JPH09289748A - Motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor where the reduction of the manufacture cost and the general weight reduction can be made and also the manufacture becomes possible, by arranging the constitution such that the inner stress caused by thermal expansion and shrinkage does not work on a permanent magnet therefore making the thickness dimension of the permanent magnet small. SOLUTION: A rotor 55 has a cylindrical permanent magnet 20 and a rotor support 10 made of synthetic resin which is press-fitted in the center of this permanent magnet 20 and at the center of which a bearing hole 10a in which to insert a rotor shaft is made, and at the inside periphery of the permanent magnet 20, irregularity 20b is made in circumferential direction, and besides irregularity 10b for whirl stopping which engages with the irregularity of permanent magnet is made at the outside periphery of the rotor support, and also a cavity 10c for thickness escape is made at the thick part between the outside periphery of the rotor support and the bearing hole.

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 having a cylindrical permanent magnet on its outer peripheral portion.

[0002]

2. Description of the Related Art Conventionally, in various devices such as an air conditioner for indoor heating and cooling, as a drive source of a drive device with a reduction mechanism that is combined with a reduction gear group to open and close a damper and the like,
Various motors such as PM type stepping motors are used. For example, in the above stepping motor, a bobbin is integrally provided on the outer circumference of a yoke in which comb teeth are arranged on the inner circumferential surface, and a coil is wound around the outer circumference of the bobbin to form a multi-phase coil. A stator part formed by
The rotor is roughly configured to be rotatably assembled in the central space of the stator portion.

FIG. 1 shows the structure of a rotor in a conventional stepping motor of this type.
It is composed of a rotor support 1 made of synthetic resin and a cylindrical permanent magnet 2. At the center of the rotor support 1, there is formed a bearing hole 1a for rotatably attaching to a rotor shaft fixed to a motor casing, and at an upper outer peripheral portion, a rotor pinion 1b meshing with a reduction gear. Are formed. The permanent magnet 2 is formed into a substantially cylindrical appearance, and its outer peripheral surface 2a is sequentially magnetized with different poles in the circumferential direction corresponding to the pole teeth of the stator portion. Further, the thickness of the permanent magnet 2 is reduced in a stepwise manner toward the center portion, whereby the permanent magnet 2 is strongly assembled with the rotor support 1 made of synthetic resin, and rotation prevention in the circumferential direction is realized.

By the way, in order to manufacture the rotor having such a structure, when the rotor support 1 is injection-molded,
The mold in which the cavity having the entire contour surface of the rotor is formed is opened, the above-mentioned permanent magnet 2 produced by sintering is fixed to the inner peripheral surface of the cavity, the mold is closed, and the resin is placed in the mold. Is injected to mold the rotor support 1 and integrate it with the permanent magnet 2. As described above, in the rotor, when the rotor support 1 is molded by injection molding, the rotor support 1 and the permanent magnet 2 are integrated, so that there is an advantage that the rotor support 1 is easy to manufacture and suitable for mass production.

[0005]

However, in the conventional stepping motor having the rotor having the above structure, the rotor has two different physical physical properties, that is, the rotor support 1 made of synthetic resin and the permanent magnet 2 made of metal. Since the two materials are integrated by heat molding, expansion and contraction of each material causes internal stress in the molded product, so that the rotor support 1 and the permanent magnet 2 made of synthetic resin have a mutual thickness. There has been a problem that the ratio has to be limited to a predetermined narrow range, so that it is particularly difficult to reduce the thickness of the permanent magnet 2 to reduce the overall weight. The present invention has been made to effectively solve the problems of the conventional motors described above, and internal stress due to thermal expansion and contraction does not act on the permanent magnets. It is an object of the present invention to provide a motor that can be thinned to reduce the manufacturing cost and the overall weight and to be easily manufactured.

