JP2005210806A - Motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the diameter of a motor by minimizing a gap between a magnet and an inner yoke. <P>SOLUTION: The motor comprises a rotatable cylindrical magnet 1, outer yokes 3 having magnetic poles that oppose each other in the radial direction at the outside diameter side of the magnet with a gap between, the inner yokes having magnetic poles that oppose each other in radial direction at the inside diameter side of the magnet and constituting a magnetic circuit together with the outer yokes, and coils 9, 10 that are wound around to circumferences of the inner yokes and excite the outer yokes and the inner yokes. Each inner yoke is constituted of a stator 7 to which the coil is wound around, and a rotor 5 having the magnetic poles that oppose each other in the radial direction at the inside diameter side of the magnet and rotating integrally with the magnet. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a motor such as a small stepping motor.

  5 and 6 show an example of a conventional motor. The conventional motor is a cylindrical magnet 21 having an output shaft that is magnetized by n poles in the radial direction and is rotatably supported by inner yokes 24 and 25, which will be described later, and a thrust direction across the magnet 21. Outer yokes 22 and 23, which are stator yokes made of a soft magnetic material disposed opposite to each other, inner yokes 24, 15 which are stator yokes made of a soft magnetic material that rotatably supports the magnet 21, Coils 26, 27 for exciting the yokes 24, 25 and the outer yokes 22, 23, coil bobbins 28, 29 for supporting the coils 26, 27, a motor cover 30 for supporting the outer yokes 22, 23, and the inner yoke 24 , 25 are constituted by bearings 31 and 32 fitted to the inner diameter.

As described in FIGS. 5 and 6 and Patent Document 1 and the like, the conventional motor has an inner yoke or an outer motor provided with a magnetic pole facing the inner diameter side (empty wall) gap of the cylindrical magnet. It has a yoke.
Japanese Unexamined Patent Publication No. 2003-224958 (see FIG. 3, etc.)

However, the conventional examples disclosed in FIGS. 5 and 6 and Patent Document 1 have the following problems.
1) Since there is a gap on the outside and inside of the magnet, the space for the gap becomes an obstacle to reducing the diameter.
2) Since the magnetic pole of the inner yoke is provided on the inner diameter side as compared with the outer yoke provided with a magnetic pole facing the magnet on the outer diameter side, the facing area is reduced and magnetic saturation is likely to occur.
3) Since there is a gap in the radial direction on both sides of the outer diameter and inner diameter of the magnet, it is difficult to manage the gap.
4) Since it is difficult to remove dust such as magnetic particles adhering to the inner diameter side of the magnet, it rubs against the inner yoke.

  In order to solve the above-mentioned problems, the invention described in claim 1 includes a rotatable cylindrical magnet, an outer yoke having a magnetic pole facing the gap in the radial direction of the outer diameter side of the magnet, and the magnet. An inner yoke that has a magnetic pole facing in the radial direction of the inner diameter side and forms a magnetic circuit together with the outer yoke, and a coil that is wound around the inner yoke and that excites the outer yoke and the inner yoke In the motor, the inner yoke is a motor constituted by a stator portion around which the coil is wound and a rotor portion that has a magnetic pole facing the inner diameter side radial direction of the magnet and rotates integrally with the magnet. It is.

  In the above configuration, the radial gap between the inner yoke rotor and the magnet can be minimized (including the close contact state) to reduce the diameter of the motor and prevent dust from adhering between the magnet and the inner yoke. Further, the rotor portion of the inner yoke functions as a magnet back yoke.

  According to a second aspect of the present invention, there is provided the motor according to the first aspect, wherein a gap is provided in the thrust direction between the stator portion and the rotor portion of the inner yoke.

  In the above configuration, the radial gap in the radial direction of the inner yoke is replaced with the thrust gap between the stator portion of the inner yoke and the rotor portion, thereby improving the space efficiency in the radial direction.

  According to a third aspect of the present invention, there is provided the motor according to the first or second aspect, wherein a gap is provided in the radial direction between the stator portion and the rotor portion of the inner yoke.

  In the above configuration, the conventional radial gap in the inner diameter side of the magnet is replaced with a radial gap between the stator portion and the rotor portion of the inner yoke, facilitating the management of the gap, and improving the accuracy of the gap.

