JP3272626B2 - motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor provided with a rotor portion constituted by a rotor magnet,
More specifically, the present invention relates to a motor in which a rotor magnet is coupled to an outer periphery of a shaft via a bush.

[0002]

2. Description of the Related Art As a motor of this type, for example, PM
There are known stepping motors and the like. Conventionally,
In such a motor, as a bush interposed between the shaft and the rotor magnet, a resin bush integrally formed with the rotor magnet or an aluminum bush (commonly called "aluminum bush") is used. .

[0003]

However, when the former resin bush integrally molded with the rotor magnet is integrally molded inside the rotor magnet, a high resin pressure acts on the rotor magnet. Therefore, there is a problem in that the rotor magnet may be broken by the pressing force, and the production yield is reduced.
Therefore, when trying to increase the thickness of the rotor magnet, the rotor magnet is expensive,
There has been a problem that the production unit price has risen, which is uneconomical. Therefore, in consideration of the weight of the entire rotor, a motor in which the thickness of the rotor magnet is made as thin as possible and which is bonded and fixed to the outer periphery of a relatively lightweight aluminum bush has been proposed. In addition, since the outer diameter must be cut with high accuracy, the processing cost is increased, and cracks are easily generated when the thin rotor magnet is magnetized.

SUMMARY OF THE INVENTION The present invention has been made to effectively solve the problems of the conventional motor having a rotor. The present invention aims to reduce the thickness of the rotor magnet and greatly improve the manufacturing yield, thereby improving the motor itself. It is an object of the present invention to provide a motor that can reduce the cost and improve the startability by reducing the inertia of the rotor. Another object of the present invention is to allow the rotor magnet to be magnetized either before or after coupling to the shaft, thereby enabling single-piece management of the rotor magnet and enabling reuse of the rotor magnet. It is in.

[0005]

According to a first aspect of the present invention, an annular rotor magnet is coupled to an outer periphery of a rotatably supported shaft via a bush, and a predetermined outer periphery of the rotor magnet is fixed to the outer periphery of the rotor magnet. A motor in which an excitation coil is disposed with an air gap, wherein the bush is formed of a resin material, the shaft is coupled to an inner peripheral portion of the motor, and the rotor magnet is detachably attached to an outer peripheral portion of the motor. The bush and the rotor magnet are provided , and a detent means for preventing the rotor magnet from coming off from the bush is provided .
With a cylindrical part, the cylindrical part can be fitted into the large diameter hole of the bush
A retaining member made of a suitable resin material .

[0006] The invention described in claim 2 is the invention according to claim 1.
, A plurality of the rotor magnets are detachable in an axial direction on an outer peripheral portion of the bush, and a first engaging portion is formed on the outer peripheral portion of the bush at a position shifted in the circumferential direction. By forming a second engagement portion that engages with the engagement portion on an inner peripheral portion of each of the rotor magnets, by restricting a fitting position of each of the plurality of rotor magnets, A phase difference between magnetic poles in a circumferential direction of a plurality of rotor magnets is determined. Furthermore, a third aspect of the present invention is the bush according to the first or second aspect, wherein the shaft is inserted into a center portion of the bush and is integrally formed.

According to the present invention, the bush interposed between the shaft and the rotor magnet is formed of a resin material, and the shaft is integrally connected to the inner periphery thereof. By making the outer periphery of the rotor magnet detachable, a large external force is applied to the rotor magnet at the time of assembling the rotor magnet, thereby avoiding the occurrence of cracks and reducing the thickness of the rotor magnet. As a result, the cost of the motor itself can be reduced due to the reduced thickness of the rotor magnet, and the inertia of the rotor portion can be reduced to improve the motor startability. Further, the rotor magnet can be magnetized before or after the connection to the shaft, so that the rotor magnet can be managed individually, and the rotor magnet can be removed from the motor and reused.

