JPH03253249A - Rotor for motor using permanent magnet - Google Patents

Abstract

PURPOSE:To make a permanent magnet hard to cause cracks, etc., so as to prevent the occurrence of breakdown or damage by catching and fixing the permanent magnet to a rotary shaft through a retainer by axial force-bonding. CONSTITUTION:A rotor is composed of a rotary shaft 1, a pair of retainers 2 and 3, and a permanent magnet 4. The rotary shaft 1 is cylindrical or columnar, consisting of, for example, stainless steel, and the retainers 2 and 3 are the same shapes, and consist of cylinders 5 and circular collars 6. Moreover, the permanent magnet 4 is cylindrical, and a total of twenty four poles of S poles and N poles are arranged, in parallel in axial direction, in the circumferential direction. What is more, the circular collars 6 of the retainers 2 and 3 press-fit in the rotary shaft 1 catch and fix both ends of the cylindrical permanent magnet 4 in the axial direction. Hereby, the permanent magnet becomes hard to crack during assembling or thermal expansion attendant upon temperature change, and the fixation of the permanent magnet 4 is performed securely to the rotary shaft.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a rotor used in an electric motor.

(Prior Art) In recent years, rare earth-iron magnets have been developed and are attracting attention as permanent magnets, which have even better magnetic properties than ferrite-based, alnico-based, rare-earth-cobalt-based permanent magnets, etc. ing. Motor rotors using rare earth-iron permanent magnets are well known.

Methods for assembling a motor rotor using such permanent magnets include, for example, attaching a retainer to the rotating shaft with permanent magnets bonded with adhesive, or integrally injection molding the permanent magnet with the rotating shaft by resin injection molding. Methods are known. The former method of bonding with an adhesive has the disadvantage that rare earth-iron permanent magnets are particularly fragile and are likely to break when press-fitted onto a rotating shaft.

(Problem to be Solved by the Invention) However, when a conventional adhesive is used as a method of fixing a permanent magnet to a rotating shaft, the adhesive tends to protrude from the applied area and adhere to the surface of the permanent magnet, causing the adhesive to harden. The rotating shaft and permanent magnet must be temporarily fixed until the end of the magnet, making the temporary fixing work complicated, the adhesive taking a long time to dry, and the adhesive having a relatively low holding power, resulting in insufficient strength. Depending on the adhesive selected, the curing time may be longer or shorter, resulting in variations in curing characteristics, mechanical properties may be poor against temperature changes, and automatic assembly may be difficult depending on the type of adhesive.

Furthermore, with the conventional integral injection molding method in which the rotating shaft is molded and the permanent magnet is fixed at the same time, the accuracy of the assembled finished product varies depending on the dimensional accuracy of the permanent magnet, and the material of the rotating shaft is made of resin. This causes problems such as poor mechanical properties against temperature changes and the need for expensive injection molds.

The present invention was made to solve these problems, and it is easy to assemble, the bonding strength of the permanent magnets is high, the permanent magnets are difficult to break during assembly, and the finished product has good accuracy and low cost. An object of the present invention is to provide a motor rotor using permanent magnets that can be manufactured at low cost.

(Means for Solving the Problems) For this purpose, the motor rotor using the permanent magnet of the first aspect of the present invention can be press-fitted to a cylindrical or cylindrical rotating shaft and the outer periphery of the rotating shaft. The present invention is characterized in that it is comprised of a retainer having a circular cylindrical body and an annular collar portion, and a cylindrical permanent magnet clamped and fixed to the side end surface of the annular collar portion of the retainer.

A motor rotor using permanent magnets according to a second aspect of the present invention is characterized in that an adhesive is applied to an end surface of the annular collar portion of the retainer.

(Function) According to the motor rotor of the present invention, the annular collar of the retainer press-fitted onto the rotating shaft is configured to clamp and fix both ends of the cylindrical permanent magnet in the axial direction. Since there is a degree of freedom in expansion and contraction in the radial direction, the permanent magnet is less likely to break during assembly due to thermal expansion due to time or temperature changes, and the permanent magnet is reliably fixed to the rotating shaft.

Since both ends of the permanent magnet are held between the side end surfaces of the annular collar of the retainer, the permanent magnet is firmly fixed even if a compressive force is applied in the axial direction of the cylindrical permanent magnet, and the cylindrical permanent magnet It has the advantage of being resistant to cracks and cracks.

