JP2008182798A - Magnet rotor and motor equipped it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnet rotor, which reduces its inertia in simple constitution practically without affecting the magnetic circuit of a magnet magnetized askew, and also to provide a motor equipped with it. <P>SOLUTION: This rotor magnet 1 is equipped with: a magnet 12 which is magnetized slantingly so that N poles 12a and S poles 12b appear alternately in its circumferential direction and that they have skew angles θs to its axial direction; a rotor core 10 which is arranged on the inner circumferential side of the magnet 12; and a rotating shaft 11 which is arranged at the center of the rotor core 10. A first hole 10a and a second hole 10b, which extend along the rotating shaft 11, are made each on the side of its one end and the other end of the rotor core 10, and the axis C1-C1 of the first hole 10a and the axis C2-C2 of the second hole 10b do not overlap each other. It has such simple constitution that it has holes on the sides of both end faces of the rotor core 10, thereby achieving the weight reduction and reducing the inertia. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a magnet rotor and a motor including the same, and more particularly to a magnet rotor including a skew magnetized magnet and a motor including the magnet rotor.

2. Description of the Related Art Conventionally, there has been known a technique for improving rotor responsiveness and controllability by reducing rotor inertia to reduce rotor inertia.
For example, a rotor yoke of a brushless motor described in Patent Document 1 has a structure in which a plurality of magnetic rings and a non-magnetic auxiliary ring that is lighter than this are laminated in the axial direction. Thus, by having a lightweight auxiliary ring, the weight of the entire rotor can be reduced, and as a result, the inertia of the rotor can be greatly reduced.

However, the brushless motor of Patent Document 1 has a disadvantage that the effect of reducing the inertia is not so great because the magnetic circuit between the stator and the rotor is affected by the auxiliary ring.
That is, the presence of the auxiliary ring that is a non-magnetic material reduces the magnetic flux density between the stator and the rotor, causing a reduction in torque. Conversely, in order to ensure sufficient torque, it is necessary to increase the thickness of the magnetic ring. However, increasing the thickness of the magnetic ring increases the rotor mass, resulting in an increase in inertia. For this reason, with the brushless motor of Patent Document 1, it is difficult to achieve both the rotational characteristics of the motor and the inertia reduction effect at the same time, and a motor having sufficient rotational torque cannot obtain the expected inertia reduction effect. .

Therefore, as another method for reducing the weight of the rotor without using a non-magnetic material as described above, a technique for reducing the rotor mass by providing a space in the rotor has been developed.
For example, the rotor of a DC brushless motor described in Patent Document 2 has a slot that is a space portion at a portion of the rotor along the extension of the center of each magnet pole. Since the magnetic flux density is low due to the extension of the center of the magnet pole, there is little influence on the rotation characteristics, so removing the unnecessary mass in this part can reduce the mass of the entire rotor with almost no change in the rotation characteristics. It becomes possible. Thereby, the inertia of a rotor can be reduced significantly.

JP-A-5-276697 JP-A-9-275552

Generally, as a method of forming a space portion in a DC brushless motor as in Patent Document 2, a method of manufacturing a rotor by laminating a plurality of sheets in which holes having a shape corresponding to the space portion are formed in advance, and the rotor are integrated. A method of perforating the space after the formation is formed.
When laminating sheets as in the former case, the shape of the space can be complicated by appropriately adjusting the positions of the holes in each sheet.
However, this method requires a caulking space for narrowing the laminated sheets and complicates the structure of the rotor, and thus has a disadvantage that the manufacturing cost is higher than that of an integrated rotor described later.

On the other hand, when the rotor is integrally formed as in the latter case, the space portion is formed by drilling the rotor using a drill or the like, so that the above-described caulking space or the like is not required, and manufacturing is possible at low cost.
However, when the rotor is long, it is difficult to form a space portion penetrating from one end side to the other end side of the rotor because of a problem in processing accuracy. For this reason, it is actually very difficult to reduce the inertia to the maximum by forming a space portion penetrating from one end of the rotor to the other end in the rotor to reduce the entire mass of the rotor.