In particular, according to the second aspect of the present invention, a plurality of rotor magnets can be attached to and detached from the outer periphery of the bush, and furthermore, by restricting the fitting positions thereof,
The phase relationship between the plurality of rotor magnet magnetic poles is optimally and accurately determined, and the rotor can be rotated with high accuracy. Therefore, as the rotor magnet, the same parts are prepared which are sequentially magnetized to different polarities in the outer circumferential direction and have the second engaging portions formed on the inner circumferential surface. A plurality of rotor magnets, such as a stepping motor, are magnetized with a phase difference in the circumferential direction by being mounted on the outer circumferential portion of the bush by being engaged with a first engaging portion formed at a position shifted in the circumferential direction. The manufactured motor can be manufactured very easily. According to the third aspect of the present invention, by inserting the shaft into the center of the bush, they can be managed and assembled as one part.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIGS. 1 to 3 show a motor of the present invention.
1 shows a first embodiment applied to a PM type stepping motor. In FIG. 1, reference numeral 1 denotes a shaft, and an annular rotor magnet 4 is coupled to an outer periphery of the shaft via a bush 2 and a retaining member 3 described later. Here, the rotor magnets 4 are magnetized so as to alternately have different polarities along the circumferential direction. Further, both ends of the shaft 1 are rotatably held by a case 7 forming a stator core by bearings 5 and 6. Here, the case 7 is divided into two parts in the axial direction, and stator poles 7A and 7B which are bent into comb teeth and become magnetic poles are provided on the inner peripheral side opposed to the respective rotor magnets 4.
Similarly, the first and second stator cores 12 and 1 having a comb shape are formed.
3 and are alternately formed in the circumferential direction at a predetermined interval. Note that reference numeral O denotes a rotation axis of the shaft 1, reference numeral 8 denotes a first bobbin around which the first excitation coil 9 is wound, and reference numeral 10 denotes a second bobbin around which the second excitation coil 11 is wound. Each is shown.

As shown in FIG. 1, when the motor is a two-phase stepping motor, for example, the first exciting coil 9
, Two coils are bifilar wound so as to create a magnetic field having a phase relationship of 180 ° with each other. Similarly, as the second excitation coil 11, the two coils are 180 ° with each other.
The bifilar winding is performed so as to create a magnetic field having a phase relationship of. Then, the first and second stator cores 1
Stator poles forming magnetic poles are formed on the inner peripheral sides of the magnets 2 and 13, and the magnetic poles are arranged so as to face the outer peripheral surface of the rotor magnet 4 via a predetermined air gap.

The bush 2 is integrally connected to the shaft 1 by being injection-molded integrally with a synthetic resin material in a state where the shaft 1 is provided at the center thereof. A cutout 1A is formed in the portion of the shaft 1 located in the bush 2, and when the molding material of the bush 2 enters the cutout 1A, the shaft 1 and the bush 2 are prevented from rotating. It is integrated and stopped. Here, the code 2A is
An outer peripheral portion fitted to the inner peripheral surface of the rotor magnet 4,
2B is an outer flange portion for positioning the right end of the rotor magnet 4 in FIG. A large-diameter hole 2C is formed in the center of the bush 2 on the left side in FIG. 1, and a plurality of holes 2D that open into the large-diameter hole 2C are formed in the outer peripheral wall of the large-diameter hole 2C. I have. A key portion 2E that fits into a key groove 4A (see FIG. 3) formed in the inner peripheral portion of the rotor magnet 4 is formed in the outer peripheral portion 2A of the bush 2. The fitting of the key portion 2E and the key groove 4A prevents the rotor magnet 4 from rotating with respect to the bush 2.

The retaining member 3 is a cylindrical body made of a synthetic resin, and has a through hole 3A (see FIG. 2) for fitting with the shaft 1 at the center thereof. Reference numeral 3B denotes an outer flange portion for positioning the left end portion of the rotor magnet 4 in FIG. 1, and reference numeral 3C denotes a small-diameter portion fitted into the large-diameter hole 2C of the bush 2. The small diameter portion 3C is formed with a plurality of hook portions 3D that are detachable from the hole 2D on the bush 2 side. In addition, hook part 3D
An inclined surface 3E (see FIG. 2) is formed at the leading edge on the right side in FIG.

