JPH065350U - Electric motor rotor - Google Patents

Abstract

(57) [Abstract] [Purpose] In a rotor of an electric motor, the work of adhering the ring magnet and the rotor yoke is simplified and the misalignment of the ring magnet is eliminated. [Structure] The amount of the gap 14 between the outer circumference of the motor shaft 18 or the rotor yoke 10 and the inner circumference of the ring magnet 12 is made different depending on the circumferential position of the rotor.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a rotor of an electric motor in which a ring-shaped permanent magnet is attached to the outer peripheral surface of a motor shaft or a rotor yoke.

[0002]

[Prior art]

 As a rotor of an electric motor constructed by bonding permanent magnets to the motor shaft or the outer peripheral surface of the rotor yoke, a plurality of segment type permanent magnets are generally bonded directly to the motor shaft or the outer peripheral surface of the rotor yoke. Is. However, since many work processes and work time are required, recently, a ring-shaped permanent magnet has been increasingly adhered to the motor shaft or the outer peripheral surface of the rotor yoke. Among them, rare earth magnets made of neodymium-iron-boron have been widely used as magnet materials because of their high magnet density. FIG. 2 is a sectional view of a rotor of a conventional electric motor perpendicular to the axis. A rotor yoke 20 made by laminating a plurality of steel plates made of magnetic material is integrally attached to the motor shaft 18 by press fitting or the like. Then, a ring magnet 12 having four poles made of neodymium-iron-boron is fixed to the outer periphery of the rotor yoke 20 by adhesion or the like.

Here, the ring-shaped permanent magnet made of neodymium-iron-boron has a peculiar thermal expansion coefficient that the inner diameter of the ring decreases as the temperature rises. Therefore, when the temperature of the rotor rises due to heat generation of the electric motor, the inner diameter of the ring magnet 12 decreases and the rotor yoke 20 expands, so that in some cases thermal stress causes stress destruction of the ring magnet 12. Therefore, a gap 22 is provided between the inner diameter of the ring magnet 12 and the outer diameter of the rotor yoke 20, and the ring magnet 12 and the rotor yoke 20 are bonded and fixed by filling the gap 22 with a soft adhesive. The thermal stress destruction of the magnet 12 is prevented. For example, when the inner diameter of the ring magnet 12 is about 62 mm, the gap 22 is empirically required to have a radius of about 0.2 to 0.25 mm.

[0004]

[Problems to be solved by the device]

 In the conventional rotor of the above-mentioned electric motor, since it is necessary to provide a gap between the motor shaft or the rotor yoke and the ring magnet, there is a drawback that a special setup is required for centering each other at the time of bonding. there were. In addition, when torque is applied between the ring magnet and the rotor yoke at the time of output of the electric motor, the core of the ring magnet may be displaced due to softening of the adhesive due to temperature rise of the rotor or uneven application of the adhesive. There was a risk of vibration and noise. The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide an electric motor rotor capable of simplifying the work of bonding a ring magnet and a rotor yoke and eliminating the misalignment of the ring magnet. is there.

[0005]

[Means for Solving the Problems]

 The present invention relates to a rotor of an electric motor in which a ring-shaped permanent magnet is attached to an outer peripheral surface of a motor shaft or a rotor yoke, and the above object of the present invention is to provide an outer peripheral surface of the motor shaft or the rotor yoke. This is achieved by configuring the amount of gap between the ring magnet and the inner circumference of the ring magnet to be different depending on the circumferential position of the rotor.

[0006]

[Action]

 In the present invention, the gap between the motor shaft or the outer circumference of the rotor yoke and the inner circumference of the ring magnet is made to differ depending on the position in the circumferential direction of the rotor, and the ring magnet is centered at a portion with a small gap. By filling in a large number of parts with an adhesive, the setup for centering the ring magnet is unnecessary, and the risk of vibration or noise of the electric motor at the time of output of the electric motor can be eliminated.

[0007]

【Example】

 FIG. 1 is a cross-sectional view of the rotor of the electric motor of the present invention perpendicular to the axis. A bulge portion 16 is provided in a region where the outer circumference of the rotor yoke 10 is equally divided into four parts, and the bulge portion 16 is provided in the axial longitudinal direction of the rotor yoke 10. It is arranged. When considering a magnetic circuit as an electric motor, for example, the magnetic path between the magnetic pole centers becomes the furthest as a magnetic path for the magnetic flux from the N pole to go to the adjacent S pole. The effective magnetic flux density becomes low. Therefore, the effective magnetic flux density of the electric motor is increased and the efficiency of the electric motor is improved by reducing the magnetic resistance by reducing the gap 14 at the center of the magnetic pole.

It should be noted that the distance between the outer diameter of the bulge portion 16 of the rotor yoke 10 and the inner diameter of the ring magnet 12 is set to be substantially zero due to the temperature rise of the rotor. For example, since the temperature rise of the rotor is about 100 ° C. up in a normal electric motor, a radius of about 0.04 mm is sufficient when the inner diameter of the ring magnet 12 is about 62 mm, and a ring magnet of this size can be used. Even if 12 is displaced in the radial direction, there is no particular problem in terms of the characteristics of the electric motor. When considering the efficiency of the electric motor, it is better to match the bulge portion 16 of the rotor yoke 10 with the magnetic pole center of the ring magnet 12 as described above, but if only the adhesive workability is considered, the magnetic pole center of the ring magnet 12 is considered. And the number of the bulging portions 16 of the rotor yoke 10 do not necessarily match, and the bulging portions 16 do not have to be at the center of the magnetic pole. Further, the bulge portion 16 does not necessarily have to be a straight line in the axial longitudinal direction, and may be skewed. Further, instead of the rotor yoke 10, the motor shaft 18 itself may have the shape shown in FIG. In this case, it can be easily processed by using a cam lathe or the like.

[0009]

[Effect of device]

 As described above, according to the motor rotor of the present invention, it is possible to reduce the cost of the motor and to reduce the core of the ring magnet, because the dedicated setup for centering the rotor yoke and the ring magnet is not necessary. Since it is possible to prevent vibration and abnormal noise of the electric motor due to the displacement, it is possible to provide a highly reliable and safe electric motor.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a rotor of an electric motor of the present invention perpendicular to the axis.

FIG. 2 is a cross-sectional view perpendicular to the axis of a rotor of a conventional electric motor.

[Explanation of symbols]

 10 and 20 rotor yoke 12 ring magnets 14 and 22 gap 16 bulge 18 motor shaft

Claims (2)

[Scope of utility model registration request] 1. A rotor of an electric motor, comprising a ring-shaped permanent magnet adhered to an outer peripheral surface of a motor shaft or a rotor yoke, wherein the motor shaft or the outer periphery of the rotor yoke and the inner periphery of the ring magnet are connected to each other. A rotor for an electric motor, characterized in that the gap amount is different depending on the circumferential position of the rotor. 2. The rotor for an electric motor according to claim 1, wherein the amount of the gap is minimized in the vicinity of the magnetic pole center of the ring magnet.