JPH08280163A - Permanent-magnet dc motor - Google Patents

Abstract

PURPOSE: To improve the manufacturability of a permanent magnet and, at the same time, to obtain stable cogging torque from the magnet by using a material having a skewed magnetized area, an unmagnetized area, and a notched section for the magnet and making the peripheral edge of the unmagnetized area nearly parallel to the axial direction of a rotor. CONSTITUTION: The material of a permanent magnet 2 is provided with a magnetized material 22 skewed in the axial direction of a rotor, a magnetized area 21, and an unmagnetized area 22 and a notched section 23 which are respectively formed on both sides of the magnetized area 21 and, at the same time, the peripheral edge of the unmagnetized area 22 is made nearly parallel to the axial direction of the rotor. It is preferable to make the length of the outer peripheral section of the unmagnetized area 22 which is nearly parallel to the axial direction of the rotor when the area 22 is projected from the center side of the rotor longer than the 1/2 of the total length of the permanent magnet 2 in the length direction of the shaft of the rotor. As a result, the manufacturability of the permanent magnet is improved and, at the same time, stable cogging torque can be obtained from the magnet, because the skewed magnetized area 21 smoothes the magnetic variation which occurs when an armature is rotated in the skewed magnetized area 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a permanent magnet field type DC electric motor, and more particularly to a permanent magnet type DC electric motor suitable for use in an air conditioner for automobiles.

[0002]

2. Description of the Related Art Generally, as a technique for reducing the cogging torque of a small electric motor using a permanent magnet as a field pole, a) the inner radius of the permanent magnet is set to the outer radius of the rotor core as described in Japanese Utility Model Publication No. 3-40869. A so-called "eccentric system", in which the magnetic flux passing through the inner circumferential arc of the permanent magnet is made larger, and the so-called "eccentric system" is used. It is roughly classified into a "skew system" in which the rotor core is arranged so as not to be parallel to the slots provided in the core.

Further, in the "skew system", the outer circumference in the radial direction of the permanent magnet material is made non-parallel to the rotor shaft as in Japanese Utility Model Laid-Open No. 63-15162, and it is magnetized uniformly. In addition, the "magnet shape skew method" in which the slots of the rotor core are arranged in parallel with the rotor shaft, and the rotor shaft on the outer circumference in the radial direction of the permanent magnet material as disclosed in Japanese Utility Model Laid-Open No. 58-46280. "Rotor skew system" in which the rotor core slot is arranged non-parallel to the rotor axis while the magnet is evenly magnetized there.
-277450, the shape of the permanent magnet material is projected from the center side of the rotor shaft into a substantially rectangular parallelepiped shape, and a magnetized portion and a non-magnetized portion are provided on the outer peripheral portion in the magnet radial direction. There is known a "magnetization skew system" in which a boundary portion with the rotor portion is not parallel to the rotor axis and the rotor core slots are arranged to be parallel to the rotor axis.

[0004]

However, the above-mentioned conventional techniques have the following problems, respectively.

First, in the "eccentric system", there is a problem that the amount of effective magnetic flux passing between the permanent magnet and the rotor iron core is reduced and the output of the electric motor is reduced, so that a high output is obtained. However, there is a problem that the permanent magnet and the rotor must be upsized, and the size of the electric motor is increased.

As for the "magnet shape skew method", since the shape of the outer peripheral portion in the radial direction of the permanent magnet is not parallel to the axis, it sits on the yoke (attached state).
Not only makes it difficult to finish the magnet (it is common to perform grinding work on the inner and outer cylindrical surfaces of the magnet to stabilize the gap between the inner and outer peripheral surfaces of the magnet). There is a problem in that the work of attaching to the product becomes difficult and the manufacturing cost increases.

Next, regarding the "rotor skew system", in the case of a rotor core in which punched and formed electromagnetic steel sheets are laminated, the steel sheets must be laminated one by one by rotating at a predetermined angle, which increases the assembly time. In addition to the above, there is a problem that the winding length increases due to the increase in the slot length, and the output decreases due to the increase in the electric resistance of the rotor.

Further, in the "magnetization skew system", there is a problem that the magnet mass increases because many unmagnetized portions remain in the permanent magnet material.

An object of the present invention is to obtain a stable cogging torque while improving the manufacturability of a permanent magnet constituting a field pole.
Another object of the present invention is to provide a lightweight, compact and inexpensive permanent magnet field type DC motor.

[0010]

According to the present invention, a plurality of permanent magnet members arranged annularly on the inner peripheral surface of a yoke and constituting field poles, and a rotor shaft inside the permanent magnet member are provided. In a permanent magnet field type DC electric motor, wherein armature cores having parallelly formed slots are arranged to face each other through a rotary air gap,
The permanent magnet material is provided with a magnetized region skewed in the axial direction, an unmagnetized part formed at each diagonal position across the magnetized region, and a notch formed at each opposite angle position. This is achieved by making the peripheral end of the non-magnetized portion substantially parallel to the rotor axis.

In the present invention, preferably, the length of the outer peripheral portion of the non-magnetized portion, which is projected from the center side of the rotor shaft and is substantially parallel to the rotor axis, is 1 / the total length of the permanent magnet in the rotor shaft longitudinal direction. Achieved by having longer than 2.