Next, a procedure for assembling the rotor magnet 4 will be described with reference to FIGS. As described above, the resin bush 2 is integrally connected to the shaft 1 simultaneously with its molding. Then, as shown in FIG. 2, the key portion 2E and the key groove 4A are fitted to the outer peripheral portion 2A of the bush 2, and the rotor magnet 4 is fitted. Next, the small diameter portion 3C of the retaining member 3 is fitted into the large diameter hole 2C of the bush 2. At that time, hook part 3D
Presses against the inner peripheral surface of the large-diameter hole 2C of the bush 2, and the hook portion 3D and / or the bush 2 are temporarily elastically deformed. Then, when the hook 3D and the hole 2D face each other, the hook 3D and / or the bush 2 elastically return, and the hook 3D and the hole 2D are fitted. In this way, the coupling of the bush 2 and the retaining member 3 prevents the outer flange portion 3B of the retaining member 3 from detaching the rotor magnet 4 to the left in FIG.

The rotor magnet 4 thus assembled to form the rotor section is used for the assembly.
Since a large external force is not applied, even if the thickness of the rotor magnet 4 is reduced, there is no possibility of cracking. Therefore, as the rotor magnet 4 is made thinner, the cost of the motor itself can be reduced, and the inertia of the rotor portion can be reduced to improve the startability. Incidentally, the rotor magnet 4 can be magnetized before being assembled in this way, that is, before forming the rotor portion, or it can be magnetized after such assembling, that is, after forming the rotor portion. You can also. Further, as shown in FIG. 1, the rotor magnet 4 after being incorporated in the motor can be removed and reused. The hook 3D may be formed on the bush 2 side, and the hole 2D may be formed on the retaining member 3 side.

(Second Embodiment) FIG. 4 shows a rotor portion of a motor according to a second embodiment of the present invention, and other structures are the same as those shown in FIGS. It is. In the present embodiment, the bush 2 shown in FIG.
A hook portion 2F that is continuous or dotted along the circumferential direction is formed on the outer peripheral edge on the middle left side, and the rotor magnet 4 is prevented from coming off using the hook portion 2F. When assembling the rotor magnet 4, the left side portion of the bush 2 in FIG. 4 is fitted into the rotor magnet 4. At this time, the left side portion of the bush 2 including the hook portion 2F in FIG. 4 is temporarily elastically deformed by pressure contact with the inner peripheral surface of the rotor magnet 4, and then elastically returns. As a result, the rotor magnet 4 is prevented from coming off by the hook 2F at the position indicated by the two-dot chain line in FIG.

Third Embodiment FIG. 5 shows a third embodiment of the present invention. In the present embodiment, first and second two rotor magnets 4-1 and 4-2 are attached to the bush 2. That is, an outer flange portion 2G is formed on the outer periphery of the bush 2, and the outer flange portion 2G is formed.
Of the left side in FIG. 5, the outer peripheral portion 2A-1 detachable from the first rotor magnet 4-1 is formed, the outer flange 2
On the right side in FIG. 5 of G , an outer peripheral portion 2A-2 detachable from the second rotor magnet 4-2 is formed. A key portion (first engagement portion) 2E-1 that fits with the key groove (second engagement portion) 4A-1 of the rotor magnet 4-1 is formed on the outer peripheral portion 2A-1. Similarly, a keyway (second engaging portion) of the rotor magnet 4-2 is provided on the outer peripheral portion 2A-2.
A key portion (first engagement portion) 2E-2 to be fitted with 4A-2 is formed. Here, the key portions 2E-1 and 2E-2
Are formed so as to be shifted from each other by a predetermined angle in the circumferential direction, and the rotor magnet 4-
The fitting positions of 1, 4-2 are shifted in the circumferential direction. Therefore, the phase relationship between the magnetic poles is accurately set according to the fitting position of the rotor magnets 4-1 and 4-2.