[0006]

According to a first aspect of the present invention, a motor is provided with a stator portion in which a coil is wound in a casing, and an outer peripheral surface is provided in a central space of the stator portion. In a motor in which a rotor having a permanent magnet is rotatably assembled to a rotor shaft provided in the casing, the rotor is press-fitted into a cylindrical permanent magnet and a central portion of the permanent magnet, and A rotor support made of synthetic resin in which a bearing hole into which the rotor shaft is inserted is formed, and a concavo-convex portion is formed in the center in the inner peripheral surface of the permanent magnet in the circumferential direction, and The outer peripheral surface of the rotor support is formed with a concavo-convex portion for preventing rotation that engages with the concavo-convex portion of the permanent magnet, and the wall relief is formed in the thick portion between the outer peripheral surface of the rotor support and the bearing hole. It is characterized in that the air gap of the use are formed. Further, the invention according to claim 2 is characterized in that the rotor support according to claim 1 is composed of upper and lower two-divided bodies arranged with a gap therebetween.

According to the motor of the first aspect, a rotor support made of a synthetic resin having different physical properties constituting the rotor of the motor and a permanent magnet made of fired metal powder are separately molded. Therefore, no thermal internal stress is generated in the assembled rotor. Therefore, when manufacturing the rotor support and the permanent magnet, it is not necessary to limit the mutual thickness ratio between the rotor support and the permanent magnet made of respective materials or synthetic resins,
Therefore, it is possible to reduce the thickness of the permanent magnet and reduce the weight of the entire motor. Also, assembling the rotor support to the permanent magnet is easy because the rotor support can be lightly press-fitted into the inner side of the cylindrical permanent magnet by utilizing the elasticity of the cavity for the meat relief of the rotor support. The coupling between the rotor support and the permanent magnet after assembly can be sufficiently secured by the elasticity of the voids, and the detents in the circumferential direction of each other are formed on the contact peripheral surfaces of each other. It can be ensured by the formed unevenness.

According to the motor of the second aspect, in addition to the effect of the invention of the first aspect, inside the cylindrical permanent magnet, from the upper and lower openings of the permanent magnet, The rotor support is assembled to the permanent magnet by inserting the upper and lower divided bodies that make up the rotor support into the permanent magnet only by inserting them lightly until their locking edges engage with the upper and lower ends of the permanent magnet. The advantage is that the rotor support is easier to assemble.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIGS. 2, 3 and 5 show a PM in which a motor according to the present invention is incorporated in a drive unit with a reduction mechanism.
1 shows a first embodiment applied to a mold type stepping motor. FIG. 5 shows the entire structure of the drive unit with the reduction mechanism, and in the figure, reference numeral 50 is a metal casing formed in a bottomed cylindrical shape. This casing 5
A stepping motor 51 is housed in the bottom portion of 0. The motor 51 includes a stator portion 54 in which a multi-phase coil is formed by winding a coil winding 53 around an outer circumference of an annular bobbin 52 having a plurality of comb-teeth-shaped pole teeth formed on the inner peripheral edge thereof. The rotor 55 is rotatably provided in the central space of the stator 54 and is roughly configured.

Here, the rotor 55 is composed of a rotor support 10 and a permanent magnet 20, as shown in FIGS. The rotor support 10 is integrally molded by injection molding using synthetic resin, and a bearing hole 10a for penetrating the rotor shaft is formed in the center thereof. A serration (uneven portion) 10b for preventing rotation is formed on the outer peripheral surface of the rotor support 10. The serrations 10b are arranged parallel to each other in the axial direction of the rotor support 10 and at equal intervals in the inner circumferential direction. Further, in the thick portion between the outer peripheral surface of the rotor support 10 and the bearing hole 10a, a void portion 10c for flesh relief is formed. The void portion 10c is opened downward and is continuously formed in the circumferential direction. Reference numeral 10d in the drawing denotes a rotor pinion in which the rotor 55 having the rotor support 10 meshes with the first-stage gear 60a of the reduction gear group 60 described later.

The permanent magnet 20 is externally mounted on the outer circumference of the rotor support 10. As shown in FIG. 3, the permanent magnet 20 has a cylindrical shape formed by separately sintering metal powder, and has an outer peripheral surface 20a.
Are alternately magnetized to different poles in the circumferential direction. A groove portion (uneven portion) 20b that engages with the serration (uneven portion) 10b on the outer peripheral surface of the rotor support 10 is formed on the inner peripheral surface of the permanent magnet 20. Then, in the rotor 55, the rotor support 10 is inserted from the upper opening of the permanent magnet 20 so that the serrations 10b and the groove portions 20b of the rotor support 10 are aligned with each other, and the rotor support 10 is elasticized by the void portion 10c for meat escape. It is configured by lightly press-fitting and integrating.

