JPH0993844A - Rotor for synchronous motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rotor for synchronous motor having an easily formable structure for holding a plurality of permanent magnets rigidly on the surface of rotor core while resisting the external force. SOLUTION: The rotor 10 comprises a rotor core 14 being secured to a shaft 12, a plurality of permanent magnets 18 being secured to the tubular surface 16 of rotor core 14, and a member 32 for securing the plurality of permanent magnets 18 onto the tubular surface 16 of rotor core 14 at predetermined positions thereof. Each permanent magnet 18 is beveled at the corner part between the outer circumferential surface 22 and the axial end face 26 thus forming an including end face 28. The securing member 32 comprises a tubular body 34 surrounding all permanent magnets 18 while touching the outer circumferential surface 22 thereof tightly, and an annular flange 36 extending radially inward from one axial fringe part of tubular body 34 integrally therewith. The tubular securing member 32 is shrink fitted to the outer circumferential surface 22 of all permanent magnets 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synchronous motor,
In particular, the present invention relates to a rotor for a synchronous motor in which a plurality of permanent magnets are fixed on the cylindrical surface of a rotor core.

[0002]

2. Description of the Related Art In a rotor of a synchronous motor of the type described above, generally, each permanent magnet has conventionally been fixed to the cylindrical surface of a rotor core by an adhesive means such as an adhesive. In addition, multiple permanent magnets are fixed to the rotor core by winding a wire made of non-magnetic metal material around all permanent magnets of the rotor, or covering the outer peripheral surface of all permanent magnets with a tube made of non-magnetic metal material. The configuration is also known.

[0003]

In a rotor structure in which a plurality of permanent magnets are fixed to a rotor core by an adhesive means such as an adhesive, the adhesive means is applied so as to generate a uniform adhesive force to the plurality of permanent magnets. That requires skill
It has a problem of consuming working time. When this rotor structure is applied to a high-torque electric motor or a high-speed electric motor that reaches tens of thousands of revolutions per minute, the radial external force such as magnetic attraction force or centrifugal force acting on the permanent magnet during rotation of the rotor exceeds the adhesive force. At times, peeling may occur at the adhesive interface, causing the permanent magnet to fall off and scatter. Further, there is a possibility that peeling may occur at the adhesive interface due to aging of the adhesive.

On the other hand, when a wire made of a non-magnetic metal material is used, a magnet fixing force that is generally stronger than the bonding means can be obtained against an external force in the radial direction. However, in this case, since the wire is manually wound around all the permanent magnets, it is difficult to wind the wire so that it does not protrude from the gap size between the rotor and the stator, and the same wire is used for many rotors. It is difficult to manufacture a rotor of uniform quality because it lacks reproducibility enough to apply a magnet fixing force.

When using a tube made of a non-magnetic metal material,
Generally, in order to facilitate the mounting work of the pipe, a clearance-fitting relationship is provided between the pipe and the plurality of permanent magnets, and the plurality of permanent magnets are fixed to the cylindrical surface of the rotor core in advance by bonding means and Was fixed to the permanent magnet by, for example, resin impregnation. In such a structure, the tube only serves to prevent the permanent magnet from falling off and scattering, and the fixing of the permanent magnet to the rotor core depends on the adhesive force of the adhesive means. Therefore, there is a problem that skill is required for the work of applying the bonding means and the impregnating material and the work time is consumed.

In order to solve such a problem, when an attempt is made to provide an interference fit relationship between the tube and the plurality of permanent magnets, the diameter of the tube is slightly increased and all permanent magnets are inserted from one axial end of the rotor. It is necessary to slide under pressure in the axial direction along the outer peripheral surface of the. At this time, depending on the relationship between the pressure applied to the tube and the frictional force generated between the tube and the permanent magnet, distortion occurs near the edge of the tube that directly receives the pressure, which causes the tube to move to the rotor accurately. Tends to be difficult to install.