[0012]

[Function] The unmagnetized portion formed in the permanent magnet material stabilizes the processing and installation posture of the magnet itself in a portion substantially parallel to the rotor axis line, and the magnetic change generated when the armature rotates in the skewed magnetized region. To reduce the cogging torque.

Further, the magnetized region portion is at least a predetermined distance in the center direction of the rotor shaft with respect to an end portion or an end portion where at least an outer peripheral portion substantially parallel to the rotor axis of the permanent magnet and an outer peripheral portion substantially orthogonal to the rotor axis intersect. By passing the magnets away from each other, the deviation between the position of the magnet and the position of the magnetizing device during the magnetizing work is absorbed.

[0014]

Embodiments of the present invention will be described in detail below with reference to FIGS.

In FIG. 1, two permanent magnet members 2 are fixed to the inner peripheral surface of a cylindrical yoke 1 made of a magnetic material at positions facing each other, and bearings are provided at both ends of the yoke 1. 5
End brackets 3 and 4 are provided to support the. The rotating shaft 7 of the rotor 6 is rotatably supported by the bearing 5. Here, in this embodiment, as the bearing 5, a rolling ball bearing filled with grease is used and is press-fitted and held in the mounting recesses formed in the respective end brackets 3 and 4.

The armature core 8 which is press-fitted and fixed to the rotating shaft 7 is formed by laminating electromagnetic steel sheets, and the rotating shaft 7
The armature winding 10 is housed by forming the slot portion 9 that is substantially parallel to the axis of the armature winding. On the other hand, armature core 8
A commutator 11 is press-fitted and fixed to the rotary shaft 7 at one end of each of the above, and each commutator piece is electrically connected and fixed to one end of the armature winding by welding or the like.

A brush holder 12 fixed to the inner surface of the end bracket 3 by screwing or the like is arranged on the outer periphery of the commutator 11. This brush holder 12
The carbon brushes 13 and 14 are slidably housed therein, are pressed by a spring member so as to obtain a constant contact pressure, and are connected to an external power source by a lead wire or the like.

Next, referring to FIGS. 2 and 3, the field pole, which is a feature of the present invention, will be described. The permanent magnet material 2 serving as the field pole is arcuate as shown in FIG. A line B that has a rectangular shape and connects each vertex B, C and F, E
-C and FE are substantially parallel to the axis of the rotation axis (preferably parallel, although they are not necessarily parallel, they are substantially the same as long as they have an approximate shape). Lines A-F and C-D connecting C, D are substantially perpendicular to the axis of the rotation axis, and lines A-B and D-E connecting vertices A, B and D, E are the axes of the rotation axis. The chamfered notch 23 is inclined at an angle θ ₁ . Therefore, the lines AB and D-E of the notch are substantially parallel to each other.

Next, the skewed magnetized area portion 21 will be described. The magnetized area portion is a parallelogram C, G, F, I which is substantially parallel to the lines AB and ED, and each vertex is It has lines CG and FI extending from C and F, and the other region 22 constitutes an unmagnetized portion.

With the above structure, the permanent magnet material 2
Between the inner lines B-C and the line E-F of the outer periphery of the are parallel to each other,
Further, since it is parallel to the axis of the rotating shaft, when the inner and outer peripheral surfaces 2a and 2b of the permanent magnet material 2 are ground, the dimensional accuracy of the plate thickness t is improved because the processing attitude of the magnet itself is stable. At the same time, it is possible to perform processing without using a special jig or the like, which improves manufacturability. In addition, by chamfering the magnet material as described above, the material of the non-magnetized portion 22 can be reduced, and the weight of the magnet material can be reduced.

In general, the pole isolation β of a permanent magnet is usually found in a two-pole DC machine.

[0022]

[Equation 1]

Is generally used in. In addition,
(The number of slots-4) means that the coil current direction in the slots of the rotor alternates, and there are two parts that do not contribute to the generation of the rotational torque, and the adjacent iron core parts (a total of four parts in each two parts) are avoided. Given.

For example, when 10 slots are used, β is β = 108 °, which means that the magnet width R corresponds to the angle of 3 slots, and the presence of the notch greatly affects the reduction in size and weight. Here, the width R'when performing skew magnetization having the same amount of magnetic flux as that of the conventional case on the rectangular magnet material must be lengthened by y corresponding to a predetermined skew angle. If one slot angle (set angle) is used, the magnet volume in this case corresponds to four slot angles.

Further, in the embodiment of FIG. 3, the length L2 of the outer peripheral lines BC and EF of the permanent magnet material 2 is made longer than 1/2 of the total length L1 of the magnet material, and the chamfered portion AB. And the chamfering angle θ ₁ of D-E is larger than the skew angle θ ₂ of the magnetized portion 21.