As shown in FIG. 5, the rotor 55 having the above-described structure is rotatably attached to a rotor shaft 56 fixed to the casing 50, and serves as a lower end surface of the rotor support 10 constituting the rotor 55. A small gap is formed between the bottom surface of the casing 50 and the top end surface of the rotor support 10 and the lid 57 of the casing 50. Therefore, the rotor support 10 does not displace vertically and fall off from the permanent magnet 20.

The motor 51 having such a rotor 55 is fixed in the casing 50, and in this drive device, a gear plate 58 is provided on the upper surface of the motor 51. This gear plate 58
An opening 58a is formed in the center of the rotor 51, and the motor 51 extends from the opening 58a.
6 and the rotor pinion 10d are projected. Then, the reduction gear group 6 is provided between the cover 57 that closes the upper opening of the casing 50 and the gear plate 58.
0 is provided. The rotor shaft 56 is supported by the bottom surface of the casing 50 and the lid 57. Incidentally, reference numeral 61 in the drawing denotes the reduction gear group 60.
Output shaft.

The stepping motor 51 having the above structure
In this case, since the rotor support 10 made of synthetic resin and the permanent magnet 20 made of metal, which are different from each other in physical properties of the rotor 55, are molded separately, the thermal interior of the rotor 55 that has been assembled is completed. No stress is generated, so that it is not necessary to limit the materials used to manufacture the rotor support 10 and the permanent magnet 20. Further, the mutual thickness ratio between the rotor support 10 made of synthetic resin and the permanent magnet 20 can be selected from a wide range, so that the permanent magnet 20 can be made thinner than the conventional one.
It is possible to further reduce the weight of the entire motor 51, and since the permanent magnet 20 is additionally molded, the injection control of the rotor support 10 has a wide range of injection pressure selection control, which facilitates molding.

In addition, the rotor support is assembled to the permanent magnet 20 by arranging the rotor support 10 inside the cylindrical permanent magnet 20 and evacuating the rotor support 10 for the meat.
Since it is only necessary to press-fit using the elasticity of 0c,
It is easy to work, and the coupling between the rotor support 10 and the permanent magnet 20 after assembling can be ensured as necessary and sufficient by the elasticity generated by the void portion 10c. It can be secured by the serration formed on the contact peripheral surface.

(Second Embodiment) FIG. 4 shows a rotor support 30 in a motor according to a second embodiment of the present invention, and the same components as those shown in the first embodiment will be described. Are assigned the same reference numerals and explanations thereof are omitted. In the rotor support 30, the upper and lower half bodies 31, which are arranged with a gap therebetween, in the assembled state,
It is composed of 32. These divided bodies 31, 32
Bearing holes 31a and 32a for penetrating the rotor shaft are formed at the center of the shaft. Further, serrations (concavo-convex portions) 31b and 32 for preventing rotation are provided on the respective outer peripheral surfaces that fit into the groove portions 20b on the permanent magnet 20 side.
b is formed. These serrations 31b, 32
b have the same shape and the same size as each other, and
It is formed parallel to the axial direction of. In addition, the lower divided body 32
In the thick portion between the outer peripheral surface of the and the bearing hole 32b, a void portion 32c for meat escape is formed. This void 3
2C is open upward and is formed continuously in the circumferential direction. The reference numeral 31d in the figure indicates the rotor support 30.
The rotor having the gear is the first gear 6 of the reduction gear group 60.
It is a rotor pinion that meshes with 0a. A locking edge 31e for locking the permanent magnet 20 is formed on the upper edge of the upper divided body 31 of the rotor support 30, and the lower edge of the lower divided body 32 has a similar engagement. A toe 32e is formed. Then, the upper and lower divided bodies 31, 32 constituting the rotor support 30 are integrally formed by injection molding using a synthetic resin.