Therefore, an object of the present invention is to reliably and firmly fix and hold a plurality of permanent magnets on the surface of a rotor core against an external force such as a magnetic attraction force or a centrifugal force that acts on the permanent magnets when the rotor rotates, and is sufficient. It is an object of the present invention to provide a rotor of a synchronous motor having a magnet fixing structure which can be easily formed with high reproducibility and which has high operation reliability.

[0008]

In order to achieve the above object, the present invention provides a rotor for a synchronous motor in which a plurality of permanent magnets are fixed to a cylindrical surface of a rotor core in a circumferentially spaced arrangement. A tubular body that includes a fixing member that fixedly holds the magnet at a predetermined position on the cylindrical surface of the rotor core, and the fixing member closely contacts the outer peripheral surfaces of all the permanent magnets in an interference fit relationship to surround the permanent magnets. And an annular flange integrally extending radially inward from one axial end of the tubular body, and all permanent magnets are chamfered between their outer peripheral surface and at least one axial end surface. A rotor for a synchronous motor is provided.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in more detail based on its embodiments with reference to the accompanying drawings. In the drawings, the same or similar components are designated by common reference numerals. 1 to 4 show a rotor 10 of a synchronous motor according to an embodiment of the present invention. The rotor 10 has a shaft 12
And a plurality of (four in the illustrated embodiment) permanent magnets 18 fixed to the cylindrical surface 16 of the rotor core 14. Each of the permanent magnets 18 has substantially the same roof tile shape, and the inner peripheral surface 2 that is in close contact with the cylindrical surface 16 of the rotor core 14
0, an outer peripheral surface 22 that extends substantially parallel to the inner peripheral surface 20 and faces a stator (not shown), an inner peripheral surface 20 and an outer peripheral surface 22.
And a pair of side surfaces 24 and an axial end surface 26 that connect the

The corner portion between the outer peripheral surface 22 of each permanent magnet 18 and at least one axial end surface 26 is chamfered to form an inclined end surface 28. A gap 30 is defined between the permanent magnets 18 adjacent to each other in the circumferential direction by the side surface 24 of each permanent magnet 18. Further, all the permanent magnets 18 are arranged at predetermined positions on the cylindrical surface 16 of the rotor core 14 with a gap 30 having the same shape between adjacent permanent magnets 18.

Further, the rotor 10 includes a plurality of permanent magnets 18
Is provided on the cylindrical surface 16 of the rotor core 14 with a fixing member 32. Preferably the fixing member 3
Reference numeral 2 is made of a non-magnetic metal material such as aluminum or stainless steel, and does not affect the magnetic field generated by the permanent magnet 18. Further, the fixing member 32 integrally extends inward in the radial direction from the tubular main body 34 that closely contacts the outer peripheral surfaces 22 of all the permanent magnets 18 and surrounds the permanent magnets 18 and one axial edge of the tubular main body 34. And an annular flange 36 that is provided. The tubular body 34 has a circular cross section with an inner diameter slightly smaller than the diameter of the outer peripheral surface 22 of the permanent magnet 18 fixed to the rotor core 14, so that the tubular fixing member 32 is
The permanent magnets 18 are mounted on the outer peripheral surface 22 in an interference fit relationship.

The fixing member 32 holds the plurality of permanent magnets 18 against the rotor core 14 against external force in the radial direction such as centrifugal force.
It has sufficient rigidity to be fixedly held on the cylindrical surface 16 and has a thickness necessary to exert such rigidity. Further, the thickness of the fixing member 32, particularly the tubular body 34, depends on the size of the gap defined between the fixing member 32 and the stator (not shown) and the rotor diameter (the outer peripheral surface 22 of the permanent magnet 18 fixed to the rotor core 14). The diameter is set so that it is not reduced enough to affect the characteristics of the electric motor. Further, it is preferable that the tubular body 34 of the fixing member 32 has an axial length substantially the same as the axial length of the permanent magnet 18 as shown in the figure, from the viewpoint of exerting a uniform magnet fixing force on the entire rotor.

