JP4552267B2 - motor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a structure of a motor using a permanent magnet used for home appliances and the like.
[0002]
[Prior art]
Conventionally, a rotor using a permanent magnet has used the following means as means for fixing the permanent magnet.
(1) The inner periphery of the permanent magnet and the outer periphery of the rotor yoke are fixed with an adhesive.
(2) Fixed by fitting a tube made of non-magnetic metal around the permanent magnet.
[0003]
According to the above means, in (1), the reliability at high speed rotation is low, and since an adhesive layer is formed between the rotor yoke and the permanent magnet, permeance is lowered and efficiency is lowered. In (2), the motor gap was reduced due to an increased air gap or eddy current generated in the pipe.
[0004]
As one method for solving these problems, there is a motor rotor disclosed in Japanese Patent Publication No. 2000-78787. FIG. 11 is a cross-sectional view of a rotor of an electric motor disclosed in Japanese Patent Publication No. 2000-78787. The permanent magnet 43, the rotor yoke 42, and the output transmission unit 44 are connected, and the permanent magnet 43 is fixed to the outer periphery of the rotor yoke 42 by the resins 46 and 48, and the rotor yoke 44 and the output transmission unit 44 are fixed, and The permanent magnet 43 and the output shaft 45 are insulated.
[0005]
[Problems to be solved by the invention]
In the motor rotor disclosed in Japanese Patent Publication No. 2000-78787 as described above, there are problems in terms of resin strength and resin shrinkage after resin molding. In particular, when a sintered ferrite magnet is used, the permanent magnet may crack due to resin shrinkage.
[0006]
Moreover, since resin exists in the outer peripheral part of a permanent magnet, a magnetic air gap becomes large and efficiency falls.
[0007]
The present invention solves the above-described problems, and can provide a motor that has sufficient strength and is stable even in resin shrinkage after molding.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention is such that the outer peripheral portion of the permanent magnet is not a perfect circle with respect to the rotor rotation center, and the distance from the rotor rotation center of the outer periphery of the permanent magnet is near the circumferential center of each permanent magnet. And a small gap at the circumferential end, and a constant gap is provided between adjacent permanent magnets. Furthermore, resin is poured into at least the outside of the end portion of the permanent magnet and the gap between the adjacent permanent magnets, and the permanent magnet is fixed to the rotor yoke.
[0009]
Moreover, resin was poured also into the axial direction both ends, and the hole or groove | channel for resin contraction relaxation was provided between the permanent magnets adjacent to each other in the axial direction both ends of the permanent magnet.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
According to a first aspect of the present invention, in the motor having a rotor and a stator, the rotor has a plurality of substantially arc-shaped permanent magnets on the surface of a rotor yoke made of a high permeability material such as iron by resin molding. The outer periphery of the permanent magnet is not a perfect circle with respect to the rotor rotation center,
The distance from the rotor rotation center of the outer periphery of the permanent magnet is the maximum near the circumferential center of each permanent magnet, and is small at the circumferential end,
At least the outer side of the circumferential end of the permanent magnet and the axially both ends of the resin, the rotor fixed the permanent magnet to the rotor yoke,
A motor using a rotor, characterized in that a resin shrinkage relaxation hole or groove is provided between adjacent permanent magnets in both axial ends of the permanent magnet, without a nonmagnetic insulator, The magnetic flux of the permanent magnet can be directly transmitted to the rotor yoke, and the resin contraction can be reduced after the resin molding and a highly reliable motor can be provided.
[0011]
The invention according to claim 2 of the present invention is the motor according to claim 1, wherein the outer periphery of the rotor yoke has a cylindrical shape centered on the rotor rotation axis, and the thickness of the permanent magnet is non-uniform. Thus, the gap magnetic flux density can be made sinusoidal.
[0012]
According to a third aspect of the present invention, the thickness of the permanent magnet is substantially uniform, the radius of curvature of the outer periphery of the permanent magnet is smaller than the distance from the rotor rotation center to the outer periphery of the permanent magnet, and the outer periphery of the yoke is fixed to the permanent magnet. 2. The motor according to claim 1, wherein the motor has a petal shape in accordance with the inner diameter shape of the magnet, machining of the magnet is facilitated, and the gap magnetic flux density can be made sinusoidal.
[0013]
According to a fourth aspect of the present invention, in the outer peripheral side of the rotor, the vicinity of the center in the circumferential direction of the permanent magnet is not covered with resin. It is a motor of description, Comprising: An air gap can be made small and a motor with high efficiency can be provided.