Then, from the upper and lower openings of the permanent magnet 20, the upper and lower divided bodies 31 and 32 constituting the rotor support 30 are respectively attached to the engaging edges 31e and 32e.
Is inserted into the upper and lower ends of the permanent magnet 20 until they are engaged with each other, thereby forming an integrated rotor. By the way, even when the motor having this rotor is incorporated in the drive unit with a reduction mechanism shown in FIG.
In the rotor support 30 composed of 1 and 32, the respective divided bodies 31 and 32 are configured so that the respective locking edges 31e and 32e do not cause displacement to the center of the rotor 55, and the two divided bodies 31 and 32, 32 and the casing 50
Since only a slight gap is formed between the two divided bodies 31 and 32, there is no possibility that the two divided bodies 31 and 32 will fall off from the permanent magnet 20.

According to the stepping motor having the above structure, in addition to the effects of the first embodiment, there is an advantage that the rotor support 30 can be easily attached to the permanent magnet 20. That is, according to the second embodiment, the rotor support 30 for the permanent magnet 20 is provided.
The rotor support 3 is installed inside the cylindrical permanent magnet 20 from the upper and lower openings of the permanent magnet 20, respectively.
The upper and lower divided bodies 31 and 32 that form the
1e, 32e until the upper and lower ends of the permanent magnet 20 are locked,
This is because it is completed by inserting it very lightly.

[0019]

As described above, according to the motor of the present invention, the rotor support made of synthetic resin and the permanent magnet made of metal, which are different in physical properties of the rotor, are molded separately. No internal stress occurs in the completed rotor. Therefore, when manufacturing the rotor support and the permanent magnet, it is not necessary to limit the respective materials used, and the mutual thickness ratio between the rotor support and the permanent magnet made of synthetic resin can be selected from a wide range. In addition, the permanent magnet can be made thin to reduce the weight of the motor as a whole, and in the injection molding of the rotor support, the selection control range of the injection pressure is widened and the molding is easy. In addition, assembling the rotor support to the permanent magnet is easy because the rotor support can be lightly press-fitted inside the cylindrical permanent magnet by utilizing the elasticity of the cavity for the meat relief of the rotor support. Is.

[Brief description of drawings]

FIG. 1 is a sectional view of a rotor in a conventional motor.

FIG. 2 is a sectional view showing a rotor in the motor according to the first embodiment of the present invention.

FIG. 3 is a plan view of a permanent magnet forming a rotor of the motor shown in FIG.

FIG. 4 is a sectional view showing a rotor of a motor according to a second embodiment of the present invention.

FIG. 5 is a cross-sectional view showing an example of a drive unit with a reduction mechanism that incorporates the motor according to the first embodiment of the present invention.

[Explanation of symbols]

 10, 30 Rotor support 10a Bearing holes 10b, 31b, 32b Serration (uneven portion) 10c Meat escape void 20 Permanent magnet 20a Peripheral surface of permanent magnet 20b Groove (uneven portion) 31 Upper divided body of rotor support 32 Rotor support Lower divided body 32c Void portion for meat escape 50 Casing 51 Stepping motor (motor) 53 Coil winding 54 Stator portion 55 Rotor 56 Rotor shaft

Claims (2)

[Claims] 1. A stator portion, in which a coil is wound, is provided in a casing, and a rotor having a permanent magnet on its outer peripheral surface is rotated on a rotor shaft provided in the casing in a central space of the stator portion. In a freely assembled motor, the rotor is a synthetic resin in which a cylindrical permanent magnet and a bearing hole into which the rotor shaft is inserted are formed in the center portion of the permanent magnet by press fitting. A rotor support made of, and a concavo-convex portion is formed in the central portion on the inner peripheral surface of the permanent magnet in the circumferential direction, and the outer peripheral surface of the rotor support is engaged with the concavo-convex portion of the permanent magnet. The moat is characterized in that a concave and convex portion for stopping is formed, and a cavity portion for meat escape is formed in a thick portion between the outer peripheral surface of the rotor support and the bearing hole. . 2. The motor according to claim 1, wherein the rotor support is composed of upper and lower halves which are arranged with a gap therebetween.