JP3701183B2 - Motor rotor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a motor rotor, and more particularly to a rotating field type motor rotor suitable for a power steering (hereinafter referred to as PS) motor.
[0002]
[Prior art]
FIG. 6 is a cross-sectional view of a main part of a motor rotor incorporated in an industrial or general household device or device disclosed in Japanese Patent Publication No. 5 (1993) -20979, wherein 1 is a rotating shaft and 2 is a yoke. 3 is a magnet, ad is an adhesive, and 4 is a protective case. The yoke 2 has a cylindrical shape and is coaxially mounted on the outer peripheral surface of the rotating shaft 1. The magnet 3 has a structure in which a plurality of magnet pieces having a circular arc shape are used to gather in a cylindrical shape, and the arc-shaped magnet pieces are bonded to the outer peripheral surface of the yoke 2 with an adhesive ad. The protective case 4 includes cup-shaped upper and lower members 41 and 42 formed of a non-magnetic material. The protective case 4 is inserted from the upper and lower sides of the rotary shaft 1 to cover the outer surface of the magnet 3 with an adhesive ad. It is glued. The protective case 4 is applied for the purpose of preventing scattering of the magnet 3 during rotation of the motor rotor.
[0003]
Japanese Laid-Open Patent Publication No. 6-54472 discloses a method of fixing ferrite magnets to a motor rotor used in a fully automatic washing machine or the like, in which a large number of ferrite magnet pieces are individually bonded with an adhesive and a screw. Are combined to form a cylindrical body as a whole, and the outer surface of the assembly thus formed is covered with a heat-shrinkable tube to prevent the ferrite magnets from scattering.
[0004]
By the way, even with the above-described conventional rotor in which measures for preventing the scattering of magnets have been taken, there still remains a problem of scattering of small magnet pieces during the rotation of the rotor. The reason is that in the conventional rotor, the magnet is an assembly of a plurality of magnet pieces, particularly an assembly of magnet pieces divided in the axial direction of the rotor. A part of the edge of the magnet piece is missing due to local contact between the magnet pieces adjacent in the rotation direction in the middle or due to external force such as vibration, and the resulting magnet piece rotates from the periphery of the protective cover such as a heat shrink tube May fly out of the child. When such magnet pieces are scattered between the rotor and the stator of the motor, a motor lock may occur. In full-automatic washing machines and many industrial motors, motor locks can be as much as an accident that stops the motor, and eventually the equipment stops operating, but in PS motors, it can lead to a steering lock, resulting in a tragic accident. There is a risk of triggering. Therefore, when the above-described conventional motor rotor is used for a PS motor, it is required to prevent or reduce the problem of scattering of magnet pieces to a higher degree.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to provide a motor rotor suitable for PS motors, in view of the above-mentioned situation in the prior art, which further prevents or reduces the problem of scattering of magnet pieces.
[0006]
[Means for Solving the Problems]
The motor rotor according to the present invention is formed of (1) a rotating shaft, a yoke coaxially provided on the rotating shaft, a cylindrical magnet that covers the outer peripheral surface of the yoke, and a heat-shrinkable tube that covers the outer surface of the magnet. And a groove for accommodating the end portion of the heat-shrinkable tube on the axial end surface of the yoke .
(2) In the above (1), the yoke is provided with ring-shaped grooves for accommodating the end portions of the heat-shrinkable tube on both end faces of the yoke.
(3) In the above (2), the end surface of the yoke on the side where the motor is inserted into the motor stator is covered with a nonmagnetic end surface covering member having a tapered tapered side surface.
(4) In (1) above, the magnet is bonded to the outer peripheral surface of the yoke.
(5) In the above (1) or (4), the magnet is made of a metal material mainly composed of iron, and is used without being subjected to rust prevention treatment on the surface.
(6) In the above (5), the metal material is a neodymium-iron-boron system.
(7) In the above (1), the rotating shaft and the yoke are integrally formed with each other.