The fixing member 32 can be formed, for example, from a metal plate through a deep drawing process. In this case, it is advantageous that the tubular body 34 with a bottom is formed by one deep drawing step, and the bottom is drilled, whereby the tubular body 34 and the annular flange 36 can be integrally formed. . Alternatively, the fixing member 32 can be formed by bending a flange on a metal plate, bending the flange further into a tubular shape, and then joining the edges together.

The process of assembling the rotor 10 having the above structure will be described below. First, the rotor core 14 is fixed to the shaft 12, and the plurality of permanent magnets 18 are arranged at predetermined positions on the cylindrical surface 16 of the rotor core 14. At this time, it is advantageous to temporarily fix each of the permanent magnets 18 to the cylindrical surface 16 of the rotor core 14 with a simple adhesive for working, for example. In this state, one end faces of the rotor core 14 and the permanent magnet 18 in the axial direction are supported by a jig (not shown), and the fixing member 32 is pressed from the other end faces of the rotor core 14 and the permanent magnet 18 in the axial direction under pressure. It is attached to the outer peripheral surface 22 of 18.

When mounting the fixing member 32, first, the fixing member 32 is arranged concentrically with the plurality of permanent magnets 18 (FIG. 1), and the tip edge 38 of the tubular main body 34 opposite to the annular flange 36 is completely removed. It contacts the inclined end surface 28 of the permanent magnet 18. Next, mechanical pressure is applied to the annular flange 36 in the axial direction (shown by an arrow), and the distal end edge region 38 ′ of the tubular body 34 is slightly expanded and fixed along the outer peripheral surface 22 of all the permanent magnets 18. The member 32 is slid in the axial direction (FIG. 2 (a)). At this time, the annular flange 36 receives a pressure over a wider area as compared with the case where pressure is applied to the end edge of the pipe, so that the annular flange 36 is less likely to be strained. Further, the tubular body 34 has a distal edge region 3
A radial inward force acts near the annular flange 36 as the diameter of 8 ′ increases, but the annular flange 36 has a shape that expands in the radial direction and resists the inward radial force, and thus the tubular main body. Prevent distortion of 34.

As described above, the fixing member 32 slides along the outer peripheral surface 22 of the permanent magnet 18 under pressure while gradually expanding its diameter while substantially maintaining its original tubular shape. The magnet is accurately mounted at a predetermined position on the outer peripheral surface 22 (FIG. 2B). At this time, it is difficult to increase the diameter of the annular flange 36 itself, but the portion 39 of the tubular main body 34 adjacent to the annular flange 36 has the inclined end surface 2 of the permanent magnet 18.
Since it is bent along 8, the fixing member 32 can be easily slid and arranged to a predetermined position where the annular flange 36 contacts the axial end surface 26 of the permanent magnet 18 (FIG. 4). Since the fixing member 32 is expanded in diameter, that is, stretched in the circumferential direction when mounted on the magnet outer peripheral surface 22, it is important that the fixing member 32 has a toughness and a thickness that do not cause breakage during mounting.

The fixing member 32 mounted on the outer peripheral surface 22 of the magnet in this manner resists an external force in the radial direction such as a magnetic attraction force and a centrifugal force when the rotor is rotating, and the plurality of permanent magnets 1 are prevented.
8 is fixedly held on the cylindrical surface 16 of the rotor core 14. Here, the magnet fixing force of the fixing member 32 is determined by the material characteristics of the fixing member 32 and the interference between the permanent magnet 18 and the fixing member 32. As long as this magnet fixing force is sufficient to fix the plurality of permanent magnets 18 on the cylindrical surface 16 of the rotor core 14 in the circumferential direction as well, when the fixing member 32 is attached, the simple adhesive as described above is used. Each permanent magnet 18
May be temporarily fixed to the rotor core surface 16. However, in order to further secure the fixing action in the circumferential direction, it is desirable that the permanent magnets 18 be firmly bonded to the rotor core surface 16 to some extent.

As described above, according to the fixing member 32, there is no fear that the permanent magnet will fall off and scatter, unlike the conventional magnet fixing structure using only the adhering means, at the adhesive interface. In addition, since it is not necessary to fix the fixing member to the permanent magnet by resin impregnation or the like, the magnet fixing work becomes extremely easy as compared with the case of using a conventional tube or wire, and the same method can be applied to many rotors. The rotor can be manufactured with sufficient reproducibility to apply the magnet fixing force.