In particular, a technique for tilting (skewing) a magnet with respect to an output shaft of a rotor in order to reduce cogging torque is known. When the magnet is skewed in this way, the pole of the magnet is disclosed as in Patent Document 2. In order to provide the space on the center, it is necessary to form the space in an oblique direction with respect to the output shaft of the rotor. For this reason, the shape of the space becomes more complicated, and it becomes more difficult to form a space that penetrates from one end of the rotor to the other end.
In addition, since it is necessary to cut the space by tilting the drill diagonally with respect to the rotor output shaft, it is difficult to perform accurate machining, and if the region with high magnetic flux density is cut by mistake, the rotor rotation characteristics There is also a risk of adverse effects.

In view of the above problems, an object of the present invention is to provide a magnet rotor that has a simple structure and reduces inertia while hardly affecting the magnetic circuit of a skew magnetized magnet.
Another object of the present invention is to provide a motor with improved responsiveness and controllability by reducing the inertia of the magnet rotor.

  The problem is that, according to the magnet rotor of the present invention, the magnetic pole changes along the circumferential direction, and the magnet is tilted and magnetized so as to have a predetermined skew angle with respect to the axial direction. A magnet rotor comprising a rotor core disposed on the circumferential side and a rotating shaft disposed at the center of the rotor core, wherein one end side and the other end side of the rotor core extend along the rotating shaft. Are formed, and the holes on the one end side and the holes on the other end side are solved by the positions where the respective central axes do not overlap each other.

As described above, since the holes are formed on one end side and the other end side of the rotor core, it is not necessary to form a hole penetrating from one end side to the other end side along the axial direction of the rotor core. The rotor core can be reduced in weight with a simple configuration having holes, and inertia can be reduced.
Further, since the central axes of the holes do not overlap each other, the holes can be provided by shifting the positions of the central axes of the holes in accordance with the inclination of the magnetic poles. That is, each hole can be formed at a position where the loss of magnetic flux of the magnet is small. Thereby, the fall of the magnetic flux density by forming a hole can be decreased, and the influence on the rotation characteristic of a magnet rotor can be decreased.

  In this case, it is preferable that the center axis of each of the hole on the one end side and the hole on the other end side is substantially parallel to the axis center line of the rotating shaft.

  In this way, since each hole can be drilled in a direction parallel to the axis center line of the rotation shaft, the machining becomes easier as compared with the case of forming the hole by tilting along the skew angle of the magnet, The manufacturing cost of the magnet rotor can be reduced.

  The centers of the one end side hole and the other end side hole are preferably formed at different positions across a bisector that bisects the skew angle.

  The magnetic field formed between the magnetic poles formed on the skew magnetized magnet as a whole across the straight line passing through the center of the magnetic pole and the center of the rotation axis (that is, the bisector that bisects the skew angle). It is symmetrical. For this reason, by forming the hole on the one end side and the hole on the other end side with the bisector, the deviation in the balance of the magnetic field due to the formation of these holes can be reduced. Therefore, the influence on the rotation characteristics of the magnet rotor can be reduced.

In this case, the hole on the one end side and the hole on the other end side are L for the entire length of the rotor core, L1 for the length of the hole on the one end side, L2 for the length of the hole on the other end side, and the skew angle. Θs, the deviation angle of the center of the hole on the one end side from the bisector on the one end side of the rotor core is θ1, and the other end side from the bisector on the other end side of the rotor core When the deviation angle of the center of the hole is θ2,
The following general formulas (1) and (2)
θ1 = (θs / 2) × (1−L1 / L) (1)
θ2 = (θs / 2) × (1−L2 / L) (2)
(Here, L ≧ L1 + L2.)
It is preferable that it is formed at a position satisfying the above.