  According to a fourth aspect of the present invention, there is provided the motor according to any one of the first to third aspects, wherein a bearing function for rotatably supporting a magnet is added to the stator portion of the inner yoke.

  In the above configuration, the inner yoke has a bearing function and acts to support the rotor magnet rotatably.

  The invention according to claim 5 is the motor according to claim 4, wherein the stator portion of the inner yoke is made of an iron-based oil-impregnated magnetic material, and the bearing functions as an oil-impregnated bearing. is there.

  In the above configuration, the lubricating oil of the iron-based oil-impregnated bearing which is the inner yoke acts so as to continue to support the rotor magnet smoothly and freely.

  The invention according to claim 6 is the motor according to any one of claims 1 to 5, wherein the rotor portion of the inner yoke is a single pole.

  In the above configuration, it is possible to increase the opposing area between the magnet and the magnetic poles of the inner yoke, which acts to improve magnetic saturation.

  The invention according to claim 7 is provided with two outer yokes, two inner yokes, and two coils, respectively, and arranged respectively facing the thrust direction with a magnet interposed therebetween. It is a motor.

  In the above configuration, the yokes opposed to each other in the thrust direction act so as to maintain the magnetic balance, and the coils act independently or jointly to rotate the magnet.

  The invention according to claim 8 is the motor according to claim 7, wherein a member made of a non-magnetic material is disposed between the rotor portions of the two inner yokes.

  In the above configuration, the nonmagnetic material member acts to reduce magnetic interference between the rotor portions of the inner yoke.

  The invention according to claim 9 is the motor according to claim 7, wherein a member made of a hard magnetic material is disposed between the rotor portions of the inner yoke.

  In the above configuration, the member of the hard magnetic material acts so as to reduce the magnetic interference between the rotor portions of the inner yoke so as not to be affected by the magnetic force induced in the rotor portion of the inner yoke.

  According to a tenth aspect of the present invention, there is provided the motor according to any one of the first to ninth aspects, wherein the shaft for supporting the magnet so as to rotate integrally is made of a nonmagnetic material.

  In the above configuration, the shaft of the non-magnetic material acts to reduce magnetic interference between the rotor portions of the inner yoke so as not to transmit magnetism between the rotor portions of the inner yoke.

  The invention according to claim 11 is the motor according to claim 10, wherein the shaft of the non-magnetic material supports the rotor portions of the two inner yokes so as to rotate integrally.

  The above configuration acts to improve the accuracy of assembling the rotor portion of the inner yoke.

  According to the present invention, a motor that achieves a small diameter with improved space efficiency by minimizing the gap between the magnet and the inner yoke and improving magnetic efficiency and positioning accuracy by improving magnetic saturation and magnetic interference of magnetic poles. It can be provided.

  The best mode for carrying out the present invention will be described below as Embodiments 1 to 3.

  1 and 2 are views showing a configuration of a motor according to Embodiment 1 of the present invention. Specifically, FIG. 1 is a sectional view of the motor, and FIG. 2 is an exploded perspective view of the motor of FIG.

  In these figures, reference numeral 1 denotes a cylindrical magnet, which is magnetized to 2n poles (for example, n = 5) in the radial direction. Reference numeral 2 denotes a shaft made of a non-magnetic material such as stainless steel that is rotatably supported by inner yoke stators 7 and 8 described later, and integrally supports the magnet 1 and rotor yokes 5 and 6 described later. Reference numerals 3 and 4 denote outer yokes which are stator yokes made of a soft magnetic material having a magnetic pole of n poles (for example, n = 5) facing the magnet 1 in the radial direction of the outer diameter side of the magnet 1 and facing each other. The magnets 1 are arranged to face each other with a predetermined facing angle in the thrust direction across the magnet 1. Reference numerals 5 and 6 denote inner yoke rotors (hereinafter referred to as inner yoke rotors) made of a soft magnetic material having a single-pole magnetic pole that is closely opposed to the inner diameter side of the magnet 1 in the radial direction. Be placed. Reference numerals 7 and 8 denote inner yoke stators (hereinafter referred to as inner yoke stators) that also serve as iron-based oil-impregnated bearings that rotatably support the shaft 2, and coils 9 and 10 (described later) are wound around the outer yoke 3 and 4, and a magnet 1 having a hard magnetic material in between, and is disposed opposite to each other in the thrust direction.