[0020]
【Example】
Embodiments of the present invention will be described below with reference to FIGS.
[0021]
Example 1
FIG. 1 is a perspective view of a rotor used in the motor of the present invention. FIG. 2 is an exploded perspective view of a rotor used in the motor of the present invention before being molded. FIG. 3 is an AA ′ sectional view of a rotor used in the motor of the present invention. FIG. 4 is a BB ′ sectional view of a rotor used in the motor of the present invention. FIG. 5 is a C-O-D cross-sectional view of a rotor used in the motor of the present invention. FIG. 6 is a plan view of a stator used in the motor of the present invention. Note that crossover wires, lead wires, and the like are omitted for convenience. Also, in the case of a molded stator, the mold resin diagram is omitted. FIG. 7 is a view showing a punching pattern of a stator core sheet of a stator used in the motor of the present invention. FIG. 8 is a view showing a state where the stator core of the stator used in the motor of the present invention is developed. FIG. 9 is a plan view of the motor of the present invention. In the case of molding the stator, the state immediately before molding is shown, and the shaft, bearing, bracket, crossover wire and lead wire are omitted.
[0022]
Eight substantially arc-shaped permanent magnets 11 are arranged on the surface of a rotor yoke 12 made of a high permeability material such as iron. The outer peripheral portion of the permanent magnet 11 is not a perfect circle with respect to the rotor rotation center, and the distance from the rotor rotation center of the outer periphery of the permanent magnet takes a maximum value Rmax near the circumferential center of each permanent magnet. The minimum value Rmin is taken at the direction end.
[0023]
A certain gap W is provided between the adjacent permanent magnets.
[0024]
The permanent magnet 11 is thick at the circumferential center 11c and thin at the circumferential end 11e, and the outer periphery of the rotor yoke 12 has a cylindrical shape centered on the rotation center of the rotor. That is, the magnetic air gap between the inside of the stator and the permanent magnet is the smallest at the circumferential central portion 11 c of the permanent magnet 11 and becomes large at both circumferential circumferential ends 11 e of the permanent magnet 11.
[0025]
The permanent magnet 11, the rotor yoke 12, and the boss 13 are molded with a resin 15, and these are fixed.
[0026]
With this configuration, the magnetic flux density of the air gap becomes sinusoidal, torque pulsation is small, and vibration and noise can be reduced.
[0027]
On the inner periphery of the rotor yoke 12, there is provided a boss 13 which is fitted with a shaft at a certain distance and serves as an output transmission portion. On the inner side of the rotor yoke 12 and the outer side of the boss 13, three projections 12t and 13t facing each other with a slight distance are provided at equal intervals. The number 3 of each protrusion is relatively prime to the number 8 of rotor poles.
[0028]
With this configuration, the rotor yoke 12 and the output shaft are insulated from each other, the current generated in the rotor yoke is not transmitted to the output shaft, and the contact of the bearing that causes noise is less likely to occur. Further, since the strength of the resin is weaker than that of iron, the presence of the protrusions 12t and 13t facing each other at a slight distance can maintain high rigidity against a load caused by a radial magnetic attraction force or a load gravity. Is possible. Further, misalignment due to resin shrinkage can be prevented. In addition, since the number of protrusions 3 and the number of rotor poles 8 are relatively prime, the vibration mode node generated by the number of rotor poles during motor operation and the portion where the rigidity is improved by the protrusions are completely the same. There is nothing to do. In other words, in the case of 8 poles, the magnetic attraction force is strong at equal intervals of 4 or 8 per round, but the rigidity is weak because there are three strong portions at equal intervals in the radial direction. The portion and the portion where the magnetic attractive force is increased do not completely coincide with each other, and the ring vibration of the stator is difficult to occur.
[0029]
Since the shape of the outer circumference of the permanent magnet approximates the spatial distribution of the magnetic flux density of the air gap to a sinusoidal shape, noise and vibration can be reduced.
[0030]
When resin molding is performed, the permanent magnet 11, the rotor yoke 12, and the boss 13 are temporarily fixed. However, the permanent magnet may be pressed from the outside at the center portion 11c in the circumferential direction that is not covered with resin even after molding.