As described above, based on the total length of the rotor core, the length of the hole on one end side, and the length of the hole on the other end side, the angles θ1 and θ2 can be automatically determined so as to apply to the above formula.
In addition, since the deviation angle from the bisector is determined according to the length of each hole, it is difficult to form a space in a region having a high magnetic flux density, and the balance of the magnetic field can be kept optimal. Therefore, the inertia can be reduced without substantially reducing the rotational characteristics of the magnet rotor.

  Moreover, it is preferable that a plurality of the holes are provided along the radial direction of the rotor core, and the adjacent holes are connected to each other.

  Thus, by connecting adjacent holes, it is possible to further increase the space area inside the rotor core, and to reduce the overall weight of the magnet rotor. Thereby, the inertia of a magnet rotor can be made lower.

  According to the motor of the present invention, the above problem is a motor including a magnet rotor and a stator that rotates the magnet rotor, and the magnet rotor is a magnet rotor according to any one of the above. Is done.

  Thus, the motor according to the present invention includes the magnet rotor with reduced inertia as described above as a rotor, so that the responsiveness and controllability of the magnet rotor can be achieved with a simple configuration with little influence on the rotor rotational characteristics. Can be improved.

According to the magnet rotor of the present invention, it is possible to reduce inertia with a simple configuration in which holes are provided on one end side and the other end side of the rotor core. Further, by not overlapping the central axes of the holes according to the skew angle, it is possible to reduce the magnetic flux loss of the magnet and reduce the influence of the holes on the rotation characteristics of the magnet rotor. Therefore, a magnet rotor having high responsiveness and controllability can be realized with a simple configuration.
Further, according to the motor of the present invention, a motor having high responsiveness and controllability can be realized with a simple configuration by providing a magnet rotor with reduced inertia by a simple configuration as a rotor of the motor. It becomes.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. It should be noted that members, arrangements, and the like described below do not limit the present invention, and it goes without saying that various modifications can be made in accordance with the spirit of the present invention.

1 to 3 are explanatory views of a magnet rotor according to an embodiment of the present invention, FIG. 1 is a front view of the magnet rotor according to the first embodiment, and FIG. 2 is a view of the magnet rotor of FIG. FIG. 3 is a side view showing the magnet rotor of FIG. 1 as viewed from the direction of arrow A. FIG.
FIG. 4 is an exploded perspective view of the motor including the magnet rotor according to the first embodiment.

An embodiment in which the brushless motor of the present invention is applied to a brushless motor of an electric power steering apparatus (EPS) will be described.
FIG. 1 is a side view of the magnet rotor 1, and in order to facilitate understanding of the invention, one of the first hole 10a and the second hole 10b that are formed inside the rotor core 10 and cannot be visually recognized. The part is indicated by a dotted line.
The magnet rotor 1 of the present embodiment includes a cylindrical rotor core 10, a rod-shaped rotating shaft 11, and a ring-shaped magnet 12. The rotor core 10 is disposed on the inner peripheral side of the magnet 12, and the rotation shaft 11 is disposed at the center of the rotor core 10. This magnet rotor 1 constitutes an inner rotor type brushless motor together with a stator 2 described later.

The rotor core 10 is a member made of a soft magnetic material having a small coercive force and a high magnetic permeability. Examples of such soft magnetic materials include iron, silicon steel, and permalloy. In the present embodiment, a laminated core core in which a plurality of disc-shaped iron plates are laminated is used as the rotor core 10.
The shape of the rotor core 10 is not limited to a cylindrical shape, and may be a substantially polygonal shape.

  At the center of the rotor core 10, the rotary shaft 11 is fixed in a state of passing through the axial direction (that is, the longitudinal direction of the rotor core 10). The rotating shaft 11 is an output shaft of the magnet rotor 1 and is configured to rotate by the rotation of the rotor core 10.

