JPH05276694A - Motor - Google Patents

Abstract

PURPOSE:To reduce in size and weight a motor without using a rare earth element magnet having high performance by suppressing a function of a yoke to a minimum limit. CONSTITUTION:A stator 3 is manufactured by integrally molding a cylindrical yoke 1, a permanent magnet 2 arranged on an inner periphery of the yoke, a bearing 9 and a resin housing 21 by insert molding. A length L2 of the yoke 1 is formed shorter than that L of the housing 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor in which a rotary armature is coaxially arranged in a stator in which a permanent magnet is arranged on the inner peripheral surface of a yoke.

[0002]

2. Description of the Related Art Recent automobiles are equipped with dozens of electric motors per vehicle in order to improve high performance, safety and convenience, and most of them are magnetic field electric motors. 8 and 9 show a conventional example of this type of electric motor, in which 1 is a cylindrical yoke made of mild steel or the like, 2
Is a pair of permanent magnets provided on the inner peripheral surface of the yoke 1 so as to form a stator 3, and a rotary armature 4 is coaxially arranged therein. The rotary armature 4 includes an iron core 5, a coil 6, a commutator 7, and an output shaft 8, and the output shaft 8 is rotatably supported by a bearing 9. The yoke 1 forming a magnetic circuit accommodates the permanent magnet 2 and the rotary armature 4 and is fixed to the device fixing portion directly by a bolt or via a vibration absorbing member such as rubber, thereby adding the original function of the yoke. It also has the function of a mechanical structure and the function of a motor housing. In this case,
In the electric motor of (1), the yoke 1 is a tubular body with both ends open, and one end opening portion of the yoke 1 is covered with a disc-shaped lid body 10 that is manufactured separately from this, and the yoke 1 is provided at the center portion of the lid body 10. An example in which the bearing 9 is fitted and fixed in a cylindrical bearing portion 11 will be shown. On the other hand, in the electric motor of FIG. 9, an example in which the yoke 1 is formed in a bottomed cylindrical body with one end open, and the bearing 9 is fitted and fixed in a cylindrical bearing portion 11 provided at the center of the bottom plate portion 1a. Show.

[0003]

However, in the yoke 1 in the above-described conventional electric motor, in addition to the yoke function of forming a magnetic circuit, it has other functions, that is, a function as a mechanical structure and a housing function. Therefore, there is a problem that the weight cannot be reduced because it is made of a magnetic material such as mild steel that has a large occupied area other than the yoke function and has a large specific gravity. By the way, diameter 6
In the case of an automobile electric motor of cm, the plate thickness of the yoke 1 is as large as 2 mm, which is a major obstacle to weight reduction and size reduction. Also,
There is also known one that uses a high-performance rare earth magnet in order to reduce the weight and size, but in that case, there has been a problem that the cost becomes extremely high.

Therefore, the present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to use a high-performance rare earth magnet by suppressing the yoke function to the minimum. The object is to provide an electric motor that is designed to be compact and lightweight without the need.

[0005]

An electric motor according to the present invention is made to achieve the above object, and a first invention thereof is a rotating armature and an outer periphery of the rotating armature. In an electric motor having a stator, the stator is integrally molded with the yoke and the permanent magnet by insert molding, and a cylindrical yoke having the permanent magnet on the inner peripheral surface thereof. In addition, the yoke covers the outside of the permanent magnet, and the bearing portion of the rotating armature is integrally provided in the housing.

A second invention is an electric motor provided with a rotating armature and a stator arranged on the outer periphery of the rotating armature,
The stator comprises a plurality of permanent magnets, a cylindrical yoke in which the permanent magnets are arranged on the inner peripheral surface, and a resin housing integrally molded with the yoke and the permanent magnets by insert molding. The housing is integrally provided with a bearing portion of the rotary armature, and the yoke covers the outer side of the permanent magnet and has a reinforcing portion on both end faces, the reinforcing portion having a tip extending near at least one end of the housing. It has been extended corresponding to.