(Example) Embodiments of the present invention will be described below based on the drawings.

1 to 3 show a first embodiment of the invention.

A rotor for generating an electromotive force by electromagnetic induction in a stator attached to the inner peripheral surface of a cylindrical housing of an electric motor is shown in FIGS. 1 and 2.

This rotor 1 is composed of a rotating shaft 1, a pair of retainers 2.3, and permanent magnets 4. The rotating shaft l is made of a cylindrical rod made of stainless steel, for example.

The cage 2 and the cage 3 have the same shape, and the inner diameter of the base cylinder 5, which is composed of a cylinder 5 and an annular collar 6 provided at the outer peripheral end thereof, is equal to or slightly larger than the outer diameter of the rotating shaft 1. The cylindrical body 5 is made to have a small diameter, and is fitted and fixed to the outer periphery of the rotating shaft l by press-fitting. The annular collar portion 6 is integrally molded with the cylindrical body 5, for example, from resin.
The outer peripheral end surface 6a is made larger than the outer diameter of the cylindrical body 5, and the permanent magnet 4 is held between the annular collar side end surface 6b. Since the retainer 3 has a similar shape to the retainer 2, substantially the same components are given the same reference numerals and their explanations will be omitted.

The permanent magnet 4 is cylindrical and has an S pole and an N pole in the circumferential direction.
A total of 24 magnetic poles are arranged in parallel in the axial direction. The material of the permanent magnet is not limited to rare earth-iron based permanent magnets, but may be permanent magnets made of other materials. Annular grooves 8.9 are formed at both ends of the inner circumferential surface 4a of the permanent magnet 4. .

The inner diameter of the annular groove inner circumferential surfaces 8a and 9a of the ffi-shaped member 8.9 is larger than the outer diameter of the outer circumferential end surface 6a of the annular collar portion 6 of the retainer 6. In other words, a gap δ1 is formed.

The axial distance of the annular groove 8.9 is the same as that of the annular collar 6 of the retainer 2.
The thickness is almost equal to that of the Inner peripheral surface 4 of permanent magnet 4
The inner diameter of a is slightly larger than the outer diameter of the cylindrical body 5 of the cage 2, and a gap δ is formed between the inner peripheral surface 4a and the cylindrical body 5.

Next, I will explain how to assemble this motor rotor.
As shown in FIG. 3, the cage 2 is first press-fitted into the end 1a of the rotating shaft l from the annular collar 6 side, then the permanent magnet 4 is inserted into the cylindrical body 5 of the cage 2, and then the cage 2 is inserted into the cylindrical body 5 of the cage 2. The cylindrical body 5
The end face 8b of the permanent magnet 4 on the annular groove side is clamped and fixed between the annular collar side end face 6b of the retainer 2 and the annular collar side end face 6b of the retainer 3.

According to the rotor of the above embodiment, after the retainer 2 is press-fitted into the rotary shaft 1, the permanent magnet 4 is inserted, and the retainer 3 is press-fitted. The assembly work in step 4 becomes easier. There are dimensional errors and variations in the inner diameter of the permanent magnet 4, the outer diameter of the retainer 2.3, etc., and there is a gap δ1 between the retainer 2.3 and the permanent magnet 4.
Since δ2 is formed, this gap δ1. Since δ2 prevents the internal pressure in the radial direction from becoming excessive in the permanent magnet 4, the permanent magnet 4 is prevented from cracking or cracking. Furthermore, since the allowable range of dimensional error accuracy of the cage 2.3 is relatively large, the cage 2.3 can be manufactured at low cost by cold pressing, injection molding, or the like. By manufacturing the cage 2.3 from metal instead of resin, it is also possible to improve its mechanical properties against temperature changes. Furthermore, since the rotor is assembled using a press-fitting method, the assembly is automated and labor-saving, resulting in a reduction in man-hours.

In the above-mentioned embodiment, the permanent magnet 4 was fixed only by being held between the retainers 2 and 3, but according to the present invention, it is also possible to use an adhesive in combination. In this case, the holding force for joining the permanent magnet to the cage is increased. By applying the adhesive to the annular collar side end surface 6b of the retainer 2.3, it is possible to prevent the adhesive from leaking out and avoid adhesion of the adhesive to the surface of the permanent magnet 4. Furthermore, one side of the cage can also be molded integrally with the rotating shaft.