5 and 6 show a rotor 40 of a synchronous motor according to another embodiment of the present invention. The rotor 40 includes a substantially cylindrical rotor core 42 fixed to the shaft 12 and a plurality of permanent magnets 1 fixed to a cylindrical surface 44 of the rotor core 42.
8 and. Further, the rotor 40 includes a plurality of permanent magnets 1.
A fixing member 32 for fixing 8 to the cylindrical surface 44 of the rotor core 42 is provided. The configurations of the permanent magnet 18 and the fixing member 32 are the same as those in the rotor 10 of FIG.

On the cylindrical surface 44 of the rotor core 42, at the positions corresponding to the gaps 30 between the adjacent permanent magnets 18,
Protrusions 46 extending in the axial direction are respectively provided. Each protrusion 46 defines a side surface 24 of each permanent magnet 18 that defines a gap 30.
To position each permanent magnet 18 at a predetermined position on the cylindrical surface 44. Further, when the fixing member 32 is attached to the outer peripheral surface 22 of the permanent magnet 18 by the above-described procedure, each protrusion 46
Serves to hold each permanent magnet 18 fixedly in the circumferential direction. Therefore, in this case, it is not necessary to firmly bond the permanent magnets 18 to the rotor core surface 44 regardless of the magnitude of the magnet fixing force of the fixing member 32.

In the rotor 10 and the rotor 40, depending on the thickness of the fixing member 32 and the tightening margin between the permanent magnet 18 and the fixing member 32, each portion of the tubular main body 34 corresponding to each gap 30 between the adjacent permanent magnets 18 is formed. A pair of markings 4 along the corner between the outer peripheral surface 22 and the side surface 24 of each permanent magnet 18.
8 are formed respectively (see FIGS. 5 and 6B).
The marking 48 is generated because each portion of the tubular main body 34 corresponding to the gap 30 between the permanent magnets 18 is linearly extended. The marking 48 serves to hold the fixing member 32 fixed to the permanent magnet 18.

7 and 8 show a rotor 50 according to yet another embodiment of the present invention. The rotor 50 includes a substantially cylindrical rotor core 14 fixed to the shaft 12 and the rotor core 1
And a plurality of permanent magnets 18 fixed to the cylindrical surface 16 of No. 4. Further, the rotor 40 includes a pair of fixing members 52 for fixing the plurality of permanent magnets 18 to the cylindrical surface 16 of the rotor core 14. Rotor core 14 and permanent magnet 18
1 is substantially the same as that of the rotor 10 of FIG. 1, but each permanent magnet 18 has the inclined end faces 2 at both axial ends thereof.
8 are provided.

Each fixing member 52 has a tubular body 54 having a circular cross section with an inner diameter slightly smaller than the diameter of the outer peripheral surface 22 of the permanent magnet 18 fixed to the rotor core 14, and the tubular body 5
4, an annular flange 56 integrally extending radially inward from one edge in the axial direction. Therefore, each fixing member 52 comes into close contact with the outer peripheral surface 22 of all the permanent magnets 18 in an interference fit relationship. Further, the fixing member 52 is the fixing member 32 of FIG.
It has the same thickness as. Further, it is preferable that the tubular body 54 of the fixing member 52 has an axial length that is approximately half the axial length of the permanent magnet 18 as shown in the figure, from the viewpoint of exerting a uniform magnet fixing force on the entire rotor. .

The pair of fixing members 52 are attached to the outer peripheral surface 22 of the permanent magnet 18 under pressure, one from each axial end surface of the rotor core 14 and the permanent magnet 18. At this time,
First, one fixing member 52 is arranged concentrically with the plurality of permanent magnets 18, and the tip edge 58 of the tubular body 54 on the opposite side of the annular flange 56 is brought into contact with the inclined end surface 28 of each permanent magnet 18,
Axial pressure is applied to the annular flange 56 (illustrated by the arrow). Thereby, while gradually increasing the diameter of the tubular body 54,
The permanent magnets 18 are mounted on the outer peripheral surface 22 at predetermined positions.