A ring-shaped magnet 12 is disposed on the outer peripheral surface of the rotor core 10. The magnet 12 is configured such that the magnetic pole changes along the circumferential direction. That is, a plurality of magnetic poles are continuously formed on the magnet 12 so that different magnetic poles (N pole 12a and S pole 12b) appear alternately.
Each magnetic pole of the magnet 12 is disposed so as to have a predetermined angle with respect to the axial direction of the rotating shaft 11. This angle is referred to as a skew angle θs.

  As a material of the magnet 12, a magnetic material such as a ferrite magnet or a neodymium magnet is used. The magnet 12 of this embodiment forms a magnetic pole by magnetizing a magnetic body with a magnetizing device after previously arranging a magnetic body that is not magnetized on the outer peripheral surface of the rotor core 10. The magnet 12 may be formed by fixing a permanent magnet made of a ferromagnetic material such as ferrite to the outer peripheral surface of the rotor core 10.

The rotor core 10 has a first hole 10a extending in parallel along the rotation axis 11 from one end side (an end side in the direction of arrow A in FIG. 1) and the other end side (an end side in the direction of arrow B in FIG. 1). And a second hole 10 b extending in parallel along the rotation axis 11.
The center axis C1-C1 of the first hole 10a and the center axis C2-C2 of the second hole 10b are both parallel to the axis center line OO of the rotating shaft 11. Further, the central axis C1-C1 of the first hole 10a and the central axis C2-C2 of the second hole 10b are in positions that do not overlap each other.

Next, the position of each hole will be described with reference to FIG.
2 is a side view showing both side surfaces of the rotor core 10 of FIG. 1, (a) is a side view seen from the direction of arrow A in FIG. 1, and (b) is a side view seen from the direction of arrow B in FIG. is there.
As shown in this figure, the magnetic pole center position of the magnetic pole of the magnet 12 on one end side of the rotor core 10 is different from the magnetic pole center position of the magnetic pole on the other end side, and the positions are shifted from each other along the circumferential direction. Yes. As shown in FIG. 3, which will be described later, this shift angle is the skew angle θs.

2A and 2B, each of the first hole 10a and the second hole 10b has a shape in which the shape perpendicular to the axis center line OO of the rotating shaft 11 is circular. is doing.
As shown in FIG. 2A, the first hole 10a on one end side of the rotor core 10 is a straight line (magnetic pole center line Ya) connecting the center of the magnetic pole width Wa of each magnetic pole of the magnet 12 and the axis center O. Formed on top. The center C1 of the first hole 10a is slightly displaced from the magnetic pole center line Ya along the skew direction (counterclockwise direction in FIG. 2).
Further, as shown in FIG. 2B, the second hole 10b on the other end side of the rotor core 10 is a straight line (magnetic pole center) connecting the center of the magnetic pole width Wb of each magnetic pole of the magnet 12 and the axis center O. Formed on line Yb). The center C2 of the second hole 10b is slightly displaced from the magnetic pole center line Yb along the skew direction (clockwise direction in FIG. 2).

Thus, the first hole 10a and the second hole 10b are formed in the region of the rotor core 10 on the magnetic pole center line Ya and the magnetic pole center line Yb.
Usually, the magnetic flux density of the magnet 12 is highest on the extension line of the boundary region between the magnetic poles (N pole 12a and S pole 12b) and lowest on the extension line of the magnetic pole center of each magnetic pole.
The first hole 10a and the second hole 10b of the present embodiment are both formed in regions on the magnetic pole center line Ya and the magnetic pole center line Yb, but this region has a low magnetic flux density as described above. Even if there is a hole in this region, the magnetic circuit is hardly affected. For this reason, it is possible to reduce the weight of the magnet rotor 1 with almost no influence on the rotational characteristics, thereby reducing the inertia of the magnet rotor 1.