In these constructions, the longer the plane parallel to the axis is, the more stable the processing posture of the magnet itself is, and the further the manufacturability such as the grinding of the magnet is further improved. The outer peripheral portion that is substantially parallel to the rotor axis can be adjacent in the circumferential direction by the length of L3, which makes it easier to control the magnet assembly accuracy and presses the central portion of the magnet outer peripheral in the longitudinal direction. Since the bonding to the yoke is possible, the assembling posture of the magnet is stable, the assembling property of the electric motor can be improved, and a low-cost DC electric motor with a small cogging torque can be provided.

Further, in FIG. 3, the skew magnetization area 21 is formed.
Among them, the points of vertices G, H, I, and J have passed the respective positions of the vertices A, C, D, and F of the outer peripheral portion of the permanent magnet material 2 at positions separated by a predetermined distance in the direction of the center of the rotor axis. Although this is shown, this configuration will be described below with reference to FIG.

FIG. 5 is a sectional view showing the positional relationship between the permanent magnet material 2 and the magnetizing device, and shows the case where the magnetizing device 15 is placed on the inner peripheral side of the magnet material 2. Although not shown here, the outer peripheral portions 15a and 15b of the magnetizing device 15 are skewed.

Here, the inner circular arc angle θ ₄ of the permanent magnet material 2 (see FIG. 3)
(Corresponding to the angle between A and F and between C and D in Fig. 4) is taken into account the dimensional error of a single magnet, the error in assembling the magnet when adhered to, and the positional deviation when the magnetizing device 15 and the yoke 1 are aligned. However, it is made larger than the inner circumferential arc angle θ ₃ of the outer circumferential portions 15b and 15a of the magnetizing device 15.

As a result, G of the skew magnetized region 21,
H, I, and J can obtain a continuous skew magnetization region of a constant angle without deviating from the outer peripheral portions A, C, D, and F of the permanent magnet material 2, and can stabilize the cogging torque.

FIG. 6 shows still another embodiment in which the unmagnetized portion is removed to L / 2 while leaving a part of the outer peripheral end portion, and the removed portion is 75% of the unmagnetized portion. The magnet volume is 4−0.75 = 3.25 slot angle, which is about 19% lighter than the rectangular magnet skew magnetized, and the effect is remarkable.

[0032]

According to the present invention, the manufacturability of the permanent magnet can be improved, the material cost can be reduced, a stable cogging torque can be obtained, and the assembling property is inexpensive and the quality of the permanent magnet is stable. Form DC motor can be provided.

[Brief description of drawings]

FIG. 1 is a sectional view of a permanent magnet field type DC motor according to an embodiment of the present invention.

FIG. 2 is a sectional view of a yoke in the embodiment of the present invention.

FIG. 3 is a plan view of a permanent magnet material used in another embodiment of the present invention.

FIG. 4 is a side view of the permanent magnet material shown in FIG.

FIG. 5 is a cross-sectional view of essential parts showing the relationship between the magnet material and the landing gear in the embodiment of the present invention.

FIG. 6 is a sectional view of a yoke according to still another embodiment of the present invention.

[Explanation of symbols]

1 ... Yoke, 2 ... Permanent magnet material, 2a ... Permanent magnet inner peripheral surface, 2
b ... Peripheral surface of permanent magnet, 7 ... Rotating shaft, 15 ... Magnetizing device, 1
5a ... Magnetizer outer peripheral part, 15b ... Magnetizer peripheral part, 21
... skew magnetized area, 22 ... non-magnetized portion, 23 ... notched portion (chamfered portion).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshinori Fukasaku 2520 Takaba, Hitachinaka City, Ibaraki Prefecture Hitachi Ltd. Automotive Equipment Division, Hitachi Ltd. Address 3 Within Hitachi Automotive Engineering Co., Ltd.

Claims (4)

[Claims] 1. A plurality of permanent magnet members, which are annularly arranged on the inner peripheral surface of the yoke and constitute field poles, and a slot formed inside the permanent magnet member and parallel to the rotor shaft. In a permanent magnet field type DC electric motor in which armature cores are arranged to face each other with a rotating air gap, the permanent magnet material includes a magnetized region skewed in the axial direction and a diagonal position across the magnetized region. Permanent magnets, each of which has a non-magnetized portion formed therein and a notch formed in an opposite angular position, and the peripheral end of the non-magnetized portion is substantially parallel to the rotor axis. Field type DC motor. 2. The magnetized region according to claim 1, wherein the magnetized region is at least at an end portion where an outer peripheral portion substantially parallel to the rotor axis and an outer peripheral portion substantially perpendicular to the rotor axis intersect, or in the rotor shaft center direction with respect to the end portion. A permanent magnet field type DC motor characterized in that it passes through a position separated by a predetermined distance. 3. The rotor of the permanent magnet material according to claim 1, wherein the unmagnetized portion has a length of an outer peripheral portion projected from the rotor shaft center side of the permanent magnet material and substantially parallel to the rotor axis. A permanent magnet field type DC motor characterized by being made longer than 1/2 of the total length in the longitudinal direction of the shaft. 4. The magnetized region according to claim 2, wherein the magnetized region is located at an end portion where the outer peripheral portion substantially perpendicular to the rotor shaft intersects with the chamfered portion or at a predetermined distance in the rotor shaft center direction from the end portion. A permanent magnet field type DC motor characterized by passing through.