Next, another fixing member 52 is arranged concentrically with the plurality of permanent magnets 18, and the tip edge 58 of the tubular body 54 opposite to the annular flange 56 is brought into contact with the other inclined end surface 28 of each permanent magnet 18. In the same manner, the permanent magnets 18 are similarly mounted on the outer peripheral surface 22 of the permanent magnet 18 at predetermined positions under pressure.

With such a structure, the axial length of the rotor core 14 is comparatively long, and therefore, the fixing member having the axial length substantially equal to the axial length of the permanent magnet 18 can be formed by the deep drawing process. When it is difficult, the axial length of the fixing member can be reduced by dividing the fixing member into two, which is advantageous. In this configuration, the tubular body 5 of the fixing member 52 is
The axial length of 4 may be less than approximately half the axial length of the permanent magnet 18. In that case, it is desirable that both fixing members 52 have the same shape in consideration of the dynamic balance of the rotor.

[0027]

As is apparent from the above description, according to the present invention, a tubular main body which is in close contact with the outer peripheral surfaces of all the permanent magnets due to an interference fit is integrally formed with one end of the tubular main body in the radial direction inward. Fixing member with an annular flange that extends in a
By chamfering between the outer peripheral surface of all permanent magnets and at least one end surface in the axial direction, the magnet outer peripheral surface can be easily and accurately mounted under pressure. A plurality of permanent magnets can be securely and firmly fixed and held on the surface of the rotor core against an outward force in the radial direction such as a force or a centrifugal force. The fixing member can be easily formed by a well-known molding process with sufficient reproducibility. Therefore, according to the present invention, there is provided a rotor of a synchronous motor which is easy to manufacture and has high operation reliability.

[Brief description of drawings]

FIG. 1 is a perspective view showing a rotor of a synchronous motor according to an embodiment of the present invention at a stage immediately before mounting a fixing member.

FIG. 2 is a perspective view showing the rotor of FIG. 1 in each state (a) during mounting of the fixing member and (b) at the completion of mounting of the fixing member.

FIG. 3 is a sectional view taken along the line III-III in FIG.

FIG. 4 is a sectional view taken along line IV-IV in FIG.

FIG. 5 is a perspective view showing a rotor of a synchronous motor according to another embodiment of the present invention at a stage during mounting of a fixing member.

6A is a sectional view taken along line VI-VI in FIG. 5, and FIG. 6B is a partially enlarged sectional view of FIG.

FIG. 7 is a perspective view showing a rotor of a synchronous motor according to still another embodiment of the present invention at a stage immediately before mounting a fixing member.

FIG. 8 is a perspective view showing the rotor of FIG. 7 in a state where the fixing member is completely attached.

[Explanation of symbols]

 12 ... Shaft 14, 42 ... Rotor core 16, 44 ... Cylindrical surface 18 ... Permanent magnet 22 ... Outer peripheral surface 28 ... Inclined end surface 30 ... Gap 32, 52 ... Fixing member 34, 54 ... Tubular body 36, 56 ... Annular flange 46 ... Protrusion 48 ... Stamp

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Sakae Takeda 3580 Koshinoba, Oshinomura, Minamitsuru-gun, Yamanashi Prefecture, Fanac Co., Ltd. Address within FANUC CORPORATION

Claims (1)

[Claims] 1. In a rotor of a synchronous motor in which a plurality of permanent magnets are fixed to a cylindrical surface of a rotor core in a circumferentially spaced arrangement, the plurality of permanent magnets are fixedly held at predetermined positions on the cylindrical surface of the rotor core. A fixing member, the fixing member is in close contact with the outer peripheral surfaces of all the permanent magnets in an interference fit relationship, and surrounds the permanent magnets; and a tubular body radially inward from one axial end of the tubular body. An integrally extending annular flange, and all permanent magnets are chamfered between their outer peripheral surfaces and at least one axial end surface thereof.