  The inner yoke rotors 5, 6 and the inner yoke stators 7, 8 have a gap in the thrust direction and the radial direction, and the outer yoke 3, the inner yoke rotor 5, and the inner yoke stator 7 constitute a magnetic circuit, and the outer yoke 4, the inner yoke rotor. 6 and the inner yoke stator 8 constitute a magnetic circuit independently.

  Reference numerals 9 and 10 denote coils for exciting the inner yoke stators 7 and 8, the inner yoke rotors 5 and 6, and the outer yokes 3 and 4. The coils 9 and 10 are supported by coil bobbins 11 and 12, which will be described later. It is wound around. Reference numerals 11 and 12 denote coil bobbins which are sandwiched between the inner yoke stators 7 and 8 and the outer yokes 3 and 4 and support the coils 9 and 10. A motor cover 13 supports the outer yokes 3 and 4. Reference numerals 14 and 15 denote spacers for maintaining a gap in the thrust direction between the inner yoke rotors 5 and 6 and the inner yoke stators 7 and 8.

  In the above configuration, when the coils 9 and 10 are energized, the inner yoke rotors 5 and 6 are excited through the outer yokes 3 and 4 and the inner yoke stators 7 and 8 and the gaps in the thrust and radial directions so that the magnetic poles are excited. The magnet 1 is attracted, repels and attracts the magnetized magnetic pole of the magnet 1, generates torque, and is driven so that the magnet 1 rotates according to the energization of the coils 9 and 10, and the driving force is transmitted from the shaft 2 to the outside. The outer yokes 3 and 4 and the inner yoke rotors 5 and 6 have a gap in the radial direction across the magnet 1, and the inner yoke rotors 5 and 6 are in close contact with the inner diameter side of the magnet 1 and rotate integrally as a back yoke. .

  Here, there is no gap in the radial direction of the inner diameter side of the magnet 1 between the inner yoke rotors 5 and 6 and the magnet 1, and the magnetic pole area of the inner yoke rotors 5 and 6 can be further increased. In addition, it is possible to eliminate rubbing between the magnet and the inner yoke due to dust adhering, and to reduce the magnetic resistance. Specifically, by eliminating the gap on the outer diameter side of the inner yoke rotors 5, 6, the outer diameter of the inner yoke rotors 5, 6 can be increased and the magnetic pole area of the inner yoke rotors 5, 6 can be increased, thereby reducing the magnetic resistance. Magnetic efficiency can be improved. Even if the gap on the outer diameter side is changed to the gap on the inner diameter side of the inner yoke rotor and the inner yoke rotor having the same thickness is used, the radial sectional area is increased and the magnetic resistance is reduced. Of course, the radial gap between the inner yoke rotors 5 and 6 and the inner yoke stators 7 and 8 set in this embodiment may be eliminated so that only the thrust direction gap is provided, and the size may be further reduced.

  In addition, since the gap in the radial direction on the inner diameter side, which has been conventionally provided, is replaced with the gap in the thrust direction between the inner yoke rotors 5 and 6 and the inner yoke stators 7 and 8, the space efficiency in the radial direction is improved. Furthermore, the existing radial gap in the radial direction is replaced with a radial gap between the inner yoke rotors 5 and 6 and the inner yoke stators 7 and 8, thus improving the accuracy of the gap, which was difficult to manage with a magnet. it can. And the adsorption | suction force which generate | occur | produces between a rotor part and a stator part can be reduced by sharing the gap of a radial direction and a thrust direction. That is, since the magnetic flux in the thrust direction can be divided into the magnetic flux in the radial direction, the attractive force in the thrust direction can be divided into the attractive force in the radial direction, reducing the attractive force generated between the rotor part and the stator part. It becomes possible.

  Further, since the magnet 1 is rotatably supported by the inner yoke stators 7 and 8, and the shaft is supported by the inner diameter portions of the inner yoke stators 7 and 8 around which the coils 9 and 10 are wound, Even if a large stress is applied from the outside, the inner yoke stators 7 and 8 have sufficient strength as bearings, so that the magnet 1 can be rotated while preventing the shaft loss torque from increasing.