FIG. 4 shows a second embodiment of the present invention, in which the permanent magnet is clamped by a retainer and also prevented from rotating by a key.

A key protrusion 12 is provided on the outer peripheral surface of the cylindrical body 5 of the retainer 2 in the axial direction. A key groove 13 is formed on the inner circumferential surface of the permanent magnet 4 in correspondence with the key protrusion 12 . When the key protrusion 12 and the key groove 13 are fitted, the key is fixed in addition to the clamping fixation between the retainer 2.3 and the permanent magnet 4.
The permanent magnet 4 is fixed in the axial direction by crimping the annular collar 6 of the retainer 2.3, and the permanent magnet 4 is fixed in the rotational direction by shearing frictional force on the side end surface 6b of the annular collar of the retainer 2.3. In addition, fixation is added by fitting the key projection 12 and the key groove 13. This prevents the axial movement of the permanent magnet 4, and also reliably prevents the rotation of the permanent magnet 4 in the circumferential direction. Since gaps δ and δ2 are formed in the radial direction between the retainer 2 and the permanent magnet 4, the permanent magnet 4 is less likely to receive internal pressure in the radial direction and is therefore less likely to be damaged.

FIG. 5 shows a third embodiment of the present invention, in which a permanent magnet is clamped by a retainer and splined by a spline groove.

A spline projection 14 is provided on the outer peripheral surface of the cylindrical body 5 of the retainer 2. A spline groove 15 (not shown) is also formed on the inner circumferential surface of the permanent magnet 4 in correspondence with the spline protrusion 14.
are fitted together to prevent movement in the rotational direction.

FIG. 6 shows a fourth embodiment of the present invention, in which both end surfaces of a permanent magnet are clamped and fixed by a retainer.

The permanent magnet 20 is a cylindrical body, and the flange side end face 24 of the retainer 22 is in contact with and press-fitted to the end face 20a of the cylindrical body. In this fourth embodiment, since the permanent magnet 20 has a simple cylindrical shape, the permanent magnet 4 can be easily processed.

(Effects of the Invention) As explained above, the motor rotor using permanent magnets of the present invention has a structure in which the permanent magnets are clamped and fixed to the rotating shaft by crimping in the axial direction via the retainer. ,
Since the structure is such that internal pressure in the radial direction is less likely to act on the permanent magnet, cracks are less likely to occur in the permanent magnet, which has the effect of preventing breakage and damage. Further, the assembly can be performed simply by pressing the retainer onto the rotating shaft and clamping and fixing the permanent magnet by the retainer.

Furthermore, in the case of conventional fixing using only adhesive, it took a long time for the adhesive to dry, but with the present invention, there is no need for drying time and assembly can be completed in a short time, resulting in improved assembly work efficiency. In addition, there is an effect that an assembled finished product with good accuracy can be manufactured even if the dimensional accuracy of each component is relatively low compared to the injection molding method.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway sectional view showing a motor rotor using permanent magnets according to the first embodiment of the present invention, FIG. 2 is a partial perspective view showing a permanent magnet mounting part, and FIG. 3 is an assembled FIG. 4 is a perspective view showing a retainer and permanent magnet according to the second embodiment of the present invention, and FIG. 5 is a perspective view showing the retainer and permanent magnet according to the third embodiment of the present invention. FIG. 6 is a perspective view showing the container and the permanent magnet, and FIG. 6 is a partially cutaway sectional view showing the attachment portion of the permanent magnet and the cage, showing a fourth embodiment of the present invention. 1... 2, 3 a b a b δ wheel ・Rotating shaft, ... cage. Permanent magnet, cylindrical body, annular flange, outer circumferential surface of annular flange, end surface of annular flange, annular groove, inner periphery of annular groove, end surface of annular groove, ... gap.

Claims (2)

[Claims] (1) A retainer having a cylindrical or cylindrical rotating shaft, a cylindrical body that can be press-fitted to the outer periphery of the rotating shaft, and an annular collar, and a retainer that is clamped and fixed to the side end surface of the annular collar of the retainer. A rotor for a motor using a permanent magnet, characterized in that it is composed of a cylindrical permanent magnet. (2) The rotor for a motor using a permanent magnet according to claim 1, wherein an adhesive is applied to an end surface of the annular collar portion of the retainer.