[0031]
The molded resin is formed on the outer side 14a of the end 11e in the circumferential direction of the permanent magnet 11, the gap 14b between the permanent magnets 11 adjacent to each other, the outer space 14c at both ends in the axial direction of the permanent magnet, and in some cases the inner portion of the rotor yoke 12. The permanent magnet 11 is fixed to the rotor yoke 12 by flowing into the periphery. At this time, the outer periphery of the permanent magnet 11 in the vicinity of the center in the circumferential direction is not molded with resin, and the vicinity of the center of the permanent magnet in the circumferential direction from the rotor rotation center is not covered with the resin, that is, in the circumferential direction of the permanent magnet Assuming that the distance of the central portion is Rmax, if only resin molding is performed within a range less than the radius Rmax, the air efficiency is not increased and the motor efficiency is not lowered.
[0032]
Further, the protrusions 12t and 13t provided on the inner peripheral side of the rotor yoke 12 and the outer peripheral side of the boss 13 and the gap 14f between the opposing protrusions are molded with resin to insulate the rotor yoke 12 and the boss 13 from each other.
[0033]
Of the portion between the rotor yoke 12 and the boss 13, the axial thickness Ln of the mold at the portion without the protrusion is smaller than the mold thickness Lt (including the protrusion) of the protrusion. By doing so, the amount of resin used can be reduced while ensuring the strength of the rotor. Further, the resin amount can be reduced by providing a through hole in a portion without a protrusion (not related to the Ln), or by making a space without a protrusion.
[0034]
After the permanent magnet 11, the rotor yoke 12, and the boss 13 are molded by resin molding, the resin tries to shrink and gives stress to the permanent magnet. Therefore, it is necessary to relieve stress. In view of this, a resin shrinkage relaxation hole 16 is provided between adjacent permanent magnets having a large amount of resin in both axial end portions of the permanent magnet. From the viewpoint of productivity, the resin shrinkage relaxation hole 16 is opened in the axial direction, and is a hole or groove having a depth until reaching or near the end of the permanent magnet.
[0035]
Furthermore, a resin shrinkage relaxation hole 17 is provided in a portion of the resin mold provided on the inner side of both axial ends of the permanent magnet, in which the protrusion is extended in the radial direction. This is because when the resin covering both ends in the axial direction of the protrusion 12t of the rotor yoke contracts, a force acts on the inner peripheral side of both ends in the axial direction of the permanent magnet 11, and the stress tends to concentrate. Therefore, a resin shrinkage relaxation hole 17 is provided in the vicinity of a portion where stress is likely to concentrate. This is particularly effective when the axial length of the rotor yoke 12 is smaller than the axial length of the permanent magnet 11 and both end portions of the permanent magnet 11 in the axial direction have portions that are not in contact with the rotor yoke 12. If necessary, holes 18 and 19 other than those described above may be appropriately provided. By providing these holes 16, 17, 18, and 19, the incidence of cracking of the permanent magnet due to resin shrinkage after molding was reduced to about 1/10.
[0036]
In the above configuration, when the rotor yoke and boss are drawn from a pipe-like material or formed by forging, or when the thickness of the permanent magnet is large, the stator core may be divided into one or more teeth.
[0037]
As shown in FIG. 8, the stator core piece 23 divided by each tooth and laminated with the stator core sheet piece 22 is connected in a straight line, insulated between the winding and the core, and wound in a state of being linearly developed. 25, and making it annular after winding, the winding property is good and the slot space factor can be increased. Further, when the stator core is formed by laminating and forming a stator core sheet in which electromagnetic steel sheets are punched, if the punching pattern as shown in FIG. 7 is used, material removal is good and scrap can be reduced. In addition, since an alternating magnetic flux is generated in the stator core, it is preferable to use a magnetic steel sheet having a small iron loss, and since the change in magnetic flux is small in the rotor yoke, a material having a larger iron loss than the stator core can be used. It is.
[0038]
The vicinity of the center in the circumferential direction of the permanent magnet means that the resin is molded in a circle centered on the rotor rotation center with the radius being the distance from the rotor rotation center at the circumferential center. This is a range in which a large thickness cannot be provided.
(Example 2)
FIG. 10 shows a cross-sectional view of another rotor used in the motor of the present invention.
[0039]
The thickness of the permanent magnet 31 is substantially uniform, and the radius of curvature of the outer periphery of the permanent magnet is smaller than the distance from the rotor rotation center to the outer periphery of the permanent magnet. Therefore, the distance from the rotor rotation center to the circumferential central portion 31c of the permanent magnet 31 Is larger than the distance from the rotor rotation center to both circumferential ends 31 e of the permanent magnet 31. That is, the magnetic air gap between the inside of the stator and the permanent magnet is the smallest at the circumferential central portion 31 c of the permanent magnet 31 and becomes large at both circumferential ends 31 e of the permanent magnet 31.