[0007]

In the first and second inventions, the resin housing, together with the yoke, functions as a mechanical structure and a housing. In the second invention, the reinforcing portion extending to the yoke receives the fastening force when the fixing portion of the housing is fastened and fixed to the mounting portion of the device with a bolt or the like,
Relieves the compressive stress applied to the housing.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the embodiments shown in the drawings. 1 is a sectional view showing an embodiment of an electric motor according to the present invention, FIG. 2 is a sectional view taken along line II-II of FIG. 1, and FIG. 3 is a perspective view of a yoke. In the figure, the same members as those in FIGS. 8 and 9 are designated by the same reference numerals, and the description thereof will be omitted. In these drawings, the present invention relates to a yoke 1 formed of a cylindrical body with both ends open, a pair of permanent magnets 2 arranged to face the inner surface of the yoke 1, and a bearing 9 that pivotally supports one end of an output shaft 8. The stator 3 of the electric motor 20 is formed by a bottomed cylindrical resin housing 21 integrally formed by insert molding with these members.

The yoke 1 is made of mild steel or the like, is smaller than the axial length L of the resin housing 21, and is 1.2 to 1.6 times as long as the length L1 of the permanent magnet 2.
2 and the outer peripheral surface is exposed to the outer peripheral surface of the housing 21 to form the same surface. Further, two small holes 22 having an appropriate hole diameter into which a molten resin is injected at the time of insert molding are formed so as to penetrate through the peripheral surface of the yoke 1 while being shifted by 180 ° in the circumferential direction. These small holes 22 are formed so as to be located between the two permanent magnets 2, 2.

The permanent magnet 2 is formed in a semi-cylindrical shape, the outer peripheral surface thereof is in close contact with the inner peripheral surface of the yoke 1, and the inner peripheral surface is exposed or slightly protruded from the inner peripheral surface of the resin housing 21. The required gap G (0.5mm
The following) is set. Both circumferential end faces 2 of each permanent magnet 2
a is opposed to each other, and the resin housing 21 is filled between the opposed surfaces to prevent the permanent magnet 2 from moving toward the center.

The resin housing 21 is formed in a cylindrical shape with a bottom, one end of which is open, and a cylindrical bearing portion 23 is integrally projectingly provided at the center of the bottom surface, and the bearing 9 is incorporated therein. ing. At the time of insert molding of the housing 21, the yoke 1, the permanent magnet 2 and the bearing 9 are inserted in a mold, and a molten resin is filled in the mold by an injection molding method to form the yoke 1, the permanent magnet 2 and the bearing 9. And the housing 21 is integrally molded. At this time, the permanent magnet 2 is molded with the inner diameter of the permanent magnet 2 as a dimensional reference.
Is constant over the entire circumference of the rotating armature 4. Then, the resin housing 21 is fixed to the mounting portion of the device by a plurality of bolts (not shown).

Thus, the electric motor 2 having such a structure
In 0, the size and weight can be reduced. That is, the length L2 of the yoke 1 forming the magnetic circuit is shortened to minimize the original function of the yoke, and the resin housing 21 having a smaller specific gravity than the yoke 2 has a function as a mechanical structure and a housing function. Therefore, the yoke itself is lightweight, and the electric motor 20 can be lightened. By the way, it was possible to reduce the weight by 15 to 20% compared with the conventional electric motor.

In the conventional electric motors shown in FIGS. 8 and 9, the permanent magnet 2 is fixed to the inner peripheral surface of the yoke 1 with an adhesive. In this method, the inner diameter of the yoke 1 is fixed. Since the permanent magnet 2 is bonded and fixed as a dimensional reference, it is difficult to set a constant gap between the permanent magnet 2 and the rotary armature 4, which must ensure the most uniformity in the magnetic circuit, and therefore the gap G is set to 0. It was necessary to widen it to about 0.5 mm. On the other hand, in the present invention, since the inner diameter of the permanent magnet 2 can be used as a dimensional reference by insert molding, the gap G is made constant, and if the gap G is constant, it is made narrower than the gap in the conventional electric motor. It is possible (about half). Therefore, the electric motor 20 can be downsized without using a high-performance rare earth magnet.

Furthermore, since the bearing 9 is formed integrally with the housing 21, the step of assembling the bearing 9 is not required,
It also has an advantage that the number of work steps can be reduced.

FIG. 4 is a sectional view of a stator showing another embodiment of the present invention. In this embodiment, in order to enhance the rustproof effect of the yoke 1, the yoke 1 is embedded inside the resin housing 21 so as not to be exposed to the outside, and other configurations are the same as those of the above-mentioned embodiment. Since the small hole 22 that functions to prevent the rotation of the yoke 1 and the resin housing 21 is provided at a position corresponding to the permanent magnet 2, the molten resin passes through the small hole 22 and forms the permanent magnet 2 into a mold during molding. It also has a pressing function and prevents the resin from flowing into the inner peripheral surface of the permanent magnet 2.