(8) In the above (1), the power steering motor is used.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
FIGS. 1 to 2 are for explaining the first embodiment of the motor rotor of the present invention, and FIG. 1 is a cross-sectional view of a PS motor incorporating the motor rotor of the first embodiment. FIG. 2 is an enlarged sectional view of a main part of the motor rotor. 1-2, 1 is a rotating shaft, 2 is a yoke, 3 is a magnet, 5 is a magnet protective cover, 6 is a bearing, 7 is a stator, 8 is a bracket, and 9 is a frame.
[0008]
The yoke 2 is formed coaxially and integrally with the rotating shaft 1 on the rotating shaft 1, and the outer peripheral surface 21 is covered with a cylindrical magnet 3. The magnet 3 and the yoke 2 are bonded with an epoxy resin or other adhesive. The magnet protection cover 5 is formed of a heat shrinkable tube 51 and covers the entire outer surface of the magnet 3. Ring-shaped grooves 221 and 231 are formed in both end faces 22 and 23 of the yoke 2 concentrically with the rotary shaft 1, and the end portions 511 and 512 of the heat shrinkable tube 51 are respectively connected to the ring-shaped grooves 221 and 221. 231 is contained.
[0009]
The yoke 2 may be a cylindrical yoke member bonded to the rotary shaft 1 with an appropriate adhesive as in the conventional example. However, in the case of being integrally formed with the rotary shaft 1 as in the first embodiment, in addition to the advantage that the assembly work of the motor rotor is simplified, the possible extra adhesion scattering during the rotation of the motor. There is also an advantage that the problem of steering lock based on the scattering does not occur.
[0010]
As the magnet 3, in terms of chemical composition, magnets made of metal materials mainly composed of iron such as alnico magnets, ferrite magnets, iron-chromium-cobalt magnets, neodymium-iron-boron magnets, and samariums. Examples include non-ferrous magnets such as cobalt-based magnets and manganese-aluminum-carbon-based magnets, and bonded magnets composed of the above or other various magnetic metal materials and organic polymers. Among these, a relatively inexpensive and high performance neodymium-iron-boron magnet is particularly preferable. Since magnets made of a metal material mainly composed of iron have a problem of rusting, the surface thereof is usually subjected to rust prevention treatment. However, in the present invention, the magnet 3 is always tightly protected by the magnet protective cover 5, and the magnet protective cover 5 exhibits a rust preventive action, so that the magnet 3 is not subjected to the conventional rust preventive treatment. It can be used, and the cost required for the rust prevention treatment can be reduced. The magnet 3 is used by being magnetized in advance in the radial direction, for example.
[0011]
In the first embodiment, a single cylindrical magnet 3 is used as a magnet. In general, in the present invention, a magnet is formed by cascading a plurality of ring-shaped or cylindrical magnets. There may be. In any case, the magnet is used by being magnetized in the radial direction, for example.
[0012]
Examples of the heat-shrinkable tube 51 that forms the magnet protective cover 5 include thermoplastic resins such as nylon and fluorine resin, various thermoplastic elastomers, a mixed composition of a crosslinked rubber and a thermoplastic resin, and electron beam crosslinked polyethylene. Or a crosslinked polymer having a three-dimensional structure.
[0013]
In the motor rotor of the first embodiment, the rotary shaft 1 is inserted into the cylindrical magnet 3 and bonded together at a position where the outer peripheral surface 21 of the yoke 2 is covered by the magnet 3, and then the whole magnet 3 is wrapped. The heat-shrinkable tube 51 is covered, and finally the heat-shrinkable tube 51 is heated and heat-shrinked to assemble. Regarding the dimensions of the heat-shrinkable tube used at that time, after heat-shrinking, it adheres to and covers the entire outer surface of the magnet 3, and both ends 511 and 512 of the yoke 2 as shown in FIG. A tube whose diameter and length are determined in advance so as to fall into and accommodate in ring-shaped grooves 221 and 231 formed in both end faces 22 and 23 is used.
[0014]
When the ring-shaped grooves 221 and 231 are not provided, both end portions 511 and 512 of the heat-shrinkable tube 51 contract and rise at the both end surfaces 22 and 23 of the yoke 2, thereby obstructing miniaturization of the motor rotor. There is a problem to do. On the other hand, if the ring-shaped grooves 221 and 231 are provided, the above-described rise is prevented by dropping the both ends 511 and 512 into the ring-shaped grooves 221 and 231, thereby reducing the size of the motor rotor. Can be achieved.
