JPH04334937A - Radial type rotor structure - Google Patents

Abstract

PURPOSE:To reduce a rotor manufacturing cost and to reduce a main component wave of a torque ripple. CONSTITUTION:A rotor yoke 12 and a magnet 14 are alternately circumferentially arranged on a rotor. Positions of centers 12C of poles of an outer surface 12S of each yoke are unidirectionally rotatably polarized by lambda/4 corresponding to lambda/4 pitch of a main component wave of a torque ripple to be generated at the time of rotating a motor at the rotating center of the rotor as a center with respect to a magnet arranging position. A through hole 16H for a tie rod is provided at a central position L1 between both magnet arranging positions adjacent to each yoke 12 to form a yoke assembly, the same other yoke assembly as the yoke assembly is inverted front side rear in contact, the magnet 14 having twice a length as long as the yoke assembly, is arranged, a tie rod 16 is inserted into each hole 16H, and clamped.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called radial type rotor structure in which rotor yokes and magnets are alternately arranged in the circumferential direction.

0002

2. Description of the Related Art Generally, when a motor rotates, small torque fluctuations occur, and this can have various causes. For example, there are slot ripples caused by the slot shape of the stator core, ripples caused by unbalance in the three-phase balanced power output from the amplifier, and others, which are obstacles to obtaining smooth output torque. In order to reduce such torque ripple, there is a rotor structure disclosed in, for example, Japanese Unexamined Patent Publication No. 178750/1983 by the present applicant. This is a rotor constructed by assembling two unit rotors offset from each other by an angle corresponding to a half wavelength of the torque ripple that originally occurs.

0003

[Problems to be Solved by the Invention] However, in the rotor structure disclosed in the above publication, since each unit rotor is shifted from each other as a whole, the magnet itself does not span the entire length of the rotor, but has two magnets. It is divided into As described above, the restriction of the length of the magnet itself relative to the length of the rotor causes various problems in rotor design. For example, even in a thin motor, it is necessary to prepare a short magnet corresponding to a unit rotor that is half as thin as the motor, which is uneconomical. In addition, when designing a motor that has a rotor that is 1.5 times longer than a motor that has a rotor of the basic length, a magnet that is half the length of the rotor of the basic length is not sufficient. Furthermore, it is necessary to prepare another magnet with half the length, or to design a completely different new unit rotor without using the above basic length rotor as a standard, and prepare a magnet with a corresponding length. be. From the viewpoint of manufacturing magnets, increasing the variety of magnet lengths results in an increase in costs.

Accordingly, it is an object of the present invention to reduce the manufacturing cost of a rotor and to reduce the principal component wave of torque ripple.

[0005]

[Means for Solving the Problems] In view of the above object, the present invention provides a radial type rotor structure in which rotor yokes and magnets are arranged alternately in the circumferential direction, and the magnetic pole center position on the outer surface of each rotor yoke is is rotationally deflected in one direction around the rotation center of the rotor by 1/4 pitch of the torque ripple principal component wave generated when the motor rotates with respect to the magnet arrangement position, and both magnets adjacent to each rotor yoke are A yoke assembly is formed by providing a through hole for a tie rod at the center position between the installation positions, and another yoke assembly that is the same as this yoke assembly is turned upside down and brought into contact with the other yoke assembly, and the length is twice that of the yoke assembly. To provide a radial type rotor structure characterized in that magnets are disposed, and tie rods are inserted and fastened through each through hole.

[0006]

[Operation] By inserting tie rods into the through holes of both yoke assemblies and aligning them, each through hole is provided at the center position between adjacent magnets, so each unit rotor can be reversed and aligned. Even if the magnets are arranged in the same position in each yoke assembly, it is possible to use a magnet having a length equal to the entire length of the rotor.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained in more detail below based on embodiments shown in the accompanying drawings. FIG. 3 shows a radial type rotor in which rotor yokes 12 and magnets 14 are arranged alternately in the circumferential direction. have. As described later, both yoke assemblies are the same, but
During assembly, the tie rods 16 are passed through the through holes 16H (FIGS. 1 and 2) so that they are fastened in opposite directions. Reference number 18 is an end plate and reference number 20 is an output shaft.