[0040]
Further, the outer periphery of the rotor yoke 32 is shaped like a petal according to the inner diameter shape of the permanent magnet 31, and the distance from the rotor rotation center to the portion 32c in contact with the circumferential central portion 31c of the permanent magnet 31 is the largest. The distance to the part 32e which contact | connects the circumferential direction center part 31e of the magnet 31 is small.
[0041]
Other configurations and operations are the same as those in the first embodiment, and are omitted.
[0042]
The air gap is non-uniform, the gap magnetic flux density can be made sinusoidal, and vibration and noise can be reduced. Further, since the thickness of the permanent magnet is uniform, there is a uniform proof strength at any position of the permanent magnet against demagnetization, and a permanent magnet can be required to achieve the minimum thickness. In addition, permanent magnets can be easily processed.
[0043]
The number of poles of the rotor, the shape of the rotor yoke, the shape of the permanent magnet, the shape of the boss, the number of slots in the stator, the winding method, etc. can be modified in various ways according to the purpose of the present invention. Is not excluded from the scope of the present invention.
[0044]
【The invention's effect】
As is clear from the above description, according to the first aspect of the present invention, it is possible to provide a highly reliable motor having sufficient strength for fixing the permanent magnet.
[0045]
According to the first aspect of the present invention, after resin molding, the shrinkage of the resin can be alleviated and a highly reliable motor can be provided.
[0046]
According to the second aspect of the present invention, the processing of the rotor yoke is facilitated, the gap magnetic flux density is made sinusoidal, and vibration and noise can be reduced.
[0047]
According to the third aspect of the present invention, the magnet can be easily processed, the gap magnetic flux density can be made sinusoidal, and vibration and noise can be reduced.
[0048]
According to invention of Claim 4 of this invention, an air gap can be made small and a highly efficient motor can be provided.
[Brief description of the drawings]
FIG. 1 is a perspective view of a rotor used in the motor of the present invention. FIG. 2 is an exploded perspective view of the rotor used in the motor of the present invention before molding. FIG. A 'sectional view [Fig. 4] BB' sectional view of the rotor used in the motor of the present invention [Fig. 5] C-O-D sectional view of the rotor used in the motor of the present invention [Fig. 6] Fig. 7 is a plan view of a stator used in the motor. Fig. 7 is a diagram showing a punching pattern of the stator core sheet of the stator used in the motor of the present invention. Fig. 8 is a state where the stator core of the stator used in the motor of the present invention is unfolded. FIG. 9 is a plan view of the motor of the present invention. FIG. 10 is a sectional view of another rotor used in the motor of the present invention. FIG. 11 is a sectional view of a conventional rotor.
11 Permanent magnet 12 Rotor yoke 13 Boss 15 Resin 16 Resin shrinkage relief hole 17 Resin shrinkage relief hole 22 Stator core sheet piece 23 Stator core piece

Claims (4)

In the motor having a rotor and a stator, the rotor has a plurality of substantially arc-shaped permanent magnets fixed to the surface of a rotor yoke made of a high magnetic permeability material such as iron by a resin mold, and the outer periphery of the permanent magnet is the rotor rotation center. Is not a perfect circle,
The distance from the rotor rotation center of the outer periphery of the permanent magnet is the maximum near the circumferential center of each permanent magnet, and is small at the circumferential end,
At least the outer side of the circumferential end of the permanent magnet and the axially both ends of the resin, the rotor fixed the permanent magnet to the rotor yoke,
A motor using a rotor, characterized in that a resin shrinkage relief hole or groove is provided between adjacent permanent magnets in both axial ends of the permanent magnet.   The motor according to claim 1, wherein the outer periphery of the rotor yoke has a cylindrical shape centered on the rotor rotation axis, and the thickness of the permanent magnet is non-uniform.   The thickness of the permanent magnet is substantially uniform, the radius of curvature of the outer periphery of the permanent magnet is smaller than the distance from the rotor rotation center to the outer periphery of the permanent magnet, and the outer periphery of the yoke is shaped like a petal according to the inner diameter of the permanent magnet. Item 2. The motor according to Item 1.   The motor according to any one of claims 1 to 3, wherein the periphery of the permanent magnet is not covered with resin on the outer peripheral side of the rotor.

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