In particular, when the magnet 12 is skew-magnetized as in the magnet rotor 1 of the present embodiment, the magnetic pole center position of each magnetic pole differs between the one end side and the other end side of the rotor core 10, which may affect the magnetic circuit. The few positions are also different on one end side and the other end side.
The rotor core 10 of the present invention has two holes, a first hole 10a extending from one end side and a second hole 10b extending from the other end side, and the positions of the holes are optimal positions on the respective end sides. By forming them so as to be offset, inertia can be reduced while minimizing the influence on the magnetic circuit.
Furthermore, since the rotor core 10 has holes formed separately from one end side and the other end side, the holes can be easily formed as compared with the case of forming a hole penetrating from one end side to the other end side. Is possible.

Next, with reference to FIG. 3, the positions of the first hole 10a and the second hole 10b will be described in more detail.
FIG. 3 is a side view in which the side view of (b) is superimposed on the side view of FIG. In this figure, a side view (side view of FIG. 2B) viewed in the direction of arrow B in FIG. 1 is indicated by a broken line.

In this figure, when viewed from one end side of the rotor core 10, when the magnetic pole center line Ya on one end side of the rotor core 10 and the magnetic pole center line Yb on the other end side are superimposed on the same plane, The angle formed is the skew angle θs.
The center C1 of the first hole 10a and the center C2 of the second hole 10b are shifted by θ1 and θ2 in the circumferential direction of the magnet rotor 1 with a bisector X dividing the skew angle θs into two equal parts, respectively. Is provided. These angles are defined as shift angles θ1 and θ2, respectively.
That is, the angle between the straight line connecting the center C1 of the first hole 10a and the axis center O of the rotor core 10 and the bisector X of the skew angle θs is the shift angle θ1. Similarly, the angle formed between the straight line connecting the center C2 of the second hole 10b and the axis center O of the rotor core 10 and the bisector X is the shift angle θ2.

Returning to FIG. 1, the total length along the axial direction of the rotor core 10 is L, the length of the first hole 10 a along the axial direction of the rotor core 10 is L1, and the second along the axial direction of the rotor core 10. When the length of the hole 10b is L2, the shift angles θ1 and θ2 can be expressed by the following equations, respectively.
θ1 = (θs / 2) × (1−L1 / L) (1)
θ2 = (θs / 2) × (1−L2 / L) (2)
(Here, L ≧ L1 + L2.)

  For example, when the total length L of the rotor core 10 is 50 mm, the length L1 of the first hole 10a is 20 mm, the length L2 of the second hole 10b is 25 mm, and the skew angle θs is 10 degrees, the skew angle θs is bisected. The deviation angle θ1 of the center C1 of the first hole 10a with respect to the line X is 3.0 degrees, and the deviation angle θ2 of the center C2 of the second hole 10b is 2.5 degrees.

  By determining the respective shift angles of the center C1 of the first hole 10a and the center C2 of the second hole 10b so as to satisfy the expressions (1) and (2), the first from the bisector X The displacement between the hole 10a and the second hole 10b is totally offset along the axial direction of the rotary shaft 11. Hereinafter, this reason will be described.

Usually, the magnetic field of the magnetic pole constituting the magnet is symmetrical with respect to a straight line passing through the center of the magnetic pole and the axis center of the rotating shaft.
When the magnetic pole is skewed as in the magnet 12 of this example, the magnetic pole center position is different between the one end side and the other end side of the rotor core 10, but the magnetic field formed between the magnetic poles divides the skew angle θs into two equal parts. The entire bisector X is balanced along the axial direction of the rotary shaft 11.
Therefore, by determining the center positions of the first hole 10a and the second hole 10b across the bisector X, the deviation of the magnetic field balance due to the formation of these holes is minimized. Therefore, the influence on the magnetic flux of the skew magnetized magnet 12 can be minimized.