By precisely setting the magnetic poles of the two rotor magnets 4-1 and 4-2 in a predetermined phase relationship in this manner, the excitations arranged with a predetermined air gap around their outer circumferences are provided. Due to the relationship with the coil, the rotor section can be rotated with high precision and smoothness. Note that the phase difference between the magnetic poles of the rotor magnets 4-1 and 4-2 is optimally and accurately set according to the type of the motor by changing the formation position of the key portions 2E-1 and 2E-2. Can be. In the case of a hybrid stepping motor, one of the rotor magnets 4-1 and 4-2 is an N-pole gear-shaped rotor and the other is an S-pole gear-shaped rotor, and their magnetic poles are, for example, 190 °. It may be a phase relationship.

[0018]

As described above, according to any one of the first to third aspects of the present invention, the bush interposed between the shaft and the rotor magnet is formed of a resin material, and is formed on the inner peripheral portion thereof. By connecting the shaft and attaching and detaching the rotor magnet to the outer periphery, it is possible to avoid the occurrence of cracks due to a large external force applied to the rotor magnet when assembling the rotor magnet, and to reduce the thickness of the rotor magnet. Can be planned. As a result, the cost of the motor itself can be reduced due to the reduced thickness of the rotor magnet, and the inertia of the rotor portion can be reduced to improve the motor startability. Furthermore, the rotor magnet can be managed separately so that the rotor magnet can be magnetized before or after coupling to the shaft,
Further, the rotor magnet can be removed from the motor and reused.

Here, in particular, according to the second aspect of the present invention, a plurality of rotor magnets can be attached to and detached from the outer peripheral portion of the bush, and furthermore, by restricting the fitting positions thereof, the plurality of rotor magnets can be provided. The phase relationship between the magnetic poles can be determined optimally and accurately, and the rotor portion can be rotated with high precision. Further, according to the invention described in claim 3, by inserting a shaft into the center portion of the bush, they can be rotated. The advantage is obtained that the components can be managed and assembled as one component.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a first embodiment of a motor according to the present invention.

FIG. 2 is an exploded cross-sectional view showing the rotor unit of FIG.

FIG. 3 is a different exploded sectional view of the rotor unit of FIG. 1;

FIG. 4 is an exploded cross-sectional view illustrating a rotor unit according to a second embodiment of the present invention.

FIG. 5 is an exploded perspective view showing a rotor unit according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shaft 1A Notch 2 Bush 2A Outer peripheral part 2B Outer flange part 2C Large diameter hole 2D hole 2E Key part (1st engaging part) 3 Retaining member 3A Through hole 3B Outer flange part 3C Small diameter part 3D hook part 4 Rotor magnet 4A Keyway (second engaging portion) 5, 6 Bearing 7 Casing 8, 10 Bobbin 9, 11, Exciting coil 12, 13 Stator core

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02K 1/00-1/16 H02K 1/18-1/26 H02K 1/28-1/34

Claims (3)

(57) [Claims] 1. A motor in which an annular rotor magnet is coupled via a bush to an outer periphery of a rotatably supported shaft, and an exciting coil is disposed at a predetermined air gap around the outer periphery of the rotor magnet. The bush is formed of a resin material, the shaft is coupled to an inner peripheral portion of the bush, and the rotor magnet is detachably provided on an outer peripheral portion of the bush. the provided with detent means for the detent, and a retaining means for the retaining of the rotor magnet from the bush, the detachment preventing
The means has an outer flange portion, and the cylindrical portion is formed of the bush.
Equipped with a retaining member made of resin material that can fit into the large-diameter hole.
Motor, characterized by comprising e. 2. A plurality of said rotor magnets are detachable in an axial direction on an outer peripheral portion of said bush, and a first engaging portion is formed on an outer peripheral portion of said bush at a position shifted in a circumferential direction. And a second engaging portion that engages with the engaging portion is formed on an inner peripheral portion of each of the rotor magnets, thereby restricting a fitting position of each of the plurality of rotor magnets. 2. The motor according to claim 1, wherein a phase difference between magnetic poles of the plurality of rotor magnets in a circumferential direction is determined. 3. The motor according to claim 1, wherein the bush is formed integrally with the shaft by inserting the shaft at a central portion thereof.