Referring to FIG. 1, which is an enlarged view of one rotor yoke 12 and two adjacent magnets 14, the surface 12S of the rotor yoke 12 facing the stator ST has a radius indicating the center position of the spacing between both magnets 14. They are unevenly distributed in the right direction with respect to the direction line L1. More precisely, it is rotated by a certain angle λ/4 around the rotation center of the rotor. Therefore, the position of the magnetic pole center 12C is rotationally deflected by an angle λ/4. Here, the magnetic pole center refers to the center position of the outer surface of the rotor yoke 12 where the distance from the stator ST is the minimum.

Therefore, the outer peripheral surface 14S of the magnet 14 adjacent to the right side of the rotor yoke 12 is covered by the outer peripheral end of the rotor yoke 12, and conversely, the outer peripheral surface 14S of the magnet 14 adjacent to the left side The outer peripheral end of the rotor yoke 12 is hardly covered. Further, a through hole 16H into which the tie rod 16 is inserted is provided on the line L1. Therefore, when the rotor is assembled as shown in FIG. 3, the rotor yoke 12' of the other yoke assembly 10' is placed on the outer circumferential surface 14S of the left magnet 14 as shown in FIG. The end of the outer circumferential portion of the rotor yoke 12' covers the outer circumferential surface 14S of the magnet 14 adjacent to the right side. That is, the magnetic pole center 12'C moves leftward at an angle λ/
It is rotationally deflected by 4.

FIG. 2 shows an 8-pole rotor, but if the stator has 36 slots, each pole has 4.5 slots.
Slots correspond. In this case, the main component wave of the throttle ripple is generated 36×1/0.5=72 times for each rotation of the rotor. Therefore, the single wave pitch λ is 360°/72
=5°. In this case, the rotational deflection angle λ/4 described above is 1.25°, and each magnetic pole center 12 of the two yoke assemblies 10, 10'
Since C and 12'C are relatively shifted by λ/2 (=2.5°), the slot ripples are canceled by each other.

In addition, in the case of an 8-pole rotor, ripple waves due to unbalance in the three-phase balanced power described above are generated 8×3=24 times per rotation. Therefore, the single wave pitch λ is 15°.

In order to reduce the various torque ripples mentioned above, each rotor yoke 12 of the two yoke assemblies 10, 10'
Since the magnetic pole centers 12C and 12'C of 12' are relatively shifted by half a wavelength of the ripple main component wave, torque ripple is reduced, and the magnet 14 is arranged at a symmetrical position with respect to the tie rod through hole 16H. Because of this structure, the placement positions of the respective magnets do not shift between the two yoke assemblies 10, 10'. Therefore, magnets can be used over the entire length of the rotor. That is, Figure 3
The magnet 14 shown in FIG. 1 is not divided into two in the longitudinal direction of the rotor, but is a single magnet.

Although the shape of the rotor yoke 12 is not symmetrical as described above and is irregular, it is easy to manufacture because it can be constructed by simply stacking stamped and formed electromagnetic steel sheets. Further, it is also easy to mold the rotor yoke 12 by sintering.

[0014]

As is clear from the above description, according to the present invention, it is possible to provide a rotor structure that reduces torque ripple and reduces manufacturing costs.

[Brief explanation of drawings]

FIG. 1 is a partially enlarged view of a rotor according to the present invention.

FIG. 2 is a cross-sectional view of a rotor according to the present invention, and FIG.
FIG. 2 is a sectional view taken along arrow line II-II.

FIG. 3 is a side view of a rotor according to the invention.

[Explanation of symbols]

10, 10'...Yoke assembly 12, 12'...Rotor yoke 12C, 12'C...Magnetic pole center 12S, 12'S...Rotor yoke outer surface 14...Magnet 16...Tie rod 16H...Through hole

Claims (2)

[Claims] Claim 1: A radial type rotor structure in which rotor yokes and magnets are arranged alternately in the circumferential direction, in which the center position of the magnetic pole on the outer surface of each rotor yoke is set relative to the position where the magnets are arranged. Rotation is deflected in one direction around the rotation center of the rotor by 1/4 pitch of the torque ripple principal component wave, and a tie rod through hole is provided at the center position between each rotor yoke and both adjacent magnet placement positions. A yoke assembly is formed using the same yoke assembly, and another yoke assembly which is the same as the yoke assembly is turned upside down and brought into contact with the other yoke assembly, and a magnet twice the length of the yoke assembly is provided, and a tie rod is inserted into each through hole. A radial type rotor structure characterized by being inserted and fastened. 2. A radial type rotor structure according to claim 1, wherein each of said rotor yokes comprises a sintered block formed by sintering.