[0015]
Since the present invention uses a cylindrical magnet as the magnet 3 provided on the outer peripheral surface of the yoke 2 and covers the outer peripheral surface of the yoke 2 as seen in the first embodiment, the motor rotor in the conventional example is used. When a plurality of magnet pieces divided in the axial direction are individually attached, the probability of occurrence of fragments due to partial breakage of the magnet edge portion, which tends to occur, is remarkably reduced. In addition, since the cylindrical magnet is installed in a state of covering the outer peripheral surface of the yoke 2, the entire outer surface thereof is encased in close contact with the magnet protective cover 5 made of the heat-shrinkable tube 51, so there is a very slight probability. Even if magnet fragments are generated, they are retained in the magnet protective cover 5, and as a result, the problem that the magnet fragments are scattered between the rotor and the stator of the motor is substantially solved. Therefore, the motor rotor of the present invention such as the first embodiment can be suitably used for a PS motor with high safety.
[0016]
Embodiment 2. FIG.
3-5 is for demonstrating Embodiment 2 in the motor rotor of this invention. FIG. 3 is a cross-sectional view of a PS motor incorporating the motor rotor of the second embodiment, FIG. 4 is an enlarged cross-sectional view of the main part of the motor rotor, and FIG. 5 is a process for manufacturing the PS motor. FIG. 3 to 5, reference numeral 24 denotes an end face covering member. The second embodiment is different from the first embodiment in that the end surface 22 of the yoke 2 is covered with an end surface covering member 24.
[0017]
The end surface covering member 24 has a plate shape made of a nonmagnetic metal, and the side surface 241 has a tapered shape. As shown in FIG. 5, the PS motor is assembled by inserting the motor rotor shown in FIG. 4 into the stator 7 in the direction indicated by the arrow A. At this time, the end surface covering member 24 is fixed to the yoke 2. It is provided on the end surface 22 which becomes the insertion destination side when inserting into the child 7. In general, the gap between the inner wall of the stator 7 and the outer wall of the motor rotor (the outer surface of the magnet protective cover 5 in the case of Embodiment 2) is very small, but the side surface 241 of the end surface covering member 24 is tapered. The taper shape facilitates the insertion of the motor rotor into the stator 7 and improves the production efficiency of the PS motor. Further, the end surface covering member 24 also has an action of protecting the heat shrinkable tube 51 on the end surface 22 and the edge portion of the magnet 3 from local damage that tends to occur at the time of insertion. The end face covering member 24 is suitably about 2 mm thick.
[0018]
【The invention's effect】
As described above, the motor rotor in the invention of (1) of the present invention has a rotating shaft, a yoke provided coaxially with the rotating shaft, a cylindrical magnet covering the outer peripheral surface of the yoke, and the magnet In the conventional motor, a magnet protective cover formed of a heat shrinkable tube covering the outer surface of the yoke is provided , and a groove for accommodating the end of the heat shrinkable tube is provided on the end surface of the yoke in the axial direction. When a plurality of magnet pieces divided in the axial direction of the rotor are individually attached, the probability of occurrence of fragments due to partial breakage of the magnet edge portion that tends to occur is remarkably reduced. In addition, since the cylindrical magnet is installed so as to cover the outer peripheral surface of the yoke, its entire outer surface is wrapped in close contact with a magnet protective cover made of a heat-shrinkable tube. In the unlikely event that they occur, these debris are retained in the magnet protective cover, and as a result, the problem that the magnet pieces scatter between the rotor and the stator of the motor is substantially solved, and the present invention This motor rotor can be suitably used for a PS motor with high safety.