In particular, by determining the shift angles θ1 and θ2 so as to satisfy the above formulas (1) and (2), the distance to the magnetic pole according to the length of each of the first hole 10a and the second hole 10b. Each hole can be formed at an optimum position having the least influence.
That is, when the length of the hole is long, if the center position is too far from the bisector X, a space is formed in the vicinity of the boundary region between adjacent magnetic poles. Since the magnetic flux density is high in the vicinity of the boundary region, a space is formed in this region, so that the influence on the magnetic circuit is increased and the rotational characteristics of the magnet rotor 1 are adversely affected.
Therefore, when the hole length is long, the deviation angle of the hole center from the bisector X is set small, and conversely when the hole length is short, the hole center from the bisector X is set. Set a large deviation angle. Thereby, the magnetic field balance can be optimized according to the length of the hole, and the inertia can be reduced without substantially reducing the rotational characteristics of the magnet rotor 1.

  In FIG. 1, the total length (L1 + L2) of the length L1 of the first hole 10a and the length L2 of the second hole 10b is shorter than the total length L of the rotor core 10 (that is, L> L1 + L2). Shows about. That is, the 1st hole 10a and the 2nd hole 10b are not connected, and the non-space area | region of predetermined length (L-L1-L2) is provided between both. In this way, by providing a non-space region between the first hole 10a and the second hole 10b, the rigidity of the rotor core 10 can be further increased as compared with the case where a through-hole connected to both is provided. Can do.

  At this time, the length L1 of the first hole 10a and the length L2 of the second hole 10b are preferably equal (that is, L1 = L2). By doing in this way, since the weight balance and the magnetic field balance are balanced on the both end surfaces in the axial direction of the magnet rotor 1, the rotational characteristics of the magnet rotor 1 are stabilized.

In addition, the 1st hole 10a and the 2nd hole 10b may connect, without providing the non-space area | region mentioned above. That is, the total length (L1 + L2) of the length L1 of the first hole 10a and the length L2 of the second hole 10b may be the same as the total length L of the rotor core 10 (that is, L = L1 + L2).
By doing in this way, the length of the 1st hole 10a and the 2nd hole 10b becomes the maximum, respectively, and the volume of the space part in the rotor core 10 can be maximized. Thereby, the weight of the rotor core 10 can be reduced to the maximum and the inertia can be minimized.

Next, a method for manufacturing the magnet rotor 1 will be described.
First, the rotor core 10 is manufactured by laminating a plurality of disk-shaped iron plates and integrally forming them. Next, the magnetic body before magnetization is disposed on the entire outer peripheral surface of the rotor core 10. Subsequently, the magnetic body is magnetized so as to form a predetermined skew angle θs by using a magnetizing device, thereby forming the N pole 12a and the S pole 12b.

Subsequently, on one end side of the rotor core 10, the center position of the first hole 10a is determined by shifting from the bisector X of the skew angle θs by a predetermined angle θ1, and the axial direction of the rotary shaft 11 is determined using a drill or the like. Perforate in parallel. Similarly, on the other end side of the rotor core 10, the center position of the second hole 10b is determined by shifting from the bisector X of the skew angle θs by a predetermined angle θ2, and the axis of the rotary shaft 11 is determined using a drill or the like. Drill in parallel to the direction.
The manufacture of the magnet rotor 1 is completed through the above steps.

As described above, the magnet rotor 1 of the present invention can be used as a rotor of a DC brushless motor. Hereinafter, the motor 3 of the present invention will be described with reference to FIG.
FIG. 4 is a diagram for explaining an example in which the magnet rotor 1 is applied to the rotor of the motor 3, and is an exploded perspective view showing members constituting the motor 3 in an exploded manner.

  As shown in this figure, the motor 3 includes a magnet rotor 1 and a stator 2 as main components. Among these, since the magnet rotor 1 has the configuration as described above, detailed description thereof is omitted here.

  The stator 2 includes a stator core 21 and a winding 22 wound around the stator core 21. The stator core 21 includes a substantially cylindrical outer core 23 that forms an outer peripheral portion, and teeth 24 that protrude from the inner peripheral surface of the outer core 23 radially inward with a predetermined interval. Winding 22 is housed in the space between adjacent protrusions of teeth 24.