  Further, since the inner yoke stators 7 and 8 also serve as oil-impregnated bearings, the lubricating oil that exudes acts so that the magnet 1 continues to rotate smoothly without scraping the inner yoke. Note that the inner yoke may be coated instead of the oil-impregnated bearing, which improves wear resistance and reduces shaft loss.

  Since the inner yoke rotors 5 and 6 are single poles, the magnetic pole area can be increased, and when the magnetic pole width and the magnetic pole spacing are the same, they can be doubled. In addition, since the outer yoke and the inner yoke are opposed to each other in the thrust direction, the magnetic balance can be maintained, and each of them constitutes a magnetic circuit independently, so that the coils 9 and 10 are independent or jointly provided. Acts to rotate the magnet. Further, since the magnet 1 made of a hard magnetic material is disposed between the inner yoke rotors 5 and 6, magnetic interference between the inner yoke rotors can be reduced so as not to be affected by the magnetic force induced in the inner yoke rotors 5 and 6. Thereby, the magnetic interference by excitation of the coils 9 and 10 is reduced, and the positioning accuracy of the magnet 1 by each excitation can be improved.

  Further, since the shaft 2 is made of a nonmagnetic material, magnetic interference between the inner yoke rotors can be reduced by not transmitting the magnetism between the inner yoke rotors. Further, since the magnet 1 and the inner yoke rotors 5 and 6 are integrally supported by the shaft 2, the assembling accuracy is improved and the gap can be easily managed. Further, since the spacers 14 and 15 maintain the gap between the thrust gaps between the inner yoke rotors 5 and 6 and the inner yoke stators 7 and 8, the attractive force generated between the inner yoke rotors 5 and 6 and the inner yoke stators 7 and 8. Can be reduced.

  FIG. 3 is a cross-sectional view showing the configuration of the motor according to the second embodiment of the present invention. The magnet 16 has a cylindrical shape and its inner diameter is hollow. A nonmagnetic spacer 17 such as phosphor bronze is disposed between the inner yoke rotors 5 and 6 in the hollow portion so as to reduce magnetic interference between the inner yoke rotors. Other configurations are the same as those in FIGS.

  FIG. 4 is a cross-sectional view showing the configuration of a motor according to Embodiment 3 of the present invention. The magnet 16 is cylindrical and has an inner diameter that is hollow, and a nonmagnetic shaft 18 such as stainless steel is provided on the inner yoke rotor 5. , 6 to reduce magnetic interference between the inner yoke rotors. Other configurations are the same as those in FIGS.

  According to the first to third embodiments, the inner yoke has the inner yoke stators 7 and 8 around which the coils 9 and 10 are wound, and the magnetic poles facing the inner diameter side radial direction of the magnet 1. Since the inner yoke rotors 5 and 6 rotate integrally with the inner yoke rotors 5 and 6, the inner yoke rotors 5 and 6 can minimize the radial gap with the magnet 1 (including the close contact state as in each embodiment), and the motor. Can be reduced in size, and dust adhesion between the magnet 1 and the inner yoke can be eliminated. Further, the rotor portion of the inner yoke can act as the back yoke of the magnet 1.

  Further, the radial gap on the inner diameter side of the magnet 1 is replaced with a thrust gap between the inner yoke stators 7 and 8 and the inner yoke rotors 5 and 6 and a radial gap between the inner yoke stators 7 and 8 and the inner yoke rotors 5 and 6. As a result, the space efficiency in the radial direction can be improved, and the accuracy of the gap, which was difficult to manage with the magnet, can be improved. Further, by sharing the gap in the radial direction and the thrust direction, it is possible to reduce the generated attracting force, and to smoothly rotate the rotor portion that rotates integrally with the magnet with respect to the non-rotatable stator portion.

  Further, since the inner yoke stators 7 and 8 also serve as bearings for rotatably supporting the magnet 1, the magnet 1 can be rotatably supported while eliminating the need for a dedicated bearing. Therefore, it can be set as the small motor which eliminated the bearing occupation space.

  Further, since the inner yoke stators 7 and 8 are made of an iron-based oil-containing porous magnetic material and function as a bearing, the lubricating oil continues to smoothly and smoothly support the magnet 1. Therefore, the motor can improve the bearing strength and reduce the shaft loss torque.

