis software JMAG manufactured by JSOL Corporation. As can be seen from Figure 3, a large amount of magnetic flux flows through the multiple second electromagnetic steel members 12B (12A), resulting in a high magnetic flux density.

[0030] In the stepping motor 100 configured as described above, the control circuit (not shown) alternately supplies pulsed current to the first and second coils 11A and 11B using drive control signals, causing the rotor 2 to rotate circumferentially by half the predetermined angle at a time. For example, when pulsed current is supplied to the first coil 11A using one drive control signal, the rotor 2 rotates circumferentially by half the predetermined angle and comes to a stop at a magnetically stable position. When pulsed current is subsequently supplied to the second coil 11B using one drive control signal, the rotor 2 rotates circumferentially by half the predetermined angle and comes to a stop at a magnetically stable position. When pulsed current is subsequently supplied to the first coil 11A using one drive control signal, the rotor 2 rotates circumferentially by half the predetermined angle and comes to a stop at a magnetically stable position. When pulsed current is subsequently supplied to the second coil 11B using one drive control signal, the rotor 2 rotates circumferentially by half the predetermined angle and comes to a stop at a magnetically stable position. The magnetically stable position is a position where the position of high magnetic flux density generated by the magnets 21 (21a, 21b) of the rotor 2 overlaps with the first portions 121 (121A, 121B) of the electromagnetic steel members 12 (12A, 12B) of the stator 11 (11A, 11B) on the power supply side. In the example shown in Figures 1 and 2, twelve first electromagnetic steel members 12A (12B) are provided, so the predetermined angle is 360 / 12 = 30 degrees, and one drive control signal rotates the rotor 2 by half that angle, or 15 degrees. Therefore, once the predetermined angle is designed, the number of first electromagnetic steel members 12A (12B) is determined. The direction of rotation is controlled by a not-shown device configured using well-known conventional means.

[0031] As described above, the stepping motor 100 in the embodiment does not require changing the number of first and second coils according to the angle of one rotation, and only requires providing the columnar first and second electromagnetic steel members 12A, 12B according to the angle of one rotation, thereby further improving the simplicity of the structure and ease of manufacture.

[0032] In the stepping motor 100, the first and second electromagnetic steel members 12A, 12B are formed by bundling wire rods together, which reduces the so-called eddy currents that occur in the first and second electromagnetic steel members 12A, 12B compared to when the first and second electromagnetic steel members 12A, 12B are formed integrally from electromagnetic steel, thereby contributing to improved responsiveness.

[0033] The stepping motor 100 includes the first non-magnetic member 13A between the 1A portions and the second non-magnetic member 13B between the 1B portions, so that the first and second electromagnetic steel members 12A and 12B can be appropriately fixed in position, thereby enabling the stepping motor 100 to achieve higher accuracy in its stationary position.

[0034] In order to express the present invention, the present invention has been properly and sufficiently described above through the embodiments with reference to the drawings, but it should be recognized that those skilled in the art can easily change and / or improve the above-mentioned embodiments. Therefore, unless the changes or improvements made by those skilled in the art are at a level that causes departure from the scope of the claims described in the claims, such changes or improvements are interpreted as being included in the scope of the claims. [Explanation of symbols]

[0035] 100 stepper motor 1A 1st stator 1B 2nd stator 2, 2a, 2b rotors 11A 1st coil 11B Second coil 12A 1st electromagnetic steel member 12B 2nd electromagnetic steel member 13A 1st non-magnetic member 13B 2nd non-magnetic material 121A Part 1A 122A Part 2A 121B Part 1B 122B Part 2B

Claims

1. a first stator including a first coil; a second stator including a second coil; a rotor that is disposed between the first and second stators in the axial direction and rotates while magnetically interacting with the first and second stators; the first stator includes a plurality of first electromagnetic steel members each having a columnar shape elongated in one direction and each having first A and second A portions formed by bending the first stator; the second stator includes a plurality of second electromagnetic steel members each having a columnar shape elongated in one direction and each having first B and second B portions formed by bending, the plurality of first electromagnetic steel members are arranged such that a plurality of first A portions in the plurality of first electromagnetic steel members extend radially from the rotation axis at equal angular intervals of a predetermined angle, and such that magnetic flux generated by the first coil flows through a plurality of second A portions in the plurality of first electromagnetic steel members; the plurality of second electromagnetic steel members are arranged such that a plurality of first B portions in the plurality of second electromagnetic steel members spread radially from the rotation axis at equal angular intervals of the predetermined angle, and such that magnetic flux generated by the second coil flows through a plurality of second B portions in the plurality of second electromagnetic steel members, the plurality of first electromagnetic steel members and the plurality of second electromagnetic steel members are arranged such that each of the plurality of first A portions in the plurality of first electromagnetic steel members is circumferentially shifted from each of the plurality of first B portions in the plurality of second electromagnetic steel members by an angle that is half the predetermined angle; Stepping motor.

2. the first electromagnetic steel member is formed of a plurality of bundled first electromagnetic steel wires, The second electromagnetic steel member is formed of a plurality of bundled second electromagnetic steel wires.

2. The stepping motor according to claim 1.

3. the first stator further includes a plurality of first non-magnetic members; the second stator further includes a plurality of second non-magnetic members; each of the plurality of first non-magnetic members is disposed between each of the plurality of first A portions formed by the plurality of first A portions of the plurality of first electromagnetic steel members; the plurality of second non-magnetic members are respectively disposed between the plurality of first B portions formed by the plurality of first B portions of the plurality of second electromagnetic steel members, Stepping motor.

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