[0019]
(2) The yoke is provided with ring-shaped grooves for accommodating the end portions of the heat-shrinkable tube on both end faces of the yoke. When the ring-shaped groove is not provided, both ends of the heat-shrinkable tube contract and rise on the both end surfaces of the yoke, and there is a problem that hinders miniaturization of the motor rotor. If it is provided, the above-described bulge is prevented by dropping into the ring-shaped grooves at both ends of the heat-shrinkable tube, and the motor rotor can be reduced in size. Furthermore, since the both ends of the heat-shrinkable tube are housed in the ring-shaped groove, the action of retaining magnet fragments by the magnet protective cover is improved.
[0020]
(3) If the end surface of the yoke on the side where the motor stator is inserted is covered with a nonmagnetic end surface covering member having a tapered tapered side surface, the narrowness of the motor rotor during motor assembly is reduced. Insertion into the motor stator becomes easy and the production efficiency of the motor is improved. The end face covering member also has an effect of protecting the heat-shrinkable tube and the edge part of the magnet on the end face from local damage that tends to occur during insertion.
[0021]
(4) When the magnet is bonded to the outer peripheral surface of the yoke, the possibility of generating a magnet piece is smaller than when the magnet is attached with a screw or the like.
[0022]
Further, (5) the magnet is composed of a metal material mainly composed of iron, for example, (6) a neodymium-iron-boron magnet, and the surface is used without being subjected to rust prevention treatment. In the present invention, since the magnets are always closely protected by the magnet protective cover, the magnets described above, particularly neodymium-iron-boron magnets, which are relatively inexpensive and have high performance but have the problem of rusting, are prevented. It can be used without performing rust treatment, and the cost required for rust prevention treatment can be reduced.
[0023]
(7) If the rotating shaft and the yoke are integrally formed with each other, there is an effect of simplifying the assembly work of the motor rotor.
[0024]
Further, (8) when the motor rotor of the present invention is used for a PS motor, as described above, a problem that magnet pieces are scattered between the motor rotor and the stator from the motor rotor of the present invention. Therefore, the obtained PS motor has high performance not seen in the prior art in terms of motor lock resistance and steering lock resistance.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a PS motor incorporating a motor rotor according to a first embodiment.
FIG. 2 is an enlarged cross-sectional view of a main part of the motor rotor according to the first embodiment.
FIG. 3 is a cross-sectional view of a PS motor incorporating a motor rotor according to a second embodiment. FIG. 4 is an enlarged cross-sectional view of a main part of the motor rotor according to the second embodiment.
5 is a cross-sectional view illustrating a manufacturing process of a PS motor using the motor rotor of the second embodiment. FIG.
FIG. 6 is an enlarged cross-sectional view of a main part of a conventional motor rotor.
[Explanation of symbols]
1 Rotating shaft, 2 Yoke, 22 End face of yoke, 23 End face of yoke,
221 ring-shaped groove, 231 ring-shaped groove, 24 end face covering member, 3 magnet,
5 Magnet protective cover, 51 Heat shrinkable tube, 6 Bearing, 7 Stator,
8 brackets, 9 frames.

Claims (8)

A rotating shaft, a yoke coaxially provided on the rotating shaft, a cylindrical magnet covering the outer peripheral surface of the yoke, and a magnet protective cover formed of a heat-shrinkable tube covering the outer surface of the magnet . A motor rotor comprising a groove for accommodating an end of the heat-shrinkable tube on an end face in the axial direction . The motor rotor according to claim 1, wherein the yoke is provided with ring-shaped grooves for accommodating end portions of the heat-shrinkable tube at both end faces of the yoke. 3. The motor rotor according to claim 2, wherein an end surface of the yoke that is an insertion destination side of the motor stator is covered with a nonmagnetic end surface covering member having a tapered side surface that is tapered. The motor rotor according to claim 1, wherein the magnet is bonded to the outer peripheral surface of the yoke. 5. The motor rotor according to claim 1, wherein the magnet is made of a metal material mainly composed of iron, and is used without being subjected to rust prevention treatment on the surface. . 6. The motor rotor according to claim 5, wherein the metal material is of a neodymium-iron-boron system. The motor rotor according to claim 1, wherein the rotating shaft and the yoke are integrally formed with each other. The motor rotor according to claim 1, wherein the motor rotor is used for a power steering motor.

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