5 to 7 are an external perspective view, a sectional view and a perspective view of a yoke showing still another embodiment of the present invention. In this embodiment, the bearing 2 is provided in the upper opening of the resin housing 21.
A pair of fixing portions 3 each having a disc 29 for storing and holding 8 and having bolt insertion holes 30 on the outer periphery of the disc 29 are provided.
Reinforcing portions 1 and 31 integrally projecting and having their tips exposed at both end faces of the housing 21 or extending to the vicinity of the end faces at positions corresponding to the fixing portions 31 and 31 on both end faces of the yoke 1. 32 is extended in the axial direction, and the reinforcing portion 32 reinforces the housing 21 in the vicinity of contact with the fixed portion 31. In addition,
33 is a mounting portion of the electric motor 20, 34 is the bolt insertion hole 3
It is a bolt for fixing the electric motor 20 to the mounting portion 33 by being inserted into 0 and screwed into the screw hole of the mounting portion 33.

In such a construction, when the bolt 34 is screwed into the screw hole and the electric motor 20 is fixed to the mounting portion 33, the fastening force of the bolt 34 is received by the yoke portion of the yoke 1 provided with the reinforcing portion 32. A large compressive stress does not act on the housing 20 itself, which has the advantage of preventing damage to the housing 20.

The present invention is not limited to the above embodiment, but various changes and modifications are possible. For example, the number of permanent magnets 2 may be 2n (where n is an integer), and the fixed portion is also possible. It is also possible to provide 31 between the permanent magnets that are adjacent to each other on the inner side without projecting outside the housing 21. Furthermore, the yoke 1 is not limited to being integrally formed, and may be formed in a cylindrical shape by combining a plurality of arc-shaped divided mild steel plates.

[0019]

As described above, in the electric motor according to the present invention, the yoke, the permanent magnet and the resin housing are integrally formed by insert molding, so that the electric motor itself can be made lighter and the insert molding can be performed. According to, since the inner diameter of the permanent magnet can be used as the dimensional reference,
The gap between the rotating armature and the permanent magnet can be set small, and the electric motor can be downsized. Further, according to the present invention, the reinforcing portions are extended on both end surfaces of the yoke corresponding to the fixing portions provided on the housing. Therefore, when the electric motor is fixed to the attaching portion by fastening means such as bolts, the housing itself is not damaged. It is possible to prevent it, and it is possible to obtain an effect that it can be stably and surely attached.

[Brief description of drawings]

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

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a perspective view of a yoke.

FIG. 4 is a sectional view of a stator showing another embodiment of the present invention.

FIG. 5 is a perspective view showing still another embodiment of the present invention.

FIG. 6 is a sectional view.

FIG. 7 is a perspective view of a yoke.

FIG. 8 is a sectional view showing a conventional example of an electric motor.

FIG. 9 is a cross-sectional view showing another conventional example of an electric motor.

[Explanation of symbols]

 1 yoke 2 permanent magnet 3 stator 4 rotating armature 5 iron core 6 coil 7 commutator 8 output shaft 9 bearing 20 electric motor 21 resin housing 22 small hole 23 bearing portion 31 fixing portion 32 reinforcing portion

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenji Matsushima 1-4 Chome, Fujimi-cho, Gyoda-shi, Saitama 1 Jeco Corporation

Claims (2)

[Claims] 1. A motor comprising a rotating armature and a stator arranged on the outer periphery of the rotating armature, wherein the stator has a plurality of permanent magnets and the inner peripheral surface is provided with the permanent magnets. And a housing made of resin integrally formed with the yoke and the permanent magnet by insert molding, the yoke covers the outer side of the permanent magnet, and the bearing portion of the rotating armature is provided in the housing. An electric motor characterized by being provided integrally. 2. A motor having a rotating armature and a stator arranged on the outer periphery of the rotating armature, wherein the stator has a plurality of permanent magnets and the inner peripheral surface is provided with the permanent magnets. And a housing made of resin integrally formed with the yoke and the permanent magnet by insert molding. The bearing portion of the rotary armature is integrally provided in the housing, and the yoke is made of the permanent magnet. An electric motor characterized in that a reinforcing portion, which covers the outside and has a tip extending to the vicinity of at least one end of the housing, is provided on both end faces so as to correspond to a fixing portion of the housing.