  Moreover, since the inner yoke rotors 5 and 6 are single poles, the opposing area of the magnet 1 and the magnetic pole of an inner yoke can be increased, and magnetic saturation can be improved. Therefore, it is possible to make the motor capable of increasing the torque by balancing the suction force and reducing the shaft loss torque and the detent torque.

  The outer yoke, the inner yoke, and the coil are disposed opposite to each other in the thrust direction with the magnet 1 interposed therebetween, and the two outer yokes 7, 8 and the inner yoke (7, 8, 5, 6) and the coil 9, respectively. Therefore, the yokes opposed to each other in the thrust direction act so as to maintain the magnetic balance, and the coils 9 and 10 act independently or jointly to rotate the magnet. Therefore, a high-efficiency motor can be obtained by magnetically balancing in the thrust direction to reduce the shaft loss torque and detent torque.

  Further, in the second and third embodiments, since the space between the inner yoke rotors is the spacer 17 and the shaft 18 made of a nonmagnetic material, magnetic interference between the inner yoke rotors can be reduced. In the first embodiment, since the magnet 1 made of a hard magnetic material is disposed between the two inner yoke rotors, the hard magnetic material does not interfere with the magnetic interference between the inner yoke rotors so as not to be affected by the magnetic force induced in the inner yoke rotor. Can be reduced. Further, since the shaft 2 supporting the magnet 1 is made of a nonmagnetic material, magnetic interference between the inner yoke rotors can be reduced so as not to transmit magnetism between the inner yoke rotors. From the above, it is possible to reduce the magnetic coupling between the inner yoke rotors and to obtain a motor with good positioning accuracy.

  Further, since the shaft 2 supports the inner yoke rotors 5 and 6 so as to rotate integrally, the assembling accuracy of the inner yoke rotor can be improved.

It is sectional drawing which shows the structure of the motor concerning Example 1 of this invention. It is a disassembled perspective view of the motor of FIG. It is sectional drawing which shows the structure of the motor concerning Example 2 of this invention. It is sectional drawing which shows the structure of the motor concerning Example 3 of this invention. It is sectional drawing which shows the structural example of the conventional motor. FIG. 6 is an exploded perspective view of the motor of FIG. 5.

Explanation of symbols

1,16 magnet 2,18 shaft 3,4 outer yoke 5,6 inner yoke rotor 7,8 inner yoke stator 9,10 coil

Claims (11)

A rotatable cylindrical magnet, an outer yoke having a magnetic pole facing the outer diameter side radial direction of the magnet, and a magnetic pole facing the inner diameter side radial direction of the magnet together with the outer yoke In a motor having an inner yoke constituting a magnetic circuit, and a coil wound around the inner yoke and exciting the outer yoke and the inner yoke,
The inner yoke includes a stator portion around which the coil is wound, and a rotor portion having a magnetic pole facing the inner diameter side radial direction of the magnet and rotating integrally with the magnet. .   The motor according to claim 1, wherein the stator portion and the rotor portion of the inner yoke have a gap in the thrust direction.   The motor according to claim 1, wherein the stator portion and the rotor portion of the inner yoke have a gap in the radial direction.   The motor according to claim 1, wherein the stator portion of the inner yoke has a bearing function for rotatably supporting the magnet.   The motor according to claim 4, wherein the stator portion of the inner yoke is made of an iron-based oil-impregnated magnetic material, and the bearing functions as an oil-impregnated bearing.   6. The motor according to claim 1, wherein the rotor portion of the inner yoke is a single pole.   7. The outer yoke, the inner yoke, and the coil are provided two by two, respectively, and are arranged to face each other in the thrust direction with the magnet interposed therebetween. Motor.   The motor according to claim 7, wherein a member made of a nonmagnetic material is disposed between the rotor portions of the two inner yokes.   The motor according to claim 7, wherein a member made of a hard magnetic material is disposed between the rotor portions of the two inner yokes.   10. The motor according to claim 1, wherein the shaft that supports the magnet so as to rotate integrally is made of a nonmagnetic material. The motor according to claim 10, wherein the shaft supports the rotor portion of the inner yoke so as to rotate integrally.

Images