As a method of manufacturing the motor 3, first, the magnet 12 disposed on the outer periphery of the rotor core 10 is skew-magnetized to form a magnetic pole. Subsequently, a first hole 10a is formed from one end side of the rotor core 10, and a second hole 10b is formed from the other end side. Since this drilling step is the same as the method for manufacturing the magnet rotor 1 described above, detailed description thereof is omitted here. Further, the stator 2 is manufactured by accommodating the winding 22 in the space between the teeth 24.
And the magnet rotor 1 is arrange | positioned in the internal space of the stator 2, and the annular stator 2 and the magnet 12 of the magnet rotor 1 are made into the state which opposes the radial direction through a slight air gap. Next, the stator 2 and the magnet rotor 1 are accommodated in a bottomed cylindrical housing (not shown), and the opening of the housing is closed with an end plate, whereby the assembly of the motor 3 is completed.

Next, a magnet rotor according to another embodiment of the present invention will be described.
5 and 6 are explanatory views of a magnet rotor according to another embodiment of the present invention, FIG. 5 is a front view of the magnet rotor according to the second embodiment, and FIG. 6 is an arrow A indicating the magnet rotor of FIG. It is a side view which shows the state seen from the direction and arrow B direction.

  As shown in FIG. 5, the magnet rotor 31 of the present embodiment includes a rotor core 40, a rotating shaft 41, and a magnet 42 as main components. The magnets 42 are continuously arranged so that N-pole 42a and S-pole 42b magnets appear alternately. Since these members are the same as those in the first embodiment, detailed description thereof is omitted here.

The rotor core 40 is formed with a first connection hole 40 a extending from one end side and a second connection hole 40 b extending from the other end side in parallel with the axial direction of the rotary shaft 41. These connecting holes will be described with reference to FIG.
6 is a side view showing both end portions of the rotor core 40 in FIG. 5, (a) is a side view seen from the direction of arrow A in FIG. 5, and (b) is a side view seen from the direction of arrow B in FIG. 5. It is. As shown in this figure, each of the first connecting hole 40a and the second connecting hole 40b includes a region where a cylindrical circular hole similar to that of the first embodiment is formed, and adjacent circular holes. And a connected annular region. An annular space connecting the circular holes is formed on the axis center O side of the rotor core 40. This region is on the extended line of the boundary region between adjacent magnetic poles of the magnet 42, but the magnetic flux density is not so high because it is away from the magnet 42. Even if a space is provided in this region, the magnet rotor 31 Almost no influence on the rotation characteristics.

  Further, by connecting the circular holes in an annular shape in this way, it is possible to increase the space area and further reduce the weight of the magnet rotor 31 as compared with the first embodiment. The inertia of 31 can be further reduced.

  The rotor core 40 is formed by forging in a form in which a second connection hole 40b which is an annular hole is provided in advance. Then, the 1st connection hole 40a is formed by cutting a some circular hole using the drill along the 2nd connection hole 40b which is a ring.

  In each of the above embodiments, one hole is formed in each magnet (in the second embodiment, a circular hole), but it is not necessary to be formed in all of the magnets in this way, and only in a part. It may be formed. For example, holes may be formed corresponding to only the N pole or only the S pole of the magnet. In this case, it is preferable to form it at a symmetrical position with respect to the axis center of the rotor core since the weight balance of the entire magnet rotor is balanced.

  Further, in each of the above embodiments, any hole is formed as a space hole in which nothing is filled, but the inside of the hole may be filled with a resin having a specific gravity smaller than that of the material of the rotor core. In this way, it is possible to reduce the weight of the magnet rotor and improve the rigidity of the rotor.

Furthermore, in the second embodiment, the annular second connecting hole 40b is formed in advance by forging, and then the first connecting hole 40a is formed. However, the second connecting hole 40b is formed by the method shown in the following steps. May be.
In order to form the first connecting hole 40a, first, a plurality of circular holes are formed in a direction parallel to the axial direction of the rotor core 40 using a drill or the like. Next, the diameter of the drill is changed to a smaller one, and the drill is inserted into one of the circular holes by approaching the axial center O side of the circular hole, and the drill is moved in an annular shape around the axial center O. Then, the rotor core 40 is cut and the adjacent circular holes are connected. Thereby, an annular region is formed.
The first connection hole 40a is formed through the above steps. The second connection hole 40b can also be formed by the same process.

It is a front view of the magnet rotor which concerns on 1st Embodiment. It is a side view which shows the state which looked at the magnet rotor of FIG. 1 from the arrow A direction and the arrow B direction. It is a side view which shows the state which looked at the magnet rotor of FIG. 1 from the arrow A direction. It is a disassembled perspective view of the motor provided with the magnet rotor which concerns on 1st Embodiment. It is a front view of the magnet rotor which concerns on 2nd Embodiment. It is a side view which shows the state which looked at the magnet rotor of FIG. 5 from the arrow A direction and the arrow B direction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Magnet rotor, 2 ... Stator, 3 ... Motor, 10 ... Rotor core, 10a ... 1st hole, 10b ... 2nd hole, 11 ... Rotating shaft, 12 ... Magnet, 12a ... Magnet (N pole), 12b ... Magnet (S pole), 21 ... stator core, 22 ... winding, 23 ... outer core, 24 ... teeth, 31 ... magnet rotor, 40 ... rotor core, 40a ... first connecting hole, 40b ... second connecting hole, 41 Rotating shaft, 42 Magnet, 42a N pole (magnetic pole), 42b S pole (magnetic pole), L Total length of rotor core, L1 Length of first hole, L2 Length of second hole, C1... Center of the first hole, C2... Center of the second hole, O... Center axis of the rotation axis, C1-C1... Center axis of the first hole, C2-C2. OO: Axis center line of rotation axis, X ... Bisect of skew angle Ya ‥ magnetic pole center line, Yb ‥ magnetic pole center line, Wa ‥ pole width, Wb ‥ pole width, [theta] s ‥ skew angle, θ1, θ2 ‥ deviation angle

Claims (6)

A magnet that is magnetized so that the magnetic pole changes along the circumferential direction and has a predetermined skew angle with respect to the axial direction;
A rotor core disposed on the inner peripheral side of the magnet;
A magnet rotor having a rotation shaft disposed at the center of the rotor core,
On one end side and the other end side of the rotor core, holes extending along the rotation axis are formed, respectively.
The magnet rotor according to claim 1, wherein the hole on the one end side and the hole on the other end side are positioned so that their central axes do not overlap each other.   2. The magnet rotor according to claim 1, wherein the center axis of each of the hole on the one end side and the hole on the other end side is substantially parallel to the axis center line of the rotating shaft.   The center of each of the hole on the one end side and the hole on the other end side is formed at different positions across a bisector that bisects the skew angle. Magnet rotor. The hole on the one end side and the hole on the other end side are:
L is the total length of the rotor core.
The length of the hole on the one end side is L1,
The length of the hole on the other end side is L2,
The skew angle is θs,
A deviation angle of the center of the hole on the one end side from the bisector on the one end side of the rotor core is θ1,
When the deviation angle of the center of the hole on the other end side from the bisector on the other end side of the rotor core is θ2,
The following general formulas (1) and (2)
θ1 = (θs / 2) × (1−L1 / L) (1)
θ2 = (θs / 2) × (1−L2 / L) (2)
(Here, L ≧ L1 + L2.)
The magnet rotor according to claim 3, wherein the magnet rotor is formed at a position satisfying the above.   The magnet rotor according to claim 1, wherein a plurality of the holes are provided along a circumferential direction of the rotor core, and the adjacent holes are connected to each other.   A motor comprising a magnet rotor and a stator for rotating the magnet rotor, wherein the magnet rotor is the magnet rotor according to any one of claims 1 to 5.

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